High Tension: Caterpillar-inspired Architecture

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Caterpillar-inspired Architecture

Biomimetic strategies for incremental tensioning and aggregation of bending-active plate structures

Module name: Integrative Technologies and Architectural Design Research - Architectural Biomimetics Module number: 311331800 Term/Year: WS 2016/17 Examination number: 49841 Examiners: Prof. Jan Knippers and Prof. Achim Menges In collaboration with: Prof. Oliver Betz, Prof. James Nebelsic and Tobias Grun Tutors: Anja Mader, Daniel Reist, Evy L.M. Slabbinck and Lauren Vasey University of Stuttgart Institute for Computational Design and Construction (ICD) Institute of Building Structures and Structural Design (ITKE) University of TĂźbingen Department of Evolutionary Biology and Invertebrates Department of Palaeontology of Invertebrates Israel Luna MiĂąo Jacob Russo Marie Razzhivina Jacob Zindroski

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Contents Chapter 01: Introduction..............Page 07 Chapter 02: Behavior & Construction Process..............Page 11 Chapter 03: Biological Role Models..............Page 17 Chapter 04: Analysis..............Page 25 Chapter 05: Abstraction..............Page 37 References..............Page 63

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Chapter 01

Introduction

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CHAPTER 01

FIGURE 1: Caterpillar nest structure. (Source: tidcf.nrcan.gc.ca/en/insects/factsheet/11968 last consulted January, 2017)

INTRODUCTION Natural systems have a lot to offer when it comes to the optimization of function. With 3.8 billion years of R&D[1], nature has become the ultimate problem solver, from how to manage ecosystems to energy efficiency to the building of structures. Thus, it should go without saying that looking at nature for inspiration in design would be a valuable model. This is the biomimetic method.

CHAPTER 01

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FIGURE 2: Caterpillar larva. (Source: tidcf.nrcan.gc.ca/en/insects/factsheet/11968 last consulted January, 2017)

Biomimicry is “an approach to innovation that seeks sustainable solutions to human challenges by emulating nature’s time-tested patterns and strategies. The goal is to create products, processes, and policies—new ways of living—that are well-adapted to life on earth over the long haul.”(Benyus, 2015)[2] Many of the problems that humans face have already been solved by nature. In fact, for each problem, biological systems have developed multiple strategies to solve them based on their own needs and the context in which they exist.

This was the starting point for our research in this course. Our aim was to investigate biological role models that are champion species in their respective problem solving arena. Our particular focus was biological behavior and construction processes.

Working closely with biology students and professors at the University of Tübingen, we explored fascinating organisms and natural principles and produced this proposal for the biomimetic integration of these principles into architectural design.

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Chapter 02

Behavior and Construction Process

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CHAPTER 02

BEHAVIOR & CONSTRUCTION PROCESS Our research began with the study of Mike Hansell’s book, Animal Architecture. Our focus was on Chapter 3--Construction: behavior and anatomy, and Chapter 4--Work organization and building complexity. These two chapters complement each other by demonstrating the intrinsic relationship between biological behavior and anatomy as well as the organization differences between, and evolution of complex construction processes found in nature.

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FIGURE 3: Catalogue of construction behaviors in nature. (Source: Hansell 2008 last consulted November, 2016.)

Chapter 3 provided a solid foundation for our understanding of behavior and anatomy in the context of construction as well as behavior gained through experiences, learning from others and interaction with the environment. According to Hansell: “Construction involves the coordination of appropriate anatomy in effective action.”[3a] As we came to learn, specific anatomical features of organisms have critical implications for the construction behaviors displayed by them. Hansell goes on to catalogue various

construction behaviors from “piling up” to “interlocking and weaving” to “folding and rolling” and “spinning”.

One of the main takeaways from this chapter was that “the parts of the anatomy used in construction are overwhelmingly legs and mouthparts (mandibles, beaks, and jaws). The only other significant anatomical feature is spinnerets or other structures concerned with the secretion of building materials.” We will explore these anatomical traits in more detail in the next chapter.

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CHAPTER 02

(a)

(d)

(b)

(c)

FIGURE 4: Various building behaviors in nature.

(Source: www.missouribotanicalgarden.org last consulted January, 2017) (a) Close-up of fern leaves tied together (b) Leaf roller inside pin oak leaf (c) Leaftier on redbud with stitches (d) Rolled leaf nest

We were also interested in augmenting our understanding of behavior in nature through further research. Daniel A. Levitis states that in Animal Behavior Volume 78 that “behavior is the internally coordinated responses (actions or inactions) of whole living organisms (individuals or groups) to internal and or external stimuli.�[4] One way to think of this is that you have an environment, which provides a stimulus to an organism and the organism exhibits some sort of response in the form of an action or inaction. Minton & Khale assert that these responses can be conscious or

CHAPTER 02

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Rolled Leaf Nest

Leaf Midrib

subconscious.[5] This led us to our own interpretation of animal behavior: a composition of inherent behavior, which is coded in the genes, as well as behavior gained through experiences and interaction with the environment.

The more adaptability an organism has, the more it is able to diverge from its inherent behavior and display

behavioral flexibility.

With a more robust frame of reference. Next to the organisms with an advanced central nervous system keeping and comparing information through learning and understanding, Chapter 4 examines work organization and building complexity, probing the subjects of spatial knowledge, building sequence and self-organization of basal organisms using coordination without direct communication - stigmergy.

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Chapter 03

Biological Role Models

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CHAPTER 03

FIGURE 5: Basic caterpillar anatomy. (Source: www.enchantedlearning.com/subjects/butterfly/anatomy/Caterpillar.shtml)

Caterpillar Group

Caterpillar Foraging

FIGURE 6: Caterpillar group behavior. (Source: facultyweb.cortland.edu/fitzgerald/hylesia.html last consulted February, 2017. Fitzgerald)

BIOLOGICAL ROLE MODELS Initially, following Hansell’s framework, we delved into the anatomy of caterpillars. We were interested in their anatomy related to sensing. Most frequently caterpillars sense touch through tiny hairs called setae that are all over the caterpillars body. These hairs are attached to nerve cells and arise from a socket. Neural stimulation results from displacement of the hair in the socket and with this the information about touch gets relayed to the nervous system including the brain.[14] They also sense touch with their tentacles. In addition, caterpillars are able to perceive any mechanical distortion of the body through mechanoreception. This mostly operates subcuticular and with neuron cells attached directly to the tissue (for example on muscles) getting stimulated by movement of the tissue itself.[14] These anatomical features were important in our appreciation of the caterpillar behavior that we would be analyzing later.

Another key characteristic of caterpillars related

CHAPTER 03

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FIGURE 7: Caterpillar sensing mechanism. (Source: www.enchantedlearning.com/subjects/butterfly/anatomy/Caterpillar.shtml)

FIGURE 8: Caterpillar pheromone trails. (Source: facultyweb.cortland.edu/fitzgerald/hylesia.html last consulted February, 2017. Fitzgerald)

to behavior and organization is the way that they communicate. With using their mechanical receptors they are able to use vibration caused by scraping parts of their body against the surface as a way to communicate.[15] One of the main modes of communication between caterpillars is through the use of pheromone trails. According to our research, “caterpillars are able to distinguish between trails of different strengths.”[8] A pertinent implication of this for us was that when groups of caterpillars break into subgroups, they are able to find their way back to the larger groups via pheromone trails. The strength of a trail can be varied on a small scale by a single caterpillar, but the main part of the trail strength is varied by the number of caterpillars using this way. The more caterpillars move on the same trail the more the strength of the trail increases. And if there are very few individuals using this trail the trail will become weaker.[15]

Thigmotaxis--the motion or orientation of an organism in response to a touch stimulus--is the mechanism that maintains single-file, head-to-tail movement of the groups of caterpillars.[9] The trails also have an age related to the strength of the pheromone. The caterpillars are able to respond to the trail age because the pheromones evaporate with time and if there are no new pheromones added the trail will become weaker until it finally disappears. Our investigation uncovered that “trails were still detectable by the caterpillars five days after deposition. The ability of the caterpillars to discriminate among trails based on trail age allows them to move efficiently….” In a sense, the trails act as sort of “attractors” to guide the caterpillars in their nest building processes.

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CHAPTER 03

FIGURE 9: Solitary caterpillar, Caloptilia serotinella. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

Our next step was to focus on biological role models that exemplified the core concepts of behavior and building construction that we outlined in the previous chapter. The nests of caterpillars are varying in their functions depending on the species. But in general there can be said that all nests serve as a shelter protecting the caterpillars from hostiles and from severe environmental conditions like rain, temperature, wind etc. In the case of the social caterpillars Archips

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FIGURE 10: Social caterpillar, Archips cerasivoranus. (Source: tidcf.nrcan.gc.ca/en/insects/factsheet/11968 last consulted January, 2017)

cerasivoranus nest gets an additional function which is that of a food storage. It was also important for us to be able to compare organisms with similar characteristics but which perhaps contrasted in the scale and context of their activity.

We decided to look into two species of caterpillar, which fit these criteria: the leaf rolling caterpillar, Caloptilia serotinella, and the ugly-nest caterpillar, Archips cerasivoranus. This was an ideal juxtaposition for us because the leaf rolling caterpillar operates individually,

while the ugly-nest caterpillar--a social insect--works in groups. This distinction made for a very compelling comparison of behavior and construction.

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CHAPTER 03

FIGURE 11: Super contraction of silk. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

According to Hansell, “the C. serotinella larva periodically interrupts the spinning behavior to enter the leaf roll to bite into the leaf midrib, so facilitating the rolling process. As the leaf rolls up, threads that have previously been in tension slacken as the gap between the two attachment points shortens under the force exerted by new threads.�[3] As previously discussed, this is where the super contraction properties of the silk come into play to help retention the silk strands. The concept of re-tensioning elements that become slack at various points throughout the construction process was an idea we would review in our abstraction phase.

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Weakening Branch

The caterpillar chews slits in the midrib

It continues this process incrementally to weaken the midrib, so that it is easier to tension and roll

Bending Element

FIGURE 12: Biting as a tool for bending. (www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

Both role models were compelling for their use of silk to tension leaves for nest construction. The properties of the silk itself is a contributing factor in the processes by which the caterpillars manipulate leaves through incremental tensioning. Hansell discusses the potential of the silk threads to super contract if wetted and its influence in the leaf rolling process. Citing Fitzgerald and Clark’s “Analysis of leaf-rolling behavior of Caloptilia serotinella (Lepidoptera: Gracillariidae)”[10] he states: “in mature leaf rolls most of the threads do seem to be in tension. This suggests that super contraction does ultimately contribute to the rigidity of

the leaf roll.”[3] The ability for the silk to maintain tension during nest construction was a significant insight for us.

The notion of accumulation of small forces to generate large deformations would be a central theme in the development of biomimetic strategies throughout this project.

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Chapter 04

Analysis

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CHAPTER 04

FIGURE 13: Leaf rolling process of the solitary caterpillar. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

ANALYSIS After looking at some of the fundamental aspects of the caterpillar anatomy, we moved into a more critical phase of analysis. Our intent was to undertake a thorough comparison of our two role models to gain essential knowledge about their construction processes and associated behaviors. Additionally, the organization of building endeavours and the formation of complex built structures was integral to our research.

One of the main differences between the solitary caterpillar and the social caterpillar is that the former uses creates its nest structure from one leaf, while the latter uses multiple leaves and branches of its host

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FIGURE 14: Leaf tensioning process of the social caterpillar. (Source: www.youtube.com/watch?v=Hrg3WsGBeoc&t=74s last consulted January, 2017. Fitzgerald)

plant.

The solitary caterpillar typically creates its shelter from the leaves of cherry trees. Hansell provides a detailed description of their building process: “the leaf is rolled from its tip against the force exerted by the midrib. To do this the larva spins a sequence of several hundred silk strands linking the outer surface of the leaf roll to the underside of the leaf. Each thread is stretched by 13−14% by the spinning movement of the caterpillar, this creates traction forces of greater than 0.1 N. A feature of the spinning behavior of the larva is a repetitive, rhythmic swinging of the body between the

two anchor points of the thread.”[3] This behavior is also seen in the social caterpillar.

However, while the solitary caterpillar uses this technique to roll leaves from the tip, the social caterpillars seem to apply the procedure to multiple edges of leaves to bring them closer together into clusters. This behavioral process will be discussed in more detail in a later section.

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CHAPTER 04

Caterpillar begins to survey the leaf

As the caterpillar explores the leaf, he is looking for the midrib as well as the tip of the leaf

Caterpillar begins to walk the midrib

Caterpillar walks the midrib laying down silk along its path

FIGURE 15: Leaf exploration of the solitary caterpillar. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

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Strands are generated from the midrib to the edge of the leaf

The caterpillar continues the process of drawing between the edge of the leaf to the midrib

Silk strands are hyperextended

Process continues until it reaches the apex of the leaf

FIGURE 16: Silk deposition of the solitary caterpillar. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

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PHASE I (baseline behavior): Single leaf to single leaf tensioning

PHASE II (aggregate behavior): Leaf clusters formed by phase I additive logic

PHASE III (subtraction and expansion): Leaves are eaten and silk network expands

PHASE IV (reinforcement): Large branch structure is integrated to finalize FIGURE 17: Construction phases of the social caterpillar. (Source: www.youtube.com/watch?v=Hrg3WsGBeoc&t=74s last consulted January, 2017. Fitzgerald)

While the leaf tensioning process of the solitary caterpillar is limited to one leaf, the social caterpillars deal with multiple leaves and branches within the context of their host plant, which are also usually cherry trees.[11] We were able to analyze a video of their nest construction process and extrapolated that there is a form of hierarchy in the behavior associated with the construction.[12]

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FIGURE 18: Leaf clustering and nest expansion of the social caterpillar. (Source: www.youtube.com/watch?v=Hrg3WsGBeoc&t=74s last consulted January, 2017. Fitzgerald)

Specifically with regard to the tensioning operations, there seems to be a phased approach. The first phase, or baseline behavior, involves tensioning single leaves together. The second phase entails the aggregation of multiple leaves from the first phase into clusters.

A third phase involves the expansion of the nest from one area of the host plant to another. Finally, in the documentation we examined, the nest is reinforced by incorporating a large branch into the structure. Here, we also see the use of biting as a means to weaken stems and branches in order to bend them more easily.

The fact that the social caterpillars are working on an existing structure with multiple components leads to these fascinating hierarchical behavioral patterns. We will return to this hierarchy in the next chapter as we start to hypothesize on their potential implications in architecture.

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Caterpillar begins to tension the ends of the leaf

Positioning itself on the mid section

It continues the process until the end

Second layer of tensioning

Silk acts as a scaffolding

Closes the leaf from the inside

FIGURE 19: Enclosure through edge tensioning of the solitary caterpillar. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

Another comparison between the two caterpillars reveals the process of creating enclosure through tensioning in more detail. When the solitary caterpillar has sufficiently rolled its leaf to a certain extent, it uses its silk to tension the edges of the roll ends.[13] This seems to provide a final level of enclosure of the nest.

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FIGURE 20: Enclosure through bridging of social caterpillar. (Source: www.youtube.com/watch?v=Hrg3WsGBeoc&t=74s last consulted January, 2017. Fitzgerald)

The social caterpillar employs a different strategy to achieve its final nest state. At certain points during construction, the caterpillars encounter portions of the host plant that are further away from the nest in its current state. Yet, somehow they manage to manipulate these portions–in some cases whole branches–and incorporate them into the nest, as highlighted in the previous discussion of tensioning phases.

What we found was that the caterpillars create silk bridges from the current nest state to the portion of the host plant they aim to include. It is unclear how the initial silk strands of the bridge are laid to allow for the bridge construction. However, we were fascinated by this behavior. Here, it seems that smaller sub-groups of caterpillars operate on the bridge construction while the larger main group works on one side of the bridge.

The silk bridge expands from a central cord, which appears thicker. The result is a 3-dimensional network with varying levels of material thickness.

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FIGURE 21: Process and final nest state of the solitary caterpillar. (Source: www.youtube.com/watch?v=4YoKaR9AMhc last consulted January, 2017. Fitzgerald)

Lastly, we juxtaposed the final nest states of the two caterpillars. As previously mentioned, the solitary caterpillar uses one leaf and the social caterpillar uses a whole plant. Besides the biting of the midrib, the leaf of the solitary caterpillar remain intact throughout the construction process. On the other hand, the leaves are almost entirely consumed by the social caterpillars during the process in order for them to produce silk.

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FIGURE 22: Process and final nest state of the social caterpillar. (Source: www.youtube.com/watch?v=Hrg3WsGBeoc&t=74s last consulted January, 2017. Fitzgerald)

In this sense, the leaves were only providing a sort of temporary scaffold, which we found to be a compelling phenomenon. Structurally significant branches and leaf midribs do, however, remain intact. Finally, in the case of the solitary caterpillar, the leaf provides the primary enclosure for the nest. On the contrary, for the social caterpillar, their silk provides the enclosure.

This analysis was pivotal in our understanding of our biological role models and gave us key insights into their behavior and construction processes. From here, we moved into our abstraction phase and looked for biomimetic translations from biology to design.

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Chapter 05

Abstraction

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CHAPTER 05

FIGURE 23: Bending plate with string. (Source: Luna, Russo, Razzhivina, Zindroski)

ABSTRACTION The biomimetic application of our biological role model research was developed during our abstraction phase.

Considering the behaviors and processes we had discovered, we decided to look at how they could be relevant to the incremental tensioning of bending plate structures. This topic was also closely related to our studio explorations of textile hybrid structures.

We began our abstraction phase with simple experiments. Similar to the how the caterpillars work, we were interested in using minimal amount of tensioning forces to bend plates. We tested this with basic shapes, such as a rectangle, cut out of paper.

We used an array of holes to allow for small tension forces to be built up with string and incrementally bend the plates.

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Testing incremental tensioning

FIGURE 24: Incremental tensioning of paper. (Source: Luna, Russo, Razzhivina, Zindroski)

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FIGURE 25: Plastic plate test with string. (Source: Luna, Russo, Razzhivina, Zindroski)

We also tested plastic, which proved to be a more adequate bending element because it was less likely to deform in unpredictable ways and would typically return to a flat position when the tension was released.

We then pinpointed three subtopics to delve into, which we felt were closely related to the biological role model research: anchor point, geometric variation, and tensioning hierarchy.

With regards to anchor point, what was fascinating to us about the caterpillars was how they attach the silk to the leaves. Essentially, certain adhesive properties of the silk facilitate this connection extremely efficiently.

However, since we could not actually use silk in our processes, we were interested in developing abstracted anchor point strategies to connect tensioning elements to the bending plates.

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FIGURE 26: Plastic plate tests with string. (Source: Luna, Russo, Razzhivina, Zindroski)

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Plate geometry variation

Plate corner manipulation

FIGURE 27: Plastic plate geometry and manipulation studies. (Source: Luna, Russo, Razzhivina, Zindroski)

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Tensioning hierarchy 2

Tensioning hierarchy 1

Tensioning hierarchy 2

Tensioning hierarchy 1

FIGURE 28: Plastic plate tensioning hierarchy studies. (Source: Luna, Russo, Razzhivina, Zindroski)

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FIGURE 29: Incremental tensioning test with paper, string, and mesh. (Source: Luna, Russo, Razzhivina, Zindroski)

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Anchor Points

FIGURE 30: Incremental tensioning test with paper, string, and mesh: close-up of anchor points. (Source: Luna, Russo, Razzhivina, Zindroski)

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CHAPTER 05

Analog Force Gauge

Spread Forces (Anchor Points)

FIGURE 31: Anchor point tests and force measurement. (Source: Luna, Russo, Razzhivina, Zindroski)

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(LATERAL FORCES)

F

F

F

F

F

F

FIGURE 32: Tripod force tensioning logic. (Source: Luna, Russo, Razzhivina, Zindroski)

We started with the simple holes in the plates for ease of modeling and testing forces and tried to come up with a tensioning force logic. Our tests revealed that a tripod shape resulted in good force distribution while also allowing for increased geometric variation as opposed to the more compact shapes from our previous tests.

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FIXED POINT FIXED POINT

FROM FROM SINGLESINGLE TO MULTIPLE TO MULTIPLE CONTROL CONTROL POINTSPOINTS

CONTROL CONTROL POINT POINT

FROM FROM STRAIGHT STRAIGHT TENSIONING TENSIONING STRANDS STRANDS TO REDIRECTING TO REDIRECTING ONES ONES

TENSIONING FROM FROM SINGLESINGLE TENSIONING ELEMENTS TO HIERARCHICAL ELEMENTS TO HIERARCHICAL

STRAND NETWORK FROM FROM SINGLESINGLE STRAND NETWORK TO GRID TO GRID

FROM FROM SINGLESINGLE TOCHAPTER MULTIPLE TO MULTIPLE 05 49 CONTROL CONTROL POINTSPOINTS

CONTROL CONTROL POINT POINT

FROM FROM STRAIGHT STRAIGHT TENSIONING TENSIONING STRANDS STRANDS TO REDIRECTING TO REDIRECTING ONES ONES

TENSIONING FROM FROM SINGLESINGLE TENSIONING ELEMENTS TO HIERARCHICAL ELEMENTS TO HIERARCHICAL

STRAND NETWORK FROM FROM SINGLESINGLE STRAND NETWORK TO GRID TO GRID

FIGURE 33: Study of tensioning strategies. (Source: Luna, Russo, Razzhivina, Zindroski)

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Reinforced hole with glass fiber rovings

Reinforced hole with carbon fiber rovings

FIGURE 34: Anchor point tests at the ITFT: hole reinforcement. (Source: Luna, Russo, Razzhivina, Zindroski)

The investigation into novel anchor point strategies was supplemented by the ongoing research of the Institute of Textile Technology and Process Engineering Denkendorf (ITFT). We were able to collaborate with researchers on this project, who provided key insight into the translation from biology to real world application. Our initial experiments conducted at the ITFT facilities aimed at creating anchor points for tensioning elements within glass fiber plates, which was one of the materials we were looking at for use to scale in our studio project as well. These tests involved making holes in the glass fiber sheets by pushing the fibers apart. We also reinforced the holes with glass fiber and carbon fiber rovings (separate tests) prior to vacuum infusion, the process by which the plates were

created.

Our hypothesis was that by reinforcing the holes, we could achieve an appropriate anchor point for incrementally bending the plates. However, we were subsequently encouraged to move away from penetrating the plates with holes. One reason for this was that at larger scales, the material could possibly become compromised by the holes in the glass fiber. In addition, the conclusion was that the hole method was not utilizing the principles we found in our biological role models. We decided to rethink the anchor point methodology to look for ways to actually embed the connection within the material without compromising it and promote the use of minimal tensioning forces to incrementally bend the plates.

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of glass fiber sheets 45, 45 degree fiber orientation ed holes with glass fiber 30cm 4 layers of glass fiber sheets 45, 45, 45, 45 degree fiber orientation Reinforced holes with glass fiber 30cm x 30cm

of glass fiber sheets 45, 45, 45 degree fiber orientation ed holes with carbon fiber 30cm 5 layers of glass fiber sheets 45, 45, 45, 45, 45 degree fiber orientation Reinforced holes with carbon fiber 30cm x 30cm

of glass fiber sheets 90, 90, 90 degree fiber orientation ed holes with glass fiber 30cm 5 layers of glass fiber sheets 90, 90, 90, 90, 90 degree fiber orientation Reinforced holes with glass fiber 30cm x 30cm

of glass fiber sheets 45, 90, 45 degree fiber orientation ed holes with glass fiber 30cm 5 layers of glass fiber sheets 45, 90, 45, 90, 45 degree fiber orientation Reinforced holes with glass fiber 30cm x 30cm

FIGURE 35: Anchor point tests at the ITFT : fiber orientation. (Source: Luna, Russo, Razzhivina, Zindroski)

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REINFORCEMENT (FRAME) WITH CONNECTION POINTS

STRAND AS A FRAME

OPEN LOOPS (FIBERS)

MAGNET NODES (REMOVABLE)

CLOSED LOOPS (FIBERS)

FIBER BECOMES A TENSIONING STRAND

FIGURE 36: Strategies for embedded anchor points. (Source: Luna, Russo, Razzhivina, Zindroski)

This led us to the “loop” method. With the help of our colleagues at the ITFT, we came up with a new hypothesis: by embedding an array of small loop structures into the glass fiber plate lay up, we could achieve a more integrated, biomimetic technique for our anchor points. We were able to conduct preliminary trials of this strategy using glass fiber rovings for the loops. Resin was not applied to the loops, which was a challenge in the experiment setup. One problem with this was that the rovings are susceptible to fraying. As a countermeasure, we considered applying resin to the loops. This has not yet been tested. Other materials for the loops, such as polyester rovings, should be considered in future tests as well. We also discussed the possibility of using tufting to generate the loops.

We hope to continue our joint effort with the ITFT to develop more integrated and biologically inspired material systems for architectural application.

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Open loops (glass fiber rovings) Glass fiber plate

Embedded fiber woven in middle of 4 layers of glass fiber sheets

Open loops (glass fiber rovings)

FIGURE 37: Embedded loop anchor point test. (Source: Luna, Russo, Razzhivina, Zindroski)

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AGGREGATION THROUGH TENSIONING HIERARCHY CHAPTER 05 Tensioning Process Aggrega�on Process UNIT

PAIR

CLUSTER

EXPANSION

MASS

FIGURE 38: Abstraction of the social caterpillar tensioning and aggregation processes. (Source: Luna, Russo, Razzhivina, Zindroski)

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FIGURE 39: Study of aggregation logics. (Source: Luna, Russo, Razzhivina, Zindroski)

The ability to reconcile ease of tensioning with a geometric logic of bending plates that could also be aggregated was an ongoing challenge throughout the abstraction process. We were very interested in the implications of the social caterpillar tensioning hierarchy for our architectural application. The tripod shape as well as a simple triangle were informed by this too due to their ability to aggregate well. An example of the combination of tensioning hierarchy and aggregation logic with triangular plates is shown on the next page.

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Unit tensioning

Aggregation of second piece

Aggregation of third piece

Aggregated units tensioning

FIGURE 40: Tensioning hierarchy and aggregation logic with triangular plates: assembly. (Source: Luna, Russo, Razzhivina, Zindroski)

This model was successful in that sense but was limiting because the strict geometry of the triangle did not afford us much flexibility in how the plates were connected. In other words, each plate had to be aligned along the whole edge length for the logic to be maintained. This, however, is not the case in the natural model. The social caterpillar is able to deal with uncertain conditions and “plate� (leaf) geometries. It can manipulate them in complex ways and the resulting aggregation is not dictated by the requirement of perfect alignment. In fact, many leaves overlap during the aggregation process.

Therefore, we sought to design a framework for accommodating plate overlap, which could produce a more adaptable aggregation logic. We also took into account the need to pursue further possibilities for embedded anchor points and the possibility of having a system that could reconcile the two ideas.

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FIGURE 41: Tensioning hierarchy and aggregation logic with triangular plates: cluster. (Source: Luna, Russo, Razzhivina, Zindroski)

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FIGURE 43: Study of plate overlap. (Source: Luna, Russo, Razzhivina, Zindroski)

FIGURE 42: Study of plate overlap and aggregation. (Source: Luna, Russo, Razzhivina, Zindroski)

This led us to the examination of hook and loop, or velcro, systems for embedded fastening. We found some interesting examples of metal systems, which could carry large loads. However, the challenge would be to integrate metal components into a predominantly textile-based composite. A textile-based embedded hook and loop strategy would be more in line with our biomimetic approach.

The abstraction phase culminated in the design of a final model that aimed to reconcile the tensioning and aggregation processes we had investigated throughout the project. We were able to implement a geometric logic, which allowed for the incremental tensioning of bending plates to achieve various degrees of curvature. We also attempted to integrate the concept of overlap as a means to connect the plates. For fullscale applications, further research and development must be conducted to create an appropriate strategy for plate connection. However, the goal is for the system to be able to adapt to many different configurations and overlapping conditions similar to the nest building process of the social caterpillar.

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FIGURE 44: Final model. (Source: Luna, Russo, Razzhivina, Zindroski)

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Through a bottom-up biomimetic approach, this project sought to critically examine how behaviors and patterns found in nature can be integrated into architectural design methodologies. The key paradigm is that by considering functional performance as a design driver, biological processes are extremely well-suited to provide insights into achieving functional criteria.

By analyzing and comparing two biological role models, the solitary caterpillar, Caloptilia serotinella, and the social caterpillar, Archips cerasivoranus, we were able to gain a rich vocabulary of behavioral logics that demonstrate how these organisms solve complex problems related to the building of structures. These examples were invaluable in our pursuit of building architectural structures using principles of incremental tensioning and aggregation. Our biomimetic research helped us to think of innovative ways to solve these problems and put forth novel strategies for biologicallyinspired materials and building assembly.

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References [1] Biomimicry 3.8 2016, Who We Are, Biomimicry 3.8, Available from: biomimicry.net/who-we-are/ [12 February 2017].

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