An intermediate strain rate LSHPB system for soft materials and its application

Biological soft materials, often with high water content and ultra-softness, display mechanical properties that non-linearly enhance over a broad range of strain rates. However, existing experimental constraints make it challenging to perform large deformation tests on these materials at intermediate strain rates. This study introduces a 15-meter-long long split Hopkinson pressure bar (LSHPB) system, driven by a dual-bullet electromagnetic mechanism, designed for large deformation intermediate strain rate testing of ultra-soft materials. Comparative tests conducted using both the LSHPB and a high-speed SHPB system validated the reliability of the newly developed system. The LSHPB system was then applied to measure the dynamic mechanical performance of polyvinyl alcohol (PVA) hydrogel at intermediate strain rates. The results, combined with existing data from low and high strain rate analyses, underscore the necessity for intermediate strain rate dynamic performance testing. This work not only broadens our understanding of the mechanical behavior of ultra-soft materials like PVA hydrogel across various strain rates but also introduces an innovative experimental technique for studying materials under intermediate strain conditions, thereby advancing the field of soft material dynamics.