Alberto Lago | ICD | Master Thesis

ADAPTIVE WOOD PLATES I T E C H MA S T E R T H E S I S

P ER FO R M ATIV E WO O D TR AC K B 2014-2015 A LB ER TO LA GO M AT R IC UL A N UM B E R 2 90 90 64 U N IV E R S IT Y O F S TU T TGAR T I NSTI TUTE O F C O M P UTATIO N AL D ES IGN P R O F . A. M EN GE S T UTOR S: DAV ID C O R R EA, DY L AN WO O D

ADAPTIVE WOOD PLATES H YG R OS CO P I C r e sp on s i v e ELEM E N TS IN ARCHIT ECT URAL P LAT E S YS TE M S

M A STE R TH E S I S I TE CH

ADAPTIVE

WOOD

PLATES

HYGROSCOPIC rESPONSIVE ELEMENTS IN ARCHITECTURAL PLATE SYSTEMS

PERFORMA TIV E WOOD TRA CK B SUMMER SEMEST ER 2014-2015 ALBE RTO L A GO MA T RICUL A N UMBER 29 09 06 4 UN IV ERSIT Y OF STUT TGA RT IN STITUT E OF COMPUTA TION A L D ESIGN PROF. A . MEN GES T UTORS: DA V ID CORREA , DYL A N WOOD

OCTOBER 2015

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BRIEF The project uses the anisotropic responsive properties of wood, as a driving factor in plate systems for architecture. The interaction between elastic and hygroscopic material behavior can lead to the development of a climatic responsive wood plate system that can be programed to deform in response to changes in environmental humidity levels. This is achieved with a combination of non-responsive rigid and flexible parts (plywood base), with integrated responsive wood elements (maple actuators). Digital form finding, computational fabrication methods and material selection define the system performance. In this context, the designer can gain additional control over the design space: modifying the geometrical outcome as a function of the responsive actuators location. The result is a series of full-scale self-forming building elements that demonstrate a range of possible architectural application.

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INSIGHT Several biological organisms existing in nature are constituted of plate structural systems (e.g. sand dollar, sea urchin, etc.). These are usually composed of harder (i.e. stiffer) plates and softer (i.e. flexible) tissues to allow the system to evolve and growth based on external forces and interior constraints.

These biological features can be expanded to an architectural system with similar plate configuration. Indeed, harder and softer parts, achieved varying the wood layering thicknesses, could lead to different plate configurations based on their intrinsic differential elastic behavior. Moreover, the utilization of wood hygroscopic actuators can be the driven factor for the achievement of an adaptive morphological space.

Distribution of flexible and rigid components, as main factors for a morphological and responsive system research, can lead to wooden structures that can find their shape “naturally� with the insertion of actuators that can enforce the system to achieve its natural shape.

This affinity leads to the possible development of responsive structures. The advantages of having a system like this rely on its adaptability to the various external and internal circumstances. Indeed, the outcome is not chained to a particular geometrical configuration or specific environmental constraints.

The architectural geometry is not anymore a constraint, leading to the exploration of the system more from a material behavior point of view. The outcomes of this research could lead to a different approach for the design of wooden plate structures. This will lead to new possibilities in the architectural field creating a synergy between different systems (e.g. wood systems and material layouts) and intrinsic actuators (e.g. different wood thickness will lead to different hygroscopic behavior).

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HOW

TO USE THE DOCUMENT TAGS

Chapter Indicators

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Main Section Indicator

Sub Section Indicator

Tools Indicators

Angle Indicator 4 . 5째

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I NDEX HIGHLIGHTS

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AIM

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CONTEXT

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STATE OF THE ART

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METHODS

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DESIGN RESEARCH DEVELOPMENT

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DESIGN RESEARCH PROPOSAL

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DISCUSSION

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OUTLOOK

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ACKNOWLEDGMENTS

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REFERENCE

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LIST OF FIGURES

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A DA P T I V E WO O D P L A T E S

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CONTEXT

STATE OF THE ART

METHODS RESEARCH TOOL FABRICATION Saw Blade

6-axes Robot Arm KUKA KR 2-125 ELASTIC WOOD PROPERTIES HYGROSCOPIC WOOD PROPERTIES

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HYGROSCOPIC WOOD PROPERTIES AIR VENTILATOR

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ADAPTIVE WOOD PLATES

L AG O , 2 0 1 5

The thesis research scope is explained and described in detail. The main aspects of the project are reviewed and the importance and contributions to the performative wood field are defined.

Several build project has contribute to define the scope of this research. In this section the most important ones are considered with particular focus on the contributions that are important for the development of this specific project.

ICD, 2014

The current state of the art on performative wood for what regards rigid plates and hygroscopic actuators. This is important, in order to understand what has been already done and what are the contributions that this research would lead to this field.

ULTRASONIC HUMIDIFIER

HUMIDITY CHAMBER

MATERIAL

MECHANICAL TEst SET-UP

DRYING OVEN

L A GO, 2015

Different methods and tools have been developed, both in terms of physical and computational aspects. All of them are reviewed in this chapter.

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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HIGHLIGHTS

DESIGN RESEARCH DEVELOPMENT

DESIGN RESEARCH PROPOSAL

L A GO, 2 0 1 5

LAG O, 20 15

The conducted research have been an escalation of different areas of investigations. Starting form the basic concept to the most developed ideas, each individual experimental investigation is described in detail.

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The experimental research outcomes have lead to the development of a prototype showcase that could lead to the development of a new morphological solution in the performative wood area of research. The particular aspects of the proposal are explained with particular reference to the techniques utilized for computationally and physically developing the architectural system.

DISCUSSION

OUTLOOK

L A GO, 2015

L A GO, 2015

The major outcomes of the research development and proposal are discussed.

A critical review of the most important aspect has been carried out in detail.

The develop research is just the first step towards the development of a complete system that can be utilized as a part of a more global building system. Several, open question will be addressed to understand what are the objectives to be complete as part of the future research.

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Algo Umbrellas. Lalvani, 2003

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Buildings would grow, respond, adapt and recycle, they would self-assemble and self-organize, they would remember and be self-aware, they would evolve, and they would reproduce and die.

Lalvani, 2003

’’ PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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AIM

B uildings as living organisms has been the manifesto of the architecture history in the last decades.

Prior to the first industrial revolution, the construction techniques and materials were related with the local availability and climatic conditions. “Generally, this meant that the environment was little impacted from the construction activities, and there was a distinct diversity in international architecture designs, since each had particular unique regional features: for instance, bamboo houses in Cambodia, turf roof houses in Iceland, and adobe houses in Mexico.” (Sonal, 2011) “This vernacular forms differed from locale to locale in a similar way that plants and animals differ from biome to biome” (Berkebile, McLean, 2004).

The introduction of new machineries and the development of new materials, during and after the industrial revolution, lead to a shift in the building construction inspiration, that was not anymore in symbiosis with the surrounding environment, but it was more an external entity that was not fitting anymore in the context. This is reason why buildings start to look alike the same in different areas of the world, losing their national and traditional identities. This concept could be well described by Le Corbusier famouse quote: “houses were machines for living in” (Corbusier, 1923).

“One of the most important difference between our living and the nature is the production of waste as intended by the human being. Indeed, only mankind creates things useless to all other forms of life.

In a ecological waste treatment system, the effluents moved by gravity from tank to tank, each forming a complete and increasingly complex ecosystem, where it is attacked and consumed by microorganisms” (Berkebile, McLean, 2004). Futhermore, one of the major carbon footprint contributor is building usage and through a more optimal climate and resources usage control this can be reduce drastically (Stein, 1977).

Looking at this reality, there is the feeling to find again the old link with the surrounding environment. Indeed, while using modern technologies to enhance the wealthiness state, it is important to discover new route for developing technologies. One of the most prominent one is to look at biomimetic (Berkebile, McLennan, 2004). Indeed, this could be a better way to find more optimal solutions, not only useful for the building industry. However, architecture can use this as a beneficial tool, that could create a new expression in the way we conceive buildings and how they are operated.

According to these principles the term of “living

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building” (Berkebile, McLean, 2004) can be introduced, and among all the different features, the most important will be: | “Harvest all its own water and energy needs on site. | Be adapted specifically to site, and climate and built primarily will local materials. | Operate pollution free and generate no wastes that aren’t useful for some other process in the building or immediate environment. | Promote the health and well being of all inhabitants–consistent with being an ecosystem. | Be comprised of integrated systems that maximize efficiency and comfort. | Be beautiful and inspire us to dream.”

(Berkebile, McLean, 2004) The architectural system will be not, anymore a static entity. Indeed, as Lalvani (2003) says: “buildings would grow, respond, adapt and recycle, they would self-assemble and self-organize, they would remember and be self-aware, they would evolve, and they would reproduce and die.” This is an important new concept in the architectural philosophy since builders and architects need to understand the present and the evolution of buildings. Allowing these changes human being will benefit from an augmented spatial system that will evolve with the user needs.

The natural inspiration as a driven factor for new architectural morphologies has been the leading aspect to the development of this research project on the realm of performative wood.

As a basic factor several biological organisms existing in nature have been taken as a source of inspiration. In particular, those ones that are based on plate structural systems (e.g. sand dollar, sea urchin, etc.). These categories are more fascinating that others especially for the application of wood structural plate systems. Indeed, these organisms are usually composed of harder (i.e. stiffer) and softer (i.e. flexible) parts to allow the system to evolve and growth based on the external forces and interior constraints. These biological features can be expanded to an architectural system with similar plate configuration. Indeed, harder and softer parts, achieved varying the wood layering thicknesses, could lead to different plate configurations based on their intrinsic differential elastic behavior.

Moreover, wood hygroscopic actuators can be the driven factor for the achievement of an adaptive morphological space.

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WHY Distribution of flexible and rigid components, as part of a morphological and responsive system research, can lead to wooden structures that can find their shape “naturally” with the integration of actuators that can enforce the system to achieve its natural shape.

The aim is to design a material fabrication (assembly) process that through its intrinsic material properties can inform many formal variations and complex geometries. The outcome will be a design method and a material language that can interact and impact the global surface morphology.

The utilization of a standard material like plywood will allow inserting the project in the context of wooden structural system. Therefore, while maintaining similar spatial quality of standard wood projects, this new structural system will enhance the material possibility and permit to achieve a new definition in the possible geometrical solutions.

Therefore, the goal is to develop a “smarter” surface and a fabrication technique to enhance and promote the utilization of this system for architectural applications.

Creating of a homogeneous surface with the possibility of having geometrical variations that can be both static and dynamic, depending on the type of interlocking devices utilized. This construction system will allow reducing the construction and materi-

al limits (i.e. wood material properties) for creating adaptable architectural surfaces.

Natural materials are utilized to create a more organic and common ground space. Different species of the same material (wood) are utilized to create a logical system between different material programmable behaviors. The different parts of the surface are used for different logic. The more flexible parts with the actuator allow the system to gain its geometrical form. While the more rigid ones give greater stability and create a more variegate geometrical solution.

The idea is to create a more intelligent system that can utilized simple material principles to obtain complex geometrical forms. A homogeneous correlation between passive and active systems that work together to create a harmonious architectural space. Structure and skin coexist at the same level and all the different elements work together.

Moreover, the developed fabrication and design process is independent and not project specific, since standards fabrication techniques are utilized without requiring specialized skills. This leads to infinite possible variations of the geometry that can be achieved while utilizing the same technique, logic, material and fabrication processes.

ADAPTIVE wood PLATES: ELASTIC and anisotropic MATERIAL PROPERTIES AS A DRIVEN ARCHITECTURAL FACTOR.

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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AIM

ELASTIC WOOD PROPERTIES HYGROSCOPIC WOOD PROPERTIES

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MORPHOLOGICAL RESPONSIVE SPACE

ADAPTIVE WOOD PLATES

Adaptive wood plates | Aim diagram. Lago, 2015

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WHY THIS SOLUTION IS IMPORTANT The alternation of rigid and flexible parts will allow to create a greater variability in the possible geometrical forms that could be achieved. Moreover, the possibility to add cuts at selected location will expand the material limits and constraints. Indeed, while looking at the digital surface there is always the constraint of the material properties to be manipulated and stretched. Building from these principals to make the system, allowing for the creation of a morphological exploratory surface.

The addition of the actuators lead to a dynamic system that can respond automatically to different human and environmental inputs providing a pre-informed output that can be changed through human\environment interaction.

The concept is to seamlessly link form, structural and material responsiveness while informing global morphology both from a geometrical and material behavior point of view. Correlation between embedded material physical properties (flexible and hygroscopic wood properties) and geometrical manipulation of the system. The result of these explorations is the possibility to use known material properties in a not standard way, leading to the

exploration of new geometrical possibilities while testing an enhance fabrication and construction techniques.

The idea is to develop an hybrid system that is based on three different exploration levels: | Study on the geometrical possibility of a standard plywood sheet with an alternation of flexible and rigid parts with the possible integration of cuts for allowing to go beyond single curvature surfaces. | Exploration on the deformation capacities with the utilization of a natural induced activation mechanism that serves also as an interlocking system to maintain the morphological characteristics of the system. | Possibility to create a dynamic or static system depending on the interlocking mechanism properties. This will allow differentiating between static and dynamic portion on the same surface system.

Along with the material behavior characterization the human impact is important. The user can interact with the geometrical space and define it.

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CONSTRUCTION noT OF FORMS BUT OF STRUCTURES, THAT MEANS OF SYSTEMS OF ENDLESS TRANSFORMATIONS, CONNOTED BY FLEXIBILITY And the ability to self-managed, just like the language we all speak, in accordance with social-cultural dynamics and the environment.

Leonardo Mosso | Interview. Hermann and Lago, 2015

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PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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AIM

WHY WOOD AS PASSIVE ELEMENT Wood is a natural material, on contrary to plastic or metal sheets. This will create a more synergistic connection between the actuators and the main non-responsive system. Moreover, the local available fabrication and construction techniques make wood a more optimal material solution.

Local aspect: availability of wood and plywood rather than plastic/metal material allow the possibility to utilized the proposed architectural system in other areas of the world without restrictions.

Moreover this becomes a more ecological solution.

Architectural appearance: having wood as base for the passive system will generate a more uniform system and a continuous surface; while, for example, having plastic and wood will produce a more architectural discontinuous system.

Contrary to other materials (like plastic, carbon fibers, etc.), wood provides ease of connection and possible expansion of the system between single surface to make the system expandable. For example it would be easy to connect different plate system with simple finger joint or glued connection.

Intrinsic behavior: several material have been taken into consideration in this research project and all of them have pros and cons that can be summarized as described in the following.

Plastic: | pros: material flexibility, elastic/plastic deformation, homogeneous properties. | cons: heat can deform the material, expensive, lamination possible but difficult, petrol based product.

Carbon Fiber: | pros: strength | cons: not flexible, not ease of production, costs and availability Wood: | pros: material flexibility, elastic/plastic deformations, naturally available, possibility of easy lamination to create a custom material behavior properties, non-uniform properties | cons: grain cuts.

Several tests have been made comparing mainly plastic and wood, and one of the results are shown below (more detailed explanations of the results and test conducted will be given in the design development chapter). The experiments illustrated below show the behavior of the actuated plate system achieved when the actuator goes from the minimum to the maximum (design) equivalent moisture content (EMC). The minimum and maximum (design) EMC is achieved having equalized the wood EMC first with the atmosphere relative humidity at 10% (that is almost equivalent to the lowest EMC value) and at 90% (that is almost equivalent to the highest EMC value).

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PLYWO OD

Rigid plate comparison: plywood and plastic. Lago, 2015

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CONTEXT CO

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he developed research project resides in a specific trend of the architectural realm that is related with structural wood system. In this area, several experimental projects have been fabricated in the last years and among all the most important for this study are reviewed with specific focus on the aspects that are relevant for the subsequent discussion.

KERF PAVILION. MIT, 2012

The outcome pavilion is a novel digital fabrication techniques that resemble an old technique of cutting wood to increase material flexibility: kerfing.

“The conducted research is a combination of the kerfing material logic with the flexibility of parametric modeling and the accuracy of a CNC router.

The parametric model integrates all the digital steps of the modeling and fabrication processes, from initial control over the global form to the unrolling and generation of the cut patterns required to make each unit. The patterns allow the plywood to be bent into a predictable shape without the use of

external tools mechanical fasteners.

The geometrical shape of the pavilion is coming from a study of a conical shape and how the structural integrity of the system is enhanced (e.g. buckling) when cones are packed (MIT, 2012). Moreover, material efficiency was integrated (e.g. size and wood grains) in the system that lead on the differentiation between kerfed and straight sections. The final geometry utilized was a shape that could be packed in the same manner as the cones, to form an even more structurally secure canopy scheme” (MIT, 2012).

CARBON CURVE PAVILION. AA EMTECH, 2013

“The pavilion design concept was based on a tube surface that could serve as a roof, wall and floor.

The basic idea behind the design concept was the utilization of the hierarchical distribution of structures and assemblies similar to what included in natural systems” (AA EMTECH, 2013). In the case of a continuous organism the fiber density variations are optimized based on the different strength criteria that the body need to sustain during his life.

These aspects lead to new architectural strategies thanks to the utilization of physical and digital computational analysis tools.

Wood was used as the main structural material that has been reinforced by carbon fiber strips to resist tensions forces and to hold it in shape. Perforation of plywood was utilized as leading factor to achieve the design shape. “This is achieved through patten density and directionality variations based on the principal and mean curvatures of the global surface. The variation would lead in stiffness variations within the surface allowing the plywood to take different curvature through bending. An algorithm was developed to generate the cutting pattern that was then fed in a CNC machine. The algorithm starts from the edge of highest curvature, where a sphere based on the curvature is drawn.

A new point is defined at the intersection between the circle and the edge curve. This recursive algorithm was repeated through the edge, resulting in a number of points of the density gradient based on the curvature. The subsequent step in the algorithm is the generation of the lines in the other direction using the points evaluated in the previous step. To create the density variation, the lines are divided into a specific number of analysis points, which lead to a grid of points on the surface. By remapping the points generated on the previous step, based on the mean curvature, the grid become denser in areas of higher curvature and less dense in flat regions” (AA EMTECH, 2013).

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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CONTEXT

Kerf Pavilion. MIT, 2012 Carbone Curve Pavilion. AA EMTECH, 2013

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Expandable Surface Pavillion. Zamorano, MartĂŹ and Bek, 2011 Hygroskin: Metereosensitive Pavilion. ICD, 2013

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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CONTEXT

EXPANDABLE SURFACE PAVILION. ZAMORANO, MARTI’, BEK, 2011

The designed pavilion was installed at the design exhibition in Cologne. The project was carried out at the Emergent Technologies and design at the Architectural Association in London.

“The Expandable Surface System looks to integrate all elements into a one-structure system (facade and shading) while developing a sustainable mode of fabrication. In order to achieve this out of a flat sheet material, the system will need to utilize double curvature. For this reason, a non-homogeneous cut pattern was required to allow for vertical resistance, while allowing for rotation and/or bending to permit a reasonable horizontal span for creating an inhabitable space.

A system of mathematical relationships were derived to control the material properties digitally.

This iterative process was then scrutinized and revised by the results from the structural analysis.

The construction process was also very important in order to achieve a system with minimal waste and deployability. The systems where interlocked though a series of joints and bolt connection to snap the cut into shape” (Zamorano, Martì, Bek, 2011).

HYGROSKIN METEREOSENSITIVE PAVILION. ICD, 2013

Differently from the previous three discussed project this pavilion explores a novel mode of climate-responsive architecture. “This is achieved not through classical approaches (such as external energy inputs) but through the responsive capacity of the material itself (i.e. wood). The climate response of the material allows to create an adaptive skin that opens and closes in response to weather changes.“ (ICD, 2013) In this case, “the material structure itself is the machine” (ICD, 2013). The pavilion itself is composed of concave conical surface created from utilizing the material elastic behavior together with a robotically fabricated approach.

“The responsive system is created with a wood-composite material that reacts based on the changes in the relative humidity levels. The range of motion is between 30% to 90% that simulate the range between sunny and rainy days. This will allow a dynamic change in the opening area of the pavilion creating a continuous fluctuation in the perception of the interior space” (ICD, 2013). The principles basics are coming from the natural movement of spruce cones that is a composed by a two layer system that has a stable inner layer and a reactive outer layer composed of parallel, long and densely

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packed thick-walled cells (Reichert et al., 2014).

The differential strain between the two layers dictate the change in shape of the material. “To achieve the same behavior a simple quarter-cut maple veneer was utilized as per the outer layer. The inner layer is instead composed of fiber glass. The natural process of the cone is reversible as well as the created composite veneer system“ (ICD, 2013).

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the material structure itself is the machine

ICD, 2003

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ICD/ITKE RESEARCH PAVILION 2010.

ICD, 2010

The scope of this pavilion was on the potential of the material to act as a main active element. The result is a system composed of plywood strips that are elastically-bent and interlocked into shape between each other. This lead to a so-called “bending-active structural system. The forces induced by the bending of the elements define the physical form.” (ICD, 2010).

The novel approach of this project is the alternative computation design approach utilized. Indeed, while in classical theory forces and form are threated separately, in this new approach the form generation is directly driven from the physical behavior and material characteristics.

Each strip is fabricated straight and bend into shape to interlock with adjacent strips. This creates a variegate geometrical form of bend and straight (tension regions) parts. The developed solution allows to greatly increase the structural capacity of the system. In order to avoid local points of concentrated bending moments the connection points location is variated along the structure.

ICD/ITKE RESEARCH PAVILION 2011.

ICD, 2011

The second ICD/ITKE pavilion explores more in detail the architectural transfer of biological principles. The raw model is the sea urchin’s plate skeleton morphology. Through the help of computational design methods and robotic fabrication the extension of the biological principals have been possible. This is obvious looking at the morphological complexity of the pavilion built with a very thin plywood material (6.5 mm).

“The biological model lead to development of the modular system of the shell and also to the connection system based on a classical finger-joints system. Based on these principles, the conceived design lead to have three plate edges always meet at one point, which allows to transmit only shear and normal forces but not bending moments. Moreover, unlike traditional load optimized shapes, this system can be applied to a wide range of geometrical forms.

Other important aspects that were address in the pavilion are the: heterogeneity of the modular system to adapt to the curvature and the local variabilities. Anisotropy of the structural system since the cell stretch and orient based on the mechanical stresses. Hierarchy of the shell system that is built up in two-levels: a finger joint connection between plywood sheets and a screw connection in between

the cell units.

The achievement of all these innovative solutions would be not possible without the integration between an efficient computational work flow and a detailed robotic fabrication protocol” (ICD, 2011).

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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CONTEXT

ICD/ITKE Research Pavilion 2010. ICD, 2010 ICD/ITKE Research Pavilion 2011. ICD, 2011

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STATE OF THE ART SA

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A DA P T I V E WO O D P L A T E S

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urrent available projects, in the context of the outlined scope of this project, lie in between two main areas of research: | Localized flexible wood. | Hygroscopic activation mechanism.

Indeed, up to today both aspect where taken into consideration separately as can be seen from the projects shown in the following pages, as well as

those ones shown in the proposed context. Therefore, the scope of this research project would like to integrate both aspects in a unique controlled architectural system. Indeed, differently from classical segmented shell this research project look to a more coherent system.

In the following, several projects have been reviewed that lie on the scope of work of the current project.

WOOD SKIN.

MESOSTRUCTURES.

MAMMA FOTOGRAMMA, 2013|

BASTIAN, 2014|

Wood skin is a composite system that was developed based on a digital design process to allow rigid material (like wood) to enrich tridimensional spaces. The product consist of a composite system with two layers of wood with enclosed a flexible textile layer.

“The defined solution allows to develop structures that are not traditionally possible with standard wood solutions. Moreover, the system can adapt to existing geometrical constraints or create a new self-supporting volumetric space” (Mamma Fotogramma, 2013).

This project explores the capacity of the material itself to deformed based on its shape more than its mechanical properties. In particular, the author looks a the possibility of 3D printing to solve this problem. To increase deformations, it is necessary to increase the deformation capacity of the printed structure’s. Indeed, the deformation of a mesh is related to the deformation of the connection between nodes and the angular deflections about nodes. “This is why hexagonal meshes (as well as triangular and quadrilateral) are very stiff” (Bastian, 2014).

From the derived research the geometrical mesh developed is shown on the figure in the next page.

The mesh behave like a synclastic material, i.e. it can assumes compound curvature (bending in two orthogonal directions). “This is the opposite of the most common material utilized today that are anticlastic (i.e. metal, paper, fabric)“ (Bastian, 2014).

SPHIROHEDRON.

KERF BASED COMPLEX WOOD SYSTEMS.

JACKSON. BURGESS, 2014|

The sphirohedron project is based on the work conducted at the University of Westmister. The work consist in the exploration of the folding of a single sheet of material through the utilization of lattice hinge along predefined paths. The figures on the next page show how the system is able to fold along the predefined paths but the tension and compression forces along them, as well as along the joint, lead to some instability.

CRANE, MCGEE, PRADO, ZHAO, MENGES, 2010|

The scope of the project carried out at Harvard GSD is to develop an “integrated computational design tool and robotic manufacturing process that allows programming the bending and twisting behavior of tensioned wood elements through specific kerf patterns and steaming techniques.

The system tries to understand the wood’s anisotropic characteristics through removal of material perpendicular to the main grain direction without overly compromising the overall structural capacity. Through computer controlled fabrication the kerf variation allows to achieve more elaborate bending and warping forms.

The design solution comprises wooden slots with variable kerf depth due to enhance the stress distribution. This allows to achieve a system geometry with negative Gaussian geometry once an assembly of multiple kerfed elements is pre-stressed” (Crane, McGee, Prado, Zhao, Menges, 2010).

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

WO O D S K I N / M A M M A FOTO G R A M M A , 2 0 1 3

M E S O S TR UC TUR E S / B AS TI AN , 2 0 1 4

SPH I ROHEDRON / JA CK S ON A N D BURGES S , 2 01 4

K ER F- b as ed C O M P L EX wo o d S Y S TE M s / C r an e, M c Ge e, P r ad o , Z h ao , M EN G ES , 2 0 1 0

State of the art reference projects. Lago, 2015

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FABRIC WOVEN FURNITURE / MONUS, 2012

AUGMENTED GRAIN/ WOOD, 2014

3d p r i n t ed h yg r o s c o p i c m a ter i a l / C O R R EA , M EN G ES , 2 0 1 4

H YG R O S C O P I C AC TUATO R S / k al dam , k r am p e , weitz el , m e n g es, 2 0 0 9

State of the art reference projects. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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FABRIC WOVEN FURNITURE.

AUGMENTED GRAIN.

MONUS, 2012|

WOOD, 2014|

The connection between rigid and flexible system is particular interesting in the achieved solution by Monus. Indeed, fabric woven system is interconnecting two rigid wooden piece of furniture. “This almost organic furniture item is a hybrid between the fluid dynamics of braided string and the rigid structure of the wooden boxes” (Monus, 2012).

The project proposed by Wood (2014) at ICD in Stuttgart consider the creation of a programmable surface that respond to changes in enviromental relative humidity. This is achieved through the utilization of an active material composed of a bi-layer system of beech and glass fibers.

This novel solution allow to create 3D geometrical architectural components from 2D flat surface, introducing a complete new concept in the architectural context.

The investigation carried out in the project focus mainly on the selection of the main raw wood material. Based on the desired curvature the grain of the based material are oriented accordingly and each piece is join together through CNC milled finger joint.

3D PRINTED HYGROSCOPIC MATERIAL.

HYGROSCOPIC ACTUATORS.

CORREA, MENGES, 2014|

KALDAM, KRAMPE, WEITZEL, MENGES, 2009|

The inspiration for this project takes place from previously conducted research project at the same Institute for computational design at the University of Stuttgart. Similarly, to the “wood-weener composite actuation system” (Correa, Menges, 2014), in this project a 3D printed material is utilized to achieved similar shape changes in response to humidity variations. The results of the preliminary tests show that the response of the system is similar to the wood-weener solution. Therefore, this novel solution can open new possibilities in the uses of “programmable environmentally responsive architectural systems” (Correa, Menges, 2014).

Similarly to the previously describe hygroscopic actuate systems, in this research the hygroscopic behavior of wood was utilized to create a space that “interact with its environment and develops functional capacities through this behavior” (Kaldam, Krampe, Weitzel, Menges, 2009).

The system, as shown in the figures, consists of 3 parts: a non-hygroscopic material, grooves, and wood pieces that are inserted into the grooves.

When the wood change its relative humidity the relative deformations lead to change the system shape. Therefore, it is required to have a support material with low rigidity such as Perspex.

“The actuators considered were of all the same geometry and made of spruce from cuts resulting in tangential fiber direction” (Kaldam, Krampe, Weitzel, Menges, 2009).

1 M o n u s, 2 012.

2 C or r ea an d Men ges, 2014.

3 K a ld am , Kram pe, W ei tz el and Meng es, 2009.

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A DA P T I V E WO O D P L A T E S

SA 1

WOOD PLATE SYSTEM FOLDING PATTERN

The previously revised project defined the space of possible applications that this project will start to built on to define and enhanced what was already researched in the performative wood area. As explained, previously there are three main aspects in the developed system (as will be more clear in the next chapters): non-responsive rigid plate, non-responsive flexible plate and responsive actuator.

The combination of these three elements could lead to the exploration of a new chapter in the wooden plate system scope of work, as it will be shown later on.

Before starting the discussion about the material, digital and experimental explorations, it is essential to review another important aspect of wooden plate systems: the folding criteria. This is of particular relevance for wood plate systems since the review of the current techniques could be beneficial in order to understand the architectural and structural possibilities of the developed approach.

The diagram on the next page tries to briefly summarized the concepts of folding with particular reference to project already conducted in this institute with previous studies carried in the first semester (this categorization is not to be considered exhaustive of all the available existing solutions but these are considered the most relevant for the current scope of work). Two different entities are considered as part of the whole system: surface and folding. A combination of different performances are possible depending if each entity is responsive or not-responsive. Moreover, two different categories of folding are defined: linear and curve. The combinations of all these variables lead to the definition of four different subcategories depending on the responsiveness of each component (see the diagram on the right with the different acronyms as used in the following description).

NRS / NRF The first category belong to the classical solution utilized in most of the up-to-date architectural applications. Indeed, the system is not responsive and no climatic adaptation is possible. In this case, the outcome is a rigid behavior and the material properties are more-or-less constant through all the entire life of the structure. Two different projects are shown as an example: the ICD/ITKE 2011 pavilion and the lattice folding system (Lago, 2015). The first one has been already explained in the previous chapter. The second project explores the possibil-

ity of introducing localized cuts in the wood plate (lattice). This increases in the flexibility in certain location will allow the forces and deformations to be distributed according to the defined cut pattern.

NRS / RF The main plate system that composes the surface in this case is still non-responsive, as in the previous case, but the inclusion of a reactive folding system will allow the system to be responsive. The response of the system will be restrained by the rigidity of the plates as well as the external constraints (e.g. friction, humidity level, etc.). For the scope of this project no reference project where found and the two examples provided refer to some initial studies conducted by the author. The first attempt was to create an hygroscopic lattice system that resemble the same stress variation as a static lattice system. The second solution was the introduction of a series of actuators in the static lattice system that would allow creating a series of forces that deform the system. These two solutions could be really valuable have been not further developed since a more comprehensive and effective system has been studied as part of the work presented in this document.

RS / NRF The system present a responsive surface while the folding line does not present any activation system.

This will allow almost a complete adaptability of the system in which the only constraints is coming form the surface interaction at the folding line. The major project based on this principles was defined

by Wood (2014). The responsive system was defined based on a wood and fiber glass composite solution that activates through the differential in strain deformations between the two layers.

RS / RF The last category considers the full system response with both surface and folding line. This solution would lead to the maximum responsive behavior expression with the least amount on constraints compared to the other schemes. The provided examples come from previous studies conducted by the author about woven wooden system based on the work by Torres, 2014. While being the most adaptable solution this was not considered part of the scope of this work.

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

37

S TA T E O F T H E A R T

NRS \ NRF NON RESPONSIVE SURFACE NON RESPONSIVE FOLDING

FINGER JOINT SYSTEM

LATTICE FOLDING SYSTEM

ICD / ITKE PAVILION. ICD, 2011

LAGO, 2015

hygroscopic LATTICE

hygroscopic ACTUATOR

NRS \ RF NON RESPONSIVE SURFACE RESPONSIVE FOLDING

BENDING TORSION GRAIN DIRECTION

LAGO, 2015

LAGO, 2015

LATTICE FOLDING SYSTEM

REACTIVE SURFACE

RS \ RF RESPONSIVE SURFACE NON RESPONSIVE FOLDING

LAGO 2015

WOOD; 2014

RS \ NRF ReSPONSIVE SURFACE RESPONSIVE FOLDING

Double Layer Actuation

WOVEN ACTUATION

UNFOLDED SYSTEM FOLDED SYSTEM FOLDED SYSTEM UNFOLDED SYSTEM

LAGO 2015

LAGO 2015

WOOD PLATE SYSTEMS LINEAR FOLDING LAGO, 2015

CURVE FOLDING WOOD, 2014

Wood plate system | folding patterns. Lago, 2015

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METHODS ME

40

A DA P T I V E WO O D P L A T E S

PYTHON GRASSHOPPER

MECHANICAL TEST SET-UP

KANGAROO

DRYING OVEN

BE

H

UR

COM

PUT AT

IO

NA

MA

OR PL

TE

EX ATIO

N

NT

AL

Saw Blade

PR

ME

OC

IRO

ESS

N

RESEARCH TOOLS

ENV

AIR VENTILATOR

KARAMBA

L

RIA

L

HYGROMETER

IO AV

CO

NT

ROL

FA B

A RIC

TIO

ULTRASONIC HUMIDIFIER

6-axes Robot Arm KUKA KR 2-125

3 AXes CNC TaBLE

HUMIDITY CHAMBER

Methods | Exploration tools. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

41

METHODS

G

iven the multidisciplinary scope of this project, several methods are utilized for the system development. The difference processes are utilized in coordination to achieved a programmable wood plate system that responds to variation in humidity levels to reach the pre-programmed design intent. Four different areas of exploration have been investigated: | Material Behavior | Computation Exploration | Fabrication Process | Environmental Control Each of this macro-areas rely on specific methods that will be explained in the following pages and the exploration tools utilized are summarized in the diagram in next-page.

MATERIAL BEHAVIOR | ENVIRONMENTAL CONTROL The material investigation was carried out based on different requirements for the definition of the geometrical characterization of the main wood plate system. The major considerations where relative with the two main components composing the system: non-responsive plate and responsive actuator.

The non responsive plate explored is composed of plywood material. Two different types of behavior the plate need to satisfy: a more rigid one that need to sustain the expansion and shrinkage of the actuator and a more flexible one that allow the system to achieve the pre-programmed shape. To study the properties of the material, while utilizing available catalogue and scientific papers data the author decided to carry out some physical testing of the available material in order to choose the most suitable combination between plywood thickness between the rigid and the flexible part. The tool utilized was a mechanical press that allows to test the achievable plate folding angle and radius of curvature. Detailed explanations on the experimental plan is given in the next chapter.

The responsive actuator is made from solid maple. The main material properties to explore are: grain direction, log cut, expansion and shrinkage capabilities. Indeed, an important aspect for the predictability of the experimental results and of the digital simulation is based on the material selection process and of understanding its behavior. For what regards the material selection process visual inspection of different wood planks were conducted through several visits at a supplier factory. The

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experts could guide the author in the selection process based on the recognition of the cut location from a complete wood trunk.

The material properties instead were gathered from different scientific publications (see reference chapter for a detailed list) that were validated through several experimental campaigns that will be explained in detail in the next chapter. Several tools were utilized for understanding the current material properties and the most important relies on the capacity of testing the two extreme condition of the wood EMC. At low values of EMC (typically in the order of 2-4%) the material has reached almost the lowest content of moisture in its structure and this was achieved through drying in a controlled environment with low relative humidity (around 10%). In order, to obtain this extreme conditions a normal domestic oven was tested in different stages to understand the required temperature to achieve the desired humidity levels. The temperature was found not to be a greatly influenced by the environmental initial humidity. Indeed, in the range of 50-60 째C the relative humidity in the oven was constantly in between 10-15%. The results show that the average time for equalizing the moisture content is between 72h and 96h. This was considered acceptable for the scope of the project.

At high values of EMC (typically in the order of 24-28%) the material has reached almost the highest content of moisture in its structure and this was achieved through increased the air relative humidity in a controlled environment (around 90%). In order, to obtain this extreme conditions two different set-up were built. One humidity chamber that was utilized as to test small scale pieces and a partial room that was enclosed with plastic foil to reduce its initial size. A normal domestic humidifier was utilized to reach the high values of relative humidities. Several tests were conducted for different levels of humidity to understand the reliability of the instrument. The results shows that the humidifier is effective in achieving different levels of humidity with a variation of +/- 5%. Moreover,most of the architectural component testing where conducted for a relative humidity greater than 90%. In light of these findings this was set-up configuration was considered acceptable for the scope of the project.

The last important aspect related with the material behavior is the required time for equalizing the moisture content in the wood. Indeed, several endurance test were conducted to understand what could be the estimated time for each component in order to consider the test complete. In order to study the material was investigated with reference

42

A DA P T I V E WO O D P L A T E S

with its change in weight and dimensions. Once not significant variation were recorded the sample was considered to reach its equilibrium state.

While not considered a rigorous set-up system the outcome of the testing were considered valuable for the scope of this project. The results show that the average time for equalizing the moisture content is between 72h and 96h.

It is important to state that all the environmental conditions were controlled with a standard digital hygrometer, in such a way it was possible to control both the humidity and the temperature levels.

COMPUTATIONAL EXPLORATION Several computational approaches are utilized and developed in this project. The main focus has been on the design level and on the structural validation.

First, a tool that define the possible geometrical space, control by the material behavior, is defined.

Based on the available type of plywood and lumber the user can defined the possible relation between two rigid plates in between an actuator and a flexible plywood part (this would be explained more in detail in the next chapter). The so constructed morphospace (or design space) takes into consideration just the material properties of the actuator and of the flexible plywood part without considering the exterior constrains, such as: size of the non-responsive rigid plate, boundary conditions, etc. The tool was developed on a Python shell for Grasshopper (Rhinoceros3D plug-in) allows the designer to freely play with all the parameters that geometrically defined the solution: actuator and plywood dimensions and properties.

The second major tool was utilized to simulate both the responsive behavior of the plate system as well to understanding the structural properties during the different stages of response. The visual programming tool Grasshopper (plug-in for Rhino) was utilized. Several different Grasshopper add-ons were utilized in the script, such as: Kangaroo (live physical simulator), Karamba (parametric structural modeling tool). The script permit to simulate the response of the system while updating the structural analysis outcome. .

FABRICATION PROCESS A great amount of testing elements were produced and the fabrication process has been constant throughout the whole generation. The different specimens were fabricated through different techniques, mainly: CNC milling, 6-axes Kuka robot and table saw. The reason behind the use of these methods is the rapidity of production and the cur-

rent availability of the above mentioned machinery among the school facilities.

The control of the system properties is really important especially for what regards the tolerances that can greatly affect the outcome of the process.

Indeed, the 6-axes precision was not accurate enough for two main reasons: robot tolerances and milling bed out-of-level precision. For these reasons a CNC-3 axes machine was utilized that provides greater reliability. These techniques were utilized for modifying the wood plate and to create the flexible groove to fit the actuators. An important aspect that will be treated in detail in the following chapter is that the groove can be created from a solid plywood piece or from the lamination of different plywood pieces. This last procedure is more convenient in terms of material usage efficiency.

However, for the main experimental program of the thesis the first solution have been utilized due to the lack of precision that would come from the lamination process (coming from the available tool to the author).

The other important aspect was the dry fitting of the actuator. Particular attention was carried out in order to keep the material at a constant humidity level. Indeed, the material was for equalized to a low RH level and then when the system was complete the RH level was increased to achieve the maximum EMC in the wood that would allow the system to reach the pre-programmed geometrical configuration. For this reason, after equalizing the low EMC content the wood samples were sealed in plastic sheets filled with silica gel bags to maintain a constant humidity levels as close as possible to the desire one. Then the samples were cut with a circular table saw an dried fitted on the plywood plate.

Two different type of fitting were tested. The first one consists in simply sliding in the actuator in the plywood groove and the second one requires to glue the actuator edges on the groove sides (this depends on the selected connection detail utilized for the actuator as it will be explained later on). The two different techniques lead to different results as will be explained in the detail in the next chapter.

ADAPTIVE WOOD PLATE ASSEMBLY PROCESS The previously described tools are all necessary instruments for the adaptive wood plate assembly process. The diagram shown in the next pages guide through the whole conceptual, computational, fabrication and control system behavior.

TESTING PROTOCOL It is important also to state that it is necessary to adopt a testing protocol in order to get consis-

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

tent and comparable results among different tests.

In particular the following are the steps that have been followed in each experiment (if not stated otherwise): | Storage of the maple (or any other actuator material) in an humidity control area. | Milling of the non-responsive wood plate. | Maple EMC equalization at a RH of 20%. Usually, carried out in a standard kitchen oven. | Storage the maple once equalized in a vacuum bag with silica gels to keep the RH constant. | Cutting of the actuator and relative dry fitting. In case of glued connection it is necessary to clamp the two systems firmly. | Preparing the humidity chamber at the desire RH level at least 6 hours before the test starts. | Position the active wood plate in the chamber as soon as the dry fitting is complete. Indeed, the air moisture content is in generally greater than 20% therefore the swelling process is automatically starting. | At the start of the test measure the major parameters for identifying the progress of the actuation.

In most of the case the measure of the deformation have been seen as sufficient for the scope of this project. | Terminate the test once the variation in the behavior of the actuators is negligible or minimal. | Let the active wood plate to equalize at the new prescribe RH, once the test is complete. | Storage the specimen in a climate control area that does no fluctuate during the day and the seasons.

The provided testing protocol does not try to be exhaustive not mandatory but it has been seen to be good practice in order to keep the testing results constants and comparable. Moreover, the order of the operation is not considered to be strict but it usually follow the flow of the testing procedure.

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43

METHODS

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A DA P T I V E WO O D P L A T E S

HYGROSCOPIC 90% 80% 70% 60% 50% 40% 30% 20% 10% 90% 80% 70%

T

60% 50%

R

40% 30% 20%

R

10% T

MATERIAL BEHAVIOUR

ELASTICITY

Adaptive wood process | Material behavior. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

45

METHODS

COMPUTATIONAL

PA NE L A N G L E (째 )

60 40 20

a C TU A TO R W IDTH (M M

)

25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

RES TRA INE D DES IGN SPA CE BY PLY WO OD ME CHA NIC AL PRO PER

24 0 22 0 20 0 18 0 16 0 14 0 12 0 10 0 80

FUL L DES IGN SPA CE

TIES

140 MM LO NG AC TU ATOR 12

11

10 9

8

7

6

5

4

3

2

1

AC TU ATOR TH ICK NE SS (M M)

200 MM LO NG AC TU ATOR 1

2

3

4

5

6

7

8

9

10

11

COMPUTATIONAL EXPLORATION

MECHANICAL

Adaptive wood process | Computation exploration. Lago, 2015

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A DA P T I V E WO O D P L A T E S

DIGITAL

FABRICATION PROCESS

ANALOG

Adaptive wood process | Fabrication process. Lago, 2015 Methods Diagram: Fabrication Process. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

47

METHODS

UMIDITY

90%

90%

80%

80%

70%

70%

60%

60%

50%

50%

40%

40%

30%

30%

20%

20%

10%

10%

ENVIROMENTAL CONTROL

HUMAN

Adaptive wood process | Environmental control. Lago, 2015 Methods Diagram: Enviromental Control. Lago, 2015

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DD

design research development

50

A DA P T I V E WO O D P L A T E S

T

he outlined aim of this research project lays in between two main ares: wood localized flexibility and wood hygroscopic actuation. Based on these two branches the research development focus on these two aspect firstly separately and subsequently their interaction is investigated.

The adaptive wood plate system is compromised of three major parts (as briefly introduced in the previous chapters): | hygroscopic actuator | rigid plywood plate | flexible plywood plate The production and the assembly of the three components can be done according to the described tools of the previous chapters and further details will be provided in the next sections. Once the wood plate has been assemble the standard testing protocol can start (as shown in the following page).

The standard experimental protocol therefore would consist in the following steps: | Design of the architectural components. | Digital calculation and simulation of the required actuators and rigid/flexible plate portions. | Material inspection and selection (both for the actuators and the plate) | Production of the milling path for the plywood plate and eventual lamination of rigid and flexible wood plate. | Actuators moisture equalization to low values of RH. | Cut the actuators to the desire connection shape. | Drying fitting of the actuators and the plate. Eventual gluing of the actuators on the wood plate (depending on the selected connection detail). | Wood plate assembly moisture equalization to high values of RH. | Check the final geometry with the simulation and evaluation of the possible problems that raised during the test.

In this chapter, the different research aspects are individually and thoroughly presented in such a way the reader can understand the whole process. Several aspects are treated that start from the material section to the possible geometrical variations that can be achieved. Subsequently, the relative architectural possibilities can be explored as a normal exercise without requiring any specialized skill.

The several aspects that will be treated in detail are the following ones: DD|1 Non-responsive material investigation DD|2 Responsive material investigation DD|3 Actuator behavior properties DD|4 Wood plate stress distribution DD|5 Actuator/plate connection patterns DD|6 Design space DD|7 Experimental investigations | Single strip DD|8 Experimental investigations | Multi-directionality DD|9 Design catalogue

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

51

D E S I G N R E S E A R C H D E V E LO P M E N T

RIGID PLYWOOD PLATE

ACTIVATED WOOD PLATE SYSTEM

ASSEMBLED SYSTEM CONFIGURATION

FLEXIBLE PLYWOOD PLATE

SYSTEM COMPONENTS CATALOG

MAPLE ACTUATOR

Adaptive wood plate configuration of the assembly. Lago, 2015

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52

A DA P T I V E WO O D P L A T E S

FIRST TRANSFORMATION

HARVESTING MAPLE

WOOD LOGS \ PLANKS

BIRCH

ENGINEERED PRODUCT \ PLYWOOD

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

53

D E S I G N R E S E A R C H D E V E LO P M E N T

ASSEMBLY

SECOND TRANSFORMATION

ENVIROMENT WITH LOW RH VALUE

ACTUATORS

HYGROSCOPIC ACTIVATION

WOOD PLATE

ENVIROMENT WITH HIGH RH VALUE

Adaptive wood plate design development process. Lago, 2015

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54

A DA P T I V E WO O D P L A T E S

PLYWOOD CORE TYPOLOGIES

VE

N

R EE

R CO

E

VENEER CORE COMPOSITION

FA C E

VENE

ER

3-PLY 5-PLY MULTIPLY

E VEN

M

R CO F D

ER

P LY

S

E

BA

M CO

R PA

TIC

LE

PO

S

R CO E IT

AR BO

D

CO

C

E KV

NE

ER

E

VENEER CORE GRAIN DIRECTION

RE

PLYWOOD CORE PROPERTIES SIZES: 3mm to 60mm STRUCTURAL: BIRCH - HARDWOOD 12mm - 9 plies E B: 10719 MPA F b,PAR: 42.9 MPA F b,PER: 33.2 MPA

STRUCTURAL: SPRUCE- SOFTWOOD 12mm - 4 plies E B: 7000 MPA F b: 24 MPA F c: 24 MPA

HYGROSCOPIC: ALONG THE GRAIN 0.011%

(SOURCE: HANDBOOK of FINNISH PLYWOOD, 2007)

(SOURCE: VTT CERTIFICATE No 4/95, 2008)

(SOURCE: FWPA, 2013)

ACROSS THE FACE GRAIN 0.013%

Plywood material properties. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

55

D E S I G N R E S E A R C H D E V E LO P M E N T

NON-RESPONSIVE MATERIAL INVESTIGATION

The main characteristic of the non-responsive plate is its intrinsic properties of being not changing his properties with the EMC level. For this reason among all the wood products plywood is the most interesting. Due to its composition in numerous ply let more freedom in the design the flexible part (differently from other engineering wood material, as shown in the diagram on the left side). The numbers of ply are always uneven leading to an anisotropic material. This characteristic can be manipulated in the flexible part with the utilization of an even number of joints. In the case, the wood plate assembly is considered the direction of the top layer lead to the design of the whole system. As shown, afterward when the top layer and the actuator have the same grain direction, the tension side are parallel to the grain direction while the compression side have perpendicular grain direction. This situation is more optimal for structural consideration since

MIL L ED ACTUA TOR S LOT MIL L ED FL EXIBL E G RO O V E

RIGID PLYWOOD TO P MIL L ED ACTUA TOR S LOT

when loaded perpendicular to the grain wood is more brittle. This will be explained more in detail in the stress distribution section.

Having selected the type of engineering material for the non-responsive wood plate the next step is to define how to create a configuration that alternative flexible and rigid parts in the same monolithic plate configuration. The diagram below shown the two different options explored in this research. The first one consist of a unique piece of plywood in which the actuator slot and the flexible groove have been created through milling process of a whole plate. The second system consist of double plate system that are glued together to define a custom made composite system. Even in this case there is always the necessity to mill the actuator groove on the side of the flexible groove. As it will be shown in later testing the two system are equivalent when the structural properties of the flexible part are equivalent.

PLYWOOD THICKNESS Based on all the previous considerations, the first selection process is on the plywood thickness. A 12 mm thick plate is chosen as a result of the material

NON REACTIVE GLUED SYSTEM

The non-responsive material selection have been already discussed briefly in the aim while dealing on the reasons while a complete wood system was chosen for the assembly system. The main reason was to create a continuous wooden system that can be placed in the realm of performative wood.

Moreover, the natural properties of wood make it a more sustainable material.

NON REACTIVE MONOLOTIC SYSTEM

DD 1

FL EXIBL E PLYWO O D B OT TO M

Non-responsive plate fabrication process. Lago, 2015

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A DA P T I V E WO O D P L A T E S

weight, availability and geometrical considerations between non-responsive and responsive material (as it will be shown later on while discussing about actuators).

FLEXIBLE GROOVE TESTING The select plywood was then tested for different flexible groove thicknesses as shown in the following page. The major parameters of interest are the following: | main plywood grain direction. | number of layers | wood type | angle between plates | moment demand The following pages show the results of this experimental testing with the different parameters investigated. It is also shown the measured angle between plates as well as the estimated maximum bending moment demand (based on the computation model previously explained).

From a first look a the results it can be seen that poplar provide the greater resistance and the lowest angle since it has less layers and therefore at constant number of layers poplar has a thicker flexible groove compared with birch. Moreover, two layers while providing the more flexible solution it evens up the grain direction and also it provide a better structural stress distribution because the tension side has the grain direction parallel while the compression one has the grain perpendicular to the forces applied.

Based on all these considerations the experimentation conducted in subsequent sections of these document have been conducted with birch plywood and 2 layers system. The possibility of having an even material properties in both main direction will be beneficial while discussing the possible geometrical variation that can be achieved with this assembly (e.g. twisting plate, origami system, double curvature surfaces, etc.).

To summarize the findings of this section the non-responsive system is then composed of a 12 mm plywood with a flexible groove with 2 plywood layers that range on the thickness of 2.6-3.0 mm.

Knowing the exact thickness of the groove is really important to get a correct estimate of the behavior of the whole system.

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

57

D E S I G N R E S E A R C H D E V E LO P M E N T

DD 2

RESPONSIVE MATERIAL INVESTIGATION

The responsive material properties need to be careful investigated since they are the main factor that driven the forces that allow the system to activate.

The main factor is by default the grain direction since the amount of water absorption (below the saturation point) lead the system to expand and shrink. These are the two main physical mechanisms that actuate the system; therefore, the grain selection process is one of the major parameter to take into careful consideration.

GRAIN SELECTION As discussed above the grain selection is the major parameter for the control of the system behavior.

The diagram shown in the following pages show the major grain direction for a typical wood log.

Depending on the log cut different grain directions can be defined. The three major grain direction are: | Radial | Tangential | Longitudinal These defines the amount of responsiveness the actuator will have. The ranking of shrinking properties goes from tangential (the most responsive) to longitudinal (the least responsive). In particular, the longitudinal response is almost negligible and can be ignored for the scope of this work.

The actuator will be fabricated in order to have the longitudinal or radial grain direction that will activate the assembly. The ideal situation would be to have a perfect tangential grain direction but in reality there will be a combination between and tangential and radial grain direction. The closer the direction is to tangential the most responsive system will be obtained. All these parameters need to be taken into account while defining the computational and simulation model since the prediction of the response is really depending on the grain direction.

The material deformations due to change in the EMC are usually not uniform and therefore, the actuator can usually deform not uniformly. This is highly depending on the cut location in the log (as shown in the diagram). This cuts define the mainly longitudinal fiber direction. Indeed, as most regular will be the longitudinal grain direction the least uneven deformation will be associated with the change in the moisture content. This condition will be more evident while looking at the experiment results shown later on.

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WOOD TYPE SELECTION The wood type selection is based on the material hygroscopic properties. The shrinkage table shown in the next pages shown different wood qualities divided between two wood macro areas: hard and soft wood. It can be seen that hardwood in most of the cases have better hygroscopic properties.

Among the different hardwood qualities maple is selected as the most suitable wood variety due to main reasons: | the good shrinkage percentage for both tangential and radial direction. | previously conducted studies by several authors working on hygroscopic application in the architectural field (e.g. Reichert, 2014; Wood, 2015). | material availability The main structural properties of the chosen wood is shown in the following pages diagram in which both green and 12%EMC content properties are shown. It can be seen that the structural properties reduce as the moisture content increase.

From the figure the typical three step fabrication process is shown: | Main cut log: that the raw material as purchased from stock storage | Cut sheet: from the main log several cut sheet are made it based on the select actuator thick ness (which selection process is described in later section). | Actuator final shape: from the cut sheet the actuator on its final size is cut in the table saw based on the dry fitting with the non-responsive plate.

Based on the general properties found in the literature in the next section the experimental campaign on the available site material is conducted in order to understand the range of design possibilities that the system can lead to.

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A DA P T I V E WO O D P L A T E S

POPLAR

AN g l e: 1째

A N g l e : 0 . 5째

M O M EN T : 24kn m

M OM E N T : 2 7 kN M

3 LAYERS

M A I N G R A I N D I R E C T I ON : VE RT ICA L

3 LAYERS

M AIN G RAIN D IREC T IO N : HO RI ZON TA L

M A I N GRA I N D I RECT I ON : HORI ZO N TAL

M A I N G R A I N D I R E C T I ON: VE RT ICA L

A N gle : 3 째

ANgle: 2째

M OM E N T: 2 2 . 8 k n m

M OM E N T : 2 4 . 5kN M

BIRCH

PLATE PRO PER T I E S

S I ZE : 1 00x 1 00 M m

groo v e : 5 0 m m

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

59

D E S I G N R E S E A R C H D E V E LO P M E N T

M A I N G R A I N D I R E C T I ON : V E RT I C A L

ANgl e: 3 째

ANgle: 4째

MOMENT: 20kn m

M OM E N T : 2 1 kN M

2 LAYERS

2 LAYERS

MA IN GRAIN D IREC T IO N : HO RIZO N TAL

MA I N GRA I N D I RECT I ON : HORI ZON TA L

M A I N G R A I N D I R E C T I ON : V E RT I C A L

A Ngle: 5째

A N g l e : 6째

MOMENT: 18k n m

M OM E N T : 1 9kN M

Non-responsive material selection | Plywood structural flexibility exploration. Lago, 2015

ALBERTO LAGO

60

A DA P T I V E WO O D P L A T E S

WOOD GRAIN DIRECTION

TA N

GE

N

L TIA

GR

AIN

D RA

IA

l

A GR

IN

WOOD LOG CUTS

P LA I N SAWN

Q WA RT E R SAWN

SWELLING VS GRAIN DIRECTION ta N G E N T I A L T R A N S VE RSE LO N G I T U D I N A L

T

R

R

T

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

61

D E S I G N R E S E A R C H D E V E LO P M E N T

WOOD CUTS VS SHRINKAGE DEFORMATIONS

C UP

B LOW

C R OOK

KI N K

T W IS T

D I A M ON D I N G

SWELLING PROPERTIES HAR D WOODS

TA N GE TI A L

RA D I A L

S O F TWO O D S

TA N GE TI A L

R AD I AL

B E E CH , AMERICAN

11.9 %

5 .5 %

C E DA R , A L A S K A

6. 0 %

2.8%

B IRCH, YEL LOW

9 .2%

7 .2 %

D OUG L A S F I R

7.8%

5. 0 %

C HE STNUT

6 .7 %

3 .4%

LARCH, WESTERN

9. 1 %

4 . 5%

MAP LE

9 .9 %

4.8%

PINE, RED

7.2%

3. 8 %

OA K, BL A CK

11.1%

4.4%

R E D WOOD

4 . 9%

2.2%

WALNUt, BLACK

7 .8%

5 .5 %

S P R UC E , R E D

7.8%

3. 8 %

(S O UR C E: UN d e sta n d i n g wo o d , H oa d l ey , r . b )

Responsive material selection | Wood grain: shrinkage and deformations. Lago, 2015

ALBERTO LAGO

62

A DA P T I V E WO O D P L A T E S

MAIN CUT LOG

CUT SHEET

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

10.1MPA 54.0 MPA 1.61 MPA

ACTUATOR FINAL SIZE

63

D E S I G N R E S E A R C H D E V E LO P M E N T

12% EMC SHEAR PAR. GRAIN COMPRESSION PAR. GRAIN COMPRESSION PER. GRAIN

12600 MPA

MODULUS OF ELASTICITY

MODULUS OF ELASTICITY

10700 MPA

COMPRESSION PER. GRAIN COMPRESSION PAR. GRAIN 4.4 MPA 27.7 MPA 10.1 MPA

SHEAR PAR. GRAIN

(S O UR C E: K R E T S C H m A N N , 2 0 1 0 )

Responsive material selection | Actuator selection process. Lago, 2015

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GREEN

64

A DA P T I V E WO O D P L A T E S

TANGENTIAL AVE. 3.73 %

6%

5%

RADIAL AVe. 3.17 %

4%

3%

2%

1%

R

20 MM

20 MM

T

10 MM

10 MM 20 MM

5 MM

5 MM 20 MM

10 MM

10 MM 10 MM

10 MM

30 MM

20 MM

Swelling test maple samples. Lago, 2015

W + 4% W

W

30% RH 90% RH

L 90% RH

30% RH 90% RH

30% RH

Actuator swelling test. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

65

D E S I G N R E S E A R C H D E V E LO P M E N T

DD 3

ACTUATOR BEHAVIOR PROPERTIES

In the previous section, it was discussed the major material properties for what regards both hygroscopic deformations and mechanical characteristics. While these data are coming from manufactures and laboratory results, it is considered an important step, for understanding the material behavior, to carry out some standard tests on hygroscopic deformation. This would allow to understand the range of application of the chosen material and to have a comprehensive picture of the system possibilities.

SWELLING DEFORMATIONS The series of tests started with the selection of a wooden log that could best represent the typical situation that will be utilized during the successive testing protocol. Several samples are extracted with variable cross sections as shown on the chart on the left side. The selection of these sizes was based on the possible variation in the actuator size and it is not considered an exhaustive scientific experiments on the hygroscopic deformations of maple.

The longitudinal length was 200mm, that shown later on was the typical testing dimension utilized.

The samples were positioned in the chamber at a gradient humidity range that started from 30 to 90% RH. The chart shows the extreme percentage deformation for an equalization of the moisture contents for a RH of 90%. The average range is between 3 and 4% since the samples selected were never fully tangential nor radial. This selection was on purposes to represent the most typical conditions that could happen in a real case since most of the typical material grain direction is not predictable and it was considered to minimize the material waste.

The samples were kept in the chamber for 96 hours that was sufficient to get an equalization of the moisture content based on a negligible variations in the sample weight and dimensions.

It is important to note that just 5 samples per each section profile were taken. This is considered an acceptable assumption for the scope of the current research but may be a limitation for a full understanding of the material behavior.

The subsequent step was to take a series of tests of a typical actuator dimension. As shown in later sections the typical actuator width is 50 mm while the length is in the range of 100mm to 500mm.

The great range in the longitudinal dimension is a function of the non-responsive flexible structural properties since the design of the system is based

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on achieving the maximum swelling of the actuator without reaching the breakage or the plastic limit of the non-responsive system. However, as it will be shown later on, the possibility of plastic deformation of the wooden plate was considered acceptable for the morphological exploration of the system possibilities. Indeed, the user can programmed the system to whatever limit he can consider as fundamental. More details, about this will be furnished later on.

5 actuators samples were tested in the same manner as the previous ones. The test demonstrates that the range of variation that the first tests were giving are acceptable and that the typical swelling deformation are in the range of 4% (as shown also in the bottom picture on the left).

An important aspect to consider while looking at the image of the actuator sample is the color of the actuator been tested in the chamber since the humidity levels are quite height the pigmentation of the wood is changing and also if the humidity condition are not carefully planned molding is a possible problem (a greater insight about this problem will be given in the discussion chapter).

SWELLING FORCES The other important material behavior to take into consideration is the forces that the actuation process will induce on the wooden plate. This is a really important aspect since the amount of force generated during the swelling will guide the design process of both the actuator geometry and the wooden plate flexible properties. Since the mechanical force created can be measure only with a series of clamping test that can be fully restrained the swelling. For the purpose of this research, it is considered that these test were not essential. Indeed, typical swelling values can be found in the literature. Several papers discuss about this and in the paper by Rowell (1995) a comprehensive summary on the subject is given. It is reported that the true swelling pressure of wood is very large.

Several values have been proposed in the literature based on tests but a certain value is defined.

For example, Stamm (1964) reported a theoretical swelling pressure of 165MPa while Tarkow and Tuner (1958) reported a value of 83MPa that is almost half than the previous one. The different on the two values are dependent on the specific gravity of the material utilized and on the testing procedure utilized (as explained by Rowell (1995)). There-

fore, it is clear that there is not certain the true value of the swelling pressure. Moreover, the test for measuring the swelling pressure of wood are based on a fully clamped sample that is not possible in real applications, since the properties will reach the maximum compressive strength before reaching the swelling pressure. For this reason in the current research it is considered that the maximum swelling pressure that the actuator can furnish is based on the compression strength of the sample in the direction perpendicular to the grain direction. As shown in the figure below the typical value of this pressure for maple is around 44MPa (that is lower than the value found in literature). This limit is considered to be a realist estimate for both a factor of safety point of view as well as against buckling of the actuator.

However, the grain directionality in the longitudinal direction is an important factor for the definition of the real buckling properties. Its predictability is not that defined since the longitudinal grain variation in most of the case present a great variability. Further insights on the buckling problems of wooden actuator will be given in the discussion chapter after having presented the testing procedure carried out.

In light of this discussion, it is still possible to understand the amount of force generated during the swelling process just looking at the sample size required to lift a standard car. As shown in the figure below, a 70mm by 70mm sample is sufficient to start lifting the car. This is the lower limit since once the swelling deformation are starting the pressure of the car will be already at the material limits for what regards the compression in the direction perpendicular to the grains. Therefore, samples of bigger size will lead to lift the car even more up to reaching the maximum swelling deformation. However, without conducting any test on this it is impossible for the author to estimate the sample size to achieve the maximum swelling deformation of the material.

The provided discussion about wood swelling pressure is just on insight of an important topic for the hygroscopic application in architecture. While further studies will be required to have a clear understanding of the problem this is considered acceptable for the scope of this research project.

2000 KG GROSS WEIGHT MERCEDES BENZ SL500 2013

ACTUATOR MODULUS OF ELASTICITY

MERCEDES BENZ SL500 2013 7 CM + SQUARE ACTUATOR

10700 MPA

COMPRESSION PER. GRAIN SWELLING PRESSURE 75.8 MPA 4.4 MPA

66

A DA P T I V E WO O D P L A T E S

(S O UR C E: K R E T S C H m A N N N , 2 0 1 0 Ta r ko w a n d Tu n er , 1 9 58 )

Wood swelling pressure. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

67

D E S I G N R E S E A R C H D E V E LO P M E N T

DD 4

WOOD PLATE STRESS DISTRIBUTION

The previous sections has provided more insights in the material behavior of the actuators and non-responsive wood plate that will be utilized in this research. It is now important to understand how the whole assembly works synergically as a whole system. Indeed, as shown in the figure below the actuator will be positioned in the non-responsive plate groove and based on the changes in the equilibrium in the EMC the swelling of the actuator will create a series of forces that are distributed in the plate. These forces are acting in both direction of the actuator section and the ideal case would be to have a predominant tangential direction in the longest section direction (as shown in the figure).

When the actuator is dry fitted in the sample at low EMC content (i.e. equalized with low levels or RH) no forces are acting on the plate. As soon as the EMC contents changes the actuator will swell or shrink depending if the EMC content increase or decrease. The main scope of this project is to start from a lowest level of EMC possible to allow

RADIAL

GRAIN DIRECTIONALITY

the actuator to swell. This will induce a force perpendicular to the side of the actuator (as shown in the figure). This force will induce in the plate a moment that will be constant across the flexible part. Therefore, the deformation of the flexible part will be based on a circular arc, since the moment is constant all across the length. Through simple geometrical calculations it is possible to understand what is the reachable radius of curvature and angle between panels that each actuator and panel size can be design to. The figure below shows these geometrical relationships that have been implemented in the computation model.

One of the major aspect that induce more deformation in the system is the position of the actuator compared with the flexible part. Indeed, the further the load application from the center line of the flexible part, the greater will be the moment induced in the system and as a consequence the angle and radius of curvature will increase. Further, insight about

R T TANGENTIAL

AT LOW RELATIVE HUMIDITY LEVELS

A A A + f(q)

D/2

D/2 A+D

AT HIGH RELATIVE HUMIDITY LEVELS

Tw F

F Ts M TP

w

q

R

q

M

R

q q

W(a/2) = MA 2 /(8EI) = R(1-cos(q)) Q = MA/(2EI) =arctan(D/2W) q max = sa/(2eY)

Adaptive wood plate geometrical configuration and force distribution. Lago, 2015

ALBERTO LAGO

68

A DA P T I V E WO O D P L A T E S

this aspect will be given in the next section while discussing about the different connection pattern.

STRESS DISTRIBUTION After discussing how the forces are transferred from the actuator to the wooden plate it is important to see what are the typical stress flow when the system is activated. This is depending on the actuator/ plate slot connection detail as explained extensively in the next section.

Looking at a typical dove tail connection, as shown in the figure below it can be seen that there are two major areas of stress concentration: | at the connection between the actuator and the plate | at the interface between the rigid and flexible plate (groove)

all across the flexible part since the moment demand is constant all across the section as just explained above.

The amount of stresses are considered to be not exceeded the wood plate capacity as it would be shown in the testing carried out. Therefore, complex finite element analyses are outside the scope of work of this project since are not considered crucial for the geometrical and morphological exploration of the system capacities. Indeed, the most important structural considerations are coming from the global system morphology, as well as the actuator compressive strength and flexible part bending capacities. These three aspects are considered the most important and have been included in the computational and simulation model presented in the methods chapter.

Further discussion on the stress distribution is given in the next section while presenting the different possible actuator/plate connection pattern that have been studied in this project.

Moreover, there is a zone of high bending stresses

WOOD PLATE

ACTUATOR

WOOD PLATE

WOOD PLATE REDUCE STIFFNESS AREA

Actuator stress distribution pattern | closeup view. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

69

D E S I G N R E S E A R C H D E V E LO P M E N T

DD 5

ACTUATOR/PLATE CONNECTION PATTERNS

One of the main scope of this project was to understand what are the possible connection between actuator and the non-responsive plate. The major consideration was to provide the actuator the possibility to swell with the least amount of constrain and to the possibility to give a uniform EMC equilibrium on all sides of the actuator. For these reasons several pattern were experimented and among all six of them were considered relevant for this project (see diagram in the next page): | square tail | notch square tail | dove tail | butterfly tail | round tail | ball tail The geometrical behavior of each system during dry fitting and swelling condition are shown in the figure on the next page. The relative forces are shown as well and the typical stress distribution for the major connection are shown in the figure below.

One of the major aspects to take into consideration, while looking at the different pattern, is the distance between the application of the actuator swelling force and the flexible plate groove center line.

As already discussed the bigger this distance the higher will be moment applied and the greater will be the deformations (given the material mechanical properties are not exceeded). This is express qualitatively in the diagram with a curvature slider.

The other important aspect is the restrained provided to the actuator to plate movement. Indeed, the deformation of the plate will try to pivot around the point of the application of the swelling forces. This is shown qualitatively with a friction slider in the diagram.

The last major aspect is the stability of the system.

Indeed, in the diagram are shown the different fabrication and assembly tools required for each system. Only the top two consider to glue the actuator to the non-responsive plate. This provide greater stability to the whole system since the connection can take both compression and tension forces. This is not the case for the other connection expect for the ball tail and the butterfly. The butterfly have some stringent geometrical constraint that lead it to be the least ideal connection detail (as shown in the diagram). The second one provide restrain for tension when the circular groove arc length is greater than the limit of half a circle.

Stress ConCENTRATION ACTUATOR Stress ConCENTRATION PLATE BENDING Stress distribution for different actuator/plate connection patterns. Lago, 2015

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70

A DA P T I V E WO O D P L A T E S

LOW HUMIDITY LEVELS

HIGH HUMIDITY LEVELS

SQUARE TAIL FABRICATION/ASSEMBLY TOOLS CURVATURE FRICTION STABILITY

NOTCH SQUARE TAIL FABRICATION/ASSEMBLY TOOLS CURVATURE FRICTION STABILITY

DOVE TAIL FABRICATION/ASSEMBLY TOOLS CURVATURE FRICTION STABILITY

BUTTERFLY TAIL FABRICATION/ASSEMBLY TOOLS CURVATURE FRICTION STABILITY

ROUND TAIL FABRICATION/ASSEMBLY TOOLS CURVATURE FRICTION STABILITY

BALL TAIL FABRICATION/ASSEMBLY TOOLS CURVATURE FRICTION STABILITY

Actuator/plate connection pattern. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

PATTERN TESTING Based on all these considerations a series of tests were conducted on the different connection pattern.

The figures below show the results for four of the

connection previously proposed (those ones considered more valuable for the scope of this project).

In the figure the geometrical dimensions are shown as well the achieved radius of curvature and plate angle (the actuator length is 200mm while the rigN OTC H S QUA R E TA IL 5M M

5M M

260

MM

50 M M 5. 5°

D Ov e TA IL 5M M

30 °

358

MM

50 M M 4°

R OUN D TA IL 5M M

2.5M M

477

MM

50 M M 3°

B UT T E R F LY TA IL 20°

716M

M

4MM 2°

9MM 50 M M

5M M

Actuator/plate connection pattern testing. Lago, 2015

ALBERTO LAGO

71

D E S I G N R E S E A R C H D E V E LO P M E N T

id panel is 200x200mmx12mm thick). The height of the flexible part is 2.5mm that is equivalent to two layers of plywood. The grain direction of the plywood is consistent with what already explained in the previous sections in which the top and bottom layer plywood grain directions are parallel to the actuator longitudinal ones. The results show the variation in curvature per each system. Indeed, the larger is the actuator is from the centerline of the flexible part the larger is the curvature.

The followed testing protocol is similar to the other tests already explained. In the following, sections several different aspects of the tested specimens are reviewed in greater detail.

DOVE TAIL Three different type of dove tail tests were conducted for studying the flexible plate groove properties influence as well as the wood plate composition system. Indeed, two layers (equivalent to a 2.5mm thick plate) and three layers (equivalent to a 4mm thick plate) system are tested and the results are shown in the figures below. The same actuator geometry was used with a length of 200mm. The results shows that obviously the two layers system provide greater curvature, while the plate assembly pattern is not influencing the testing outcome.

3 La ye rs 30 째

358

4째

MM

50 M M 5M M

280

5째

MM

2 L aye rs/ G lue

4째

MM

3 L A YE RS/ G LUE

358

72

A DA P T I V E WO O D P L A T E S

Dove tail flexibility variation. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

73

D E S I G N R E S E A R C H D E V E LO P M E N T

ROUND TAIL Similarly to dove tail case two different testing assembly were considered for the round tail. Both of them considered a composite non-responsive plate.

As for the dove tail the system with 2 layers provides greater curvature given the less rigidity in the groove portion of the wooden plate. As shown before the radius of curvature that can be achieved with this system are bigger than the one with the dove tail since the distance between the application of the actuator forces and the center line of groove is smaller compared to the dove tail case.

2 L A Y E R S / G LUE 5M M

2.5M M

477

MM

50 M M 3째

716M

2째

M

3 L A Y E R S / GLUE

Round tail flexibility variation. Lago, 2015

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74

A DA P T I V E WO O D P L A T E S

PA N E L A N G L E (째 )

C U RVA T UR E R A D I US ( C M )

60 40 20

a C T UA T OR W IDT H (M M

)

25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1

5. 7 6. 0 6. 2 6. 5 6. 8 7.2 7.5 8.0 8.4 8.9 9. 5 10.2 11.0 11.9 1 3. 0 14.3 1 5. 9 17.9 20.5 2 3. 9 28.6 35. 8 47.7 71.1 1 4 3. 2

RE ST RA INE D DE SIG N SPA CE BY PLY W OO D ME CH AN ICA L PR OP ER

12

240 220 2 0 0 18 0 16 0 14 0 12 0 10 0 80

FU LL DE SIG N SPA CE

TIE S

14 0M M LO NG AC TU ATO R 11

10 9

8

7

6

5

4

3

2

1

AC TU ATO R TH IC KN ES S (M M)

20 0M M LO NG AC TU ATO R 1

2

3

4

5

6

7

8

9

10

11

ACTUATO

R WIDTH

PANEL ANGLE

2.5 MM

ACTUATOR THICKNESS

12 MM

Active wood plate | Design space blow-up view. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

75

D E S I G N R E S E A R C H D E V E LO P M E N T

DD 6

DESIGN SPACE

In the previous section the different geometrical, structural and material properties were reviewed in greater detail and based on these findings the computational model was developed. The defined tool allow the user to define the possible wood plate assemble possible curvature variation for a single actuator system. This might be considered limiting since the possible application of multiple actuators is more relevant but as it will be shown in the next section the validity of these have been considered fundamental for the correct simulation of the testing carried out.

The example design space shown in a blow-up view on the left is based on a series of fixes parameters (but user can easily change them in the design space tool): | 12mm thick plywood | 50mm wide by 2.5mm thick groove | 200mm and 140mm long actuator The variables parameters that define the space are defined based on the previous section considerations and are considered to be the following: | Actuator width (1 to 200mm) | Actuator thickness (1 to 10mm) It is important to note that some of these variable values are not meaningful from a design point of view but have been used to show the full spectrum of the available design space.

The design space outcome is the curvature of the assembly that is represented by angle between rigid plates and the groove radius of curvature. The results are shown for two different actuator length (140 and 200mm). The different length aim to show that based on the actuator swelling forces and the rigidity of the joint there is a strong correlation.

Indeed, for the longer actuator there is a limit in the maximum curvature based on the structural properties of the flexible groove. Therefore, the tool provided define which limit is governing in the design of the system. Several testing has been conducted to validated the influence of the actuator length on the system deformation. Results are shown in the next pages for three cases, that uses a dove tail connection and 3 sizes of actuators (50mm wide): | 1 x 200mm | 2 x 60mm | 2 x 30mm The results show that the 1x200mm and 2x60mm solution provides similar curvature behavior since the groove elastic properties are exceeded with the

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200mm actuators. Indeed, the 2x60mm actuators provide the most optimal solution for achieving the same curvature, since the actuator width is the same the swelling deformation will be identical. Instead, for what regards the 2x30mm case the swelling force is not sufficient to reach the elastic limits of the groove; therefore, the curvature is smaller compared to the other two cases and the swelling deformation has been restrained by the rigidity of the flexible portion.

It is important to note that the provided limits are based on elastic considerations. Indeed, with the longer actuator length it is considered that when the elastic properties of the flexible groove are exceeded there is no breakage of the system but plastic deformations will happen. This would be clear while discussing about the testing results.

The design space can now be expanded for different parameters as shown in the figure on the next page in which the actuator and plywood thickness are variated while keeping the other geometrical parameters similar to those one discussed before.

The chart shows that there are some extreme condition happening that would be not practically possible to achieve. Indeed, as it can be seen the full design space in some case is much bigger than the restrained one that is limiting the whole system design.

Based on these results some practical considerations can be outlined that would be useful for understanding the subsequent tests. Considering a 12mm non-responsive plate with a 2.5mm groove, and a 5mm thick and 200 mm long actuator, the angle between panels for different actuators width can be simply defined as follows: | 50mm wide actuator - 5째 panel angle | 60mm wide actuator - 6째 panel angle | 70mm wide actuator - 7째 panel angle | 80mm wide actuator - 8째 panel angle These values are important because they will be used as a reference throughout all the successive testing experimentation.

ACTUATOR TH

CURVATURE RADIUS (MM)

PANEL ANGLE (째)

76

A DA P T I V E WO O D P L A T E S

600

30

10

ICKNESS (mm)

ICKN ES

6.5

PLYW OO

D TH

9

S (m

m)

12

15

AC TU AT OR

W

IDT

H(

MM

)

18

200

4.0

3.5

3.0 FLEXIBLE ZONE

2.5

THICKNESS (m

m)

2.0

1.5

Active wood plate | Design space. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

77

D E S I G N R E S E A R C H D E V E LO P M E N T

1 x 2 00 m m A CTUA TOR

5째

2 x 60 m m A CTUA TOR

4.5째

2 x30mm A CTUA TOR

2.5째 Actuator length variation | Testing. Lago, 2015

ALBERTO LAGO

78

A DA P T I V E WO O D P L A T E S

Single ACTUATOR

DOUBLE SIDED

ACTUATORS 1

ACTUATORS 8

ANGLE (°) 5

ANGLE (°) 20

DOUBLE ACTUATOR

CIRCULAR ARC

ACTUATORS 2

ACTUATORS 14

ANGLE (°) 10

ANGLE (°) 70

TRIPLE ACTUATOR

CATENARY ARC

ACTUATORS 3

ACTUATORS 9

ANGLE (°) 15

ANGLE (°) 45

TWISTing plate

ACTUATORS 5 ANGLE (°) 25

Experimental investigation | Single strip design. Lago, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

79

D E S I G N R E S E A R C H D E V E LO P M E N T

DD 7

EXPERIMENTAL INVESTIGATIONS | SINGLE STRIP

An extensive experimental program was carried out with the intent to investigate the ranges of possibilities that the develop system can induce. The first goal is to validate some of the basic principles that were defined in previous sections. Some of these testing have been already shown in the previous section to provide a validation of the computational and mechanical calculations. This section will extend the previously shown tests to define the range of possible simple morphological variation that can be achieved with this assembly. In parallel the real behavior will be compared with the digital simulation to show the validity of the developed tool.

The outcome of these tests will inform the user on the possibility that the system can offer and it will the base for the design proposal reviewed in the next chapter.

The experimental plan is divided in two main areas of investigation: | Single strip (ribbon type) components | Multi curvature / origami components.

In the following the main parameter of the single strip solution are reviewed and the outcome of the testing are discussed with particular reference to the digital simulation results. In all the tests the non-responsive wood plate is 12mm thick with a groove of 50mm and dove tail connection.

MULTIPLE ACTUATORS The first test series was conducted on a straight assemble with equally space actuators. Three different tests were conducted with increasing numbers of actuators (1, 2, 3). The actuators geometry is 50mmx200mmx5mm (thick) with a dove tail connection. The spacing between actuators is 200mm.

The case of 1 actuator is shown in the previous page with reference to the study on the different actuator length influence on the design curvature.

The other two cases are shown in the next page with reference to the initial stage and the final stage (note that the initial stage is not completely flat since the starting relative humidity was 50% leading to higher EMC that the minimum one). The results shows that in all the cases the target angle is reached quite consistently after the actuator have been reached an EMC equilibrium state with a RH of 90%.

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DOUBLE SIDED The double sided adaptive wood plate assemble consist of a plate composed of 8 sequential actuators with 4 of them on the top side and 4 on the bottom side of the non-responsive plate. The actuators geometry is 50mmx200mmx5mm (thick) with a dove tail connection. The spacing between actuators is 115mm. The resulting response starts from an equalization of the EMC at 50%RH and end at 90%RH. The response is shown in the figures in the next pages. The measured geometry variation due to swelling of the actuator is found to be consisted with the previous founding: 20° angle between the plate and the supporting floor.

TWISTING PLATE When the actuator are rotated compared to main longitudinal plate direction a twisting rotation is added to the system. In this way, the plate can be directed in a out-of-plane direction of the main assembly. As the angle of rotation increase the twisting increase proportionally. In the tested sample 5 actuators have been utilized with a variable angle goes from 0° (for the center piece) to 15° (for the most outer piece), with the middle one angle in between the other two. While the rotation of the plate goes out-of-plane the relative rotation between the plate and the supporting floor is still function of the actuator dimension as for the other cases previously studied.

The actuators geometry is 50mmx200mmx5mm (thick) with a dove tail connection. The spacing between actuators is 115mm. The resulting response starts from an equalization of the EMC at 50%RH and end at 90%RH. The response is shown in the figures in the next pages. The measured geometry variation due to swelling of the actuator is found to be consisted with the previous findings : 25° angle between the plate and the supporting floor.

CIRCLE ARC The previous tests have shown the capacity of the programmed system to perform as intended for the design level of RH that the actuator need to equalize to. The subsequent step is to scale-up the system to understand if the computational model and the programmed assembly works as intended. For this reason a large arc is programmed to bend 140° provided that 14 actuators are assembled in

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2 A C T UA TOR S _5 0% RH

3째

2 A C T UA TORS _90% RH

10째

3 A C T U A TO R S _ 5 0 % R H

8째

3 A C T U A TO R S _ 9 0 % R H

15째

Experimental investigation | Single strip design. Lago, 2015

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Experimental investigation | Twisting strip. Lago ,2015

25째

20째 Experimental investigation | Double side strip. Lago ,2015

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a 1.20m non-responsive plate. The actuators geometry is 50mmx200mmx5mm (thick) with a dove tail connection. The resulting response starts from an equalization of the EMC at 30%RH and end at 90%RH. The response is shown in the figures in the next pages. The measured geometry variation due to swelling of the actuator is found to be quite consisted with the computational findings. Indeed, the angle between the plate and the supporting floor is around 60째 on one side and 50째 on the other.

Moreover, it is possible to see how the circle approximation is not precise. These discrepancies are coming from several reasons: | Actuator buckling. | Chamber humidity not constant during the whole process.

The reason for the actuator to buckle are coming from two reasons. The first is the compression force perpendicular to the grain direction that are quite significant since the actuator was programmed to its limit capacity. The second reason, that is considered the most important, is due to the longitudinal fiber direction that is not uniform all along the actuator as can be see in the picture below. Therefore, the user need to select carefully the grain direction in the actuator or considering to using a method of constraining the buckling of the actuators. One possible solution could be to use a square tail connection with gluing the actuator to the plate. While this solution being more optimal is reduce the freedom in the designer choice to position or not the actuator. Indeed, the user can decide to replace the actuator with a non-responsive component to make the system as a static entity in some location or in the whole system. In addition, the non-responsive plate can be actively bended manually and then the non-responsive components can be fitted in the actuator groove location.

Together with this important consideration the arc was manually tested under a simple load applied at the top of the arc. The resistance offered by the arc was very minimal since as soon as tension

force reach the top surface of the wooden plate, the groove opens up since no resistance is given by the dove tail connection. There are two means to avoid this problem one is to optimize the shape of the art to take only compression and the second one is to use a different connection detail (such as glued square tail). In the next section, the first case is review with the exploration of a catenary arc.

Instead, the other option will be described in later sections.

CATENARY ARC As discussed in the previous section in order to over the tension forces in the circular arc a different shape is utilized that is based on a catenary approach. Indeed, by definition a catenary is an arc that does not have any tension. The define shape is based on a grasshopper definition with Kangaroo add-on. The final shape is 1.20m long with 9 actuator (50mmx200mmx5mm (thick)). Contrary to before the spacing between the actuators is variable depending on the required catenary arch shape.

The location of the actuators was computationally defined based an optimization carried with Grasshopper (Galapagos component). The optimization process starts on defined the desired actuators dimension and therefore the plate angle that can be achieved. Based on these parameters the tool define the optimal location of the actuators. Having a symmetrical shape the actuators location are symmetrical along the center line of the arc.

The resulting response starts from an equalization of the EMC at 30%RH and end at 90%RH. The response is shown in the figures in the next pages.

The measured geometry variation due to swelling of the actuator is found to be quite consisted with the computational findings. Indeed, the angle between the plate and the supporting floor is around 47째. The specimen was then tested with the same loading condition of the circular arc. The resistance provided is higher than the circular arc even if it is required to constrain the catenary edge.

Experimental investigation | Circular arc buckled actuator. Lago ,2015

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Experimental investigation | Circular arc low actuator EMC. Lago ,2015

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Experimental investigation | Circular arc high actuator EMC. Lago ,2015

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Experimental investigation | Circular arc high actuator EMC. Lago ,2015

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SIDE VIEW

BACK VIEW

TOP VIEW

DOUBLE FOLDING \ KERFING

ACTUATORS 4 ANGLE (째) 5

SIDE VIEW

BACK VIEW

TOP VIEW

DOUBLE FOLDING \ UNIQUE CUT

ACTUATORS 4 ANGLE (째) 5

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TOP VIEW

DOUBLE FOLDING \ backside ACTUATOR

ACTUATORS 5 ANGLE (째) 5

SIDE VIEW

SIDE VIEW

PROSPECTIVE VIEW MOUNTAIN FOLD LINE VALLEY FOLD LINE

ORIGAMI FOLDING \ YOSHIMURA PATTERN

Experimental investigation | Multi-direction design. Lago, 2015

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DD 8

EXPERIMENTAL INVESTIGATIONS | MULTI-DIRECTIONALITY

As explained in the previous section two sets of test were conducted. The single strip one was discussed in the previous section while in this section the application of actuator in more than one direction is reviewed. An extensive experimental plan was conducted as shown in the figure on the left.

Two different direction are followed: | Double folding approximation with a single plate. | Origami folding.

In the first category three different approaches where utilized. All of them are composed on a single square plate with 2 actuators per main direction positioned in the center line. This system as it is will be not be able to fold in double direction since the geometrical restraint will have to make of the four side not planar anymore. For this reasons one of the four sides has an additional folding line along its diagonal. For this reason the actuator folding line will act as mountain and the additional folding line as a valley. The additional folding line is generated with different techniques: | | | |

No folding.

Material kerfing.

Unique cut.

Actuator on the back side.

All of these three tests will be deeply reviewed in the following sections.

Furthermore, the possibility to utilize actuators in multi-direction lead to their implementation in the field origami. The early presentation presented herein are related with the application to the Yoshimura pattern. As done before the folding lines are divided in valley and mountains (depending on the direction of the folding). For this reason the mountains are generated by the actuators and the valley by either actuator on the back side of the non-responsive plate or by material kerfing. These two different tests will be reviewed as well in the following sections.

DOUBLE FOLDING As explained above the double folding behavior was achieved for a single plate with the introduction of 2 actuator per main direction (mountain) and one additional diagonal folding line (valley) that is created via different means: kerfing, single cut, backside actuator. The three cases have been com-

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putationally defined and fabricated. The standard testing protocol was utilized (as explained in the methods section). The actuators size are 40mmx200mmx5mm (thick) with glued square connection.

The non-responsive plate size is 400mmx700mm.

In the case of the kerfing valley folding line a standard line pattern was utilized based on previous finding by the same author (Lago, 2015). In the case, of the backside actuator the lattice is substitute with actuator with the same size as utilized for the one on the front side. The single cut solution instead consist of a single line cut along the diagonal direction.

All the three specimens were studied under the same environmental conditions. The resulting response starts from an equalization of the EMC at 30%RH and end at 90%RH. The response is shown in the figures in the next pages. The measured geometry variation due to swelling of the actuator is found to be consisted with the previous findings : 10째 angle between the plates folding line. In the figure, it is also shown the case without folding line to demonstrate that the geometrical constraints are overcame just with the breakage of the non-responsive groove flexible part (as shown in the figure).

ORIGAMI FOLDING As explain before an origami pattern was chosen to understand the possible application the hygroscopic actuators to a multiple direction solution. A similar approach as defined for the double folding is utilized. The actuators size are 40mmx200mmx5mm (thick) with glued square connection. The non-responsive plate size is 400mmx700mm. In the case of the kerfing valley folding line a standard line pattern was utilized based on previous finding by the same author (Lago, 2015). In the case, of the backside actuator the lattice is substitute with actuator with the same size as utilized for the one on the front side.

Both specimens were studied under the same environmental conditions. The resulting response starts from an equalization of the EMC at 30%RH and end at 90%RH. The response is shown in the figures in the next pages. The measured geometry variation due to swelling of the actuator is found to be consisted with the previous findings : 10째 angle between the plates folding line.

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Double folding | No valley folding line _ top view. Lago ,2015

Double folding | No valley folding line _ side view. Lago ,2015

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Double folding | Actuated valley folding line _ top view. Lago ,2015

Double folding | Actuated valley folding line _ back view. Lago ,2015

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Double folding | Cut valley folding line _ top view. Lago ,2015

Double folding | Cut valley folding line _ close-up view. Lago ,2015

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Double folding | Lattice valley folding line _ top view. Lago ,2015

Double folding | Lattice valley folding line _ close-up view. Lago ,2015

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Double folding | Cut valley folding line _ top view. Lago ,2015

Double folding | Cut valley folding line _ close-up view. Lago ,2015

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Double folding | Lattice valley folding line _ top view. Lago ,2015

Double folding | Lattice valley folding line _ close-up view. Lago ,2015

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Design catalog | 18x50mm plate _ side view. Lago ,2015

UNDEFORMED TOP VIEW

80mm ACTUATOR

DEFORMED Section

DEFORMED TOP VIEW

70mm ACTUATOR

60mm ACTUATOR

50mm ACTUATOR

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ACTUATORS 7

ACTUATORS 6

ANGLE (°) 90

ANGLE (°) 90

ANGLE (°) 90

30° ACTUATOR

20° ACTUATOR

DEFORMED Section

DEFORMED TOP VIEW

15° ACTUATOR

UNDEFORMED TOP VIEW

ACTUATORS 8

ANGLE (°) 90

10° ACTUATOR

ACTUATORS 9

TWISTING ANGLE (°) 5.7

10 TWISTING ANGLE (°) 8.5

TWISTING ANGLE (°) 10

13 TWISTING ANGLE (°) 10

ANGLE (°) 90

ANGLE (°) 90

ANGLE (°) 90

ANGLE (°) 90

Design catalog | Actuator width and angle parametric study. Lago ,2015

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DD 9

DESIGN CATALOGUE

The outcome of the extensive digital and physical research have been shown in all the previous section. Based on these results in the following section the author would like to provide a sort of design catalogue in such a way the user can understand the possible geometrical variation that the assembly can lead too.

This design catalogue has served as an inspiration for the design proposal explained in the next chapter.

in order to understand the validity of the system.

The major control parameters that can be modified to control the outcome of the possible geometrical variations are considered to be the following:

| 6x80mm actuators with a glued square tail connetion. The panel in between the actuators is the minimum to be considered acceptable, and it is equal to 6mm. The sample has been designed to achieve a arc angle of 90°.

| | | | |

Actuator width Actuator angle Number of Actuator Actuator position Alternation of rigid and flexible non-responsive plates | Form finding The design exploration have been carried out mainly as one strip solution because it has been developed the most during this project.

DIGITAL EXPLORATION The figure on the left show the first exploration based on variating the actuator width, while trying to achieve the same final arc angle of 90°. It can be seen that as the width increase the number of actuators decrease and that the geometrical differentiation between the different solution is almost negligible (i.e. the length of the assembly is very similar among the four different solutions).

On the same figure at the bottom a second series of exploration is carried out in which the same 50mm actuators are utilized and the angle between the longitudinal axes of the actuator and of the non-responsive plate is change from 10° to 30°. The simulation show how the plate is not only rotating but it is twisting along the center line of the plate. Given the just shown results it will be possible to increase the arc angle from 90° till 360° (or more) as shown in the figure on the next page. The simulation show the geometrical variation that could be the starting point from a more architectural digital and physical exploration of this system (as it will be done in next chapter while discussing about the prototype proposal). Before, moving on the next chapter it is important to validate the just described simulations

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PHYSICAL EXPLORATION Three different tests are carried out in order to confirm the digital exploration just described. A 200mm wood plate assembly with a 12mm plywood is utilized. The three tests have the following characteristics:

| 9x50mm actuators with a glued square tail connetion. The panel in between the actuators is the minimum to be considered acceptable, and it is equal to 6mm. The sample has been designed to achieve a arc angle of 90°. Differently, from the above experiments the actuators are connected (at the edges) with two 300mm long rigid plates (that are part of the same piece of plywood of the actuator groove). | 18x50mm actuators with a glued square tail connection. The actuators have been rotated of 30° in order to test the out-of-plane deformation capacity of the system. The specimen should achieve a total arc angle of 180°.

The three above experiments have been conducted following the standard protocol and keep in the humidity chamber for 96 hours (until the EMC of the actuator was considered in equilibrium with the atmosphere RH).

In the following pages the results of the experiments are shown true several images and in particular it can be seen that the system perform as expected.

Indeed, all of the specimen reach the target arc radius (with the 6x80mm sample that actually slightly exceed the programmed arc angle). Furthermore, the sequence of the swelling deformations for the three tests are shown.

UA TO R AC T 15°

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90° ARC ANGL

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180° ARC AN

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270° ARC AN

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360° ARC A

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UATOR 20째 ACT

20째

ACT UAT OR

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9 ACTUATORS

18 ACTUATO

RS

27 ACTUATO

RS

36 ACTUATO

RS

Design catalog | Arc Angle parametric study. Lago ,2015

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1 1 0째

Design catalog | 6x80mm plate _ side view. Lago ,2015 9 0째

Design catalog | 6x80mm plate _ front view. Lago ,2015

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9 0째

9 0째 Design catalog | 9x50mm plate _ side view. Lago ,2015

Design catalog | 9x50mm plate _ front view. Lago ,2015

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90 째 Design catalog | 18x50mm plate _ front view. Lago ,2015 90째

Design catalog | 18x50mm plate _ top view. Lago ,2015

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Design catalog | 18x50mm plate _ close-up view. Lago ,2015

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Design catalog | 18x50mm plate _ side view. Lago ,2015

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Design catalog | Swelling test sequence. Lago ,2015

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DP

design research PROPOSAL

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T

he major development of the research have been carried out extensively in the previous section. Several tools have been developed and extensive testing have been carried out for several wood plate assembly configuration.

The study on the material properties both responsive (maple) and non responsive (plywood) have allowed to understand the possibilities of this technique to define an adaptive system that can be pre-programmed to being activated under certain environmental and human conditions. Moreover, the geometrical characterization of the assembly provide different solution both in terms of radius of curvature and out-of-plane movement.

In light of all of these findings, in this chapter there will be discussed the development of the design proposal for an architectural application, that adopt the developed system.

As a starting point several limitations were considered before starting the design exploration. The most important are: | Scaling: adaptive wood plates have several limitations especially in terms of required size of the actuators. Indeed, below 50mm wide actuator the deformation induced in the system are not valuable while looking at architectural application.

actuators can not be removed or replaced. Based on all these considerations in the following the design process is reviewed, followed by the fabrication process and the testing protocol.

DESIGN INTENT The scope is to provide an architectural component that can self-form and adapt to the environmental condition of the particular location it will be used in. The scale of the project will be looking at an installation/pavilion scale in which the user can interact with the system and learn its behavior just looking at the variation in the geometrical form due to the hygroscopic properties of the actuators.

The design intent is to create a continuous system that developed starting from a straight planar continuous wood plate system to achieve a complex geometrical space that will enhance the user experience in the particular environment it will be situated.

Other important, aspect is the structural integrity of the whole system. Indeed, while a deep structural analysis of the system developed is outside the scope of this work, the assembly should be able to sustain itself and provide a safe space for having a human, environment and architecture interaction.

| Material size: the maximum available plywood size sheet is 3.0mx1.5m. Up to know all the testing conducted considered a monolithic plate on which the groove were milled out. In the case a larger scale sample is fabricated there is the need to join it in different parts. The solution that can be chosen is to provide notches at the ends of the plates that allow the two successive assembly to be glue together.

All these design aspects were considered while looking at the possible design outcome and concept that could be developed. In particular the major aspect is related with constraint to start from a flat-straight plate. This is in reality not considered a constraint but a further demonstration of the possibilities of the proposed solution to achieve a complex geometrical spatial system starting from a flat surface system. Therefore, the idea is to create a volumetric space while having to design a two-dimensional surface system. In architecture this is not a new concept since there have been several example of so called “ribbon� architecture, in which the whole architectural space developed starting from a continuous linear system that basically wrap around the whole shell of the defined volumetric space that tries to enclose.

Together with this limitations the system chosen for the actuator connection is a square tail that is glue to the wooden plate. As already, discussed this system have several advantages such as greater structural stability and better swelling forces distribution between the actuator and the plate. On the contrary, this solution will not allow the user to manipulate the system in subsequent stages since the

Starting from this the design development was carried out in order to understand what are the possible solutions that can be achieved with the proposed system, based on material and geometrical properties. The figure on the right show the different solutions that have been looking into with particular attention to have in mind the architectural/installation scale of the project. The proposed

| Environmental control: the developed humidity chamber have limit size: volume of 1.4mx0.8mx1.4m (height). For this reason a temporary humidity chamber have been design to accommodate large size objects. Indeed, the available working volume is 9mx4mx3m (height).

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TUTORS: DAVID CORREA _ DYLAN WOOD

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Design Proposal | Initial morphological studies. Lago ,2015

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design solutions starts from three arc shape systems that applied all the principles developed in previous chapter (i.e. both circular curvature system and out-of-plane rotation coming from the rotation of inclined actuators). The subsequent proposal deal with a continuous system that is connected with a non responsive material that could be flexible surface that can accommodate the hygroscopic deformation of the plates. This system works more like a sort of ribbed structure with two main frame at the exterior to resist the loads. The fifth proposal take the previous one to a step further in which a complete unique plate composed the whole system through a succession of circular and twisted arc solutions. The last proposal is showing an adaptive square plate with active column that while deploying define a growing covered architectural space.

a good control of the system parameters and in the design criteria developed during this project. However, there are several issues that needs to be taken into consideration (that will be discussed in detail in the next chapter): | | | |

Actuator buckling Structural capacity of the flexible wood plate Friction that prevent the system to deform Requirement of a big facility for environmental control large pieces.

Among all the briefly discussed proposal the author considers that the most interesting solution, from a material and geometrical development prospective, is the continuous ribbon system (that was the fifth option explained before). Therefore, the design of this system is further developed looking at different geometrical differentiation as shown in the figure on the left (that refers to half of the system complete geometry that due to symmetrical reason is neglecting for this computational exploration). Nine different options are studied with a standard twisting angle of 10°. The last two options are also developed for three other level of twisting 15°, 20° and 30°.

Based on these last two options the system chosen is shown in the next page that consist on 5 different flexible parts that make-up for a total rotation of 450° and 4 flexible parts will be twisting with a 10° variation angle.

The complete system is shown on the figure on the next page that shown an abstract representation of the scale of a possible installation. Different elevations and plan view of the system are represented.

Just a portion of the system is fabricated for size limitations and in particular the model has been scaled to 1/3. The final length of the plate is 6m and 0.4m large requiring to fabricated 4 different pieces that are going to be glued on site, after the drying fitting of the actuators.

The total number of actuators is forty-six with forty 50mm actuators and six 80mm actuators. The 50mm actuators are used for the twisting portion that will achieve an arc angle of 360°. The 80mm actuator instead are utilized for the regular circular arc portion with a 90° angle.

The standard protocol testing procedure is applied with the actuators being equalized to a moisture content of 20% before drying fitting them on the plywood plate. After, having assemble the whole system and joined the four pieces together the 6m long plate is introduce in the custom chamber to a constant RH of 90% for four days.

The results shows that the system is able to effectively reach the programmed shape demonstrating

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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Design Proposal | Ribbon morphological studies. Lago ,2015

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1.75m

1.45m 5.70m

1.00m

1 . 50 m

Design Proposal | Prototype unfolded plate and cut pattern. Lago ,2015

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Design Proposal | Prototype full design render views. Lago ,2015

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Design Proposal | Prototype full design top view. Lago ,2015

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Design Proposal | Prototype testing set-up. Lago ,2015

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Design Proposal | Prototype testing top-view. Lago ,2015

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Design Proposal | Prototype testing time-sequence. Lago ,2015

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Design Proposal | Prototype testing time-sequence. Lago ,2015

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Design Proposal | Prototype testing time-sequence. Lago ,2015

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Design Proposal | Prototype testing time-sequence. Lago ,2015

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DISCUSSION DI

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everal consideration were drawn while carrying the numerous test and some of them where briefly introduced in previous chapter. In particular, in the following chapter, it is important to review the aspect that were not predicted and that affect the behavior of the system. The most relevant to discuss are: | | | |

Testing protocol Wood plate assembly deformation Actuator buckling Wood plate structural stiffness.

TESTING PROTOCOL The proposed testing protocol in the method chapter was developed based on previous knowledge about the institute and the personal experience gained during the testing. One of the major issue that was found during the testing was the maintenance of a low RH level between the oven dry process and the dry-fitting of the actuators. Indeed, not having a professional equipment available at any time sometime lead to wait consistent amount of time between oven dry and starting of the test.

Vacuum bags with silica gels were used but a better system should be developed for enhance the performance and the predictability of the tests.

The other major issue was the quality of the humidity chamber since a ultrasonic humidifier was used and the chamber size was not consistent there was a lot of condensation that consequently wet the sample. This problem was alleviated with the utilization of a ventilator but in some case there was the formation of mold that has to be avoided at all time. It is the author believe that a proper air circulation in the chamber will provide a better solution in future testing.

WOOD PLATE ASSEMBLY DEFORMATION One of the major concern that raised during the testing of the final prototype system was the restrain to the actuator deformation provided by the floor.

Therefore, it was necessary to move the piece every hours to get release the stress that was accumulated between the ground and the plate. A possible solution will be to utilize a smoother surface and a draining pavement in such a way the air can pass through the floor and the actuators positioned on the ground would have the possibility to find their equilibrium state without any problem. Therefore, it is important to careful define the position of

the piece. In the case of the prototype, the plate was located in the chamber with the actuators facing upwards. This would required that the whole weight of the plate to be lifted up by the actuators.

This cause two actuators two buckle (as discussed in next session).

ACTUATOR BUCKLING One of the major concern that raised during the prototype test was the buckling of two 80mm actuators (as shown with the picture on the left). These was caused by two main problems. One was already discussed in the previous section and it was caused by the position of the plate at the beginning stage. Indeed, the actuators had to lift the whole weight of the plate in addition to overcome the flexible resistance of the groove. This induced in the wider actuator a buckling problem. The second reason (that is the most important) is related with the longitudinal grain direction. Indeed, in the two actuators that buckle the grain in the longitudinal direction were not uniform (as shown in the figure on the left). This have cause a flow of stress in actuator that lead to a stress concentration and then to buckle the whole actuator. While this is an important problem to avoid, it has been seen that the actuator while buckle was able to swell as a function in the change in EMC.

WOOD PLATE STRUCTURAL STIFFNESS This section have been discussed in this chapter because it is an important aspect that has not been fully solved during the experimental program. Indeed, while the system structural behavior have been fully understood and validate through testing results, the force flow distribution in the system is quite complex when external forces are applied.

Indeed, plate analyses cannot be simple utilized and the results while valid for a uniform plate system were not considered valuable for the scope of this project. Indeed, structural analysis via FEM where carried out without obtaining results afterwards convalidated via testing. Moreover, given the scope of this project more on the material and geometrical exploration this aspect was not fully developed.

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TUTORS: DAVID CORREA _ DYLAN WOOD

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DISCUSSION

Prototype actuator buckling. Lago ,2015

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outlook OU

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A DA P T I V E WO O D P L A T E S

T

he presented research development show the potential of the system, even if several aspect have not been completely resolved. The more relevant concept that was not fully developed during this project was the possibility that the actuation would be in the double curvature and origami real. Indeed, first initial tests were conducted by the author but they were too limited to provide further insight of the possible morphological explorations.

In light of this the possible future experimentation in this subject should follow the path of double curvature and origami since this will lead to the most geometrical variation that the single curvature realm could not be able to achieve.

Moreover, it is believe of the author that a real size installation project could be the next subsequent step in this area of research.

Flocking Behaviour. Lago and Brugnaro, 2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

1 39

O U T LO O K

Outlook origami proposal. Lago ,2015

ALBERTO LAGO

ACKNOWLEDGMENTS

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A DA P T I V E WO O D P L A T E S

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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ACKNOWLEDGMENT

Prof. Achim Menges

David Correa Z.

Dylan Wood

Special thanks goes to: Julian Hรถll, Georgi Kazlachev, Yavar Khonsari and all the other fantastic ITECH students. Moreover, thanks to Eleonora, Antonio, Penelope, Martina e Alessandro for keeping up with my motivation to going back to school.

TA

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REFERENCE

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A DA P T I V E WO O D P L A T E S

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[ONLINE] Available at: http://www.achimmenges.net/?p=3138. [Accessed 15 March 2015]. _ Kretschmann D.E., 2010. Chapter 5: Wood Handbook. Forest Products Laboratory. United States Department of Agriculture Forest Service. Madison, Wisconsin. _ Lago A., 2015. Adaptive Wood Plates. ITECH Master Thesis. University of Stuttgart, Germany. _ Lalvani H., 2003. “The Organic Approach to Architecture”, eds. Deborah Gans and Zehra Kuz, 2003, Wiley-Academy. _ Mamma Fotogramma, 2013. Wood-Skin®, Redefining possibilities of wood. [ONLINE] Available at: http://wood-skin.com. [Accessed 15 March 2015]. _ MIT, 2012. Kerf Pavilion | MIT Architecture. [ONLINE] Available at: https://architecture.mit.edu/ architectural-design/project/kerf-pavilion. [Accessed 15 February 2015].

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_ Monus K., 2012. Wood Knitted Furniture. [ONLINE] Available at: http://katamonus.blogspot.de/p/ furniture.html. [Accessed 15 March 2015]. _ Porterfield A., 2014. Curved laser bent wood. [ONLINE] Available at: http://www.instructables.com/ id/Curved-laser-bent-wood/?lang=de. [Accessed 15 March 2015]. _ Reichert S., Menges A., Correa D., 2014. Meteorosensitive architecture: Biomimetic building skins based on material embeded and hygroscopically enabled responsiveness. Computer-Aided Design. _ Sonal P., 2011. Living Buildings. [ONLINE] Available at: http://www.brighthub.com/education/ homework-tips/articles/80692.aspx. [Accessed 15 March 2015]. _ Stamm A.J., 1964. Wood and Cellulose Science. Ronald Press Co., New York, NY. _ Stein R.G., 1977. Energy cost of building construction. Energy and Buildings, Elsevier. _ Tarkow H., Tuner H.D., 1958. The swelling pressure of wood, Forest Products Journal, 8(7): 193-197. _ Torres B., 2014. Programmable matter. ITECH Master Thesis. University of Stuttgart, Germany. _ VTT Certificate No 4/95, 2008. VTT Technical Research Centre of Finland. _ Wood D., 2014. Augmented Grain. ITECH Master Thesis. University of Stuttgart, Germany. _ Wood D., Correa D., Krieg O., Menges A., 2015. Material Computation - 4D Timber Construction, Towards Building Scale Hygroscopic Actuated, Self-Constructing Timber Surfaces, in, Briscoe, D., Daas, M., Jabi, W., Luhan, G., ThĂźn, G., Sentience and Systems Boundaries in Architecture, International Journal of Architectural Computing, Multi-Science Publishing, UK, Issue 3, Vol. 13, (publication pending). _ Zamorano, P.E., MartĂŹ, N, and Bek, B., 2011. Expandable Surface Pavilion. [ONLINE] Available at: http://www.archdaily.com/186069/expandable-surface-pavilion-pablo-esteban-zamorano/. [Accessed 18 February 2015].

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REFERENCE

LIST OF FIGURES

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_PAGE _PAGE _PAGE _PAGE

16 19 23 25

_PAGE 2 6 _PAGE 2 9 _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE

33 34 37 38 44 45 46 47 51 53 54 55 59 61

_PAGE 6 3 _PAGE 6 4 _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE _PAGE

66 67 68 69 70 71 72 73 74 76 77 78 80 81

_PAGE 8 2 _PAGE 8 3 _PAGE 8 5 _PAGE 8 6 _PAGE 8 8 _PAGE 8 9 _PAGE 9 0 _PAGE 9 1 _PAGE 9 2 _PAGE 9 3 _PAGE 9 4 _PAGE 9 6 _PAGE 9 9

A lg o U mb r ella s . La lv a n i, 2003 A d a p t iv e w ood p la t es | Aim d iag r am . L ag o , 2 0 1 5 Rig id p la t e c omp a r is on : p lyw oo d an d pl as ti c . L ag o , 2 0 1 5 Ker f Pa v ilion . M IT , 2012 C a r b on e Cur v e Pa v ilion . A A EM TE C H , 2 0 1 3 E xp a n d a b le Sur f a c e Pa v illion . Z am o r an o , M ar tĂŹ an d B e k , 2 0 1 1 H yg r os k in : M et er eos en s it iv e Pa vi l i o n . I C D , 2 0 1 3 I CD/IT K E R es ea r c h Pa v ilion 201 0 . I C D , 2 0 1 0 I CD/IT K E R es ea r c h Pa v ilion 201 1 . I C D , 2 0 1 1 S t a t e of t h e a r t r ef er en c e p r ojec ts . L ag o , 2 0 1 5 S t a t e of t h e a r t r ef er en c e p r ojec ts . L ag o , 2 0 1 5 W ood p la t e s ys t em | f old in g p atte r n s . L ag o , 2 0 1 5 Methods | Exploration tools. Lago, 2015 Adaptive wood process | Material behavior. Lago, 2015 Adaptive wood process | Computation exploration. Lago, 2015 Adaptive wood process | Fabrication process. Lago, 2015 Adaptive wood process | Environmental control. Lago, 2015 Adaptive wood plate configuration of the assembly. Lago, 2015 Adaptive wood plate design development process. Lago, 2015 Plywood material properties. Lago, 2015 Non-responsive plate fabrication process. Lago, 2015 Non-responsive material selection | Plywood structural flexibility exploration. Lago, 2015 Responsive material selection | Wood grain: shrinkage and deformations. Lago, 2015 Responsive material selection | Actuator selection process. Lago, 2015 Swelling test maple samples. Lago, 2015 Actuator swelling test. Lago, 2015 Wood swelling pressure. Lago, 2015 Adaptive wood plate geometrical configuration and force distribution. Lago, 2015 Actuator stress distribution pattern | closeup view. Lago, 2015 Stress distribution for different actuator/plate connection patterns. Lago, 2015 Actuator/plate connection pattern. Lago, 2015 Actuator/plate connection pattern testing. Lago, 2015 Dove tail flexibility variation. Lago, 2015 Round tail flexibility variation. Lago, 2015 Active wood plate | Design space blow-up view. Lago, 2015 Active wood plate | Design space. Lago, 2015 Actuator length variation | Testing. Lago, 2015 Experimental investigation | Single strip design. Lago, 2015 Experimental investigation | Single strip design. Lago, 2015 Experimental investigation | Twisting strip. Lago ,2015 Experimental investigation | Double side strip. Lago ,2015 Experimental investigation | Circular arc buckled actuator. Lago ,2015 Experimental investigation | Circular arc low actuator EMC. Lago ,2015 Experimental investigation | Circular arc high actuator EMC. Lago ,2015 Experimental investigation | Circular arc high actuator EMC. Lago ,2015 Experimental investigation | Multi-direction design. Lago, 2015 Double folding | No valley folding line _ top view. Lago ,2015 Double folding | No valley folding line _ side view. Lago ,2015 Double folding | Actuated valley folding line _ top view. Lago ,2015 Double folding | Actuated valley folding line _ back view. Lago ,2015 Double folding | Cut valley folding line _ top view. Lago ,2015 Double folding | Cut valley folding line _ close-up view. Lago ,2015 Double folding | Lattice valley folding line _ top view. Lago ,2015 Double folding | Lattice valley folding line _ close-up view. Lago ,2015 Double folding | Cut valley folding line _ top view. Lago ,2015 Double folding | Cut valley folding line _ close-up view. Lago ,2015 Double folding | Lattice valley folding line _ top view. Lago ,2015 Double folding | Lattice valley folding line _ close-up view. Lago ,2015 Design catalog | 18x50mm plate _ side view. Lago ,2015 Design catalog | Actuator width and angle parametric study. Lago ,2015 Design catalog | Arc Angle parametric study. Lago ,2015

PROF. ACHIM MENGES

TUTORS: DAVID CORREA _ DYLAN WOOD

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103 105 107 111 113 114 115 117 118 119 120 121 122 123 127 131

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Design catalog | 6x80mm plate _ side view. Lago ,2015 Design catalog | 6x80mm plate _ front view. Lago ,2015 Design catalog | 9x50mm plate _ side view. Lago ,2015 Design catalog | 9x50mm plate _ front view. Lago ,2015 Design catalog | 18x50mm plate _ front view. Lago ,2015 Design catalog | 18x50mm plate _ top view. Lago ,2015 Design catalog | 18x50mm plate _ close-up view. Lago ,2015 Design catalog | 18x50mm plate _ side view. Lago ,2015 Design catalog | Swelling test sequence. Lago ,2015 Design Proposal | Initial morphological studies. Lago ,2015 Design Proposal | Ribbon morphological studies. Lago ,2015 Design Proposal | Prototype unfolded plate and cut pattern. Lago ,2015 Design Proposal | Prototype full design render views. Lago ,2015 Design Proposal | Prototype full design top view. Lago ,2015 Design Proposal | Prototype testing set-up. Lago ,2015 Design Proposal | Prototype testing top-view. Lago ,2015 Design Proposal | Prototype testing time-sequence. Lago ,2015 Design Proposal | Prototype testing time-sequence. Lago ,2015 Design Proposal | Prototype testing time-sequence. Lago ,2015 Design Proposal | Prototype testing time-sequence. Lago ,2015 Prototype actuator buckling. Lago ,2015 Outlook origami proposal. Lago ,2015

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LIST OF FIGURES

NOTES