Non - Linear maters: Auxetc surfaces
Document Type Conference Proceeding
Abstract
Auxetc structures exhibitng non-linear buckling are a prevalent research topic in the material sciences due to the ability to tune their reversible actuation, porosity, and negative Poisson's rato. However, the research is limited to feature sizes at scales below 10 mm2, and to date, there are no available efficient design and prototyping methods for architectural designers. Our study develops design principles and workflow methods to transform standard materials into auxetc surfaces at an architectural scale. The auxetc behavior is accomplished through buckling and hinging by subtractng from a homogeneous material to create perforated paterns. The form of the perforations, including shape, scale, and spacing, determines the behavior of multple compliant "hinges" generatng novel paterns that include scaling and tweening transformations. An analytcal method was introduced to generate hinge designs in four-fold symmetric structures that approximate non-linear buckling. The digital workflow integrates a parametric geometry model with non-linear finite element analysis (FEA) and physical prototypes to rapidly and accurately design and fabricate auxetc materials. A robotc 6-axis waterjet allowed for rapid production while maintaining needed tolerances. Fabrication methods allowed for spatially complex shaping, thus broadening the design scope of transformative auxetc material systems by including graphical and topographical biases. The work culminated in a large-scale fully actuated and digitally controlled installation. It was comprised of auxetc surfaces that displayed different degrees of porosity, contractng and expanding while actuated electromechanically. The results provide a promising application for the rapid design of non-linear auxetc materials at scales complimentary to architectural products.
