An Impact Protective Structure with Bistable Links

Abstract

This article discusses a protective structure of a special morphology with an advanced impact resistance. We use a ‘bistable’ structure that is designed to have a non-unique stress–strain relation. When the strain reaches a threshold, some parts (sacrificial elements) yield and subsequently fail and the remaining parts (waiting elements) become active; the waiting elements carry the load and preserve structural integrity. Damage in bistable structures is more stable; the cracks do not develop due to yielding of structural elements and damage delocalization. The damage spreads in a larger region than in a conventional structure, and the load is redistributed. As a result of these effects, more impact energy is absorbed. We describe the response of bistable structures in macro- and microscales, numerically investigate a problem of projectile impacting a protective net, and introduce a mesoscale damage tensor that measures the degree of damage in a small region. We compare the structural responses of the bistable and conventional structure depending on mass and speed of the projectile. Typically, the bistable structure dissipates more energy by creating a partial damage in a large area.