Beyond the Analogue and the Digital: Constraint design of form‐active systems
Abstract
This work attempts to revisit the interest of designers ‐ during the last quarter of the 20th century and more recently ‐ in form‐active systems. Looking at fabric behavior under stress, we have set up exercises to understand the potential of fabric for form‐finding, while combining various working methodologies. Analogue testing is reinforced by digital/parametric exploration, and further hypotheses are framed in order to identify rules/analogue algorithms to guide the system. As these experiments are framed within undergraduate architectural education, the authors would like to assess the potential of such systems to integrate complementary approaches for design protocols which promote both analogue and digital form‐finding. An additional context is introduced, that of live agents (Bombyx Mori), which cannot be assessed digitally and also exceed conventional physical materiality by introducing more complex behavior.
1 Introduction
This work concentrates on the study of "form-active systems" as a strategy for architectural design, focusing on process and identifying specific experiment criteria that consider Analogue vs. Digital modes of operation. A "form-active" system does not resist bending, but welcomes tensile forces throughout the material, as these drive the form to a state of equilibrium.
The notion of form-active system is present in the natural and, by extension, the man-made domain (Architecture). In nature, it is, mathematically defined as a "minimal surface", which describes the topology a soap film assumes within a specific frame (scaffold). Implementing the natural principles into construction, such systems are found in buildings and structures like the Olympic Park Stadium in Munich (1972) and the Institute for Lightweight Structures in Stuttgart, both partly attributed to German architect and engineer Frei Otto.
The work herewith has been influenced by the early research and work of Otto, who was "...particularly interested in the natural processes of self-generation of forms". Within the context of the "Biology and Building" research group, established in 1960, Otto collaborated with biologist/anthropologist Johan-Gerhard Helmcke to study building systems. Their approach was open-ended, exploring, rather than that of preconceived formal strategies; the benefits from this working methodology are discussed in this paper.
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2 Background and Historical Precedents
Architects are very often form-makers; they extrapolate shapes with properties yet unexamined through a cognitive process. Although this romanticized idea of the contribution of the 'individual genius' to science at large, and more precisely, the architectural discipline, seems appealing, it is in some ways counter-intuitive. The properties of the form are willfully pursued and not discovered from within their natural and systemic habitat.
Perhaps one reason for this kind of incongruous approach, on the part of architects, has been their reluctance to embrace the generalist ethos of their own discipline. Architecture calls for engagement with other areas of expertise, naturally the most evident being engineering. Frei Otto, an architect and -subsequently- engineer by training acknowledged this potential early on, since the 1950s and defined a research trajectory that was based on working within multidisciplinary teams.
The Pritzker prize jury, which recently awarded Otto posthumously, described him as a "researcher, inventor, form-finder, engineer, builder, teacher, collaborator, environmentalist, humanist and creator”. His acknowledgment of Architecture's necessity and tendency to bridge out elsewhere was perhaps influenced by his early experience flying glider planes, which caused Otto to reflect on "...how thin membranes stretched over light frames could respond to aerodynamic and structural forces."
According to the Emergence Design Group (Hensel, Menges, Weinstock), "the range of possible forms is determined by the choice and definition of the conditions under which the form-finding process takes place" (Emergence Design Group 2004) During the tests conducted, we attempt to explore the potential for creatively varying, and often disrupting, these conditions using both analogue and digital media.
Otto frequently spoke of the necessity for both scientists and architects to understand each other's perspective: "...a technician observing living nature just cannot grasp living objects which die so quickly...a biologist looking on technology sees how imperfect technical activity is". This juxtaposition illustrates the potential for architecture to go beyond its own frame of reference and consider design methods as an inclusive flexible framework of thought. Among other objectives, our proposals later on describe how an attempt is made to embed living agents of transformation into a form-active system of fabrics as an intent to re-calibrate its performance.
3 Methods: Testing System Constraints
Fabrics are an assembly of interlaced fibers. Their assembly fashion influences their performance and efficiency, specifically their topology and tensile resistance. Since these fibers are assembled with anchor points, there is a threshold beyond which the fabric can no longer stretch Since there may be several anchor points on a rather small piece of material, they behave as a single system. Tensile forces on the anchor points continuously push the fabric towards equilibrium.
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3.1 Analogue Experiments: Fabric Tensioning
To clarify the material behavior, we conducted a series of simple investigations, looking at various types of fabrics in terms of their thread consistency. The preliminary stages of the investigation consisted of constant intuitive experiments, which contributed to our understanding of the characteristics of two types of fabrics: white performance fabric, and black power mesh.
From these experimentations, we identified limitations and assessed the material’s reaction in different scenarios. The need to define rules and document the process in a rigorous manner became evident right from the start. Both the controlled experiments and the documentation process produced data that defined further investigations. Such data includes material performance under certain stress conditions, and correlation between stretched and relaxed stages of the material.
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Figure 1.
Figure 2.
Using Photoshop and other simple graphic techniques to understand the material behavior is possible due to analogue properties like material texture. The overall experimentation and documentation was done using digital resources and analogical methods. When trying to document a specific factor, such as mapping tensile stresses, very similar characteristics were found based on how the geometry was manipulated, as well as how many tensile points and direction there were. One primitive way of mapping includes drawing a grid, spraying paint on a relaxed piece, then deforming it. When stretched, deformations of the grid and the gradients of color within that piece could be visually appreciated. The digital approach was taking photographs and adjusting the image color and contrast levels to reveal the same stress regions. In addition, using a program called SpringFORM, developed by Sean Ahlquist, gave the ability to simulate the behavior and map stresses visually with color gradients and points was gained.
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Figure 3.
Figure 4.
These techniques led to further experimentations addressing the notion of “optimization”. Our main objectives were achieving a specific geometry that is completely tensioned, while using as little material as possible, and fabricating in the most efficient way. At this point in time we were able to use the information gathered from previous experiments and apply this further.
There were two methods of doing this investigation. The first method was to laser cut the relaxed mesh, with the profile being scaled the same amount as the stretch factor. Since we know this stretch factor, we can assume that it will stretch to the desired geometry. The second method was to pre‐stretch the fabric to its maximum stretch point and cut out templates at the 1:1 desired scale. The results were similar, but there was a lower tolerance in the pre‐stretched method due to its absolute stretching point.
3.2 Digital Experiments Mesh Relaxation in Grasshopper/Kangaroo
As an initial starting point, a three‐dimensional crucifix was analyzed to find its minimal surface while keeping the endpoints affixed. Using Kangaroo, a mesh‐relaxation plug‐in for Grasshopper, we were able to simulate this optimal geometry. A portion of the resulting geometry was isolated in order to physically recreate it using a minimal amount of material.
SpringFORM Surfaces/Musmeci Bridge
After carrying out the previous experiments to understand the system at hand, we considered to examine these principles as they relate to an existing project in order to further understand fabrics as a performative process of form finding. We selected the bridge over the Basento River in Potenza, Italy, built by Sergio Musmeci in 1968.
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Figure 7.
Figure 08.
Since there was little information on what the process was, we took it upon ourselves to recreate it using the fabric techniques learned thus far. The idea was to try to recreate the complex geometry using a simple piece of fabric. After modeling the bridge digitally and analogically, we decided to also three‐dimensionally map the stresses. This raised in to question of how tensile forces can be compared to compressive forces.
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Figure 9. The Basento river bridge in Potenza, 1968 (Sergio Musmeci)
Figure 10.
The information that was learned about fabrics and its capabilities makes it easier to understand how the material behaves and most importantly, why it behaves this way Although the experimentations gave a specific outcome, what emerged was more complex and yielded more lessons than anticipated. Not only did the investigation and experimentations result in a more sophisticated understanding of this material, but it contributed to a greater appreciation of these materials and their behavior. Instead of taking for granted what others had already investigated, these processes can be used to extract more information than that of which could be abstracted by solely reading and researching. It was intriguing to not know where exactly the project was headed, and opting for the unknown path was a rewarding decision. Regarding the issue of introducing a responsive element within the project was a topic of interest, but it was the consensus that there was still more to investigate before taking that step.
There are certain directions of interest, such as furthering the investigations of the Musmeci Bridge and collaborating with the team that carried out a parallel emergent form-making exercise utilizing fabric threads to recreate the geometry examining threads and soap bubbles. Following more in depth analysis of comparing compressive and tensile forces, that would yield more conclusions and assumptions, would be complementary. Further ideas regarding responsive facades emerged. Because of the impressive transformability in size, opacity, weight and efficiency, it seems that there could be useful applications of this material to a responsive system. A lesson from working with fabrics is that this material can be used in many different applications, but a more complete understanding of how and why the material may be used was gained.
3.3 Organic Experiments
A challenge for this project is focusing on the best method to illustrate self-organizing form-making rather than examining material performance, which can be carried out in an
almost infinite number of ways. As for the illustration of surfaces via digital resources, limitations have been encountered in the realm of this exercise, which have demonstrated to be more explanatory in analog ways. The various types of fabric, acquired and experimented with, have displayed different boundaries of strength, elasticity, density, etc. These inherent properties can be digitally analyzed today, with limited capability and relatively high level of difficulty. On the other hand, the digital realm is capable of presenting multiple iterations of the diagrams that explain the natural growth functions, which serve as parameters in this project, making the digital complementary to the result and the process.
Figure 12: Parallel projects examining emergence of form through sand
The introduction of the phenomena of emergence, as a form of organization and survival in nature and as a catalyst of form in design, gave rise to the idea that form (a concern often that arrives at the wrong point on the timeline of the design process) can be an organic product of a set of parameters that respond to particular conditions when allowed to occur without hierarchy. After observing sizable digital research performed on elastic surfaces by analysts, such as Ahlquist in recent years, and inspired by the simplicity of form making demonstrated by Frei Otto’s soap bubble experiments in the 60’s, it was decided that this fast-paced “Elastic Grids” project should study elastic fabrics' ability to clearly portray the phenomenon of emergence of unpredictable form, and to a lesser extent, general observable aspects of the fabrics’ behavior and properties. This resulted in an illustration of selforganization as a maker of form, structure and space. The main hypothesis was that the form of an elastic surface is defined by its points of attachment, the challenge being finding free agents to determine the points of attachment. In turn observable, progressive formmaking though a bottom-to-top approach was the goal, involving self-organizing, basic, independent and computational agents working together in a decentralized fashion. This idea emerged upon the analog manipulation of 6x6” pieces of fabrics with different elasticity properties on 8x8” wood frames.
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Figure 13: Basic, analog form-finding exercises with tensile fabrics
Hoping to arrive to the dynamics of surface form-making as defined by naturally-defined points of attachment, it was decided to introduce silkworms (Bombyx mori) to the study, aiming for a system that expresses the juxtaposition of the form made by this agent -as shaped by its natural, goal-oriented reasons- with an artificial medium (fabric-scaffold assemblies), which in turn would be constrained by the attachment points of the agent's form (weaved silk cocoon), but expressing higher elasticities and other properties. In a way, the medium would be the "shadow" of the agent's work. The choice of agent relates to its capability to create form in a more three-dimensional manner than the spider, for example, expressing surface more flexible in form under different spatial conditions, and in a manner not limited to "planar" designs. A challenge was keeping in mind that the primary subject under observation was the medium, not the agents. The framework was provided along with digital predictions of the forms achieved. The containment, or shell of these fabrics, thread and wood scaffold assemblies, namely “Activity HUBs: Hybrids, Unfoldings and Bluntings” was designed prior to the arrival of the caterpillars keeping in mind the requirements for these fragile animal’s protection and stimulation of natural behavior. It was originally intended that the HUBs themselves would allow the medium to be interposed after the agent would spin silk, or else the medium would be affecting the agent's form, which was not ideal for the exercise’s objective. However, due to time constraints, the HUBs had to be provided prior to their arrival, requiring parameters which would determine some of the agents’ behaviors (i.e. discouraging corner weaving), and hence undermining totally decentralized emergence.
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Figure 14: Conceptualization of silkworms’ habitats
In parallel, a way to compute elastic surface form-making digitally by allowing a Grasshopper software algorithm to model natural growth (in a way similar to L-systems that graphically translate a collection of production rules into geometric patterns) was examined, to provide abstract three-dimensional projections of natural growth. In turn, some of the surface’s points of attachment were directed by the bluntings of this growth model, therefore making the form dynamic as long as there is growth or change.
Figure 15: Reading natural growth algorithm as possible generators of fabrics’ forms
This hypothesis briefly branched into three analog experiments, in which fabrics were attached to plant’s bluntings (“Developments intended to yield evolutionary processes adapted to movements of growth and trimming” –Actar, 2003). In the short term of two weeks, minimal change of the small slices of fabric was demonstrated, but this simple adaptation over medium and long term is envisioned to produce observable dynamics of natural form production of an introduced artificial material.
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L-systems were observed as a way to digitally investigate natural sources which would create points of attachment for the elastic fabrics based on natural systems. The concept of L-systems, introduced and developed by Aristid Lindenmayer, describe the behavior of plant cells and model the growth processes of plant development. Using Morphocode, Rabbit and 3d branching structures, dynamic mesh relaxation was experimented with, in conjunction with the Kangaroo plug-in. It was hypothesized that converging with an active organism would result in a feedback loop where over time, where the fabrics would reach their maximum tensile limits, adapting to the constraints of the natural environment.
4 Results and Reflection: What have we learned from the process?
4.1 Which of the Working Models is more promising?
How can the analogue and digital tests be setup in order to compensate for each other’s shortcomings? It is important to consider the possibility afforded by the digital software: deformation in Rhino is infinite, but Kangaroo provides limitations through the values set in the mesh relaxation settings. The Kangaroo simulation is more realistic (although it would help to correlate the elasticity threshold with one of the fabrics) but a deformation in Rhino is more creative as it may lead to the discovery of new topologies which are not possible with the current fabrics we possessed. A future experiment that may be appropriate can involve combining fabrics to increase elasticity and reach these new topologies.
4.2 How is this work different to previous work of similar nature?
How can the analogue and digital tests be setup in order to compensate for each other’s shortcomings? It is important to consider the possibility afforded by the digital software: deformation in Rhino is infinite, but Kangaroo provides limitations through the values set in the mesh relaxation settings. The Kangaroo simulation is more realistic (although it would help to correlate the elasticity threshold with one of the fabrics) but a deformation in Rhino is more creative as it may lead to the discovery of new topologies which are not possible with the current fabrics we possessed. A future experiment that may be appropriate
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Figure 16: Basic, analogue demonstrations of form introduction to flexible fabrics in parallel to digital algorithms of natural growth.can involve combining fabrics to increase elasticity and reach these new topologies. While becoming familiar with case studies of natural emergence, it was proposed that MIT Media Lab’s Silkworm Pavilion experiment yields a peculiar case study where natural agents that do not seem to display the survival-guided social behaviors of animal groups -such as the ant colony- create emergent complex form when introduced to a man-made medium. This case study was proposed in parallel to a brief look at the Sociable Weaver, a bird that acts much like an ant colony. This parallel has the intent to stimulate questions on the definition and conditions of emergence. Differing from the Silk Pavilion, achieving future possible physical applications was not pursued, but primarily expressing possible organic origination of the parameters of form-making, and secondarily, the interactions of natural with artificial elastic fibers.
4.3 What is the value of the research assignment?
The objective of this work is to seek form‐finding protocols and identify potential for interesting topologies which are structurally efficient. The idiosyncrasy of this system is its ability to yield the most interesting formal outcome at the same time as reaching optimal structural performance, through a state of equilibrium; such systems are suitable for promoting collaboration among experts from more than one disciplines, therefore encouraging integration of, for example, Architecture and Engineering.
In the case of the living agent experiment, far from a priori negations of organic emergence when this phenomenon is digitally and analogically modeled by (almost unavoidably fully top-to-bottom) man-made approaches, open ends are offered with this particular exercise by introducing live, natural agents of change that effectively illustrate dynamic form determination via the patters of non-hierarchy. Although intended to be approached from bottom to top, this project’s process yielded a “top-bottom-top” result. However, the expressed potential of liberating the design process from the artificial imposition of form is a highly valuable tool for the designer, often burdened by the complexities of typical hierarchically-approached problem solving. This is what the project expects to illustrate. The fabric’s form was further defined by the silk caterpillars. After observing the agent’s tendency to weave in 90 degree corners, the fabrics were relocated to be stretched on threads pinned to walls.
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Figure 17: Staff placing silkworms at MIT Media Lab’s Silkworm Pavilion
It is speculated that the experiment may give birth to hybrids of natural and artificial constructs. By understanding the silk caterpillars’ behavior closer, a natural algorithm may be generated through computational methods, possibly applying this behavior to bridging between separate surfaces.
4.4 In terms of Performance and Pedagogy
As these systems are only efficient when they reach equilibrium through distribution of tensile forces, any interesting formal outcome is at once a viable solution. Performance and Aesthetics become tightly associated, much like in the natural domain, where Form‐Material‐Structure are inextricably linked (Weinstock 2010).
In the case of the silk caterpillar exercise, observing the self-regulation and generation of natural form has the pedagogic potential to foster a bond between the living system and the experimenter, arousing curiosity for and admiration of natural phenomena without the over reliance on computerized, resource-heavy approach to design typical of our times. Such bonds between designer and product may have the potential to foster a vested, more humane interest in the thoughtful utilization of resources, as well as a more intimate connection between designer and end user, as it offers a close look at the influence of constructed spaces on natural behaviors.
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Figure 18
5 Conclusion and Future Development
The results of the study with these phenomenal creatures were organic, with most of them successfully completing their life cycles after spinning on both intended and unintended surfaces. Limitations were observed in controlling their spinning behaviors, but closely observing patterns, and opening questions about further media and the wide range of possible unpredictable results, as well as about the feedback of natural systems on artificial ones, becoming a tangible source of interest.
Arriving to environments generated by bottom-up rationale, emerging from the investigation of natural behavior and in conjunction to material intelligence, was conducive to unexpected topologies.
6 References
Ahlquist, Sean. 2010. “Physical Drivers: Synthesis of Evolutionary Developments and Force‐Driven Design”, in AD vol.82 no.2: Material Computation: Higher Integration in Morphogenetic Design. West Sussex: Wiley‐Academy. pp.60‐67.
Ahlquist, Sean. 2011. Staedelschule Ar chitecture Class Lecture (June 2011). https://www.youtube.com/watch?v=ZnUWDcvNdio
Carpo, Mario. 2013. “The Ebb and Flow of Digital Innovation: From Form‐making to Form‐Finding and Beyond”, in AD vol.83 no.1: The Innovation Imperative: Architectur es of Vitality. West Sussex: Wiley‐ Academ y. pp.56‐61.
Hensel, Michael, Menges, Achim and Weinstock, Michael. 2010. “Chapter 6: Nets”, in Emer gent Technologi es and Design: Towards a Biological Par adigm for Architectur e. Oxon: Routledge.
Hensel, Michael, Menges, Achim and Weinstock, Michael. 2004. “Frei Otto in Conversation with the Emergence and Design Group”, in AD vol.74 no.3: Emergence: Morphogenetic Design St r ategies, West Sussex: Wiley‐Academy. pp.18‐25.
Otto, Frei and Rasch, Bodo 1996. “Natural Constructions, a Subject for the Future”, in Finding Form: Towards an Architecture of the Minimal. London: Axel Menges pp.15‐22.
Oxman, Neri. 2014. “Towards Robotic Swarm Printing”, in AD vol.84 no.3: Made by Robots: Challenging Architectur e at a larger scal e West Sussex: Wiley‐Academy. pp.108‐115.
Oxman, Neri. 2013. Silk Pavillion. http://matter.media mit.edu/environments/details/silk‐pavillion
Spinelli, Luigi “When Infrastructure becomes Landscape”, in Domus 907 (October 2007). pp 78‐85.
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