Paper for Design&Nature 2010

Abstraction of bio-inspired curved-line folding patterns for elastic foils and membranes in architecture

S. Schleicher, J. Lienhard, S. Poppinga, T. Speck & J. Knippers

Abstract

Today’s architectural foils and membranes amaze with their superior strength-to-weight ratio and are often implemented as lightweight building envelopes or shading devices. Most claddings, however, are optimized for high tensile strength, which reduces the design possibilities to pre-stressed inflexible shapes. Only few projects are exploring the potential inherent in the membrane’s low bending stiffness. Nowadays, new materials and manufacturing methods allow for customized pliability of semi-rigid thin-shell structures, which fully tap the potential of reversible elastic deformation. While this concept is hardly been used in architecture, convertible surfaces are rampant in nature. Therefore, the aim of this paper is to review in general how nature’s soft, flexible, and force-adaptive structures may inspire the development of technical membrane structures and outline their architectural potential in particular. Focusing on bio-inspired pliable systems that show distinct curved-line folding principles will be the framework for a close collaboration among architects, engineers, and biologists. Examining the flower opening of Ipomoea alba will clarify the drawbacks and opportunities of elastic kinetics. Therefore, the first part of the study will introduce this nocturnal flower, whose environmentally responsive petals adapt their geometry in circadian rhythm. Morphological and anatomical analyses will secondly lead to a better understanding of their primarily turgor-dependent cascade progression of multiple motion sequences. Examining the interaction of geometrical constraint surfaces and material-specific stress distribution in the flower’s curved-line folding is thereby of particular interest. The plant’s pattern will thirdly be abstracted and the interdependencies be tested in digital models. Recording their packaging efficiency, mechanical simplicity, and structural characteristics, will fourthly make the systems comparable. Finally, the project will deduce the physical principles by tracking the plant’s kinetics and outline their use for architectural foils and membranes with similar adaptive behavior.

Keywords: plant movements, biomimetics, deployable structures, pliable structures, curved-line folding



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