The Bending Active Approach in Lightweight Design

The bending active is a term used for structures or surfaces that are based on the elastic deformation of their initial planar geometry.

The bending active approach is nowadays leading term in lightweight design, kinetic and deployable structures. Unlike older approaches for deployable systems that were based on hinged connections the bending active approach takes advantage of the elastic deformation of the entire structure replacing the need for local hinges, which lowers the ecological footprint by pushing the material’s capabilities to the limits and taking advantage of the pre-stressing of elements providing more global stiffness and wider ranges of stability.

This paper will present further investigation in different types of deployable structures based on a series of cutting patterns on flat sheets of wood tha t manipulates their geometry after elastic deformation, this technique was inspired by the Japanese Kirigami art approach.1Keywords : Kirigami, Bending active, deployable structures, architecture.

Introduction

The term deployable characterizes a system that can change shape as to significantly change size. Examples of deployable structures are: tensile structures, bistable structures , some Origami shapes and scissor-like structures..

Standard deployable structures are usually created by the rotation of stiff elements around their fixed hinges, (Example: scissor-like structures) which makes itsomehow heavy, the reason why the lightweight systems are usually linked to tensile and pneumatic structures , these systems can be differentiated by the direct relation between force and form, resulting in an efficient use of materials.

In the last couple of years scientists and researchers started giving more attention to lightweight systems with less waste and low ecological trace with led them to the discovery of some models that can deform in size and shape due to their bending properties only by performing simple cuts in the models without removing any parts allowing it to elastically-deform and sometimes expand up to 3 times its original length. This technique was introduced in the Japanese traditional art Kirigami that consists creating multiple cut on a flat paper allowing it do deform and expand. In essence, kirigami is a variant of origami, the art of paper folding.The words derive from the Japanese for cutting ( kiru ), folding ( oru ), and paper( kami ).

The modern notion of origami as an art and recreational craft (andeschewing all cuts in its purest form) took shape last century.2Standard origami starts with a pristine sheet of paper, most often square, and proceeds solely by adding folds: no cutting or gluing is allowed. In contrast,kirigami, relies on both cutting and folding. Designs range from flat symmetrical cut-out decorations like schoolroom snowflakes to elaborate patterns that form 3Dmodels similar to book pop-ups.

Japanese paper-art Kirigami inspires twisting solar panels.Solar energy has come out as a wonderful renewable energy source with the help of solar panels. But the technology is still not fool proof. The problem with flat3solar panels is that they have to keep facing the sun in order to produce electricity at an optimum rate but the glitch here is: the sun doesn’t remain fixed at one point and moves across the sky.

In order to find a solution to this problem, the scientists of University of Michigans tumbled upon the idea of using Japanese art Kirigami to develop a simpler alternative of these flat solar panels. When no external force is applied, the sheet remains flat, but as soon as the sheet is stretched, the strips of plastic between the cuts along with the solar cells adhered to them twist to one side. It is to be noted that the angle of twist can be controlled by modulating the degree to which the sheet is stretched.

Conclusion

The deployable wooden surfaces have demonstrated a high degree of efficiency for the ability of covering up to 200% more area than its own with the lowest ecological footprint which makes it one of the cheapest techniques. The new and enhanced computational techniques and soft wares have proven the ability of simulating complex behaviors , therefore researchers should be more interested in the active bending system in order to take advantage of the different characteristics of each material , adding more material utilization, feasibility a tmore affordable ranges while having zero waste.