Bistable structures for energy absorption, I: Metallic structures

This paper presents proof-of-concept experiments on metallic bistable structures, and is followed by a companion paper about experiments on composite bistable structures.A bistable structure is characterized by a stress/strain curve with stable branches separated by unstable branches.The authors were interested in a particular bistable structure, one that once activated, has a second stronger state which has the ability to sustain higher loads.This allows for a better distribution of damage.In addition, the structure keeps its integrity for a longer time, leading to a fail safe design.Results on metallic configurations under tensile loading are shown in this paper.In particular, chains with one, two, and three bistable elements of 5052-H32 aluminum were designed, manufactured, tested, and compared to their corresponding baselines.A strain energy increase from 11% to about 30% is shown with respect to the baselines.Moreover, a comparative study with A36 annealed mild steel and C10100 copper shows the effect of the different ductility and stiffness on energy absorption.