THE FITTING CHAIR
CONTENTS
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Abstract Introduction Background Research Practice Findings Discussion Reference
1. ABSTRACT
1.1. Research brief:
tal issues, the idea of reusing and recycling material was also proposed. The result indicates that double-curvature enhances the stability and loading capacity of sheet material. 1.5mm and 2mm polypropylene equipped with better flexibility, portability and loading capacity. The property of tensile structure, that difference thickness and sizes of sheet material support different body weight, shows a sense of personalisation. This concept also corresponds to the environment, that using minimum material to satisfy our demand. The result of the study indicates a further research on the tensile strength of sheet material and the idea of flexible and personal furniture.
This project explores the tensile strength of sheet material in order to build a simple-manufacturing, portable, economy and sustainable chair for frequently moving people. The design methodology is to find the convergence from three domains: tensile structure, manufacturer and environment. In the domain of tensile structure, a practice based research on different thickness of paper, polycarbonate sheet and polypropylene sheet were tested to find a suitable tensile strength and flexibility to carry body mass. One-point bending, two-point bending and double-curvature were tested to build a stable structure. In the domain of manufacture, die-cut, 1.2. Design brief: engraving, CNC and different cutting lines Chairs have been designed as rigid forms were experimented and evaluated to make for a long time, such as the injection folding lines. Considering the environmen- moulded plastic chair, wood-joint chair
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and metal welded chair. These rigid forms of furniture not only lack flexibility when moving, but also lead to furniture waste. Living in a dynamic society in which people are always on the move, we need a flexible and adaptable chair to fit into our mobile lifestyles. The fitting chair utilises tensile strength to transform sheet material from a soft to rigid form, and from rigid back to soft again. The chairs are designed in three different sizes to support different body mass. As tensile strength has the tolerance of different weight, each chair requires people to consider which chair will fit them developing a sense of personalisation, appropriateness and the minimum use of material. The Fitting Chair challenges people to take more responsibility of their role in the structure, and encourages them to find the chair that will fit their lifestyle.
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2. INTRODUCTION Furniture has been designed rigid for a long time, such as injection moulding plastic chair, wood joint chair and metal welding chair. These rigid furniture not only loses the portability and flexibility when moving house, especially for frequently moving people, but also causes the inconvenience when recycling or carrying to second-hand shop. The manufacture process for making these kind of chair are also time-consuming when moulding shapes and connecting joints. Although some existing laser cutting wood furniture partly solves the problem of portability and flexibility, the shape of the furniture is confined by the manufacture way, which causes the the shape loses curvature. This project explores the tensile strength of sheet material in order to build a simple-manufacture, portable, economy and sustainable chair for frequently moving people. “Tension” and “folding technique” are utilised to easily create form and structure in the project. This paper will first look background research of tensile structure, collapsibility and tensegrity, and then shows the a practice-based research of sheet material which carry body mass. Since furniture making is a complex issue which involves in people, manufacture and environment, the design approach is to find the convergence from three domains: tensile structure(how body mass involves in tensile structure form both technical and emotional perspective), manufacture and environment. In the end, the evaluation of the structure and the idea of flexible chair will also been discussed.
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3. BACKGROUND
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3.1. Insights from furniture waste and frequently moving people: At first, at first I didn’t intended to to make a flexible chair. I would like to make a very beautiful wood joint furniture to solve the problem of furniture waste. I assumed that people got rid go their furniture mainly because they think their furniture are not beautiful enough. As the result, I did an interview, asking 63 people why they got rid of their furniture. However, 67% of them told me that they discarded their furniture mainly because because they have to move. It seems that making a very beautiful furniture cannot solve the problem people are unable to easily carry rigid form. We are now living in a fluid living space, and no longer live in the same place for a long time. It is necessary to make furniture more adaptable, flexible and portable. Moving house is one example. We might hold an event for only three days. Then if we need 100 chairs, how to move the chairs easily by using limited efforts. Since space has been used differently instead of using in the past, furniture also need to be designed differently.
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I was selling because I was moving out of Edinburgh
My partner and I are also designers. We LOVE that table... so the main reason is that we are moving back to Barcelona, where we are originaly from, so we were trying to sell all furtinure we bought when we came to Edinburgh.
The main reason of me selling most of my furniture (even though my final plan is to get a flat shortly with my own furniture in it ... ) Is because I am currently studying in Edinburgh but not quite sure about ky future plans yet. I am at my final year at university and I might be moving to a different location right after my studies finish here so I always think about it as a tenporary station. Since it is temporary I do not want to get attached to objects I might not be able to bring with me to my future location. I also means I dont want to spend too much money on it. Selling them means I have more space in my room when I dont need a furnitre anymore , that I probably get off second hand from another student beforehand. Its all a circle I suppose , when I need something I get it for cheap and quick and I can get rid of it for a fairly good price compare to what I purchased it for So basically its all because of ; saving money, saving space , and constatly preparing for the time when I will once need to move away (so I dont need to sell everything last minute in a rush).
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just sold it because I was moving to another flat where there was a bed-side table already ... And since it was very cheap, I could always buy it again if I need it on the future!
Well, I get rid of it because first of all it’s completely new, even though I used it for like a year. Second, I really don’t like giving my things for free - if they are so new and I know, it costs smth like 30-50 kr. but it’s something I paid for. And third, I will make the price for it unnecessarily high if I now pay to transport it to my new place. I think that’s pretty much it
i got rid of it because i was moving out of my apartment and i didn´t need it anymore and the hahah It is because I am leaving person moving in after me didn´t Edinburgh so I am getting rid of want it. that´s it. everything so I am getting rid of everything is there anything you need? i may be selling it!
The reason for getting rid of the desk is that we moved to a new place and it doesn’t fit anymore
Well the reason we are getting rid of the table is that it no longer fits the family needs - it was bought for a small student apartment and now we are a family of four so we need something more practical.
i was moving and wanted it to go to a nice home
It was because I had mine own sofa in the previous flat and as I moved in the new one I just decided to get rid of the old one in the flat, that was quite old.By the way, I disposed of it, nobody wanted.
We just moved to another house and the house already has furniture so we dont need the stuff Im selling anymore.
I sold all my furniture as I moved out of the country. It was a way to gather money as well as moving is not cheap.
I had to get rid of it, because I moved out of Denmark and thus, unfortunately, coudn’t take it with me.. It’s just as simple as that.
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Moving abroad. es. I’m doing that with our dining table and dining chairs. ‘m selling the others because it’s not worth to bring it abroad. It’s IKEA chairs which I can easily buy abroad. Unlike the dining chairs that I have is Danish design.
3.2. Actural research: exploring ways of making flexible furniture From the actual research, I found that tension is potential way to make things from soft to rigid form, and from rigid back to soft again. Therefore, I started to do the research form tensile structure.
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“The pursuit of permanence is called preservation. but preservation is for dead thing� 11
(Nerdinger, Meissner and Otto, 2009, p58).
3.3. Insights from Frei Otto: Frei Otto is a well known architecture for the contribution in tensile structure and light weight construction in the 20th century(Burkhardt, 2016, p9). The light weight construction was first proposed by Leonhardt (1909–1999) because people were facing scarcity of material in the period(Aldinger, 2016, p3). However, for Frei otto, “lightweight construction does not just mean minimising mass, materials and energy, but always building adaptably, changeably and thus ephemerally” (Nerdinger, Meissner and Otto, 2009, p12). He thinks “the pursuit of permanence is called preservation. but preservation is for dead thing” (Nerdinger, Meissner and Otto, 2009, p58). Today, we are facing a dynamic living trend, most people no longer live in the same place for a long time, his idea corresponds to the living context where we are living now. Otto’s idea might help us to understand how to make an adaptable furniture in this dynamic living environment. His soap experiment which aims to find tensile-stress pneumatic structure in nature also shows the attempt to use the minimum material. As bubble foam will always use the least energy to construct the shape (p53,Beukers and Hinte, 1998). This experiment makes me to rethink the structure from the nature: to delete everything unnecessary.
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3.4. Tensile structure in architecture: As I am doing research on tensile strength of sheet material, it could be helpful to understand the tensile structure in architecture. The definition of tensile strength covered three component: boundary tensioned membranes, pneumatic structures and pre-stressed cable nets and beams(p3, lewis, 2003). The requirement, making double curvature plays a crucial role in making tensile structure. The fabric also need to be cut into accurate size to make sure the curvature is constant (p191, Nerdinger, Meissner and Otto, 2009). One of the reason that tensile structure is proposed is due to the fact that “new materials are always more expensive than the ones they have to replace; the only way for them to be convincing is through cheap constructions and processes� (p27, Beukers and Hinte, 1998). There is a similarity between engineering and nature for the pursuit of using minimum energy (p44, Beukers and Hinte, 1998). Animals and plants have evolved ways of using the least effort to live in the competitive environment; In engineering, the cost always plays an important role for making a suitable construction (p44, Beukers and Hinte, 1998). As a result, the idea of tensile structure challenges us to develop a new structure in the 21 century. Considering the meaning of the expression of tensile structure in the living context is also worthwhile. Since tensile structure is different from rigid structure, environmental factors and human factors cause the variation of tensile structure. Some architecture have discussed the meaning before. Scheuermann and Boxer (p24, 1996) thought that tensile structure could attract people’s attention due to the irregular appearance. They (p40, 1996) also proposed that it is a way to show the hierarchical order in the public environment. Frei Otto thought that it is important to prioritise people in the relationship with tensile structure because space are created for people not for the environment (p57, Nerdinger, Meissner and Otto, 2009). I thought chairs share the similar concept or even more. When we sit on a chair, we become part of the structure.
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4. RESEARCH
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4.1. Collapsibility : 4.1-1. Literature review:
Collapsibility is a capacity to adjust in size to meet a practical need. The purpose of collapsibility is critical: no adjustment, no future (p7, Mollerup, 2006). Mollerup (p6, 2006) proposed that “man, himself a collapsible being, physically and psychologically, needs and wants collapsible tools”. There are twelve principles of collapsibility: “stress, folding, creasing, bellows, assembling, hinging, rolling, sliding, nesting, inflation, fanning and concertina” (p30, Mollerup, 2006)”. Since tension which belongs to the category of stress, is one of the principles of collapsible, a better understanding of collapsibility could help me design flexible furniture.
4.1-2. Interview with Lore Said:
Lore Said is a PHD student who did research on collapsibility. She developed the language (the expressional meaning) of collapsibility. As collapsible things are different from rigid forms, they show some expression of the objects. Such as human use this as a facial expression to express our motion; animals arch their back to express their anger. This idea helps me to develop the vocabulary of my flexible chair. Although I agree that collapsible things indicates expression of the objects, I think it is not really necessary highlight the property of expression. She also questions the idea that people designed things as rigid forms. She used collapsibility as a philosophy or a metaphor to encourage people open and interact with movement because 21 century is about wars and uncertainty. Part of being forward is not actually being scared of movement. However, I thought furniture should make people have a sense of secure, just like they are protected. Collapsibility should be the way to make people more close to the material and feel more comfortable. Some key points which relates to my project were also coded. 16
4.2. Material Research: From the beginning, both rigid and soft material are tested such as: fabric, paper, wood and plastic sheet. Fabric is too soft to create tensile strength. It requires some additional support to make the structure become rigid enough to support body mass. Paper is the material with good flexibility, but the tensile strength is not enough. The material is too easy to be torn apart. Laser cutting wood is feasible, since the material become flexible. It is the idea to create some gaps to soften material. However, wood sheet need to be thicker to support people’s weight, it will lose the portability of the material. In addition, high quality wood usually has better tensile strength, but it will cause the price of the furniture increase. I would like to make an affordable chair. The decision is use plastic sheet since it is highly flexible, unbreakable and cheap.
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4.3. Structure development
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4.3-1. Bottom structure development
The first prototype was designed as a structure with four legs from 0.75mm polypropylene sheet. The four legs are fastened by another annular shape tube. Each cylinder is fastened by the slots and arrow tabs. However, the tensile strength of the material is too strong so that the material is too hard to bend as a cylinder shape.
The second prototype was intended to alleviate the tensile strength of the material. Paper was used as the material for testing structure in this stage because it is cheaper. A bigger cylinder replaced the four legs structure so that the material can be bended easily. However, the centre of gravity changes easily when people move.
The third prototype is a double conical shape. The bottom structure has been enlarged so that the centre of gravity becomes closer to the floor. However, the pressure is concentrating on the edge between the two conical shape, this cause the shape distort then collapse.
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The fourth prototype is a single conical shape. In this stage, 1mm polycarbonate sheet is chose for the material because of its highly tensile strength property. The upper shape has been deleted to make sure that pressure is evenly separated on the single structure. However, the structure is easily to be distorted when too much pressure is pressed on the upper surface.
Several small models were tested in this phenomena so that some possible solution could be quickly developed. It was found that building ribs on the original material do not improve the structure. Due to the ribs are fastened by flexible string, it create more gaps in between the material. However, the bending technique really increases the righty of the material.
Different folding angles and different number of folding lines are tested to determine a much more stable structure. The vertical lines works worsen because it caused the bottom surface unable to be fully connected with the ground surface. The shape distorts to balance force when people press on the top, however it caused the structure unstable. 45 degree folded lines works better because the rotated folded lines become rigid and separates forces along with tangent direction.
One key advance is to make double curvature which make enhance the rigidity of the structure and prevent the structure be easily distorted. Several small models are tested first to see the feasibility of full size model. The double-curvature actually works very well in small scale. It makes the models highly rigid. Although the rigidity of the material decrease in full size model, the structure is still tough enough to support body mass.
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4.3-2. Upper shape development
The first shape is composed of four cutting lines and a string which is used to joint the four sectors. The main pressure is pressed on the string instead of the material. The curvature of the back cannot fit our body. Leaving too many gaps in between also caused the structure unstable.
The second one is composed of only one cutting line. Unnecessary lines are deleted to decrease the gaps, however, the back still cannot fit our body. The seat is uncomfortable because the ending point of the seat shrink to one point. It is also noticed that the back seat leans too backward when people lean back. Due to the material is too flexible, the part where we sit is bended along with the bottom structure.
The third version is composed of 2 cutting lines. The curvature of the back has been adjusted to fit our body. The back part is also connected along with the edge of the bottom structure so people will not lean too backward. Adding holes on the material is also tested to soften the material, but it causes the structure unstable.
Since the back part is bended a little when people leans backward, a round hole is added to soften the material so that the force can be relieved. However, it causes the structure unstable.
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This prototype with a long back support is rigid enough to support our body. The curvature of the back of the chair actually fits our back curvature so it is comfortable. However, the back support is still a little soft; the length of the back can be shorten a little so that less material were used.
The back has been shortened in this version. The angle of the back is also experimented to balance rigid and soft. Both using least material and making the chair comfortable have been achieved in this version. However, there are two drawbacks when folding polycarbonate sheet. One is that bending the material is extremely difficult. Plier was used to bend the polycarbonate sheet, but it is still quite hard to do so. Making folding lines by slightly cutting the material is also impractical. Once the material is cut a little bit, it will break immediately when fold it along with the folding line. Some bending lines have also been developed to better fold it. Another drawback is that once the material was folded, it is hard to fold back to flat sheet again.
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4.4. Personalisation-appropriateness
4.4-1. Insights from the tolerance of tensile strength
It is found that the stability of structure relates to different people’s weight. Since tensile structure has a tolerance of different weight, different thickness and sizes of material should correspond to different people’s weight. The idea shows that our body mass is involved in part of the structure. When a right person (the people ’s weight and body shape correspond to the structure ) sit on the right chair, the structure works better. This insights reminds me the appropriateness of using the least the material to do the least thing and a sense of personalisation.
4.4-2. Goldilocks and the three bear- the fit
The story, Goldilocks and the three bear, offers me more insights of the appropriateness:The girl Goldilocks came upon a house. She saw three bowls of porridge. Goldilocks was hungry. She tasted the porridge from the first bowl.” This porridge is too hot!” she exclaimed. So, she tasted the porridge from the second bowl. “This porridge is too cold,” she said. So, she tasted the last bowl of porridge.“Ahhh, this porridge is just right,” This story inspired me the idea of appropriateness. People tend to pursuit more things than they really need, but “more” is not the most suitable option for us. The one which fit your body should be the most appropriate.
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5. PRACTICE
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5.1. Material shift : from polycarbonate sheet to polypropylene Since polycarbonate sheet cannot be fully bended back to flat sheet again, it loses portability when moving. It was found out that a new material, polypropylene sheet can be bended back to flat sheet again. In addition, the tensile strength of the material is tough enough to support people’s way. Some simple manufacturing ways such as laser cutting and die cut are usually used to cut polypropylene sheet. As the result, polypropylene sheet was choose to be the final material of the fitting chair.
5.2 Thickness shift: from 1mm to 1.5mm 1mm polypropylene sheet was tested first because it is assumed that it is equipped with similar tensile property as 1mm polycarbonate sheet. Nevertheless, 1mm polypropylene is too soft, it was found out 1.5mm polypropylene shares similar tensile property as 1mm polycarbonate. It was assumed that the polypropylene back seat will be inappropriately bended as polycarbonate back seat so a round hole was still cut on the back. However, the material become too soft when adding the hole because polypropylene has less tensile strength.
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5.3. Folding line exploraton
It is found out that the middle one is most suitable.
5.4. Appearance exploration and revision Several scale models were developed in this stage to explore the appearance. Balancing the bottom structure and the seat is also quite important.
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Full size models are tested to see the real proportion and physical feasibility. 28
The final shape of scale model was laser cut to test the proportion. It was found that some details are not well considered such as the connecting edges and folding parts. Some edges and connecting parts were smoothed out later.
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5.4. finishing The finishing model is designed as three kinds of size for three different weight. The two smaller sizes are made of 1.5mm polypropylene sheet, while the bigger is made of 2mm polypropylene to support those who weight more. It was decided to design three chairs for three weight of range: 20-40kg, 40-55kg, 55-90kg. The range of weight is determined by user test. The holes are design to make people’s body fit better in the chair. A handle was also added on the two parts to easily carry the sheets. A chair cushion was also added to make the chair more comfortable.
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6. FINDINGS
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6.1. viability: assemble on Grassmarket
Three chairs were carried out to do user test on Grassmarket. The assembling process is tougher in outside than inside since some environmental factors, such as strong wind and rain. Without people sitting on the chair, the chairs are easily moved by wind. It should be further considered if the context is outside.
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6.2. feedback from people
Some user tests have been done from people with different weight. Although people thought the chairs are comfortable, a sense of unstable feeling appears when some of them lean backward. Since the chair is flexible, people are not familiar with the strange feeling when sitting on the chair. While a new interacting way, swaging on the chair, was discovered when people testing it.
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7. Discussion 7.1. back to the idea: The fitting chair is the idea to challenge permanence and preservation in the dynamic society. Since people are frequently moving in the 21st century, designing something bulky has made things lose portability and stuck us to move forward. However, if we starts to make things adaptable, we can make the material things which we produced fit better in the environment. In addition, this idea encourage people to take more responsibility of their choice, body and lifestyle. Since the weight of the chair relates to our body mass, the choice we made decide how much material we need to use. When we become part of the structure, we started to aware how we are involved in the environment instead of unintentionally producing bulky things in the environment. 7.2. Structure evolvement The fitting chair challenges the traditional structuring way since it utilises tensile structure instead of compression structure. I was stuck in the four legs structure for a long time but I finally found that it is necessary to move forward to rethink the structure. 7.3. Feedback from people: strange feeling The user tests show that some people are not familiar with the strange feeling of the chair because it is flexible. They think the chair is comfortable but they just do not get used to it. It might be a critique whether the product should be changed more understandable so people are familiar with. While I think the problem is not whether changing something that people like or not, it is more important to make people build trust on this product. One part of the problem is people dare not to lean backward. This product is just like a tougher hammock, the interaction of the product is different from a rigid chair. Some people might be afraid of lying on a hammock because they think the rope will break immediately and tensile strength still make people feel in tense. The feeling which people feel they are securely covered and protected is intended to build in this project. 7.4. Reiterate the thesis: I think flexible material could be explored more to meet the environmental demand. Although polypropylene can be recycled, the efficiency of plastic recycling is still not high enough. Since rigid material can become flexible by adding void in between, there is a potential do do more material experiment. The light-weight structure is another realm which can be explored.
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8. Reference Allen, E., Zalewski, W. and Michel, N. (2010). Form and forces. Hoboken, N.J.: John Wiley & Sons, Inc. Bechthold, M. (2008). Innovative surface structures. Abingdon [England]: Taylor & Francis. Berger, H. (2005). Light structures, structures of light. Bloomington, Ind.: Author House. Beukers, A. and Hinte, E. (1998). Lightness. Rotterdam: 010 Publishers. Bubner, E. (1975). Wandelbare Pneus =. Stuttgart: Institut für Leichte Flächentragwerke. Heatherwick, T. (2009). Thomas Heatherwick. London: Haunch of Venison. Heatherwick, T. and Rowe, M. (n.d.). Thomas Heatherwick. Herwig, O. (2003). Featherweights. Munich: Prestel. Howes, P. and Laughlin, Z. (2012). Material matters. London: Black Dog Pub. Koch, K., Habermann, K. and Forster, B. (2004). Membrane structures. Munich: Prestel. LEYDECKER, S., KÖLBEL, M. AND PETERS, S. Leydecker, S., Kölbel, M. and Peters, S. (2008). Nano materials in architecture, interior architecture, and design. Basel: Birkhäuser. Mollerup, P. (2006). Collapsibles. London: Thames & Hudson. Nerdinger, W., Meissner, I. and Otto, F. (2009). Frei Otto - complete works. Basel: Birkhäuser. Otto, F., Trostel, R. and Schleyer, F. (1967). Tensile structures; design, structure, and calculation of buildings of cables, nets, and membranes. Cambridge, Mass.: M.I.T. Press. Scheuermann, R. and Boxer, K. (1996). Tensile architecture in the urban context. Oxford: Butterworth Architecture. Schock, H. (1997). Soft shells. Basel: Birkhäuser Verlag. Sheppard, B. (1983). The practical guide to simple structures. Gloucester [England]: Coterie. Thompson, R. and Thompson, M. (2013). Sustainable materials, processes and production. London: Thames & Hudson. Aldinger, I. (2016). Frei Otto: Heritage and Prospect. International Journal of Space Structures, 31(1), pp.3-8. Burkhardt, B. (2016). Natural structures - the research of Frei Otto in natural sciences. International Journal of Space Structures, 31(1), pp.9-15. Dickson, M. (2004). Frei Otto: Researcher, Inventor and Inspired Instigator of Architectural Solutions. AA Files, (50), pp.36-49. Goldsmith, N. (2016). The physical modeling legacy of Frei Otto. International Journal of Space Structures, 31(1), pp.25-30. 36
THE FITTING CHAIR