Mechanical Responses of PBDMS-silica under Impact Loading

The impact testing, quasi-static and dynamic compressions and finite element simulation were performed to investigate the impact-resistant properties and rate-dependence mechanism of an impact-hardening polymer composite (PBDMS-silica). PBDMS-silica shows liquid-to-solid transition under impact loading, and such impact-resistant behavior is volume fraction-dependent and rate-dependent. This is confirmed by over 10⁴ times increase in compressive and shear strength in the range from quasi-static to dynamic loading. Finite element method (FEM) shows a compression-shear-coupled stress state in PBDMS-silica during impact loading, and the shear stress plays an increasingly important role in impact resistance. Jamming transition is captured during the deformation of the impact-hardening polymer by high-speed imaging with digital image correlation (DIC) technique. Combined with the mechanical responses, the conclusions are made that jamming transition induced by dynamic compression is the source of impact-resistant behavior, and the dynamic shear during impact determines how such behavior is rate-dependent. This provides a solution for the improvement of impact resistance by strengthening the dynamic shear response of the material.