Dragonlily Nov08

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Dragonlily

“Nature uses nothing uselessly.”  ~ Galileo

Biomimetics loosely translated means “life copy”, but is more precisely defined as the extraction and imitation of natural survival mechanisms or efficiencies. For architecture, and more broadly the world of design, biomimetics offers clues on how to approach design problems we encounter on a daily basis. This is done by studying models in nature which have been refined as the result of evolutionary selection.

Excess and access are common dilemmas faced in architecture. Access addresses issues of visual, acoustic, and physical presence within space, such as: how does one access the space? How do we move through it? Can we visually access the space from another? In the context of Gould Court, visual access was promoted through the exposure of infrastructure embedded within the structural elements while physical access was facilitated through cantilevered structures that minimize invasive structural components that would otherwise alter the way users function within Gould Court and the BE café. Excessive material use, separation of ornament and structure, and energy consumption are all issues that can lead to poorly performing buildings. In nature survival depends on not overextending oneself and taking every opportunity to overlap function as much as possible. This process of overlapping and defining relationships, functions largely on the logic of efficiency and optimization. Leaves, for instance, bundle the function of transferring nutrients through vacuoles that dually function as structural support, all the while displaying heliotropic qualities promoting photosynthesis. Though excess and access address different types of issues that arise in design it was the goal of this project to use the two symbiotically to optimize each other. In biology an animal’s ability to modify its environment – known as “niche construction” – acts as a positive feedback on natural selection enhancing its chances of survival. Access and Excess played a similar role in that access to the space prompted the cantilevered condition.  In order to achieve the cantilever the design needed to be light weight which speaks to a lack of excessive structure and material. In an effort to reduce the weight of the cantilever the mass was converted into a cellular frame. The level of structural integrity required to achieve the cantilever gave us the opportunity to embed infrastructure within the members and address how visual access to these elements enhance the atmospheric effect on space (access –> excess –> access). For the purposes of this project, natural models of cantilevered structures were examined for their effectiveness of overlapping vascular systems and structure that displayed a relationship between cell density, shape and the allocation of material based on need. Two natural models were examined to provide insight on cantilevered structures: dragonfly wings & lily pads. Each example is specifically designed to handle an extreme cantilever. The means by which each achieves this feat are extremely different.

The dragonfly’s complex pattern of branching and cells is an evolutionary response to force flow exhibited on the wings during flight. Stiffness and flexibility are determined by the number sides a cell has in addition to the depth and thickness of the cell walls. The top region of the dragonfly’s wing exhibits beam like stiffness denoted by quadrilaterals, while the bottom region needs to flex to allow the wing to flap and is comprised of pentagonal and hexagonal cells. In general an increase in the number of sides a cell has will tend to produce regions with flexibility while a decrease will inevitably lead to stiff members. The pattern follows the general tensile forces exhibited on the wing, and the various shapes carry the responsibility of determining the amount of stiffness or flexibility in that area. Its overall typology can be described as beam and membrane.

Lily pads need to remain rigid while in the water or they will get destroyed by strong currents and aquatic life. The giant Amazonian Victoria Cruziana can reach 9 ft in diameter and support a full grown adult’s weight. Their structural morphology consists mostly of quadrilaterals governed by hybrid logic of branching and cellular structure, similar to that seen in the dragonfly wing. The width and the depth of the lily pad’s members decrease as they approach the edge of the surface. This decrease in width and depth occurs while modulating from acute quadrilaterals to near right angled quadrilaterals as increased stiffness is needed toward the edge to compensate for its lack of depth. The under structure has evolved to provide buoyancy and stiffness to its fused countertop which undergoes photosynthesis to supply nutrients to its roots, upwards of 20 ft below the surface of the water. This typology can be categorized as a surface and pleat since opaqueness and overall composition between surface and structure remains homogenous in material rather than distinctly composite like the dragonfly wing.

The translation of biological principles to architecture can be actualized through the use of generative design tools and techniques to conceive of and alter form. This process uses bottom-up, form-finding logic that requires architects to articulate influences and define a system of relationships in the infant stages of design. This process is known as parameterization, and relies heavily on the designer’s ability to define appropriate relationships and interdependencies, as well as the ability to harness accessible computational power to control and compute the many forces of influence weighing on a design. Formal instances are generated from this system based on parametric transformation, i.e., the transformation of variables and subsequent propagation of those changes throughout the defined system, that allow for the generation of formal iterations. This methodology allows architects to quickly and effectively derive a multitude of instances for evaluation and further transformation, positioning the architect as the editor of possible formal resolutions.

In order to digitally explore the typologies examined in this study, Grasshopper, a generative modeling plug-in for Rhinoceros, was used. The definition generated explores the relationship between cellular density, shape, and the allocation of material based on structural need. The definition is comprised of two sides. The first is density control and the second deals with the allocation of material.  Inherent to many cell patterns in nature is the relationship between cellular density and armature thickness. Essentially material is allocated based on the diameter of the cell in which case the larger the cell the thicker the wall. Inversely the more tightly packed and dense the cells are the smaller their diameter and the offset of the cell wall, however, the increase in populating cells leads to an equal amount of material distribution regardless of density or diameter. In the case that there are five cells with areas ranging from 5 to 1 the smallest area will receive a minimum offset while the largest receives the maximum. This variation ensures material is distributed based on permeability and structural need.

Written by Hunter Ruthrauff, MS in Design Computing Candidate 2012. Hunter’s  interests are in biomimetic design and additive manufacturing. For his thesis, Hunter is working on a digitally reconfigurable forming surface which he calls i(m)forming. (A play on words of forming and informing. The m is in reference to mechatronics - just a blend of the fields of computer science and mechanical engineering).

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