Design and development of hybrid composite bistable structures for energy absorption under quasi-static tensile loading

The composite bistable structures discussed in this paper consist of a material-based mechanism with a saw-tooth strain/stress curve. They have a more damage-tolerant behavior, and considerably higher strain-to-failure than the corresponding monolithic material. Past work showed successful results with bistable composites made of ultra high molecular weight polyethylene (UHMWPE). This paper investigates a number of hybrid composite configurations, with geometry and manufacturing process inspired by the previous work. Bistable designs are based on the synergy of two parts, main links and waiting links, with a user-configurable balance of strain, strength and stiffness. In this paper, carbon and UHMWPE (Spectra®) hybrids are studied in terms of their maximum strain and specific strain energy. Considerably higher ductility was experienced for some configurations, while increased strength may be obtained in principle with a higher number of layers than those of the current work.