Berin Nur Kocabas Leili Ghaemi
DESIGN I / DIGITAL AND MATERIAL FABRICATION Emergent Technologies & Design Design I – Digital & Material Fabrication 18 November – 13 December 2019 1
CONTENT
01 ABSTRACT & INTRODUCTION MATERIAL DESRIPTION 02 STAGE I 03 STAGE II 04 STAGE III 05 CONCLUSION 06 RESEARCH - CASE STUDIES 07 REFERENCES
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ABSTRACT
The Design I Seminar project’s process began by geometrically rationalizing and structurally analyzing the designs created in the Natural Systems and Biomimetics seminar and conducting material tests. Through research informed material testing with Lycra and Muslin, a layered system of Lycra + Clay + Muslin + Clay was realized - Lycra provides form without binding to the clay, while Muslin embeds into the clay. The fabrication and robotic printing tests done over the 3 stages of the project, developed the design of the inhabitable outdoor structure into a 3 part material system - clay patterns printed on Muslin that was tensioned by a steel frame. The locations of clay printing on the 1:10 scale model and 1:2 scale panel were informed by FEA analysis. Various robotic arm limitations, geometric complexities and material system dependencies arose throughout the printing process, resulting in manual interference and finalization. Upon completion, it was realized that while clay’s structural value was insignificant in this design, there was potential to investigate the shading patterns clay could induce. Further analyses, observed robotic printing limitations and complexities in form allowed for a re-evaluation of design and robotic printing strategies, which are described in depth in this report.
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INTRODUCTION The aim of the Design I Seminar project was to create a self-standing inhabitable outdoor space, with a focus on Robotic 3D Clay Printing. The design of this space began by geometrically rationalizing the generative forms produced in the Natural Systems and Biomimetics project. As the project carried on, further testing informed design changes in the structure. As fabric was a chosen element to test with, research was conducted prior to and throughout the project. Topics spanned from the KnitCandela by Zaha Hadid Architects and ETH, to Mark West’s work with fabric casting, to textile hybrid systems created by Sean Ahlquist. Throughout 3 stages, this project explores the material behaviours and constraints of clay and fabric, individually and as a whole, through various fabrication techniques, in relation to form development. Multiple material tests are conducted in Stage I to arrive at a layered clay-fabric system to go forth with in designing the pavillion. Stage II tests the derived material system with Robotic 3D Clay printing in two trials - one with flat printing, the other on a steel framed curved surfaces - to understand the limitations in their robotic toolpaths. Pavilion designs are narrowed down and chosen based on FEA analysis. In Stage III, fabrication methods are proposed for the structure and a 1:10 scale model prototype and 1:2 panel prototype are created using the curved steel frames and fabric to 3D clay printed on. The printing errors faced in Stage III and the learnings gathered from the FEA tests on the pavillion design, allow us to re-evaluate the function of clay in our system and change our direction to fit it accordingly. The project concludes with reflections on the learnings and failures gained throughout 3 Stages and suggestions for further development strategies and elements to investigate.
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Figure 1: Muslin Texture
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MATERIAL DESCRIPTION
Clay Clay, a naturally occurring material, is primarily comprised of fine grained earth minerals. Throughout history, clay has been used as a construction material in elements such as bricks, adobe, wattle and daub, etc. Acting best in compression, its strengths lie in its plasticity, the ability to shaped and re-shape it into different forms with the addition of water and it’s adhesive properties. However, it shrinks and becomes brittle as it dries, which must be accounted for when designing a structure. For this project, we will be using air drying fibre-added clay. Fabric We will be looking at how we can use fabric to create form, offer reinforcement, influence the structural stability and strength of the created clay surfaces, and understand how it will bind to clay. We have chosen to work with 2 different kinds of fabric: muslin and lycra. Muslin is a relatively coarse and stiff fabric with high tensile strength and porous stitching. Unlike muslin, Lycra is a smooth and slippery in fabric, commonly used in spandex and athletic clothing, that can be stretched into any form.
Figure 2: Clay Texture
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STAGE I-A / Clay + Fabric Introduction Stage I began with creating manual tests, as shown in Figure 3, to understand the relationship between clay and fabric. Muslin and Lycra were tensioned on laser cut square frames and a piping bag was used to pour on different thicknesses and patterns of clay. For each 50 grams of clay we used 5 mL of water and a drop of Sodium Dispex. (Figure 4) It was observed that the clay bound to Muslin, seeping through the pores of the stitching and pulling the fabric into itself as it shrank while drying. It did not bind to Lycra and could easily be lifted off after drying. Moreover, to bind with the Muslin the clay needed to lie relatively flat on the fabric surface rather than in a cylindrical shape.
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Lycra
Lycra
Calico
Muslin
Muslin/Tight stitch
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Figure 3: Tests
Figure 4: Clay Mixture
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STAGE 1-B / Initial Pavillion Design
CNC former Muslin + Clay Structural Stability - removal Observing that Muslin was best for binding, a CNC former of the final pavilion surface created by Berin and Felippe from the Natural Systems and Biomimetics project was made. The muslin was layed on top and the clay poured the clay on. Once dried, the muslin-clay joint layer was removed as shown in the last image of Figure 5. The model was unable to keep itself upright. While the shape given by the former was relatively kept intact, it did not have a supporting base and spread out at the bottom area.
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Figure 5: Mold and the pavillion
Figure 6: Setting/Mold with the muslin on top and clay mixture
Figure 7: Stages of the pavillion design generated from agent behaviour
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STAGE 1-C / Hung Muslin + Clay Figure 10: Model Elevation
Figures & 9: Pouring the clay & Inside of the clay + muslin model
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Binding - catenary tests Structural stability For the next set of tests, we created catenary models using a wooden frame to hang fabric pieces of different sizes. The spatial orientation of the fabrics were determined and the clay mixture was poured in. Testing muslin, a simple catenary model with one peak, resting on 4 legs was created, as well as another model with varying and multiple peaks (as the muslin had been pinched and hung at specific areas upon the frame). 13
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STAGE 1-D / Muslin Tight Stitch Figure 14: Model Elevation
Figure 11: Frame Setting
Figure 12: Inner Surface/Clay
14 Figure 13: Outer Surface/Muslin
Binding - catenary tests, creating different peaks for the domes Structural stability In both tests the dried clay had bound to the muslin and was able to stand once taken off of the wooden frames (as shown in Figure 11) and turned over. Furthermore, no deformities occured in their shapes once the overturned models were resting on a surface. Due to the higher viscosity of the clay and the force of gravity, majority of the mixture had slid to the bottom of the hung fabric, therefore, the domed shaped tops of the models were heavier when flipped, that can be observed in Figure 14 as well. 15
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STAGE 1-E / Lycra Removal of Fabric - form finding, cut opening at the bottom Result: layering system
Figure 15: Frame Setting
Figure 16: Clay Pouring
Figure 17: Top View
16 Figure 18: Removal of Lycra
The same process was repeated with Lycra. After hanging the fabric, a small openning was cut at the bottom for the clay to pour out “Figure 16� of in order to avoid a heavier top. Once dried, the lycra was removed, revealing a clay model formed by the creases and shape of the hung Lycra. While the model could stand, the bottom areas were thin and cracking under the self-weight of the clay (cracks are visible in Figure 19).
Figure 19: Clay Model
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STAGE 1-F /Layering
Due to their different properties, the fabrics served different functions. Whereas muslin was able to bind into the clay and provide reinforcement, Lycra worked well in acting as a form-giver and giving shape to the clay model. Once dried, the Lycra could either be removed. For further testing in the next stage, a layered material system was created comprised in Figure 20.
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Figure 20: Layering System
Layer 1 - Clay Layer 2 - Muslin (For binding) Layer 3 - Clay Layer 4 - Lycra (To remove)
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STAGE 1-G / Pavillion Design Exploration
Iteration #1: Number of agents: 20 Number of attraction points: 6 Number of repeller point: 1 Movement type of agents: Linear Maximum height traveled: 50 m Iteration #2: Number of agents: 20 Number of attraction points: 4 Number of repeller point: 1 Movement type of agents: Rotating Maximum height traveled: 40 m Iteration #3: Number of agents: 20 Number of attraction points: 3 Number of repeller point: 1 Movement type of agents: Rotating Maximum height traveled: 25 m Iteration #4: Number of agents: 20 Number of attraction points: 8 Number of repeller point: 1 Movement type of agents: Rotating Maximum height traveled: 10 m Iteration #5: Number of agents: 20 Number of attraction points: 4 Number of repeller point: 1 Movement type of agents: Rotating Maximum height traveled: 25 m
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Iteration #6: Number of agents: 20 Number of attraction points: 6 Number of repeller point: 1 Movement type of agents: Linear Maximum height traveled: 25 m
Iteration 1 Iteration 2 Iteration 3 Iteration 4
In creating pavilion designs “Figure 21�, the agent based system created by Berin and Felippe in Natural Systems and Biomimetics seminar project was altered and used to generate 6 different design iterations. The system was comprised of a repelling point moving upwards in the Z direction, with a set number of attractor points rotating around it which attracted a set number of agents. Therefore, various paths were created as the agents travelled up to reach the moving attraction points. The number and movement of attractor points (in terms of rotating or linear paths) and maximum height travelled by the repeller point (thus, the entire system) were varied, and the resulting shapes were rationalized until desired forms were reached.
Figure 21: Pavillion Design Exploration
Iteration 5 Iteration 6 21
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STAGE 1-G / Pavillion Design Exploration
Iteration #1: Highest displacement: 7.27e01cm as the most displaced area, vivid yellow region Iteration #2: Highest displacement: 7.27e+01 cm, vivid yellow region Iteration #3: Highest displacement: 9.09e+01 cm, viviyellow region Iteration #4: Highest displacement area = 2.55e+02 cm - 2.91e+02 cm, white region Iteration #5: Highest displacement = 1.27e+02 cm, lighter yellow region Iteration #6: Highest displacement = 2.36e+02cm, white region (Pavilion selection criteria = moderate displacement overall, human proportionate) 22
Human Proportion Least Displacement
Using Karamba 3D, finite element analysis was carried out to understand which design would result in highest deformation and what areas of the chosen design would have to be reinforced. Analyzing with the values of clay (Young’s Modulus, E = 3.2 kN/ cm2, G = 1.14 kN/cm2)7, results showed that iteration 6 had the highest displacement (around 2.36e+02cm, in white region (maybe we should outline this in the image?)), while iteration 2 had the least (0cm in gray area) for majority of the surface. However, as iteration 1 was the most human proportionate design with medium displacement (7.27e01cm as the most displaced area, vivid yellow region) it was chosen as the pavilion design to proceed with.
Figure 22: Displacement Analysis Iteration 1 Iteration 2 Iteration 3 Iteration 4 Iteration 5 Iteration 6
Most Displacement
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STAGE 1-H / Pavillion Section
Cutting plane
3.2m
4m
4m
Figure 23: Pavillion Design Moving forward with iteration 1, we can see from the section drawing in the figure below that the layered material system would be constructed of clay and muslin. Figure 24: Pavillion Section 3.2m 2.7m Clay 50mm Muslin 10mm Clay 50mm
0.9m
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STAGE 1I /Fabrication Method As it would not be possible to create this pavilion as one continuous surface layer by layer, it was proposed to divide and construct it in sections to be assembled together ”Figure 25”. Moreover, it had to be considered that the Kuka robot arm would not be able to properly print the clay in the angles needed in our test models, especially as it’s movement would be limited by the wooden frames. To create this pavilion at such angles through Robotic 3D clay printing would require another strategy. Therefore, taking the learnings from the initial phase of the project we experimented with different robotic 3D printing techniques in the next stage.
Figure 25: Pavillion Section Pieces (Clay+Muslin+Clay) Lycra + Clay (Binding Layer) Foam Mold
Figure 26: Pieces
Rotated Pieces
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STAGE II-A / 2 Clay Layers + Load Test
Figure 27: Pouring Bag and Round Caps
Stage II began by load testing the layered clay system (lycra, clay, muslin, clay) (20cm x 20 cm), keeping the same ratio of 5 mL of water for each 50 gram of water. The top clay layer was applied immediately on the Muslin after the creating the first layer. The square piece was applied up to 100 gram of load at the center while supported on two sides in a pinned form (locked in x, y, z directions). As both sides cracked, the clay layers stayed firmly bound to the muslin. This was a valuable learning proving the fabric was holding the two layers together.
Figure 28: Filled Clay Bag
However, to ensure the value of creating a layered system, further testing was needed to understand at what weight it would buckle.
Location of the force application
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Figure 29: First layer of Clay on Lycra
Figure 30: Muslin on Clay Layer
Figure 31: Upper Side Layer (20cm*20cm)
Figure 32: Bottom Side Layer
Support 1
Support 2
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STAGE II-A / 2 Layers of Clay (Lycra+Muslin) To understand how a layered system would behave in a catenary shape, a manual test using the same frame-fabric setup was created. The Lycra-Clay layer was created first, after it had dried a certain amount, the Muslin-Clay layer was applied on top. The two layers did not bind well to each other as the first clay layer had dried and not been re-wet to enduce adhesivity. In order to have a completely bound system, we needed to ensure the bottom layer was wet.
Figure 33: First Clay Layer
Figure 34: Second Layer Clay Muslin Clay Lycra Figure 35: Binding of 2 Clay Layers into Muslin and Lycra Clay Muslin Clay 28
Figure 36: Binding of 2 Clay Layers into Muslin
Figures 37 & 38: Models showing the gap in between the muslin and clay
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STAGE II-B
A 6 axis Kuka was used for robotic printing, with an extruder strapped into the arm. 4 mm nozzle was used - it was connected to a PVC Reducer through a PVC Adaptor. The Acrylic Pipe held the clay mixture - after the clay was poured in, it was compressed down and air bubbles were taken out using a circular wooden tool. Two tubes bringing in air were connected to the top PVC coupler; air pressure controlled the rate at which clay was printed out and could be adjusted using a dial. The movement of the robot arm was controlled with a smart pad.
Nozzle Nozzle PVCCoupler Coupler PVC
Acrylic PipePipe Acrylic
PVC PVCCoupler Coupler
PVCReducer Reducer PVC
PVCAdaptor Adaptor PVC
Nozzle Nozzle
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Figure 39: KUKA, components used
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STAGE II-B / 2 Layers of Pattern /KUKA The next catenary layered test was done with Kuka robot arm. For this test, a pattern (“Figure 40�) was printed on to the fabrics to investigate what strengths and weaknesses would arise both structurally and design wise. The pattern was to be printed in 2 layers. We chose to create a design that had intersecting and overlapping lines to account for structural stability. The design had squared ends to stand on once it was overturned. 3 important factor were kept in consideration: 1. A wooden frame holding the fabrics would be significantly difficult to guide Kuka around. 2. The angles Kuka would need to print at, coupled with the limiting perimeter of the frame, would not be possible given the large size of the clay extruder. 3. After printing the first layer of clay onto Lycra, the Muslin would need to be stitched on perfectly on top of it. This would take time and potentially smudge the printed bottom layer.
32 Figure 40: First, second and both layers of clay pattern
Figure 41: Final Model
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STAGE II-B / 2 Layers of Pattern /KUKA Thus, it was decided to print on the fabrics lying flat on a base surface (50 cm x 50 cm) “Figure 41”. Once the first pattern (45 cm x 45 cm, both layers) was printed on the Lycra, the Muslin was laid on top “Figure 43” and patted down before printing the second pattern “Figure 44”. The layered piece was then hung on to the wooden frame in a catenary position.
Figure 42: Lycra + First Clay Layer
Figure 43: Muslin Layer
Figure 44 : Muslin + Second Layer of Clay
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STAGE II-B We faced a problem after removing the Lycra and cutting the excess Muslin off the sides of the model. As the fabric was pulled, the layers cracked at different areas. This was because a pulling force being applied to the entire system since all clay layers had bound to the Muslin. Still, the model was able to stand and retain rigidity. However, as the lines of the pattern were thinner in some areas, more cracks started appearing “Figure 48�. Specifically in curved edges of the model where load was being transferred. While printing on a flat surface and then creating a global form was successful in some cases, we wanted to investigate the option of a creating permanent frame to stitch the fabric and print the clay on to.
Figure 45: Hanging
36 Figure 46: Lycra Removal
Figure 47: Final Model
Figure 48: Crack on Clay
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STAGE II -C / Frame + Single Layer of Silk Mesh
Moving forward, we decided to mitigate the cracking by testing a permanent frame. A curved model using 3 mm steel rods as the frame and silk mesh as the fabric was made. Silk mesh was chosen as the new fabric due to its high elasticity and relatively large pores, a mix of Lycra’s and Muslin’s characteristics. The steel frame was produced by manual bending and spot welding to reach a desired shape (around 30 minutes). When resting on a surface, this model would rock back and forth with the slightest force applied.
Figure 49: Top View & Elevation Top View
Elevation
Figure 50: Robotic Print on the Frame + Setting
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It must be noted that this model had not been 3D scanned, therefore, a computational design could not be created to match its exact geometry. Additionally, given the fact that it would rotate back and forth with the slightest applied force, a very simple patter was printed (offset isocurves of the surface) to have more control of the system. During this process, difficulties arose in positioning the model correctly and firmly under the extruder and attaining the right clay viscosity. In order for the clay to bind to the fabric, it needed lower viscosity, however, if the clay mixture was too liquid, it would immediately flow out of the extruder even under the lowest amount of air pressure. Consequently, the printing process was not well controlled and a large amount of clay had been printed on end of the model.
Figures 51 & 52: Dense Clay Area and Penetration of Clay
Once dried, we observed that the rotating model was now resting on the side with a denser amount of clay “Figure 51�. While applied force would cause it to rotate, it would return to resting on the denser clay area once the force was lifted.
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STAGE II-D / Surface Generation
Taking this observation, 3 surfaces (Figure 53) were generated with the ability to rotate once weight was applied to one side.
Figure 53: Surface Generation
Surface 1 Surface 2 Surface 3 40
When applying a pattern onto these surfaces, one end would be chosen to apply a larger amount of clay onto. Using the same logic as our test, the weight of the clay would then be able stabilize these surfaces into a stable and further upright position as shown in Figure 54.
Figure 54: Rotation of the Surfaces After Clay Load
Denser Clay Area
Surface 1
Surface 2
Surface 3
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STAGE II-E / Karamba Analysis
Figure 55: Legends (Respectively for Surfaces 1, 2 and 3)
Figure 56: Surface Deformation Analysis
Surface 1
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Surface 2
In order to understand the structural behaviours of our surfaces, we ran a Karamba 3D FEA test for displacement under self weight. The material used for the analysis was a constant shell of aluminum with 1cm thickness. The results portrayed the rotated design of Surface 2 as the most displaced. However, as the material considered was aluminum rather than the material system of steel and fabric, the displacement values cannot be considered as accurate. Taking insights from this analysis, we wanted to investigate how the displacement of the rotated surfaces could be influenced by adding a denser pattern of clay onto one end.
Figure 57: Surface Deformation Analysis
Surface 3
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STAGE III
In Stage III of the project, necessary changes were made to the materials and decisions based on the combined learnings from Stage I and Stage II: 1) After drying, the clay had not bound to the silk mesh fabric of the final steel frame model(Figure 58). This was due to the fabrics slippery nature – in other words, the silk mesh fabric was more alike to lycra than muslin. Even though the clay had seeped through the pores of the mesh, it could easily be picked off. It was decided to change our fabric back to Muslin. 2) We decided to proceed forward with the investigation of how we could control the rotation of surfaces using higher clay densities in certain areas of the surface. 3) Furthermore, it was decided to keep the permanent steel frame. This decision had also taken influence and insights from the works of Sean Ahlquist, studied in the research section (See in Research Section-5) “Characterized as a force-active system, a textile hybrid structure is comprised of tensile surfaces operating in equilibrium with networks of elastically bent elements.” (4) Our process of production followed our learnings from the works of Sean Ahlquist. We began Stage III by creating a physical 1:10 model of our pavilion design. Taking reference from Surface 2 (Figure 56) created in Stage II, the design was altered based on desired spatial quality and required dimensions to be human proportionate.
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Figure 58: Silk Mesh Fabric and Clay (not binding)
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STAGE III-A / Production Process
3mm steel rods and 1.5 mm copper wires were used. The total amount of steel rods used were 3.2 meters (one 80 cm panel, two 83 cm panels, one 74 cm panel) and 1.5 m for the copper wires. Steel rods were cut into the needed lengths based on the panel sizes of the digital model determined from our digital model. The steel pieces were curved and their ends spot welded in order to create full circles. Finally, each circle was shaped into the right angles and curvatures based on the digital model. Finally the 4 steel panels were welded to each other at precise locations based on the digital model. This steel model frame was our primary structure. In order to achieve the correct global geometry, the curved local shapes of each panel (in terms of concavity) needed to be replicated. This would be the function of the copper wires, to guide and sustain the curvature of the panels. They were cut to the needed lengths and welded onto the panels. Each panel was split into 4 quadrants. The copper wires acted as the secondary structure of the 1:10 model. The total time taken to produce the frame was 5 hours with 2 people.
46 Figure 59: Metal Frame Production Stages
Panel 1
Panel 2 Panel 3
52 cm
Primary Structure
Panel 4
Secondary Structure
62 cm
Figure 60: Primary and Secondary Structures
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STAGE III-B / Produced Frame Structure
Stitching Process and Result The last step of the production process was tensioning and stitching the muslin onto the panels of the frame. The total time taken for the stitching process was 5 hours by 1 person. In total, the production time for the 1:10 model was 10 hours: 5 hours to create the frame, 5 hours to stitch the fabric onto it. Figure 61: Steel Frame with Fabric
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Rotation The aim was to print a denser amount of clay at one end of the model (Figure yy) to cause rotation to one side. First, the weight of the clay to be printed needed to be determined. The frame weighed 200 grams; each panel roughly 50 grams. To bring rotation, we would need to print roughly 150-200 grams of clay on the portrayed location in Figure 62, based on how much we wanted the model to rotate. The left side panel needed to lift the system and the 3 remaining panels weighed ~150 grams together. Therefore, the left side panel would need to weigh 150+ grams in total to cause a significant rotation. A dried 4cm line of clay at 5mm thickness was 1 gram, therefore, 8 m of clay would need to be printed on the left panel to print 200 grams of clay. This would not be possible, especially at this scale, regardless of how we designed the pattern. However, carbon fiber was used instead of steel, the entire frame model would have weighed about 40-45 grams in a 1:10 model as carbon fiber is 4.5-5 times lighter than steel. Proceeding with the steel frame, the design strategy needed to change.
Figure 62: Stablility of the Model After 200g Clay Load
200 g
200 g
200 g 49
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STAGE III-C / Design Change
Consequently, we observed that turning over the 1:10 model created a spatial orientation that could also act as a pavilion (with a proper ceiling height and allowing 1 main and 2 side entrances). We proceeded with the overturned version of the original model.
Figure 63: Model with Clay Patterns
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Tension & Compression The model behaved in both tension and compression on all its panels and coupling that with the fact that clay acts best in compression, our logic changed to printing the clay patterns on the compressive areas of the model to reinforce the structural capability of the system. FEA analysis using Karamba 3D was used to understand where it would be best to print the patterns. Figure 64: Tension and Compression Parts on Fabric
Tension
Compression
T
C
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STAGE III-D / Karamba
Figure 65: Tension and Compression Analysis on Karamba
High Utilization (blue areas)
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The Karamba analysis tested for both highest areas of compression and tension on both the bottom and top surfaces of the model. We chose to only focus on compression. The materials analyzed were Steel and Fabric. The surfaces were analyzed with fabric material properties, while the perimeter curves of the surfaces were analyzed as steel beams. The panel surfaces were analyzed for compression and the beams for utilization. The 4 surfaces were meshed using the “Polygon Mesh Primitives 3-D Face” command in Rhino (right?) and fed into the analysis in Grasshopper as meshes. The values used were 0.1 kN/cm2 for E (Young’s Modulus) and 0.04 kN/cm2 as G (Shear Modulus) for fabric. Polylines were created from the edges of the meshed panels and fed as lines into the FEA to analyze as steel beams, O-section. This way, the beams were a part of the meshes and Karamba could understand the system as 2 materials performing in sync. Looking at the top surfaces, all panels ranged in amount of compression. Therefore, it was decided to have a spread out pattern that would cover the lighter red and blue areas (ranging from –7.76e-05 kN/cm2 to 3.43e-04 kN/cm2 respectively). For the steel beams, the areas under most utilization were the blue regions (ranging from 10.1% - 23.6% utilization). This was mostly occurring where steel panels were touching and overlapping each other and where they were meeting the ground.
Figure 66: Legend for Figure 65
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STAGE III-E / 3D Scan
Having understood from our Karamba analysis where we would be printing the patterns, we 3D scanned our 1:10 model to create a digital model from it. This was because the physical model was made manually and not matching the original digital model’s geometry, therefore, there were many discrepancies between the two that needed to be accounted for. We would use the 3D scan model to inform Kuka.
Figure 67: 3D Scan and the Final Model
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Figure 68: 3D Scan of the Model
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STAGE III-F / Robotic Clay Print & Initial Trial
Accounting for to the complexity of our global geometry, the need for a specific viscosity for the clay to bind to the muslin and the angles Kuka would need to print the clay at, we created a very simple pattern. Each diamond like shape (geometry that is similar to the offset of the panel frames) was to be printed in 3 layers. Due to the aforementioned complexities, a number of dry tests were run with the robot arm to simultaneously adjust the location of our model on the base surface and the Grasshopper code for Kuka. This required a significant amount of time (about 1-1.5 hours). Further problems arose when the printing process started: 1) While the viscosity of the clay was relatively appropriate for both the extruder and for binding to the muslin, the cylindrical shape it was printed in (the nozzle end was circular) did not allow it to fully bind to the fabric that is shown in Figure 69. As we had learned from our initial square frame tests “Figure 3” the printed clay needed to lie in a flatter shape on the fabric to bind well. 2) One of clay’s strengths as a material is its adhesive nature – when one layer of clay is printed on top of another they stick to each other as shown in Figure 70. However, as the cylindrical shapes of the printed lines were problematic, the first layer (being the base) would not bind well to the fabric. As the Kuka robot arm moved while printing the second layer, the first (base) layer would lift off the fabric and move with it. A few times, we had to interfere by stopping the robot and reattaching the printed pattern layers onto the muslin, to then move on to the next.
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Figure 69: 3D Robot Printing-Not Binding
Figure 70: 3 Layers of Clay Pattern
Figure 71: Larger Clay Pattern Trials
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STAGE III-F / Robotic Clay Print & Initial Trial
3) The scale of the 1:10 model was too small in comparison to its geometric complexity. In order to compensate for this, we decided to use the 4mm nozzle (smallest available) for the extruder to 3D print the clay. As a result of these problems, only a few pieces of the total pattern could be printed and the rest were manually printed on the model.
Figure 72: Final Pavillion Model with Patterns
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Figure 73: Final Pavillion Model with Patterns / Side View
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STAGE III-G / Wind & Solar Analysis
Wind and Solar analyses were conducted to further understand how the designs would need to change accordingly. The wind analysis was run using a velocity of 10.00 m/s [West] to measure for the wind pressure on the surface of the model as in Figure 74. In Figure 75, the velocity vectors are represented as strips and particles respectively. The left panel is the most affected with wind pressure at 90.408 Pa travelling at 16.218 m/s. This pressure can be converted into an applied force (9.04e-06 kN/cm2) and included in the FEA analysis to understand its effects. Aside from the left panel, majority of the structure (the green areas) is under -31.584 Pa wind pressure, at a velocity of 11.468 m/s.
Figure 74: Wind Analysis on the Surface
Figure 75: Wind Analysis Through Velocity Vectors
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Solar Analysis Solar analyses were done on the surface of the structure and on the ground plane. The surface analysis (Figure 76) shows us the varying solar radiation occurring along the faces of the structure according to the set location sunpath data, which is London, UK. For the ground plane (Figure 77), the varying shadows that will be generated by the structure are illustrated. Looking at the areas with the highest densest amount of shadows (colours overlapping), we see that the most amount of shadows caused will approximately range from 9:00 AM – 15:00 PM.
Figure 76: Solar Analysis on the Surface
Figure 77: Solar Analysis on the Ground
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STAGE III-H / Joinery System
In order to create a 1:1 model of the 1:10 scaled model we had produced, we needed to understand and investigate potential joinery systems. In our considerations, the primary and secondary structure frames were chosen to be steel rods. Each primary panel would be divided into 4 sections, pre-bent and assembled on site. The same would be done with the secondary frames. As seen in Figure 78 to connect the secondary structures to each other a 4 directional connecting joint would be used as diagramed in Figure 80. A 3 directional joint to connect the primary steel frame panel sections to each other and the secondary frame rod meeting them (perpendicularly) would be used. Figure 78: Assembly Diagram
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2
1
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Finally, it was proposed to weld the areas where 2 panels would meet each other. The fabric would be stitched onto each panel once they were assembled. It was proposed to have a single sheet of fabric lying on top of each panel, as opposed having 4 pieces stitched together within one panel, respective to its 4 quadrants. There would be holes drilled into rods meant for stitching the fabric (Figure 79). The threads used to stitch the fabric would have to be proportionate to the tension acting throughout the fabric and the added weight of clay. More than one layer of muslin would be stitched on to account for the size of the fabric and weight of the clay being poured on. It must be recognized that this joinery system would have to be further investigated through smaller scaled physical prototypes and analysis, verified and iterated.
Holes for stitching
Finger joint
Figure 79: Primary Structure Detail
Figure 80: Joint Details 63
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STAGE III-H / 1:2 Model
Moving forward, a physical prototype of the 1:2 scale of a panel of the designed pavilion was created. This model was constructed manually based on the measurements and geometries of the digital model (not parametrically informed). Therefore, it was anticipated that discrepancies would arise. 3mm steel rods were used to create both the primary and secondary frames. The process of creation was the same as the 1:10 prototype: cutting at required lengths, deforming to attain the correct curvatures, welding at the required areas and stitching the fabric. With two people, the steel frame took a total of 5 hours to make and the stitching took a total of 4 hours. In total, 5 meters of steel was used and 3 meters of fabric in 1m of height. This prototype was not 3D scanned after production was complete, therefore, the computational design of it for robotic printing would have to be extremely approximated and would not be accurate. Figure 81: Clay Pattern on the Surface
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Figure 82: Clay Pattern on Secondary Structure Metal Frrame 65
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STAGE III-H / 1:2 Model
From the gathered learnings of the printing process failures of the 1:10 model, it was concluded that: 1) The discrepancies between the computational design and the physical model would make guiding Kuka difficult a considerable amount of time would need to be spent adjust the robot arms movement with dry runs. 2) Once again, the curvature of the model and the angles Kuka would need to 3D print the clay patterns at would be very complex. Due to the concave shape of the structure, the robot would need to be continuously paused, the model adjusted and the printing restarted. 3) Once again, adhesion troubles would arise between the clay and muslin due to the cylindrically printed shapes of the clay would need to manually interfere. Considering the concerns above, it was decided to manually print the patterns onto the muslin. These patterns would match the shapes of those on the 1:10 scale. This process took about 6 hours by 1 person.
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Figure 83: 1/2 Scale Model of 1 Panel
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CONCLUSION
Stage III Conclusion: Reflecting on the 1:2 and 1:10 scale models created along with our analyses, we reevaluated our logic of using clay as structural reinforcement for areas of the steel frame-fabric system that were in compression. The use of clay with this logic was perhaps redundant as the steel frame structure was already playing this role. In other words, clay’s value in this sense was relatively not significant. Consequently, it was observed that the shapes of the printed clay patterns influenced the shading properties of the structure. This discovery changed clays purpose in the material system for enhancing the design characteristics of the pavilion. The patterns could be changed based on design choices like social interaction/location choice/ concept etc. and the solar/radiation and wind analysis can be helpful for this design process.
Figure 84: 1/10 Scale Model
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Taking our learnings from all stages (Figures 85 to 87), it was proposed to print the patterns flat onto the muslin, creating a few layers, to post tension on the steel frame, while the clay is relatively wet. This would perhaps need to be done for each quadrant of the panels, as opposed to on one sheet the size of the entire panel. However many trials would need to be done at 1:2 scales of the panels to see how the clay would behave in this construction system.
Figure 85: Stage 1/ Binding with Muslin
Figure 86: Stage 2/ Flat Printing
Figure 87: Stage 3/Metal Frame
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CONCLUSION
Further Development: Throughout the 3 stages of the Design I seminar project, new materials, fabrication techniques, and structural analyses were introduced with the focus remaining Robotic Clay 3D printing. Each stage provided valuable learnings and failures:
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Stage I: Through experimentation using catenary shapes, a material system comprised of Lycra, Muslin and clay was realized. Binding was observed between Muslin and clay, while the elasticity of the non-stick Lycra functioned as formwork. However, while this layering system was a significant learning, the robotic arm, Kuka, would not be able to print in the angles provided by the catenary shapes of the hung fabric, and neither the rationalized design chosen from the NSB project. Stage II: Having 3D printed clay patterns on flat sheets of fabric to then give shapes to, as well as printing them on a steel frame – fabric structure with a rotational and curved geometry, it was realized the former strategy could be better controlled with less errors. Flat printing for each layer decreased difficulties in guiding the Kuka, while printing on an already curved structure was not efficiently manageable given the instability of the steel frame. Printing errors were also related to the high fluidity in the clay mixture - attaining the correct viscosity to induce binding and be appropriate for Kuka’s minimum air pressure was vital. Stage III: Proceeding with design decisions from Stage II, the steel frame chosen to go forth with. However, given the heavy weight and small scale of the frame, it was impossible to print the required amount (8m) of clay to create rotation. The design was altered and an FEA analysis was conducted for areas in compression, where the clay would be poured onto. Problems arose once again while printing, the cylindrical shapes the clay was 3D printed in (with circular nozzles) did not lay it flat onto the tensioned Muslin and required manual interference. Furthermore, upon re-evaluation of the completed system, it was decided that clay played more of a role in providing different forms of shading than providing structural reinforcement.
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CONCLUSION
Assessing the learnings from our project phases, we would base the direction of further development on flat printing the layers (to then manually hang) explored in Stage II (Figure 40). By returning to creating a multi-layered and textile varied system, without added frames, clay would retain its structural value and both fabrics their respective functions of form giving and reinforcement(binding). Thus, the performance of this material system as a structure would be interdependent upon each other. As done in Stage II, different patterns would be tested to be layered on top of eachother. In creating patterns, different openings, structural forms, and densities would be investigated in order to enhance the Stage 2 learnings. If the new patterns and more layers work well to create a catenary structure of the pavillion, than the metal frames will not be necessary to introduce. Some possible clay patterns and hanging conditions are drawn on the Figures 88-90. Furthermore, different catenary geometries (different number vaults, different depths, etc) would be created to analyze their respective structural behaviour, tested through FEA.4 As we had not done so for this project, additives would also be tested in the clay mixtures with the aim of increasing flexibility. Lastly, strategic stitching patterns would be tested on the Lycra and on the Muslin to investigate how different forms could emerge and if the stitching could optimize the structure in terms of stability.
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Figure 88: Flat Fabric + Clay Patterns
Figure 89: Hanged Fabrics and the Clay Structure After the Removal of Fabric
Fabric+Clay Fabric Remove Rotated
Figure 90: Pavillion Designs/Elevation
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RESEARCH - CASE STUDIES
Throughout the development of this project, many insights were taken from various existing works, research and developments. The topics explored are listed below in chronological order: 1.KnitCandela by Zaha Hadid Architects and BRG of ETH Zurich, Mexico City, Mexico https://block.arch.ethz.ch/brg/project/knit-candela-muac-mexico-city a.Popescu M., Rippmann M., Liew A., Van Mele T. and Block P.Concrete shell built using a cable-net and knitted formwork,DETAIL structure,1: 10-11,2019.
The research began with a study of KnitCandela, in Mexico City, by Zaha Hadid Architects and BRG of ETH Zurich - it’s geometry taking inspiration from the fluid forms of the traditional dress in Jalisco, Mexico. In a few words, the project is a concrete shell (50m2) built using a cable-net and knitted formwork. KnitCandela introduces KnitCrete technology. KnitCrete is a fabric formwork and cable-net system which reduces construction waste, takes away the need for moulds and is easily transportable. It is 3D-knitted to allow for more variation in direction and easy creation of openings, and coated with cement paste to remain rigid. Furthermore, it is supported by tensioned cable-nets or bending-active splines and provides insulation. The technical textile has 2 layers that perform different tasks: the visible side (inside the shell) is for aesthetic and the inner side (touching the concrete) performs the supporting needs such as guiding and positioning the formwork. There are inflated pockets between the layers that act as cavities in the cast concrete and reduce the need for difficult formwork. The initial inspiration for utilization of fabric in the project was taken from this structure. The use of fabric as a technical textile and the different properties and technicalities build into it to enhance the performance of the concrete were valuable insights for us that we wanted to investigate. (1)
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2.FattyShell by Kyle Sturgeon, University of Michigan http://k-sturgeon.com/portfolio/fatty-shell-2 Sturgeon, Kyle. FattyShell. University of Michigan. 2020 Our next case study was the FattyShell created by Kyle Sturgeon, at University of Michigan. FattyShell is a project that uses concrete and roofing rubber to create elastic formwork, in other words, the concrete is cast in the roofing rubber. The form is derived from algorithm based geometries, the unrolled rubber patterns are cut with a robot arm. Internal and external membranes are patterned the same and sewn together, with the holes cut for sleeve seem placements. The formwork is then placed on plywood ribs and tensioned using steel cables at computationally informed locations. The pour rate of the concrete (opening seams and then restitching), elasticity of the rubber and pouring locations allow for the concrete to contract or expand in thickness, thus, redefining it’s structural system. FattyShell was a different study from KnitCandela, with few similarities. While KnitCandela regulated the form of the concrete shell through the fabric, FattyShell allowed for the concrete to behave in it’s own ways due to the properties of material it had used. (2)
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3.Flexible formwork technologies: A state of the art review Hawkins, Will & Herrmann, Michael & Tim, Ibell & Kromoser, Benjamin & Michalski, A. & Orr, John & Pedreschi, Remo & Pronk, A. & Schipper, Roel & Shepherd, Paul & Veenendaal, Diederik & Wansdronk, R. & West, M.. (2016). Flexible formwork technologies: A state of the art review. Structural Concrete. 17. 10.1002/suco.201600117. https://www.researchgate.net/publication/309749990_Flexible_formwork_technologies_A_state_of_the_art_review
We further investigated fabric formwork and fabric casting by looking at the works of Mark West, the founding director of C.A.S.T, Center for Architectural Studies and Technology at the University of Manitoba. C.A.S.T. is a facility focussed to the exploration and development of fabric formwork in architecture. We specifically focused on beams and columns to understand the fabrication methods of structural elements by this method. CAST developed the largest beam (12m) using fabric formwork and basing the geometry off the diagram of the beam’s bending moment, creating various depths in the design. With this geometry, the beam would rest on two supports and carry load effectively. Columns investigated and manufactured at C.A.S.T. have been focused on a variation of anti-prismatic shapes for fabric formwork. Relative to conventional methods, fabric formwork reduces the weight and bulk of material needed to create columns. (3)
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4. Structural Design in Work of Gaudi Huerta, Santiago. Structural Design in Work of Gaudi. Department of Structural Design, Escuela Ticnica Superior de Arquitecrura, Universidad Politecnica de Madrid. 2006. http://oa.upm.es/703/1/Huerta_Art_002.pdf Stage I and Stage II of our project was influenced by the learnings we gathered from studying Gaudi’s works, particularly his use of hanging models as a method of creation and structural analysis. Gaudi would create these models by hanging simple cables and calculating the total loads that would be acting on them. These calculated loads would then be added on to the cables and their displacements (shape changes) taken into account; this process would be repeated with the self weight being modified until desired and calculated shapes were reached. Hanging models allowed designers to understand the most favorable shapes structures under compression would be able to take under the applied weights. In our case, created our hanging catenary models were created first by hanging the fabrics onto frames without analyzing the load of the clay that would be poured onto them. A desired amount of clay was poured onto the catenary fabrics with different spatial orientations (geometric shapes). (4)
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5. Sean Ahlquist In Stage II of our project, we were introduced to the works of Sean Ahlquist, Associate Professor of Architecture at University of Michigan’s Taubman College of Architecture and Urban Planning, along with the works done by the departments Master of Science in Material Systems program (where Ahlquist has ongoing involvement). From the numerous research published by Sean Ahlquist, there were 2 that we took reference from for both Stage II and Stage III: Exploring Material Reciprocities for Textile-Hybrid Systems as Spatial Structures Ahlquist, Sean & Lienhard, Julian & Knippers, Jan & Menges, Achim. (2013). Exploring material reciprocities for textile-hybrid systems as spatial structures. Prototyping Architecture: The Conference Paper. 187-210. This paper informed us about textile hybrid structures - “comprised of tensile surfaces operating in equilibrium with networks of elastically bent elements” - with a focus on their topological, structural and material properties. It explores different implementations of these systems that are comprised of glass-fibre reinforced polymer (GFRP) with homogeneous membranes or CNC knitted variegated textiles. The installation, Material Equilibria, at “ggggallery” exhibition space by Sean Ahlquist investigated how methods that could solve and manipulate bending resistance and tension using GFRP rods and knitted textiles. The installation is a force-active system. Through CNC knitting techniques, Ahlquist created surface articulation and variegation in the structure of the textile through hexagonal patterns. The organization and varying densities of the knitted patterns were computationally informed, directing its structural behaviour. The pattern was designed to carry tension and varied in knitting pattern in order to have elasticity at the edges and stiffness in the middle. (5) While our goals were different, we were interested in understanding textile hybrid structures and the properties that characterized them as we were working with different textiles, all acting under different stresses. Furthermore, we wanted to investigate the implications of applying external loads to the fabric frame system - the clay - that was already acting under internal forces.
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Toward a Pedagogy of Material Systems Research Carrying on with Ahlquist’s work, we studied the works explored by the students and faculty of the Master of Science in Material Systems program at the University of Michigan. This paper provided an investigation into the study of material systems and performances and highlighted the importance of prototyping to understand the material form and spatial behaviour. Prototyping of the design is posed “as a scalar framework where layers of material performance and spatial complexity can be engaged through continual embedding of parametric rules, tacit material knowledge, and calibrated responsiveness.� It is underlined that the fundamental properties of material systems are comprised of physical attributes (elasticity, stiffness, etc), environmental reactions (humidity, thermal, etc) and ambience/aesthetic qualities. The paper proposed that a material system can be broken down into 3 elements: topology, structurality and materiality. Topology addresses the parts of a system by type, amount, etc, without the need to consider geometry. Structurality states the conditions for the forces at play on the system. Finally, materiality embeds material properties information, including constraints, and further informs how it could behave when translated from computational data into physical fabrication. (6) As our project remained a material system throughout all stages, it was important for us to understand the different factors of a material system and how the performance of each element could affect the other.
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REFERENCES
1. Popescu M., Rippmann M., Liew A., Van Mele T. and Block P. Concrete shell built using a cable-net and knitted formwork, DETAIL structure,2019. 2.
Sturgeon, Kyle. FattyShell. University of Michigan. 2020
3. Hawkins, Will. Herrmann, Michael. Tim, Ibell. Kromoser, Benjamin. Michalski, A. Orr, John. Pedreschi, Remo. Pronk, A. Schipper, Roel. Shepherd, Paul. Veenendaal, Diederik. Wansdronk, R. West, Mark. Flexible formwork technologies: A state of the art review. Structural Concrete. 2016 4. Huerta, Santiago. Structural Design in Work of Gaudi. Department of Structural Design, Escuela Ticnica Superior de Arquitecrura, Universidad Politecnica de Madrid. 2006. http://oa.upm.es/703/1/Huerta_Art_002.pdf 5. Ahlquist, Sean. Lienhard, Julian. Knippers, Jan. Menges, Achim. Exploring material reciprocities for textile-hybrid systems as spatial structures. Prototyping Architecture: The Conference Paper. 2013. 6. Ahlquist, Sean. Newell, Catie. Thun, Geoffrey. Velikov, Kathy. Toward a Pedagogy of Material Systems Research. Conference: TxA Interactive. 2013 7.
Bowles, J.E. Foundation Analysis and Design (5th Edition). McGraw-Hill. 1996
8. Kotelnikova-Weiler, N., C. Douthe, E. Lafuente Hernandez, O. Baverel, C. Gengnagel, and J-F Caron. “Materials for Actively-Bent Structures.” International Journal of Space Structures 28, no. 3–4 (September 2013): 229–40. doi:10.1260/0266-3511.28.34.229.
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