Superelasticity and reversible energy absorption of polyurethane cellular structures with sand filler

As a promising candidate for energy absorption and resilient system, a polymer encased sand structure is studied experimentally. The polyurethane (PU) cellular structures are consisted of periodically arranged hollow truncated hemi-ellipsoids with sand particles filled inside. The resilience of PU and dissipation of sand are combined to construct a high performance energy absorption material and structure (EAMS) which exhibit superelasticity with reversible compression strain up to 0.9 and have recoverable energy absorption capability of about 3.4 MJ/m3 per loading cycle. The compressive stress of the sand filled PU cellular structures is also significantly enhanced (thanks for the sand filler) for compressive strain larger than 0.4. The sand filled PU cellular structures are soft and flexible to stretch, bend and twist, thus compatible for personnel protection. The results presented in this work provide guidelines for designing and engineering high performance EAMS that are resilient, flexible, and of high energy absorption density.