Engineering with Instability

Engineers design structures to predictably resolve forces and moments through a primary load path in which deformations are small and linear. There is an enormous opportunity to design structures that rely on nonlinearities and instabilities to perform advanced functions and propagate forces in nontrivial ways. In this talk, I will describe how ideas from soft matter physics – jamming, buckling, snapping, origami, kirigami – inform ways to engineer “defects” into structures that encode local deformation. Typical defects include grains bound to structures (elastogranular), folds (origami), cuts (kirigami), and stitchwork, and I will describe how these defects enable the design of functional mechanical metamaterials. By transmitting elastic instabilities and geometric nonlinearities across structures, we have fabricated compliance-switching structures, nonlinear actuators, artificial muscles, soft robotic grippers, and performed rudimentary mechanical computation. I will describe how geometric criteria – the spacing and orientation of defects, the presence of local or global curvature – allows us to engineer defects into thin sheets to control how they deform, thereby creating advanced functional structures.