PROGRAMMABLE MATTER /Hygroscopic Actuation of Multidirectional Lattice Structures/ by belen torres

ITECH Architectural Design Research ITECH ITECH Architectural Design Research M.Sc. Programme, Faculty of Architecture and Urban

Architectural Design Research

M.Sc. Programme, Faculty of Architecture and Urban M.Sc. Programme, Faculty of Architecture and Urban Prof. AA Dipl.(Hons.) Arch. Achim Menges Design Prof. Dr.-Ing. Jan Knippers

Prof. AA Dipl.(Hons.) Arch. Achim Menges Prof. AA Dipl.(Hons.) Arch. Achim Menges Design Prof. Dr.-Ing. Jan Knippers Design Prof. Dr.-Ing. Jan Knippers

programmable matter /hygroscopic actuation of multidirectional lattice structures/ belen torres/ october 2014 M. Sc. Integrative Technologies and Architectural Design Research /thesis DIRECTION Achim Menges/tutors Oliver David Krieg and David Correa/

00/contents 1introduction/7 2context/13 3HYPOTHESIS/19 4METHODS/23 5fabrication/85 6Design Development/99 7DESIGN PROPOSAL/117 8DISCUSSION/123 9OUTLOOK/127 10REFERENCES/131 11ACKNOWLEDGEMENTS/135

01/Introduction

introduction

abstract Wood is a cellular heterogeneous, anisotropic and hygroscopic natural composite. This three material characteristics, usually avoided for being regarded as defects in the design process, could be instead amplified and used to program structures that behave according to its material capacities. Designing with wood means dealing with heterogeneity of a natural material. This research focusses on the use of the material capacities in a integrative approach: they are not avoided or force to behave in a unnatural manner but on the contrary, fully expanded to develop a integrative design process. Commonly nowadays architecture and structural design have lost the ability to design with anisotropic materials. Therefore dealing with complex, continuously variable and heterogeneous behavior is the challenge of this integrative design research.

introduction

i.000 responsive lattice structure [40 cells] hanging model

10 | introduction

aim The object of this research is to investigate the internal forces of wood caused both by hygroscopic dimensional changes and elastic bending to control the geometry variation of a component cell unit. The addition of such cells will then serve to program the behavior of a bottom up responsive system capable of reshaping depending on external climatic changes. It is possible to develop a structure that respond to environmental relative humidity variations and that forms and behaves driven by the interaction of this two reversible states of the material. The final purpose of this process is to achieve control from first of the last level of behavior within the system, in order to be able to program the performance of a passively actuated responsive multidirectional lattice structure.

introduction

i.001 responsive lattice structure [40 cells] hanging model

| 11

02/context

14 | context

context

state of the art

Although many advances in this field had been developed since the term responsive architecture was first used by Negroponte in during the late nineteen sixties, most of the significant developed projects have had the need of a complex mechanical or electronic control apart from external energy supply.

The following precedent research projects have a relevant importance for this investigation since they take advantage of the material properties and behavior of wood to develop both climate responsive architectural systems and structures based on the elastic bending of wood.

The contribution of the present research to this context is the further investigation of the same no-tech concept of embedded material responsiveness developed by Achim Menges and Steffen Reichert, to develop a system that integrates structural and reactive elements for a fully morphing responsive structure.

On the projects Responsive Surface Structures developed by Steffen Reichert at the HfG Offenbach, the anisotropy and hygroscopicity of wood are utilized to exploit dimensional changes triggered by changing climatic conditions to induce shape changes to reactive material elements. The development of a wood veneer composite allows the use of simple material elements as sensor, actuator, and regulator at the same time with no extra energy supply. The composite is embedded in an integral system that constitutes both the reactive skin and the load bearing structure.

The same principles are developed further on the Hygroscope Meteosensitive Morphology, a responsive architecture based on the combination of material inherent behaviour and computational morphogenesis developed at the Institute for Computational Design. Achim Menges and Steffen Reichert employ the dimensional instability of wood in relation to moisture content to construct a climate responsive architectural morphology. Climate-responsiveness in architecture is typically conceived as a technical function enabled by mechanical and electronic sensing, actuating and regulating devices. In contrast to this superimposition of high-tech equipment on otherwise inert material, nature suggests a different no-tech strategy: in many biological systems the responsive capacity is quite literally ingrained in the material itself.

i.005 HygroScope 2012 (Source: Achim Menges and Steffen Reichert)

i.004 Responsive Surface Structure II 2008 (Source: Steffen Reichert)

i.003 Responsive Surface Structure II 2008 (Source: Steffen Reichert)

i.002 Responsive Surface Structure I 2009 (Source: Steffen Reichert)

context | 15

This project employs similar design strategies of physically programming a material system that neither requires any kind of mechanical or electronic control, nor the supply of external energy. Another two relevant projects in the same research line are the Hygroscopic actuators by Florian Krampe, Kadri Kaldam and Christian Weitzel of the Institute for Computational design and Warped by Matthew T. Hume of the University at Buffalo. Both prove that it is possible to strategically use the hygroscopic behavior of wood to develop an architectural material system that interacts with its environment, but the difference with the firsts mentioned projects is that they use wood without lamination, instead of amplifying the dimensional changes of wood the addition of the force of small elements is used to affect global shape variation.

On the first project, the elements that constitute the system are: a non-hygroscopic element, a set of grooves milled into a carrier-piece and wood elements inserted into the grooves. The non-hygroscopic behavior is the most important factor for the passive element: materials with a low Elastic Module are favorable as they are likely to response quicker to the pressure forces exceeded by the wooden actuators. The second project introduces mechanical joints in the system, by using mechanical fasteners surfaces can be endowed with moments of intensified strength and stability to areas with no connections that allow the material to reshape itself in direct response to environmental moisture. Also new uses for the ply process are proposed such as the introduction of space and shape between the subsequent layers of veneer and using the directionality of the wood grain.

i.009 ICD Hygroscopic actuators 2009 (Source: F. Krampe, K. Kaldam and C. Weitzel)

i.008 Warped/ Rib University at Buffalo 2008 (Source: Matthew T. Hume)

i.007 Warped/ Filleted surface University at Buffalo 2008 (Source: Matthew T. Hume)

i.006 Warped/ Un-Filleted surface University at Buffalo 2008 (Source: Matthew T. Hume)

16 | state of the art

Following the second investigation line, active bending, the most fascinating project is the ICD/ITKE Research Pavilion 2010. The project demonstrates the latest developments in material-oriented computational design, simulation and production processes in architecture. The achieved methodological advances allow innovation on the material system level, in regards to two aspects: first, the project integrates skin and structure in one mono-material, bending-active system without the need for other constructional elements; second, the elastic bending behavior is not employed to generate the global shape and structure of the systems, but rather to define a series of behavioral components that spatially mediate an intricate network of forces.

The result is a bending-active structure, made entirely of extremely thin, elastically-bent plywood strips. The combination of both the stored energy resulting from the elastic bending during the construction process and the morphological differentiation of the joint locations enables a to form complex, lightweight structures from initially simple, planar elements. Another relevant project is the Radical Wood Pavilion of the Aalto University. The main structural stiffness of the pavilion originates from the thin pre-twisted and laminated substructures, which serve to give rigidity to the whole structure. Due to the lamination and pretwisting, the final configuration of the substructure is stiffer than the plain sum of its separate parts.

i.013 ICD Design Studio Material Systems II Snap it 2009. (Source: J. Baun et al.)

i.012 Radical Wood Pavilion Aalto University 2012 (Source: E. LundĂŠn and M. Wikar)

i.011 ICD/ITKE Research Pavilion 2010 (Source: Achim Menges and Jan Knippers)

i.010 ICD/ITKE Research Pavilion 2010 (Source: Achim Menges and Jan Knippers)

state of the art | 17

The last referent research project is Snap it , a series of prototypes developed by Julian Baun, Lars Fehrenbacher, Hannes Linder and Andreas Wiebe at the ICD Design Studio Material Systems II in 2009.It consists in a bistable geometry based on the elastic anisotropic characteristics of wood which allow it to be loaded differently dependant on fiber directions. Elements consisting of 4 timber strips rigidly joined at their ends which resulted in a bistable equilibrium state, dependant on the fiber directions within each strip. If the fibers are running in parallel to the longitudinal direction of each strip, the element would be in an instable equilibrium. A minimal amount of activation energy was needed in order to cause it to snap into one of the two stable equilibria. This element remains in a complex reciprocal state between inner forces and environmental pressures.

03/hypothesis

20 | hypothesis

HYPOTHESIS Wood is a cellular heterogeneous, anisotropic and hygroscopic natural composite. This three material characteristics, usually avoided in the design process as they are seen as defects, could be instrumentalized and expanded to program a structure that behaves according to its material capacities. It is possible to quantify the hygroscopic forces and to amplify the dimensional changes in wood to control the geometry and dynamics of a responsive structure capable of reshaping depending on external changes with no extra energy supply. The study of a common material behavior such as elastic bending, combined with a specific behavior such as wood hygroscopicity could evolve as a passively actuated environmental responsive structure due to the intrinsically anisotropic nature of wood and the specific manipulation of the material.

i.014 ICD/ITKE Research Pavilion 2010, built pavilion and material tests. (Source: Institute for Computational Design) i.015 Responsive Surface Structure I, prototype and material tests. (Source: Steffen Reichert)

hypothesis | 21

04/methods

24 | methods

physical experiments| material research

geometry| parameters extraction

fabrication| material lamination and selection

computational model| simulation methods

methods and work flow The research integrates four methods in the design process loop: physical experiments, geometric research, computational modeling and fabrication. One process feeds and informs the next one: from physical tests, both geometric and material behavior parameters are extracted to inform a computational model. From computational modeling, which includes four simulation methods depending on the scale of the system, fabrication data is later obtained. This last method is implemented by a robotic computational tool to accurately select the material according the desired behavior. After fabrication, new physical experiments are carried out to extract parameters again, and to check the control

i.016 Integrative design research methods flowchart

system | structure + actuation

cells | geometry + response

material | fiber layout + lamination

methods | 25

research levels The described workflow has been conducted in three different levels: the material research, the geometric cell unit research and the system scale. The three levels are extensively investigated and each one has its own scale. Nevertheless, the final purpose of the process is to get to the control of the last level in order to program the behavior of a passively actuated responsive multidirectional lattice structure.

i.017 3 research levels and scales diagram

26 | methods

CELL WALL LAYERS S1

FIBRILS 1 nm

hemicellulose

P ML

cellulose

WOOD CELLS lignin

10 Îźm

0.1 nm

CELLULOSE CHAIN MOLECULE

MATERIAL RESEARCH ANISOTROPY Anisotropy is the property of being directional dependent. It is the difference when measured along different axes, in a materialâ&#x20AC;&#x2122;s physical or mechanical properties. Wood is a hard fibrous material which is a natural composite of stiff cellulose fibrils embedded in a matrix of lignin, pectin and hemicellulose. Plants have evolved a multitude of mechanisms to actuate organ movement. The orientation of the cellulose fibrils in the cell walls is a crucial adjustment passive mechanism to perform motion in plants. The structure of wood is different in different species of trees, but also in the same species, which have grown in different environments and conditions, or even in different parts of the tree. Due to the complexity of the internal structure of wood, biological and material properties such as strength can vary along different directions. This property is embedded in wood as an intrinsically anisotropic material. Wood has unique, independent properties in three mutually perpendicular axes: longitudinal, radial (annual), and tangential. The longitudinal axis is parallel to the grain, the tangential axis is perpendicular to the grain but tangent to the annual rings. The radial axis is perpendicular to the grain direction, and normal to the annual rings.

i.018 Illustration of the composition and scales of wood (Source: Per Hoffman and Mark A. Jones)

methods | 27

mechanical properties elasticity Twelve constants are needed to describe the elastic behavior of wood depending on the three fiber directions: three moduli of elasticity, three moduli of rigidity, and six Poissonâ&#x20AC;&#x2122;s ratios.

i.019 to i.021 Microscopic images of wood cross, radial and tangential sections (Source: David Lemke)

The Youngâ&#x20AC;&#x2122;s Modulus or Modulus of Elasticity describes tensile elasticity, or the tendency of an object to deform along an axis when opposing forces are applied along that axis; it is defined as the ratio of tensile stress to tensile strain. The elastic stiffness or Modulus of Elasticity of wood is dependent on grain orientation, moisture content, species, temperature, and rate of loading. The Modulus of Elasticity in the longitudinal direction is the highest, and varies depending on the species. The modulus of elasticity, both parallel and perpendicular to the grain, depends on the moisture content, and decreases by 1-3% for every 1% increase in the moisture content of wood.

28 | methods

R T

wood/water relationship HYGROSCOPICITY Wood has the ability to absorb water molecules from the surrounding environment, and it seeks to be in equilibrium with the humidity it. The equilibrium moisture content is the content at which the wood is neither gaining or losing moisture; this is a dynamic equilibrium and changes with relative humidity of the air at a present temperature. Bound water is namely the one that saturates the cell fibers inside wood, and it is bound to it via hydrogen bonds. The attraction of wood for water arises from the presence of free hydroxyl groups in the cellulose, hemicelluloses and lignin molecules in the cell wall. The hydroxyl groups are negatively charged electrically. Because water is a polar liquid, the free hydroxyl groups in cellulose attract and hold water by hydrogen bonding. In contrast, water contained in the cell lumen that is only held by capillary forces and is not bound chemically is called free water. During the drying process of wood, a fiber saturation point is reached when only water bound in the cell walls remain and all free water has been removed from the cell cavities. Further drying of the wood results in strengthening of the wood fibres, and is accompanied by shrinkage. It could also be defined as the equilibrium moisture content of wood in an environment of 99% relative humidity. This process is reversible: dead wood tissue will always shrink or swell due to loss or gain of bound water from the cell walls.

i.022 Illustration of the three different fiber directions of wood: L longitudinal, R radial and T tangential (Source: James E. Reeb)

methods | 29

wood dimensional changes CUT type AND FIBER DIRECTION The amount of motion within wood varies according to the orientation of the wood cells and is usually measured separately in the three principal directions: tangential, radial and longitudinal. As water molecules enter and leave the cell walls, the resulting swelling or shrinkage is mainly perpendicular to the cell walls. Depending on the species the average ratio of dimensional changes is approximately 10% of the volume in the tangential direction. The greatest shrinking and swelling of wood occurs in the tangential direction. The average amount of dimensional change is 10% of the volume in the tangential direction and it varies depending on the species. The least shrinking and swelling occurs in the longitudinal direction, it is about 0.1% usually along the grain thus, for most applications, longitudinal shrinkage is negligible. An intermediate amount of shrinking and swelling occurs in the radial direction.

i.023 Characteristic shrinkage and distortion of flats, squares and rounds, as affected by the direction of the growth rings. (Source: James E. Reeb)

The microscopic cellular structure of wood, including annual rings and rays, produces the characteristic grain patterns in different species of trees. The grain pattern is also determined by the plane in which the logs are cut. The dimensional changes that occur at a molecular level due to ambient humidity changes manifest at a bigger scale in a piece of wood, depending on the type of cut, the location of the piece in the tree trunk and the grain pattern.

30 | methods

climate responsiveness This research starts at a small scale, in order to test the material response to climate variations in a measured unit. Birch wood has been chosen for its high transversal expansion [9.2%] as well as for its bending stiffness. The tests and measurements of the experiments have been carried out inside a climate box in order to increase or decrease the relative humidity and to have a precise control of it and to observe material and shape changes. Inside the box, the climate of Stuttgart over the year and over a day can be reproduced inside a controlled space. The set of instruments used are a humidifier, a dehumidifier, an hygrometer/thermometer and a humidity controller. Due to the differences between hygroscopic and bending forces further investigations have been focused on researching the material scale to increase the hygroscopic forces necessary to equalize or overcome the strain energy of elastically bent wood. For larger experiments, the same setup has been reproduced in a controlled climate room.

i.124 Chart of the average temperature and relative humidity in Stuttgart during the period of time of one year of research (Source: https://weatherspark.com)

methods | 31

background grid humidifier

RH/Tยบ display RH/Tยบ sensor dehumidifier and openings for ventilation

camera frame

i.125 Climate box setup, perspective and front view diagrams

32 | methods

layer 1

layer 2

wood [anisotropic reactive layer]

epoxy resin + fiberglass textile [isotropic stable layer]

programmed response bilayer composite Wood will always tend to be balanced: its moisture content with the environment, the equilibrium moisture content at which the wood is neither gaining or losing moisture is a dynamic equilibrium and changes with relative humidity and temperature. It is possible to amplify the shape changes of a piece of wood by laminating it with a synthetic composite that remains stable with relative humidity variations. If one side of the wood is sealed, the resultant material will be a bilayer composite with different expansion ratios on each side. Due to this fact, just with a 10% of swelling or shrinkage of wood, the shape changes of a particular piece of wood can be highly expanded and therefore used as a responsive bending actuator. The behavior of the composite can also be physically programed through specific alterations on the fabrication process. The physical parameters that will affect the behavior and reaction time of the composite elements are the type of wood, fiber direction, layout of the natural and synthetic composite and relative humidity during the lamination process. Depending on these parameters the same geometry could perform highly differentiated shape changes. Hygroscopic strains by themselves cannot generate a force or a moment, unless the body is not completely free to deform. Therefore the lamination not only allows an expanded shape change of the wood but also the expansion or shrinkage constrain generates a high internal force in the elements that could be used as the principle for a passively actuated system.

i.026 to i.027 Diagrams of the wood lamination and its programmed behavior

equilibrium moisture content %

methods | 33

30 27 24 21 18 15 12 9 6 3 0 0

100

relative humidity % [20ยบC]

80% RH

lamination 30% RH

lamination 80% RH 30% RH

stable face epoxy resin + glass fiber textile

WOOD LAMINATION

wood

hygroscopic face

The synthetic composite used for the lamination is epoxy resin reinforced with fiberglass textile. Epoxy resin has the function of sealing the pores of the veneer while the fiberglass textile provides more stability to the lamination. It also provides wood with strength on its weakest direction, as it prevents it from spliting along the fibers while it bends. The chosen type of wood veneer used is birch, due to its high tangential expansion and bending stiffness ratio. Different thickness of veneers have been tested [0.6mm0.9mm-1.5mm-2.5mm] to find the optimal ratio between response time and geometry of the elements.

i.028 Average relation of wood EMC-RH chart (Source: Eric.Meier)

As lamination is a manual process, its due to inconsistencies, as the regular placement of fiberglass textile, uniform sealing of wood as the amount of epoxy resin penetrating into the wood. Part of the investigation consists in making the process as much consistent as possible, in order to get a more predictable behaviour of the wood composite.

34 | methods

75º

90º

60º 45º 30º 15º 0º

0º

physical tests

75º

45 º

15º 15º 15º [25x125mm] Nine birch wood15ºveneer strips 0.9mm thick are tested. Rotary cut is used to achieve bigger swell and shrinkage of wood, because this type of cut corresponds to the tangential direction of the fibers. Different fiber orientation in relation to the long side of the strip [90º, 45º and 15º]. Three samples of each orientation are tested: first wood, second wood with epoxy resin, and the third wood with epoxy and fiber glass fabric 60

The result of maximum shape change is achieved by the strips with 90º fiber orientation angle. The samples of wood undergo free expansion and contraction under º º º relative humidity variations, without remarkable shape 30 30 30 change. The samples laminated with epoxy undergo more shape variation than the ones laminated also with fiberglass textile. Although the fiberglass textile reduces the shape variation it also provides more strength to the samples on the weakest fiber direction.

15º

90º

75º

A series of strips of wood veneer are tested to observe the wood composite shape changes with relative humidity variations, depending on fiber orientation and type of 15º 0º lamination. To3test the effectiveness of wood composite lamination, samples of wood without lamination from the same piece of veneer are selected.

90º

anisotropic response

i.029 Diagram for different fiber orientation cuts in relation to the longitudinal axis of the samples of the same piece of wood veneer

i.030 to i.031 Experiment setup and result, lateral and front views at a relative humidity of 25% and 75% i.032 Diagram for shape variations under relative humidity variations of a wooden bilayer composite depending on fiber orientation

methods | 35

90º

· wood · resin

15º

· wood

+rh

90º

· wood · resin · textile

15º

90º

· wood

15º

· wood · resin · textile

· wood · resin

+rh

45º

· wood · resin

45º

· wood

45º

· wood · resin · textile

45º

· wood · resin · textile

45º

· wood

45º

· wood · resin

15º

· wood · resin

90º

· wood

15º

· wood · resin · textile

90º

· wood · resin · textile

15º

· wood

90º

· wood · resin

+rh

36 | methods

wood composite

+rh

wood

wood composite

add stress

+rh

prestressed wood

release stress

BENDING/HYGROSCOPIC forces INTERACTION Could the hygroscopic force of the wood composite overcome the stored energy of an elastically bent wood strip? The previous wood composite samples series are used to add stress in a bent wood strip [single layer]. Observation of shape changes of a bent wood strip under force variation. Interaction between the 2 type of forces: Hygroscopic force vs. Elastic strain energy. The experiment is carried out under the following setup: 6 samples of wood composite strips laminated with epoxy and fiber glass fabric: Birch 0.9mm [rotary cut] 25x125mm with different fiber orientation in relation to the long side of the strip [90ยบ, 45ยบ and 15ยบ]. Vs. 6 samples of wood veneer strips: Birch 0.9mm [flat cut] 7.5x136mm with same orientation in relation to the long side of the strip [0ยบ] The two types of samples are connected with different layer order to go with or against the elastically bent strips. The observed result shows that the hygroscopic force of the wood composite is strong enough to add stress to an elastically bent wood strip and release the stress of it, depending on the order of the layers of the exposed wood face and the laminated face.

i.033 Diagram of the experiment objective and expected result

methods | 37

i.034 to i.036 Experiment setup: front and back view at 20% relative humidity and front view at 70% relative humidity. 1· HB birch 0.9mm 90º/ EB birch 0.6mm 0º 2· HB birch 0.9mm 45º/ EB birch 0.6mm 0º 3· HB birch 0.9mm 15º/ EB birch 0.6mm 0º 4· HB birch 0.9mm 90º/ EB birch 0.6mm 0º 5· HB birch 0.9mm 45º/ EB birch 0.6mm 0º 6· HB birch 0.9mm 15º/ EB birch 0.6mm 0º

38 | methods

HYGROSCOPIC BENDING

ELASTIC BENDING 0º

90º

110%

100%

110% 100%

0º

45º

2 HYGROSCOPIC BENDING

ELASTIC BENDING

110%

100%

0º

15º

3 110%

100%

i.037 Topologic diagrams for tested samples 1 to 3, layout and force interaction logic under relative humidity variations.

methods | 39

HYGROSCOPIC BENDING

ELASTIC BENDING 0º

90º

110%

100%

110% 100%

0º

45º

5 HYGROSCOPIC BENDING 110%

100%

0º

15º

110%

100%

i.038 Topologic diagrams for tested samples 4 to 6, layout and force interaction logic under relative humidity variations.

ELASTIC BENDING

40 | methods

HB birch 0.9mm 90º EB birch 0.6mm 0º

HB birch 0.9mm 45º EB birch 0.6mm 0º

HB birch 0.9mm 15º EB birch 0.6mm 0º

add stress

i.039 to i.050 Experiment 01 samples 1 to 3 right view, relative humidity from 25% to 75%. Comparison between the composite samples moving without restriction and the same samples with the bent elements attached.

methods | 41

HB birch 0.9mm 90º EB birch 0.6mm 0º

release stress

i.051 to i.062 Experiment 01 samples 4 to 6 right view, relative humidity from 25% to 75%. Comparison between the composite samples moving without restriction and the same samples with the bent elements attached.

HB birch 0.9mm 45º EB birch 0.6mm 0º

HB birch 0.9mm 15º EB birch 0.6mm 0º

42 | methods

t = 2.5mm

thickness

4.1

radii

349 mm

radii

20.5

t = 1.5mm

2.5

t = 0.6mm

116 mm

7.8

17 mm

curvature radii vs. thickness variation One of the most decisive parameters in relation to the reaction time and the curvature radii of the strips is the thickness of the tested samples. The objective of this test is to investigate how thickness of the wood composite affects the curvature radii and the reaction time. The experiment is carried out under the following setup: Three birch wood composite strips all with the same dimensions [120x25mm] and different thickness [2.5mm1.5mm-0.9mm]. HB = hygroscopic bending As the thickness of the sample increases 4 times, the bending radii increases 20 times. After a long exposure to a high relative humidity level, the radii of the three samples tend to equalize but with different reaction times.

i.065 - i.066 Experiment 02 front view at 30% and 85% relative humidity. i.067 - i.068 Experiment 02 right view at 30% and 85% relative humidity.

methods | 43

birch 90º 20 x 120 x 2.5mm

t = 1.5mm

t = 2.5mm

birch 90º 20 x 120 x 1.5mm

birch 90º 20 x 120 x 0.6mm

t = 0.6mm

birch 90º 20 x 120 x 2.5mm

t = 2.5mm

birch 90º 20 x 120 x 1.5mm

t = 1.5mm

birch 90º 20 x 120 x 0.6mm

t = 0.6mm

44 | methods

30% RH

HB birch 90º 10 x 300 x 2.5mm

HB birch 90º 20 x 300 x 2.5mm

HB birch 90º 30 x 300 x 2.5mm

t = 2.5mm

85% RH

HB birch 90º 10 x 300 x 2.5mm

HB birch 90º 20 x 300 x 2.5mm

HB birch 90º 30 x 300 x 2.5mm

t = 2.5mm

i069 to i072 Experiment front and lateral views at 30% and 85% relative humidity

methods | 45

30% RH

curvature radii vs. wood exposed area The following test was conducted in order to investigate how an exposed wood area of the composite affects the curvature radius and the reaction time as well. The maximum thickness of birch veneers [2.5mm] has been used to test how a scale change would affect the reactiveness of the samples. Three birch wood composite strips, all with the same thickness [2.5mm] and height [300mm], and different width [10mm-20mm-30mm]. HB = hygroscopic bending The result shows how the width of the pieces does not significantly affect the bending radii, as the exposed area is proportional to the dimensions of the sample, but it does affects the reaction time. When relative humidity decreases again after the first cycle, the samples donÂ´t go back to the initial shape. This is probably because they were exposed to a relative humidity of more than 85% for a long period of time, and the fiber saturation point could have been reached, therefore free water could have penetrated the cell lumen.

i073 to i074 Experiment perspective and lateral view at 30%: irregular shape after the first cycle.

In order to get the maximum curvature of the pieces, it is necessary to orient the fibers 90Âş in relation to the longitudinal axis, so there is always material limitation of the trunk diameter. To work on a bigger scale, this limitation has to be taken in account, and also consider joining transverse pieces to have a bigger bending radii with the same reaction time.

46 | methods

cA 120x12mm strip/ t=0.6mm/ maple flat cut composite+epoxy resin+ fiberglass textile 40g/m2, lamination at 80% RH

cB 120x12mm strip/ t=0.9mm/ birch rotary cut composite epoxy resin+ fiberglass textile 20g/m2, lamination at 20% RH

cC 120x12mm strip/ t=0.9mm/ birch wood flat cut composite+epoxy resin+ fiberglass textile 40g/m2, lamination at 20% RH

response control material and geometric parameters One of the most decisive parameters in relation to the response of the pieces is humidity control during lamination. Depending on the relative humidity during lamination, it is possible to have the same geometries reacting in opposite ways to the same environmental changes.

cD 120x12mm strip/ t=1.5mm/ birch wood flat cut composite+epoxy resin+ fiberglass textile 40g/m2, lamination at 20% RH

A high degree of response control and shape variation is driven by the differentiation of the following parameters: [01] fiber direction [02] layout of the natural and synthetic composite [03] length-width-thickness ratio [04] geometry of the strips [05] actuators thickness [06] fiberglass textile density and weight [07] bending stiffness of actuators (type of wood) [08] humidity control during the production process

i.075 Test 02B setup and layout for the 4 samples i.076 - i.079 Test 02B front view at 40%, 50%, 60% and 70% relative humidity. i.080 - i.081 Test 02B right view at 40%, 50%, 60% and 70% relative humidity.

methods | 47

48 | methods

stable state 1

stable state 2

[max]

[min 1] [min 2]

[max]

[min 1]

[max]

[min 2]

BISTABLE geometries fiber direction Bistability is a fundamental phenomenon in nature. Something that is bistable can be resting in either of two states. These rest states need not be symmetric with respect to stored energy. The defining characteristic of bistability is simply that two stable states [minima] are separated by a peak [maximum]. As the Elastic Module of wood on the parallel direction of the fiber is about 10 times bigger than on the perpendicular direction [8 times in the case of birch], if four strips of wood are connected as showed in the diagrams, the resultant geometry will be bistable, depending on the fiber orientation. If the fibers are perpendicular to the longitudinal axis, the resistance to bending is very low, but if the fibers are parallel to the longitudinal axis, the resistance to bending increases. The outcome will be a bistable geometry due to the internal forces of the strips trying to go back to its flat form.

i.082 Bistable geometry diagram of the two minima stable states between a maximum unstable state, perspective and top view.

methods | 49 E Module perpendicular to the fiber direction E Module parallel to the fiber direction

90º

0º

90º

0º

90º

0º

90º

0º

i.083 Diagrams of two different geometric configurations with the same amount of material due to anisotropic nature of wood. (Source: J. Baun, L. Fehrenbacher, H. Linder and A. Wiebe)

50 | methods

Passive actuation The following experiments had the purpose of using wood composite tested on previous experiments as hygroscopic actuators integrated in a bistable cell, in order to trigger a shape change from one stable state to the other. The objective is to release the stored energy of a elastically bent element, which is strong in both positions. Birch wood veneers have been used to develop a responsive bistable cell which has the actuators embeded on their structure. For bending elements, maple wood has been chosen for having less bending stiffness than birch. Due to this difference on the bending stiffness of the two types of wood, the hygroscopic force is capable to overcome the elastic bending force. Four strips were joined, alternating their fiber orientation [0º · 90º · 0º · 90º] in relation to the long axis. The strips with the fibers oriented to 0º are birch wood veneers of 0.6mm thickness. These ones offer a high bending resistance and make the component bistable. The strips with fibers oriented to 90º are birch wood veneers of 1.5mm thickness, laminated with epoxy resin and fiberglass fabri. These ones experiment bigger shape change during the hydration, and will serve as actuators. The aim of the next tests is to trigger shape change on a wooden cell with hygroscopic actuators. The expected result is to achieve, after the hydration of the composite actuators, a snap to the other stable state.

methods | 51 E Module perpendicular to the fiber direction E Module parallel to the fiber direction

0ยบ wood birch flat cut 0.6mm

H actuator

90ยบ wood composite birch rotary cut 1.5mm

0ยบ wood birch flat cut 0.6mm

H actuator

i.084 Topologic diagram of the responsive bistable cell with embed actuators.

90ยบ wood composite birch rotary cut 1.5mm

52 | METHODS

u01

integrated cell unit active bending vs. hygroscopic actuation Could a bistable configuration snap from one stable position to the other by hygroscopic actuation? The study of actuated bistable geometries based on the interaction of the wood hygroscopic force and the stored force of a bent element which is strong in both positions. The objective of this test is to trigger a shape change on a wooden bistable element with hygroscopic actuators. The expected result is to achieve, after the hydration of the composite elements, a snap to the other stable state. The setup of the test is a bistable cell made of 4 connected wooden strips: two of them are composite wood strips with fibers oriented perpendicular to the long axis [birch wood rotary cut laminated with epoxy resin and fiberglass textile [15x125mmx 0.9mm], the other two are wood with fibers oriented parallel to the long axis [birch wood flat cut 0.7x125mmx 0.6mm]. The joints are mechanical connections of two points, in order to avoid the free rotation of the strips. The result shows that the hygroscopic force is enough to release the stored energy of the elastic bent elements, but there is no â&#x20AC;&#x153;snapâ&#x20AC;? of the elements from one state to the other. The reason is because the Elastic modulus of wood decreases with the moisture content, and possibly some fiber rearrangement occur during the humid state. Other possible explanation is that under a long exposure to a RH higher than 80%, the fiber saturation point could have been reached and free water has penetrated the

i.085 Topologic diagrams for 2 cells in dry state (30%RH) and wet state (80%RH), perspectives

methods | 53

i.086 to i.093 Test 05A actuation sequence and shape changes under relative humidity variation from 30% - 85% - 30%.

54 |

| 55

56 | METHODS

FORCE EQUILIBRIUM REACTION TIME The experiment was repeated several times with different samples of wood, in order to confirm if the different reaction time was due to the material heterogeneity. The samples were exposed to a high relative humidity level for a longer period of time. The result shows that despite the irregular reaction times, all the actuators were able to release the strain energy of the bent elements achieving the maximum position. This is possible because the elastic Module of wood decreases with moisture content, so the initial resistance to bending is decreasing as the relative humidity rises. FIBER REARRANGEMENT After a long exposure to a high relative humidity level (more than 85%) inside the climate box, the fiber saturation point may have exceeded, and during the drying process wood fibers could have rearranged according the internal forces of the module. The result shows that the module has snapped to its second stable state, but at the end of the experiment it is not a bistable geometry but a monostable one, which means that has a spring back tendency to one of the two initial stable states. System parameters and range The ratio between thickness and the bending stiffness of the elements is crucial to amplify the shape variation in the studied geometry. Several physical tests were conducted in order to find the optimal ratio. The following parameters were explored: [01] fiber direction [02] layout of the natural and synthetic composite [03] length-width-thickness ratio [04] geometry of the strips [05] actuatorsâ&#x20AC;&#x2122; thickness [06] fiberglass textile density and weight [07] bending stiffness of actuators (type of wood) [08] bending stiffness of actuators and active bending elements ratio [09] humidity control during the lamination process

methods | 57

ACTUATORS

BENding ELEMENTS

geometry 120x15mm strips

geometry 120x7.5mm strips

120mm

7.5mm

15mm

h1: birch and maple veneers quarter cut/ t=0.6mm

h2: birch veneer quarter cut/ t=0.9mm

h3: birch veneer quarter cut/ t=1.5mm

t1:

fiberglass textile 40g/m2

t2: fiberglass textile 20g/m2

i.094 Illustration of the geometric and material parameters of the system

b1: birch and maple veneers quarter cut/ t=0.6mm

b2: birch veneer quarter cut/ t=0.6mm [sealed both sides with epoxy]

b3: anisotropic fiber reinforced composite/ t=0.6mm [unidirectional fiberglass fibers + epoxy]

58 | METHODS

ACTUATORS lamination 40% geometry 120x15mm strips

120mm

15mm

h2: birch veneer flat cut/ t=0.9mm

t1: fiberglass textile 40g/m2

BENding ELEMENTS geometry 120x7.5mm strips

120mm

7.5mm

b2:

birch veneer quarter cut/ t=0.6mm [sealed both sides with epoxy]

i.095 Test 03A parameters diagram i.096 - i.103 Test 03A actuation sequence front and right views at 40%, 50%, 60% and 70% relative humidity.

methods | 59

ACTUATORS lamination 40% geometry 120x15mm strips

120mm

15mm

h2: birch veneer flat cut/ t=0.9mm

t1: fiberglass textile 40g/m2

BENding ELEMENTS geometry 120x7.5mm strips

120mm

7.5mm

b3:

anisotropic fiber reinforced composite/ t=0.6mm [unidirectional fiberglass fibers + epoxy]

i.104 Test 03B parameters diagram i.105 - i.112 Test 03B actuation sequence front and right views at 40%, 50%, 60% and 70% relative humidity.

60 | METHODS

ACTUATORS lamination 40% geometry 120x15mm strips

120mm

15mm

h2: birch veneer flat cut/ t=0.9mm

t1: fiberglass textile 40g/m2

BENding ELEMENTS geometry 120x7.5mm strips

120mm

7.5mm

b2:

birch veneer quarter cut/ t=0.6mm [sealed both sides with epoxy]

i.113 Test 04C parameters diagram i.114 - i.115 Test 04C actuation sequence front and right views at 40%, 50%, 60% and 70% relative humidity.

methods | 61

ACTUATORS lamination 40% geometry 120x15mm strips

120mm

15mm

h3: birch veneer flat cut/ t=1.5mm

t1: fiberglass textile 40g/m2

BENding ELEMENTS geometry 120x7.5mm strips

120mm

7.5mm

b2:

birch veneer quarter cut/ t=0.6mm [sealed both sides with epoxy]

i.116 Test 04B parameters diagram i.117 - i.118 Test 04B actuation sequence front and right views at 40%, 50%, 60% and 70% relative humidity.

62 | METHODS

ACTUATORS lamination 80% geometry 120x15mm strips

120mm

15mm

h4: maple veneer flat cut/ t=0.6mm

t1: fiberglass textile 40g/m2

BENding ELEMENTS geometry 120x7.5mm strips

120mm

7.5mm

b1:

birch veneer flat cut/ t=0.6mm

i.119 Test 05A parameters diagram i.120 - i.121 Test 05A actuation sequence front and right views at 40%, 50%, 60% and 70% relative humidity.

methods | 63

ACTUATORS lamination 80% geometry 120x15mm strips

120mm

15mm

t1: fiberglass textile 40g/m2

h4: maple veneer flat cut/ t=0.6mm

BENding ELEMENTS geometry 120x7.5mm strips

120mm

7.5mm

b1:

birch veneer flat cut/ t=0.6mm

i.122 Test 05B parameters diagram i.123 - i.130 Test 05B actuation sequence front and right views at 40%, 50%, 60% and 70% relative humidity.

64 | methods

i.131 Sequence of curling wood veneer composite strips.

bending curves The curve that describes an elastically bent element is more similar to a parabola, whereas the curve that describes an hygroscopic curled element is a circle. The difference between this two types of curvatures and the different stiffness due to fiber direction makes this geometric cell bistable in a dry state. Although the actuators are capable of releasing the stress of the bending elements and a shape change is performed, this geometry will not suddenly â&#x20AC;&#x153;snapâ&#x20AC;? from a stable state to the other. This effect is produced because on a wet state, the bending elements achieve their flat position so there is no force acting on them to cause them bend and to try to overcome this force. The range of the system is then confined, so no sudden shape change will be achieved but a more kinematic shape variation of the overall system.

methods | 65

i.132 Sequence of bending strip trajectories. (Source: Marten Nettelbladt)

[min]

E [max]

[min]

i.133 - i.134 Diagram of the concept of a bistable system applied to the used geometry and diagram of the range of the actuated system.

66 | METHODS

u02

u01

u02

u01

cell connection weight influence test A suspended prototype with 2 connected cells is tested under a relative humidity range from 30% to 80% to observe how the connections of more than one bistable element affect the overall shape change under relative humidity variations. The aim of the experiment is to test if the connection of two bistable modules block the hygroscopic actuation due to the extra weight of material or gravity. The result shows that each module has an internal force equilibrium, and the weight of one module hanging from the other is not affecting the actuation. The joints cause the hygroscopic force to manifest with rotation.

i.135 Topologic diagrams for 2 cells in dry state 30% RH and wet state 80% RH , perspectives

methods | 67

i.136 and i.137 Hanging model at 30% and 80% relative humidity.

68 | methods

i.138 to i.146 Sequence of actuation and shape changes under variation of relative humidity from 30% to 80%

methods | 69

i.147 to i.155 Sequence of actuation and shape changes under variation of relative humidity from 80% to 30%

70 | METHODS u02

u01

u06

u00

u05

u03

u04

u01

u03

u02

u04 u00

u05

u06

lattice system weight influence with multiple connections A suspended prototype with 7 cells and 6 connections is tested under a relative humidity range from 20% to 80% to observe how the connections between elements affect the overall shape change under relative humidity variations. The aim of the experiment is to observe if the connection of multiple cells blocks the hygroscopic actuation due to the extra weight of material or gravity. With the increase of the number of modules, the resulting global shape after the hydration is a complex form which reflects the force interaction between elements rather than a planar surface.

i.156 Topologic diagrams for 7cells [6 conections_2 anchor points] in dry state (25%RH) top view and wet state (80%RH) front view

| 71

i.157 and i.158 Hanging model at 22% and 59% relative humidity.

72 |

i.159 to i.167 Sequence of actuation and shape changes under variation of relative humidity from 30% to 80%

| 73

i.168 to i.176 Sequence of actuation and shape changes under variation of relative humidity from 80% to 30%

74 | METHODS u02

u01

u08

u06

u07

u00

u05

u03

u04

u02

u01

u08

u06

u00

u05

u07

u03

u04

lattice cohesion neighbor cell influence test A setup with 9 cells and 10 connections is tested under a relative humidity range from 20% to 80% to observe how the extra connections between elements affect the overall shape change under relative humidity variations. The aim of the experiment is to observe if the connection of multiple cells blocks the hygroscopic actuation due to the extra weight of material or gravity. With the increase of the number of connections, the resulting global shape after the hydration is a complex form which reflects the force interaction between elements rather than a planar surface. Loops are created inside the initial planar grid as the result of the accumulation of rotation angles.

i.177 Topologic diagrams for 9 cells [10 conections_2 anchor points] in dry state (25%RH) top view and wet state (80%RH) front view

| 75

i.178 to i.186 Sequence of actuation and shape changes under variation of relative humidity from 30% - 85% - 30%

76 | METHODS i.187 Hanging model [9 cells] at 26% relative humidity

METHODS | 77 i.188 Hanging model [9 cells] at 83% relative humidity

78 | methods

simulation methods The material behavior can be simulated and then programmed to control the response of the designed structure by extracting the fabrication data from the computational simulation. From the conducted physical experiments, several measurements and parameters have been extracted to inform the computational model. Once controlled the simulation, the reverse process is possible so that data is again extracted to fabricate larger prototypes and predict its responsiveness. The following computational methods have been developed to simulate and control the behavior of the system. [i] geometric representation model [ii] parametric representation model [iii] spring-based representation model [iv] spring-based abstracted model for global design

i.189 Computational simulation workflow diagram

methods | 79

cells| physical experiments

fabrication| material scanning and selection

geometry| parameters

abstracted simulation| form finding and actuation

80 | methods

geometric model This first simulation method is based on the geometric principle of the length of a circle arch and the differential expansion ratios of the bilayer composite. It has been developed and further compared to the physical experiments. It gives an accurate representation of the behavior of the strips under relative humidity variations, but it does not take into account the reaction time or other factors such as bending stiffness, that decreases as the humidity rises. The algorithm relates the thickness with bending radii according to the expansion of the wood on the due to hygroscopicity. The expansion range is on the average from 10% on the tangential fiber direction depending on the species, the range used on this model goes from 0% to 9.2% expansion [birch wood]. parameters [i] strip thickness [ii] strip length [iii] fiber direction [iv] fiber spacing [v] bending radii i.190 Diagram of the curling strips in the geometric representation model.

methods | 81

r2 l1

82 | methods

stable layer [synthetic composite] bilayer connection out of vision springs intermediate bending layer reactive layer [natural composite wood]

spring-based model The basic cell unit has been simulated with Kangaroo Physics in a model based on fiber directionality and spacing, bending springs and expandable/contractile springs (actuation wood fibers). The key for the reliability of this model is a balance between springs that simulate also the anisotropy of the material and the reduction of the force of the springs as the humidity increases and the material expands. On the first phase of the relaxation the tension forces produced by cell connections achieve an equilibrium position of the grid that corresponds to the dry state of the environment [40% RH]. On the second phase of the relaxation, the cell morphs by the expansion or contraction of the wood in the tangential direction only in the actuators, which is simulated with the separation or contraction of the fibers in the tangential direction only in the actuators. This leads to a quite realistic simulation of the behavior of an actuated cell, as it happens in the physical experiments, in terms of form and force interaction [tangential expansion or contraction from 0 to 10%].

layout diagram of 1 cell in the spring based model i.192 simulated relaxation sequence and actuated cell i.193

methods | 83

R117.00

R99.11 R97.32 R113.11 R176.44 R429.12 R2594.84 R2552.01

R2594.84 R429.12 R176.44 R113.11 R97.32 R99.11

R117.00

84 | methods

abstracted model To design and control larger scale systems [more than 2 cells] with multiple connections and grid differentiation, the limitations of the previous model in terms of computational resources and time consumption make necessary the abstraction of the model for the control of the actuation, the response degree and the extraction of the data for 1:1 scale fabrication. The basic cell unit has been reduced to 4 points connected by differentiated springs and actuators. The key for the reliability of this model is a balance between springs that simulate also the anisotropy of the material and the reduction of the force of the springs as the humidity increases and the material expands. The grid is treated as a double layer structure: with outer and inner layer on which the actuation takes place, interconnected by an intermediate elastically-bent layer that is the actuated zone. On the first phase of the relaxation, the tension forces produced by cell connections strive for the equilibrium position of the grid that corresponds to the dry state of the environment [40% RH]. On the second phase of the relaxation, the grid morphs by the expansion or contraction of the wood in the tangential direction only in the actuators, which is simulated with the bending angle variation between the lattice axisâ&#x20AC;&#x2122; finite elements. This leads to global shape variation due to the local finite elements manipulation [expansion or contraction from 0 to 10%].

topologic diagram of the lattice and its cells i.194 initial state, relaxed state and actuated state of abstracted lattice i.195

methods | 85

06/fabrication

88 | FABRICATION

i.1

i.2

i.3

i.4

i.5

i.6

material selection Due to the organic and heterogeneous nature of wood, a wood composite material and a responsive structure based on this material could not behave as expected if the material is not selected appropriately. A computational tool has been developed in order to improve and systematize the material selection to get a more predictable behavior of the composite. The tool consists in an algorithm able to select nest online a series of desired geometries in a wood sample based on scanned image. The analysis of the fiber direction in wood veneers is used to select the material and to make a robotic path decision based on the scanned image. The aim is to nest online the desired geometries in each material sample according to: · layout of geometries to mill · desired fiber orientation from 0º to 90º [vector] · desired spacing between fibers [n lines] A robot has been used for surveying the different material samples, defining a path all over the material to scan it. The most interesting part of the process is not the use of the robot, but the overall online nesting process: the image processing, the path decision generation based on the received data of each piece of material. The tool has been developed in a way that it is possible both use it as off-line and on-line process.

i.196 Specific desired ideal geometries [dimensions, fiber orientation and spacing] i.197 Ideal trunk [regular spacing and angle in relation to the longitudinal axis] i.198 Heterogeneity of the fiber orientation [variable spacing and angle in relation to the longitudinal axis] i.199 Heterogeneity of the trunks [variable length 2000 to 3000 mm - width 120 to 400mm]

birch ve er 0.9 rotÂ&#x2020;y cÂ&#x2C6; [tÂ&#x160;geÂ&#x2039;iÂ&#x152;]

NO MINATION

MINA D

0.9 rotÂ&#x2020;y cÂ&#x2C6;

birch ve er 0.9 flat cÂ&#x2C6;

birch ve er 0.9 quÂ&#x2020;Â?r cÂ&#x2C6;

birch ve er 0.9 flat cÂ&#x2C6;

birch ve er 0.9 quÂ&#x2020;Â?r cÂ&#x2C6;

birch ve er 1.5

birch ve er 1.5 + resin +fibergÂ?Â? Â?xtile 49g/m2

1 . 5mm

birch ve er 0.9 + resin +fibergÂ?Â? Â?xtile 49g/m2

0.9

2. 5mm

birch ve er 0.6

0. 6mm B I R CH

Â&#x2DC;riÂ&#x2122;n mÂ&#x161;le ve er 0.6 [belen]

Â&#x2DC;riÂ&#x2122;n mÂ&#x161;le ve er 0.6 [dyÂ?n]

0. 6mm MAP L E

FABRICATION | 89

i.000 Fabrication template for milling

90 | fabrication

CO ROL PC / KU

PR E ING PC

INITIATION input size of part to be scanned generate path need to scan part

KRL*.src

scanning program initiates movement to first point

RSI

movement pauses

Rhino / gh / sandbox

signal sent to camera to capture

web m

TA COLLE ION [loop]

Rhino / gh / Firefly / gHowl

signal sent to resume movement

RSI

movement resumes

image saved

TA PR E ING PA EXEC ION

image processed [vector] images combined Rhino / Python / C# PARTS LIST Âˇ center point Âˇ grain vector Âˇ grain spacing

part selected [grain spacing] path generation for milling path polylines and join holes

milling movement initiated

Rhino / Python / gh

i.200 Off-line nesting flowchart

fabrication | 91

CO ROL PC / KU

PR E ING PC

INITIATION input size of part to be scanned generate path need to scan part

KRL*.src

scanning program initiates movement to first point

RSI

movement pauses

Rhino / gh / sandbox

signal sent to camera to capture

web m

TA COLLE ION [loop]

Rhino / gh / Firefly / gHowl

Rhino / Python / C# movement to next area to scan

image saved image processed [vector]

PARTS LIST Âˇ center point Âˇ grain vector Âˇ grain spacing

part selected [grain spacing] path generation for milling path polylines and join holes Rhino / Python / gh

i.201 On-line nesting flowchart

RSI

milling movement initiated

TA PR E ING PA EXEC ION

92 | fabrication

i.202 image of a wood veneer to analyze [*.png file]

i.203 Analyzed hue data from the image with Grasshopper and C# [vector file, xyz point coordinates and values]

i.204 Modified hue data from the image to add contrast for fiber detection with C# [vector file, xyz point coordinates and values]

i.205 Filtered hue data for edge-pixel detection with C# [vector file, xyz point coordinates and values]

fabrication | 93

A · get image from webcam · detect image size [3568 x 1120px]

B · real time data from webcam to grasshopper using Firefly and Ghowl · unit translation from pixel to mm set the correspondence between units [1 pixel = X units in Rhino] · analyze each pixel color with C# · get a list [length = n pixels] with color values. · draw a point with Grasshopper in Rhino canvas corresponding to each pixel center point

C · analyze brightness or hue of each pixel and get a list of values. · organize point/value lists by rows and columns

D · compare the analyzed value of each pixel with the neighbor pixels. · if value > tolerance this is an edge pixel then draw a point · draw vectors between edge pixels in the main direction of the wood fibers · join vectors from left to right and extract fiber direction polylines

94 | fabrication

frame mapping The scanning path and the stop points coordinates are generated according to the dimensions of the surveyed material sample but also according to the size of the pieces to cut. The resolution of the data is adapted to the target size and scale of the geometries to mill. A formula for the robot Z position is extracted from the optical characteristics of the webcam, and it is integrated in the robot path generation algorithm.

Formula for Z position generation i.196 Grid adjustment to the camera frame camera position Z= 400mm i.197 Survey of 2 corner points of the wood veneer sample for grid fitting i.198 Robot end-effector with webcam i.199

fabrication | 95

96 | fabrication

P01

P02

P03

P04

P05

P06

P07

P08

P09

P10

P11

P12

P13

P14

P15

P16

P17

P18

P19

P20

P21

P22

P23

P24

P25

P26

P27

i.206 to i.232 robot path sequence for scanning material sample [27 camera frame points]

fabrication | 97

i.233 to i.260 webcam stored data in each stop point and analyzed images results [27 camera frame points]

98 | fabrication

end-effector A 路 webcam

online nesting and milling The most interesting part of the process is not the use of the robot, but the overall online nesting process: image processing, and path generation based on the received data of each piece of material. The tool has been developed in a way that it is possible both use it as off-line and on-line process. The off-line method is without using RSI: first scanning, storing the image and, after the processing of the overall data, a global map of the sample is constructed all the pieces are nested an milled at the end. The on-line method uses RSI to feed back on each loop the position of the robot: a part of the wood is scanned and analyzed and the geometry that fits best according to fiber direction and spacing is milled, then the robot moves to the next part and so on until all the pieces are milled or until all the material has been used. In one single process, scanning and milling could be achieved with a double end-effector consisting in a webcam with a spindle. The more accurate the material selection for the fabrication of the prototypes, the more control over the global response will be achieved.

i.261 Graphic of the scanning simulation with a webcam as end-effector

fabrication | 99

end-effector B 路 webcam 路 spindle [tool 2.5mm]

i.262 Graphic of the scanning simulation with a webcam + spindle as end-effector

100

101

06/design development

102 | design development

multidirectional lattices A series of prototypes of multidirectional lattice structures were fabricated and tested according to the material properties and behavior, in response to external conditions. The last level of the research, the global design shape control of a responsive lattice structure, is showcased in multi-cell lattice configurations. The grid is managed as a double layer structure: an outer and inner layer on which the actuation takes place, interconnected by an intermediate elasticallybent layer that represents the actuated zone. Topological and structural differentiation were explored and integrated in the design process: depending on the length of the actuators, the direction and layout of the actuation and the placement of the actuators inside the lattice the response and the form would be completely different in two identical structures. The gradient between actuation thickness to was also explored, in order to have different reaction times and the implementation of neutral or passive cells in the system, which are neutral lines or cells with no actuation that could potentially become the boundary condition of the system.

contracted sequence of 6 cells in dry environment 40% RH i.263 expanded sequence of 6 cells in wet environment 80% RH i.264

design development | 103

12/12_0.9 OO

12/11_0.9 OO

12/10_0.9 OO

12/09_0.9 OO

12/08_0.9 OO

12/07_0.9 OO

12/06_0.9 OO

12/12_0.9 OO

12/11_0.9 OO

12/10_0.9 OO

12/09_0.9 OO

12/08_0.9 OO

12/07_0.9 OO

12/06_0.9 OO

12/12_0.9 OO

12/11_0.9 OO

12/12_0.9 OO

12/12_0.9 OO 12/10_0.9 OO

12/10_0.9 OO

12/11_0.9 OO

12/11_0.9 OO 12/09_0.9 OO

12/09_0.9 OO

12/10_0.9 OO

12/08_0.9 OO 12/09_0.9 OO

12/07_0.9 OO 12/08_0.9 OO 12/06_0.9 OO

12/07_0.9 OO

12/06_0.9 OO

i.265 sequence of geometrically differentiated cells i.266 map for 2 possible connection sequence of the differentiated cells

12/07_0.9 OO 12/08_0.9 OO 12/06_0.9 OO

12/07_0.9 OO

12/06_0.9 OO

104 | design development

X [16 cells] 12/12_0.9 OO

12/12_0

12/12_0.9 OO

12/11_0.9 OO

12/12_0.9 OO

12/11_0.9 OO

12/12_0

12/10_0.9 OO 12/12_0.9 OO

12/11_0.9 OO

12/12_0.9 OO

12/10_0.9 OO 12/12_0.9 OO

12/09_0.9 OO

12/11_0.9 OO

12/12_0

12/10_0.9 OO 12/12_0.9 OO

12/09_0.9 OO 12/10_0.9 OO

12/12_0

12/09_0.9 OO

12/12_0.9 OO

actuatorsâ&#x20AC;&#x2122; length variation Introducing length variation of the actuators in the global geometry allows to have differentiated curvature in the initial non-actuated structure: from planar elements geometric variation could be achieved according to the desired target geometry. With a local manipulation of the cells, the same exact number of connected cells lead to highly differentiated structures due to the variation of the length of the bending elements and the actuatorÂ´s length ratio.

responsive lattice structure [16 cells] in dry state i.267 map for Responsive lattice structure [16 cells] i.268

design development | 105

exp X [16 cells] 12/12_0.9 OO

12/12_0.9 OO

12/11_0.9 OO

12/12_0.9 OO

12/11_0.9 OO 12/10_0.9 OO

12/12_0.9 OO

12/11_0.9 OO 12/10_0.9 OO 12/09_0.9 OO

12/11_0.9 OO 12/10_0.9 OO 12/09_0.9 OO 12/10_0.9 OO 12/09_0.9 OO

12/09_0.9 OO

12/12_0.9 OO

i.269 responsive lattice structure [16 cells] in dry state i.270 map for Responsive lattice structure [16 cells]

12/12_0.9 OO

106 | design development

i.271 responsive lattice structure [24 cells] standing model test 00h 00 min 45% RH

actuatorsâ&#x20AC;&#x2122; tHICkNESS variation Introducing variation in the actuators thicknesses in the global geometry allows to have differentiated curvature and response time in the final actuated structure. With local manipulation of the cells, the same exact geometry of cells but with a gradient variation of the thickness lead to a programed choreography of reaction sequence of the structure. The structural part should be further controlled to avoid material deformations. actuation upper layer

actuation upper layer

actuation lower layer

actuation lower layer O negative curvature I positive curvature

O /negative curvature I /positive curvature

+ OO

design development | 107

i.272 responsive lattice structure [24 cells] standing model test 02h 15 min 80% RH

exp 19A [24 cells] t= 1.5 mm 12/12_1.5 OO

t= 1.5 mm

12/12_1.5 OO

12/12_0.9 OO

12/12_1.5 OO

t= 0.9 mm t= 0.9 mm

12/12_0.9 OO

12/12_0.6 OO

12/12_0.9 OO

12/12_0.6 OO

i.273 Instructions for actuation layout diagram i.274 Map for Responsive lattice structure [40 cells]

actuationlower lowerlayer layer actuation O Onegative negativecurvature curvature positivecurvature curvature I I positive

actuation actuationupper upperlayer layer

uation lower layer egative curvature positive curvature

t= 0.6 mm 12/12_0.6 OO

12/12_0.6 OO

uation upper layer

t= 0.6 mm

108 | design development

i.275 responsive lattice structure [24 cells] suspended model test 00h 00 min 45% RH

suspended models A series of suspended prototypes were tested under climatic variation. The gravity force is used to control and avoid material deformations. The same prototype previously tested shows less material failure due to thickness difference. This is a key factor for further developments: for desired differentiated reaction times and scale transitions in the overall structure, an strategic use of the gravity force combined with the precisely anchor points of the structure could improve the system performance. actuation upper layer

actuation upper layer

actuation lower layer

actuation lower layer O negative curvature I positive curvature

O /negative curvature I /positive curvature

+ OO

design development | 109

i.276 responsive lattice structure [24 cells] suspended model test 02h 15 min 80% RH

exp 19A [24 cells] t= 1.5 mm 12/12_1.5 OO

t= 1.5 mm

12/12_1.5 OO

12/12_0.9 OO

12/12_1.5 OO

t= 0.9 mm t= 0.9 mm

12/12_0.9 OO

12/12_0.6 OO

12/12_0.9 OO

12/12_0.6 OO

i.277 Instructions for actuation layout diagram i.278 Map for Responsive lattice structure [40 cells]

actuationlower lowerlayer layer actuation O Onegative negativecurvature curvature positivecurvature curvature I I positive

actuation actuationupper upperlayer layer

uation lower layer egative curvature positive curvature

t= 0.6 mm 12/12_0.6 OO

12/12_0.6 OO

uation upper layer

t= 0.6 mm

110 | design development

xp exp 21A 21A [9[9 cells] cells] 12/12 IO

12/12 IO

12/12_0.9 OO12/12_0.9 OO

12/12 IO

12/12_0.9 OO12/12_0.9 OO

12/12 IO

12/12_0.9 OO12/12_0.9 OO

12/12 IO

12/12_0.9 OO12/12_0.9 OO

12/12 IO

12/12_0.9 OO12/12_0.9 OO

actuation direction Vs. curvature actuation upper layer

actuation upper layer

actuation lower layer

actuation lower layer O negative curvature I positive curvature

O /negative curvature I /positive curvature

+ OO

Not only the kinematic behavior of a responsive structure can be programed with the differentiated fiber layout of the cells, but also the final curvature radius and curvature direction. Two models with the same exact geometry, thickness and amount of material can respond in opposite ways to the same external stimuli due to the differentiated fiber layout and actuation direction.

12/12 IO

i.279 2 lattice structures with response differenciation [12 cells] suspended models test 00h 00 min 45% RH

design development | 111

exp 21A exp [9 21A cells] [9 cells] i.280 2 lattice structures with response differenciation [12 cells] suspended models test 02h 15 min 80% RH

12/12 IO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

12/12 IO

uation upper layer

actuation upper layer

uation lower layer egative curvature positive curvature

actuation lower layer O negative curvature I positive curvature

12/12_0.9 OO

i.281 Instructions for actuation layout diagram i.282 Map for 2 responsive lattice structures with response differenciation [12 cells]

12/12 IO

12/12_0.9 OO

112 | design development

i.283 lattice structure with response differentiation [24 cells] suspended model test 00h 00 min 45% RH

curvature transitions A curvature transition in the overall actuated shape will generate a smooth movement without structural failure of the elements when the change in curvature direction does not imply opposite forces in the same direction. A neutral line in the grid could remain non-actuated, in order to use it as anchor grid axis, and also to soften the curvature shift areas.

actuation upper layer

actuation lower layer

actuation lower layer O negative curvature I positive curvature

O /negative curvature I /positive curvature

+ OO

design development | 113

exp 21B [18 cells]

i.284 lattice structure with response differentiation [24 cells] suspended model test 02h 15 min 80% RH

12/12 IO

12/12_0.9 OO

actuationlower lowerlayer layer actuation O Onegative negativecurvature curvature positivecurvature curvature I I positive

i.285 instructions for actuation layout diagram i.286 map for Responsive lattice structure [24 cells]

actuation actuationupper upperlayer layer

uation lower layer egative curvature positive curvature

uation upper layer

12/12_0.9 OO

114 | design development

exp 22A [4

i.287 responsive lattice structure [40 cells] 00h 00 min 45% RH

12/

12/12_0.9 OO

12/

12/12_0.9 OO

12/

actuation upper layer

actuation lower layer

actuation lower layer O negative curvature I positive curvature

O /negative curvature I /positive curvature

+ OO

design development | 115

40 cells]

i.288 responsive lattice structure [40 cells] test 02h 15 min 80% RH

12/12_0.9 OO

/12_0.9 OO

12/12_0.9 OO

/12_0.9 OO

12/12_0.9 OO

12/12 OI

12/12_0.9 OO

12/12 OI

12/12_0.9 OO

12/12 OI

/12_0.9 OO

12/12 OI

12/12_0.9 OO

12/12 OI

12/11_0.9 OO

12/12_0.9 OO

12/11_0.9 OO 12/10_0.9 OO

12/12_0.9 OO

12/11_0.9 OO 12/10_0.9 OO 12/09_0.9 OO

12/11_0.9 OO 12/10_0.9 OO 12/09_0.9 OO 12/10_0.9 OO

uation lower layer egative curvature positive curvature

actuationlower lowerlayer layer actuation O Onegative negativecurvature curvature positivecurvature curvature I I positive

i.289 Instructions for actuation layout diagram i.290 Map for Responsive lattice structure [40 cells]

12/09_0.9 OO

actuation actuationupper upperlayer layer

uation upper layer

116 | design development

exp 22B [40 cells]

i.291 responsive lattice structure [40 cells] 00h 00 min 45% RH

12/09_0.9 OO

12/10_0.9 OO

12 12/11_0.9 OO

12/11_0.9 OO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

12/12 IO

12/12_0.9 OO

design development | 117

i.292 responsive lattice structure [40 cells] test 02h 15 min 80% RH

12/09_0.9 OO

2/10_0.9 OO 12/09_0.9 OO 12/10_0.9 OO

12/10_0.9 OO 12/11_0.9 OO

12/11_0.9 OO

12/12_0.9 OO

actuation upper layer

actuation lower layer

actuation lower layer O negative curvature I positive curvature

O /negative curvature I /positive curvature

+ OO

i.293 Instructions for actuation layout diagram i.294 Map for Responsive lattice structure [40 cells]

actuationlower lowerlayer layer actuation O Onegative negativecurvature curvature positivecurvature curvature I I positive

actuation actuationupper upperlayer layer

uation lower layer egative curvature positive curvature

uation upper layer

118

119

07/design proposal

120 | design proposal

proof of concept All the system capacities are summarized in a large scale prototype to showcase the possible applications of the developed material and computational research. It not only presents the range of the behavior of a responsive natural structure, but also the scale limitations due to material and structural constrains. The basic cells extensively studied during the process were scaled up, taking into account the optimal geometric ratios to perform the target behavior. A computational model provides the fabrication data for the full scale prototype: material thickness, fiber direction, geometry data are extracted from the abstracted spring based representation model. The design proposal for the proof of concept prototype has been developed according to: · 1:1 size and scale limitation · material limitation · shape variation range · actuation range : active and passive cells · reaction time and stability · structural considerations: self supporting lattice · space defining structure

Large scale prototype proof of concept during assembly process i.295

design proposal | 121

b_270x30mm/ t=2.5

1014

1113

1212

b_235x30mm/ t=2.5 b_238x30mm/ t=2.5

1216

32.5/27_2.5 --

1013

27/27_2.5 OI

1112

1211

913

32.5/27_2.5 --

1215

27/27_2.5 OI

1012

27/27_2.5 OI

1111

1210

1115

32.5/27_2.5 --

912

27/27_2.5 OI

1214

27/27_2.5 OI

1011

1110

27/24.6_2.5 OI

129

O-

27/24.6_2.5 OI

I-

27/24.6_2.5 OI

actuation lower layer

O negative curvature I positive curvature

actuation upper layer

27/24.6_2.5 OI

b_270x30mm/ t=2.5 b_123x30mm/ t=1.5

t=2.5

b_235x30mm/ t=2.5 b_235x30mm/ t=2.5

812

32.5/27_2.5 --

1114

27/27_2.5 OI

911

27/27_2.5 OI

1213

27/24.6_2.5 OI

1010

27/22.4_2.5 OI

119

-O

128

27/22.4_2.5 OI

-I

b_286x30mm/ t=2.5 b_286x30mm/ t=1.5 b_235x30mm/ t=2.5 b_325x30mm/ t=2.5

1014

32.5/27_2.5 --

811

27/27_2.5 OI

1113

27/27_2.5 OI

910

27/27_2.5 OI

1212

27/24.6_2.5 OI

109

27/22.4_2.5 OI

118

127

711

32.5/27_2.5 --

1013

27/27_2.5 OI

810

27/27_2.5 OI

1112

27/24.6_2.5 OI

1211

27/22.4_2.5 OI

108

27/22.4_2.5 OI

117

27/22.4_2.5 OI

126

913

32.5/27_2.5 --

710

27/27_2.5 OI

1012

27/27_2.5 OI

1111

27/24.6_2.5 OI

1210

27/22.4_2.5 OI

107

27/22.4_2.5 OI

116

27/20.3_2.5 OI

125

610

32.5/27_2.5 --

912

27/27_2.5 OI

1011

27/27_2.5 OI

27/24.6_2.5 OI

1110

27/24.6_2.5 OI

129

27/24.6_2.5 OI

106

27/22.4_2.5 OI

115

27/20.3_2.5 OI

124

812

32.5/27_2.5 --

27/27_2.5 OI

911

27/27_2.5 OI

27/24.6_2.5 OI

1010

27/27_2.5 OI

27/22.4_2.5 OI

119

27/24.6_2.5 OI

27/22.4_2.5 OI

128

27/24.6_2.5 OI

105

27/22.4_2.5 OI

114

27/20.3_2.5 OI

123

32.5/27_2.5 --

811

27/27_2.5 OI

910

27/27_2.5 OI

27/24.6_2.5 OI

109

27/27_2.5 OI

27/22.4_2.5 OI

118

27/27_2.5 OI

27/22.4_2.5 OI

127

27/24.6_2.5 OI

104

27/22.4_2.5 OI

113

27/20.3_2.5 OI

122

b_235x30mm/ t=2.5 b_235x30mm/ t=2.5

27/22.4_2.5 OI

b_270x30mm/ t=2.5 b_286x30mm/ t=2.5

b_286x30mm/ t=2.5 b_235x30mm/ t=2.5

b_123x30mm/ t=1.5 b_204x30mm/ t=2.5

b_270x30mm/ t=2.5 b_204x30mm/ t=2.5

b_123x30mm/ t=1.5 b_270x30mm/ t=2.5

b_235x30mm/ t=2.5 b_270x30mm/ t=2.5

b_286x30mm/ t=2.5 b_270x30mm/ t=2.5

b_204x30mm/ t=2.5 b_270x30mm/ t=2.5

711

32.5/27_2.5 --

27/27_2.5 OI

810

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

108

27/27_2.5 OI

27/22.4_2.5 OI

117

27/27_2.5 OI

27/22.4_2.5 OI

126

27/24.6_2.5 OI

103

27/22.4_2.5 OI

112

121

27/20.3_2.5 OI

b_325x30mm/ t=2.5 b_270x30mm/ t=2.5

-- OO

27/27_2.5 OI

b_286x30mm/ t=1.5

b_270x30mm/ t=2.5 b_286x30mm/ t=2.5

b_270x30mm/ t=2.5 b_192x30mm/ t=0.9

b_238x30mm/ t=2.5 b_270x30mm/ t=2.5 b_235x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_235x30mm/ t=2.5

b_270x30mm/ t=2.5 b_286x30mm/ t=1.5

b_183x30mm/ t=2.5 b_183x30mm/ t=2.5

b_235x30mm/ t=2.5 b_270x30mm/ t=2.5

b_235x30mm/ t=2.5 b_123x30mm/ t=1.5 b_183x30mm/ t=2.5 b_286x30mm/ t=2.5

b_162x30mm/ t=1.5 b_235x30mm/ t=2.5

b_286x30mm/ t=1.5 b_204x30mm/ t=2.5

b_235x30mm/ t=2.5 b_204x30mm/ t=2.5

b_270x30mm/ t=2.5 b_192x30mm/ t=1.5 b_270x30mm/ t=2.5 b_325x30mm/ t=2.5 b_235x30mm/ t=2.5 b_235x30mm/ t=2.5

b_286x30mm/ t=1.5 b_270x30mm/ t=2.5

b_123x30mm/ t=0.9 b_235x30mm/ t=2.5

b_262x30mm/ t=2.5 b_286x30mm/ t=2.5

b_270x30mm/ t=2.5 b_286x30mm/ t=2.5

b_286x30mm/ t=1.5 b_270x30mm/ t=2.5

b_204x30mm/ t=2.5 b_235x30mm/ t=2.5

b_204x30mm/ t=2.5 b_270x30mm/ t=2.5

b_192x30mm/ t=1.5 b_204x30mm/ t=2.5

b_192x30mm/ t=0.9 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5

32.5/27_2.5 --

710

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

107

27/27_2.5 OI

27/22.4_2.5 OI

116

27/27_2.5 OI

27/20.3_2.5 OI

125

27/24.6_2.5 OI

102

27/22.4_2.5 OI

111

610

32.5/27_2.5 --

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

106

27/27_2.5 OI

27/22.4_2.5 OI

115

27/27_2.5 OI

27/20.3_2.5 OI

124

27/24.6_2.5 OI

101

27/22.4_2.5 OI

110

27/20.3_2.5 OI

32.5/27_2.5 --

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

105

27/27_2.5 OI

27/22.4_2.5 OI

114

27/27_2.5 OI

27/20.3_2.5 OI

123

27/24.6_2.5 OI

100

27/22.4_2.5 OI

b_204x30mm/ t=2.5 b_270x30mm/ t=2.5

32.5/27_2.5 --

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

104

27/27_2.5 OI

27/22.4_2.5 OI

113

27/27_2.5 OI

27/20.3_2.5 OI

122

27/24.6_2.5 OI

b_270x30mm/ t=2.5 b_192x30mm/ t=0.9

32.5/27_2.5 --

27/24.6_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

103

27/27_2.5 OI

27/22.4_2.5 OI

112

27/27_2.5 OI

27/20.3_2.5 OI

121

32.5/27_2.5 --

27/27_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

102

27/27_2.5 OI

27/22.4_2.5 OI

111

120

27/20.3_2.5 OI

b_286x30mm/ t=2.5 b_123x30mm/ t=0.9

120

b_123x30mm/ t=1.5 b_270x30mm/ t=2.5 b_286x30mm/ t=2.5 b_204x30mm/ t=2.5

b_270x30mm/ t=2.5 b_235x30mm/ t=2.5

b_238x30mm/ t=2.5 b_253x30mm/ t=0.9

27/20.3_2.5 OI

b_270x30mm/ t=2.5 b_286x30mm/ t=2.5

b_235x30mm/ t=2.5 b_238x30mm/ t=2.5 b_204x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_123x30mm/ t=1.5

b_286x30mm/ t=2.5 b_238x30mm/ t=2.5

b_238x30mm/ t=2.5 b_204x30mm/ t=2.5

b_235x30mm/ t=2.5 b_286x30mm/ t=2.5

b_235x30mm/ t=2.5 b_162x30mm/ t=0.9

b_204x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_162x30mm/ t=1.5

b_270x30mm/ t=2.5 b_162x30mm/ t=0.9

b_235x30mm/ t=2.5 b_270x30mm/ t=2.5

b_238x30mm/ t=2.5 b_262x30mm/ t=2.5

32.5/27_2.5 --

27/22.4_2.5 -I

27/27_2.5 OI

27/20.3_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

101

27/22.4_2.5 OI

110

27/20.3_2.5 OI

b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_123x30mm/ t=1.5 b_270x30mm/ t=2.5

b_238x30mm/ t=2.5 b_325x30mm/ t=2.5 b_270x30mm/ t=2.5 b_286x30mm/ t=1.5

32.5/27_2.5 --

27/27_2.5 OI

27/20.3_2.5 -I

27/24.6_2.5 OI

27/20.3_2.5 OI

27/24.6_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

32.5/27_2.5 --

27/20.3_2.5 -I

27/24.6_2.5 OI

27/20.3_2.5 OI

27/24.6_2.5 OI

27/22.4_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

b_192x30mm/ t=0.9 b_286x30mm/ t=2.5

100

t=2.5

b_253x30mm/ t=0.9 b_162x30mm/ t=1.5

27/22.4_2.5 OI

b_204x30mm/ t=2.5 b_238x30mm/ t=2.5

b_270x30mm/ t=2.5 b_270x30mm/ t=2.5

b_286x30mm/ t=2.5 b_162x30mm/ t=1.5

b_162x30mm/ t=0.9 b_286x30mm/ t=2.5 b_123x30mm/ t=1.5 b_238x30mm/ t=2.5

32.5/27_2.5 --

27/24.6_2.5 OI

27/20.3_2.5 OI

27/22.4_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

b_235x30mm/ t=2.5 b_238x30mm/ t=2.5

b_162x30mm/ t=1.5 b_262x30mm/ t=2.5

32.5/27_2.5 --

27/20.3_2.5 OI

27/22.4_2.5 OI

27/24.6_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

b_270x30mm/ t=2.5 b_192x30mm/ t=1.5

27/27_2.5 OI

b_238x30mm/ t=2.5 b_270x30mm/ t=2.5

b_270x30mm/ t=2.5 b_123x30mm/ t=0.9

b_123x30mm/ t=0.9 b_183x30mm/ t=2.5

b_325x30mm/ t=2.5 b_286x30mm/ t=2.5 b_262x30mm/ t=2.5 b_123x30mm/ t=1.5

27/22.4_2.5 -I

27/22.4_2.5 OI

27/20.3_2.5 OI

27/24.6_2.5 OI

27/22.4_2.5 OI

27/27_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

32.5/27_2.5 --

27/20.3_2.5 -I

27/24.6_2.5 OI

27/20.3_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

b_286x30mm/ t=1.5 b_262x30mm/ t=2.5

b_183x30mm/ t=2.5 b_270x30mm/ t=2.5

27/27_2.5 OI

b_123x30mm/ t=1.5 b_238x30mm/ t=2.5 b_325x30mm/ t=2.5 b_162x30mm/ t=0.9

b_238x30mm/ t=2.5 b_286x30mm/ t=2.5

b_270x30mm/ t=2.5 b_235x30mm/ t=2.5

27/20.3_2.5 -I

27/20.3_2.5 OI

27/27_2.5 OI

27/22.4_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

b_238x30mm/ t=2.5 b_286x30mm/ t=2.5

b_286x30mm/ t=2.5 b_270x30mm/ t=2.5

32.5/27_2.5 --

27/20.3_2.5 OI

27/22.4_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

b_270x30mm/ t=2.5

b_262x30mm/ t=2.5 b_238x30mm/ t=2.5 b_192x30mm/ t=1.5

27/20.3_2.5 OI

27/22.4_2.5 OI

b_192x30mm/ t=1.5

27/24.6_2.5 OI

b_183x30mm/ t=2.5

27/22.4_2.5 OI

27/24.6_2.5 OI

27/27_2.5 OI

b_123x30mm/ t=1.5

b_286x30mm/ t=2.5

180

b_238x30mm/ t=2.5

27/27_2.5 OI

b_213x30mm/ t=0.9

b_286x30mm/ t=2.5

181

b_162x30mm/ t=0.9 b_262x30mm/ t=2.5

b_286x30mm/ t=2.5

b_270x30mm/ t=2.5

27/24.6_2.5 OI

b_192x30mm/ t=1.5

b_123x30mm/ t=0.9

27/27_2.5 OI

188

27/27_2.5 OI

H31

b_213x30mm/ t=1.5 b_270x30mm/ t=2.5 b_238x30mm/ t=2.5 b_235x30mm/ t=2.5

b_270x30mm/ t=2.5 b_235x30mm/ t=2.5

b_270x30mm/ t=2.5 b_204x30mm/ t=2.5 b_183x30mm/ t=2.5 b_238x30mm/ t=2.5

b_192x30mm/ t=1.5 b_183x30mm/ t=2.5 b_238x30mm/ t=2.5 b_123x30mm/ t=0.9

b_183x30mm/ t=2.5 b_123x30mm/ t=0.9 b_183x30mm/ t=2.5 b_270x30mm/

b_238x30mm/ t=2.5 b_235x30mm/ t=2.5

b_183x30mm/ t=2.5 b_262x30mm/ t=2.5

b_183x30mm/ t=2.5 b_270x30mm/ t=2.5 b_123x30mm/ t=0.9 b_235x30mm/ t=2.5

b_262x30mm/ t=2.5 b_286x30mm/ t=2.5 b_235x30mm/ t=2.5 b_286x30mm/ t=2.5

b_270x30mm/ t=2.5 b_204x30mm/ t=2.5

b_238x30mm/ t=2.5 b_162x30mm/ t=1.5 b_192x30mm/ t=0.9 b_286x30mm/ t=2.5 b_235x30mm/ t=2.5 b_270x30mm/ t=2.5

b_204x30mm/ t=2.5 b_192x30mm/ t=0.9 b_238x30mm/ t=2.5 b_270x30mm/ t=2.5

b_183x30mm/ t=2.5 b_235x30mm/ t=2.5 b_123x30mm/ t=0.9 b_262x30mm/ t=1.5 b_183x30mm/ t=2.5 b_270x30mm/ t=2.5

b_235x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5

b_286x30mm/ t=2.5 b_286x30mm/ t=2.5 b_235x30mm/ t=2.5 b_123x30mm/ t=1.5

b_235x30mm/ t=2.5 b_238x30mm/ t=2.5

b_325x30mm/ t=2.5 b_204x30mm/ t=2.5

b_286x30mm/ t=2.5 b_270x30mm/ t=2.5

b_286x30mm/ t=2.5 b_238x30mm/ t=2.5

b_162x30mm/ t=1.5 b_204x30mm/ t=2.5 b_286x30mm/ t=2.5 b_286x30mm/ t=2.5 b_270x30mm/ t=2.5 b_262x30mm/ t=2.5

b_235x30mm/ t=2.5 b_270x30mm/ t=2.5

b_204x30mm/ t=2.5 b_235x30mm/ t=2.5 b_235x30mm/ t=2.5 b_183x30mm/ t=2.5 b_262x30mm/ t=1.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_238x30mm/ t=2.5

b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_286x30mm/ t=2.5 b_238x30mm/ t=2.5 b_270x30mm/ t=2.5 b_286x30mm/ t=2.5

b_270x30mm/ t=2.5 b_235x30mm/ t=2.5

b_270x30mm/ t=2.5 b_183x30mm/ t=2.5 b_270x30mm/ t=2.5 b_123x30mm/ t=1.5

b_270x30mm/ t=2.5 b_270x30mm/ t=2.5

b_204x30mm/ t=2.5 b_123x30mm/ t=1.5 b_286x30mm/ t=2.5 b_238x30mm/ t=2.5 b_262x30mm/ t=2.5 b_235x30mm/ t=2.5

b_270x30mm/ t=2.5 b_235x30mm/ t=2.5

b_270x30mm/ t=2.5 b_162x30mm/ t=0.9

b_183x30mm/ t=2.5 b_162x30mm/ t=0.9 b_270x30mm/ t=2.5 b_325x30mm/ t=2.5 b_238x30mm/ t=2.5 b_325x30mm/ t=2.5

b_270x30mm/ t=2.5 b_325x30mm/ t=2.5 b_238x30mm/ t=2.5 b_325x30mm/ t=2.5 b_286x30mm/ t=2.5 b_123x30mm/ t=1.5

b_204x30mm/ t=2.5 b_270x30mm/ t=2.5 b_235x30mm/ t=2.5 b_238x30mm/ t=2.5

b_235x30mm/ t=2.5 b_183x30mm/ t=2.5

b_183x30mm/ t=2.5 b_270x30mm/ t=2.5 b_123x30mm/ t=1.5 b_238x30mm/

b_270x30mm/ t=2.5 b_270x30mm/ t=2.5

b_235x30mm/ t=2.5 b_162x30mm/ t=1.5

b_162x30mm/ t=0.9 b_192x30mm/ t=1.5 b_162x30mm/ t=0.9 b_213x30mm/ t=0.9

b_162x30mm/ t=0.9 b_162x30mm/ t=1.5 b_325x30mm/ t=2.5 b_262x30mm/ t=2.5

b_270x30mm/ t=2.5 b_286x30mm/ t=2.5 b_270x30mm/ t=2.5 b_286x30mm/ t=2.5 b_325x30mm/ t=2.5 b_238x30mm/ t=2.5 b_325x30mm/ t=2.5 b_162x30mm/ t=0.9

b_270x30mm/ t=2.5 b_192x30mm/ t=1.5

b_238x30mm/ t=2.5 b_123x30mm/ t=0.9

b_270x30mm/ t=2.5 b_238x30mm/ t=2.5

b_162x30mm/ t=1.5 b_262x30mm/ t=2.5 b_162x30mm/ t=1.5 b_235x30mm/ t=2.5 b_286x30mm/ t=2.5 b_270x30mm/ t=2.5 b_270x30mm/ t=2.5 b_238x30mm/ t=2.5

b_238x30mm/ t=2.5

b_162x30mm/ t=1.5

172

176 177

b_162x30mm/ t=1.5 b_262x30mm/ t=2.5

182

b_162x30mm/ t=0.9

186

191

b_238x30mm/ t=2.5 b_235x30mm/ t=2.5

27/27_2.5 OI

196 198

+ -

H32 H0 H33 H1 H34 H2 H35 H3 H36 H4 H37 H5 H38 H6 H39 H7 H40 H8 H41 H9 H42 H10 H43 H11 H44 H12 H45 H13 H46 H14 H47 H15 H48 H16 H49 H17 H50 H18 H51 H19 H52 H20 H53 H21 H54 H22 H55 H23 H56 H24 H57 H25 H58 H26 H59 H27 H60 H28 H61 H29 H62 H30 H63 H31 H64 H32 H65 H33 H66 H34 H67 H35 H68 H36 H69 H37 H70 H38 H71 H39 H72 H40 H73 H41 H74 H42 H75 H43 H76 H44 H77 H45 H78 H46 H79 H47 H80 H48 H81 H49 H82 H50 H83 H51 H84 H52 H85 H53 H86 H54 H87 H55 H88 H56 H89 H57 H90 H58 H91 H59 H92 H60 H93 H61 H94 H62 H95 H63 H96 H64 H97 H65 H98 H66 H99 H67 100 H68 101 H69 102 H70 103 H71 104 H72 105 H73 106 H74 107 H75 108 H76 109 H77 110 H78 111 H79 112 H80 113 H81 114 H82 115 H83 116 H84 117 H85 118 H86 119 H87 120 H88 121 H89 122 H90 123 H91 124 H92 125 H93 126 H94 127 H95 128 H96 129 H97 130 H98 131 H99 132 100 133 101 134 102 135 103 136 104 137 105 138 106 139 107 140 108 141 109 142 110 143 111 144 112 145 113 146 114 147 115 148 116 149 117 150 118 151 119 152 120 153 121 154 122 155 123 156 124 157 125 158 126 159 127 160 128 161 129 162 130 163 131 164 132 165 133 166 134 167 135 168 136 169 137 170 138 171 139 172 140 173 141 174 142 175 143 176 144 177 145 178 146 179 147 180 148 181 149 182 150 183 151 184 152 185 153 186 154 187 155 188 156 189 157 190 158 191 159 192 160 193 161 194 162 195 163 196 164 197 165 198 166 199 167 200 168 169

b_123x30mm/ t=0.9

171

170

173 174 175

178 179

b_286x30mm/ t=2.5

183 184 185 187 189 190 192 193 194 195 197

i.296 Full scale proof of concept prototype actuation map and fabrication template

b_286x30mm/ t=2.5 b_262x30mm/ t=2.5 b_235x30mm/ t=2.5 b_270x30mm/ t=2.5

b_270x30mm/ t=2.5

200

b_238x30mm/ t=2.5

199

122 | design proposal

OI 5.2_72/72

design proposal | 123 OI 5.2_72/72

OI 5.2_6.42/72

OI 5.2_72/72

OI 5.2_6.42/72

OI 5.2_4.22/72

OI 5.2_72/72

OI 5.2_6.42/72

IO 5.2_4.22/72

OI 5.2_3.02/72

OI 5.2_72/72

OI 5.2_6.42/72

OI 5.2_4.22/72

OI 5.2_3.02/72

-- 5.2_72/5.23

O- 5.2_72/72

OI 5.2_6.42/72

OI 5.2_4.22/72

OI 5.2_3.02/72

O- 5.2_3.02/72

-- 5.2_72/72

O- 5.2_6.42/72

OI 5.2_4.22/72

OI 5.2_3.02/72

O- 5.2_3.02/72

-- 5.2_72/5.23

IO 5.2_72/72

-- 5.2_72/72

O- 5.2_6.42/72

OI 5.2_4.22/72

O- 5.2_3.02/72

-- 5.2_4.22/72

IO 5.2_72/72

-- 5.2_6.42/72

O- 5.2_4.22/72

-- 5.2_4.22/72

-- 5.2_72/5.23

IO 5.2_72/72

-- 5.2_6.42/72

O- 5.2_4.22/72

-- 5.2_4.22/72

-- 5.2_6.42/72

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_6.42/72

-- 5.2_72/5.23

IO 5.2_4.22/72

001

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_6.42/72

-- 5.2_72/72

IO 5.2_3.02/72

011

IO 5.2_4.22/72

101

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_72/72

-- 5.2_72/5.23

021

IO 5.2_3.02/72

111

IO 5.2_4.22/72

201

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_72/72

121

IO 5.2_3.02/72

211

IO 5.2_4.22/72

301

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_72/72

-- 5.2_72/5.23

221

IO 5.2_3.02/72

311

IO 5.2_4.22/72

401

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_72/72

321

IO 5.2_3.02/72

411

IO 5.2_4.22/72

501

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_72/5.23

421

IO 5.2_3.02/72

511

IO 5.2_4.22/72

601

IO 5.2_6.42/72

IO 5.2_72/72

-- 5.2_72/72

016

521

IO 5.2_3.02/72

611

IO 5.2_4.22/72

701

IO 5.2_4.22/72

IO 5.2_6.42/72

IO 5.2_72/72

017

-- 5.2_72/5.23

621

IO 5.2_4.22/72

711

IO 5.2_4.22/72

801

IO 5.2_4.22/72

IO 5.2_6.42/72

018

-- 5.2_72/72

117

721

IO 5.2_4.22/72

811

IO 5.2_4.22/72

901

IO 5.2_6.42/72

019

IO 5.2_72/72

118

-- 5.2_72/5.23

821

IO 5.2_4.22/72

911

IO 5.2_4.22/72

0101

IO 5.2_6.42/72

119

-- 5.2_72/72

218

921

IO 5.2_6.42/72

0111

IO 5.2_6.42/72

1101

IO 5.2_72/72

219

-- 5.2_72/5.23

0121

IO 5.2_6.42/72

1111

IO 5.2_72/72

2101

-- 5.2_72/72

319

1121

IO 5.2_6.42/72

2111

IO 5.2_72/72

3101

-- 5.2_72/5.23

2121

IO 5.2_72/72

3111

-- 5.2_72/72

4101

3121

-- 5.2_72/72

4111

-- 5.2_72/5.23

4121

-- 5.2_72/72

5111

5121

-- 5.2_72/5.23

6121

Full scale proof of concept prototype surface curvature color map i.297

124

125

08/discussion

126 | discussion

â&#x20AC;&#x2DC;while technology solves problems largely by manipulating usage of energy, biology uses information and structure, two factors largely ignored by technologyâ&#x20AC;&#x2122; Julian Vincent, Biomimetics: its practice and theory (2006)

system possibilities The developed material system could be used to design an environmentally responsive surface that not reacts but also that reshapes its structure according to relative humidity changes in its environment. The architectural implications of this research are promising: due to the integration of the inherent material properties of wood in the design process, it is possible to take advantage of the material behavior and performance to get responsive structures on which the material itself is the sensor and the actuator with no need for extra energy supply. The system integrates a low-tech programmed responsive structure made of planar elements that can also be easily disassembled and transported. Although the system is not fully controlled yet in terms of structural optimization and material fatigue factors, the achieved degree of control suggest that large scale structures could be built as space defining responsive architectures.

i.298 self-supported responsive lattice structure [42 cells]

discussion | 127

128

129

09/outlook

130 | outlook

summary From the conclusions extracted from each of the developed methods, it seems possible to use this system at a larger scale and to achieve a higher control over it. The unsolved questions are the degree of control of the system due to the difficulty of finding a proper computational tool that integrates anisotropic properties of the material into the design process. The following evaluations could be further developed: [i] Analysis of the architectural impact of the research. [ii] Material fatigue phenomenon control and durability of the material system (duration cycles). [iii] Structural optimization. [iv] Development of a computational tool for the control of anisotropic material properties.

outlook | 131

conclusion The presented work is a contribution to the contemporary fields of responsive architecture and biomimetic design. It illustrates an integrative process of material computation and emphasizes the interdepence and necessary constant communication of a system and its environment: the use and control of a system that behaves at a unstable equilibrium for space defining responsive structures.

i.299 actuation and response squence of a responsive lattice structure

132

133

10/references

134 | references

[01]

Reichert S., Menges, A. and Correa,D.: Meteorosensitive architecture: Biomimetic building skins based on materially embedded and hygroscopically enabled responsiveness. Computer Aided Design (2014), [website]: http://dx.doi.org/10.1016/j.cad.2014.02.010

[02]

Menges, A.: Performative Wood: Integral Computational Design for Timber Constructions, in T. Sterk and R. Loveridge Ed., Proceedings of the Association of Computer Aided Design in Architecture Conference, 2009

[03]

Elbaum, R. and Abraham,Y.: Insights into the microstructures of hygroscopic movement in plant seed dispersal. Elsevier, Plant Science 223 (2014) 124â&#x20AC;&#x201C;133

[04]

Menges, A.: Material Computation: Higher Integration in Morphogenetic Design, Architectural Design Volume 82, Issue 2, 2012

[05]

Dinwoodie, J. M.: Timber: Nature and Behaviour, Taylor & Francis, London, 2000

[06]

Hoadley, R. B.: Understanding Wood, Taunton Press, Newton CT, 2000

[07]

Cave, I.D.: Mechanical Properties of Fibre-Reinforced Materials, The Wood-Water System, Victoria University of Wellington, 1975

[08]

Cave, I.D.: Wood substance as a Water-Reactive Fiber Reinforced Composite, Journal of Microscopy, Vol 104 (1), 1975

[09]

MĂźller, C.: Holzeimbau, Laminated timber construction, Birkhauser, Basel, 2000

[10]

Reyssat, E. and Mahadevan, L.: Hygromorphs: From Pine Cones to Biomimetic Bilayers, Journal of the Royal Society Interface 6, 2009

[11]

Masselter,T. and Speck,T.: Biomimetic Fiber-Reinforced Compound Materials, Advances in Biomimetics, Prof. Marko Cavrak Ed., 2011

references | 135

[12]

Taguchi, A.; Murata, K. and Nakano,T.: Observation of cell shapes in wood cross-sections during water adsorption by confocal laser-scanning microscopy, Holzforschung. 64. (2010): 627-631. Web. 27 Nov. 2013

[13]

Taguchi, A.; Murata, K.; Nakamura, M. and Nakano,T.: Scale effect in the anisotropic deformation change of tracheid cells during water adsorption, Holzforschung. 65. (2011): 253-256. Web. 27 Nov. 2013

[14]

Burget, I. and Fratzl, P. : Actuation systems in plants as prototypes for bioinspired devices. Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, Postdam; Phil. Trans. R. Soc. vol. 367 no. 1893 1541-1557. Web. 28 April 2009

[15]

Erb, R.M.; Sander, J.S.; Grisch, R. and Studart, A.R.: Self-shaping composites with programmable bioinspired microstructures. Nature Communications 2013;4:1712

[16]

Menges A, Reichert S.: Material capacity: embedded responsiveness. Archit Des 2012;82:52–9

[17]

Reichert S, Menges A.: Responsive surface structures. In: Kesel AB, Zehren D,editors. Bionik pat. aus. der. natur.. Bremen: Bionik-Innovations-Centrum (BI-C) Bremen; 2010. p. 28–34

[18]

Menges, A.: Material performance responsive surface structures: instrumentalising moisture-content activated dimensional changes of timber compoments. Archit Des 2008;78:39–41

[19]

Sterk, T.: Shape control in responsive architectural structures: current reasons & challenges. Riverside Architectural Press; 2006.

[20]

Sung, D.K.: Skin deep: breathing life into the layer between man and nature. AIA rep. Univ. Res. 3

[21]

Beesley, P., Hirosue, S. and Ruxton, J.:Toward Responsive Architectures. In Responsive Architectures: Subtle Technologies, Riverside Architectural Press, Toronto, 2006

[22]

De Landa, M.: Material complexity, in Neil Leach, David Turnbull and Chris Williams (eds), Digital Techtonics, John Wiley & Sons, 2004

136

137

11/ACKNOWLEDGMENTS

138 | acknowledgments

acknowledgments | 139

I would like to thank Achim Menges, David Correa Zuluaga and Oliver David Krieg for continuously supporting and encouraging this research. My special thanks to Steffen Reichert, without whose advice and previous research this thesis would not have been possible. This book is dedicated to my favorite person David Andres for walking with me and also to Jorge, Marta, Maria, Marta, Hermes and Joaquina for their unconditional long-distance love and laughs.