Nanosilica reinforced epoxy under super high strain rate loading

Nanosilica reinforced epoxy‐matrix composites have been extensively investigated for higher mechanical strengths since its emergence, while few literatures are available about enhancement characteristics under super high strain rate loading, which is usually encountered during impact. Hereby, this work investigates the composites containing various kinds of nanosilica subjected to compression of strain rate higher than 20,000 s−1. A series of stress:strain curves are obtained and it is found that peak stresses increase with increasing strain rate along with silica fraction. Excitedly, the silica particle plays another enhancement role in anti‐localization of adiabatic shearing which occurs in pure epoxy, as indicated from abruptly dropped strain‐hardening index at ~22,000 s−1. A mechanism is proposed that uniformly distributed silica delays adiabatic shearing localizations to form through cracks, which is confirmed by fracture surface observance. Highlights Higher strain rate is achieved experimentally up to ~20,000 s−1. Strain rate effect is found on the peak stress of composites. Reinforcement of nanosilica is more distinct on strain‐hardening behavior. Silica particles hinder adjacent shearing localizations from abrupt evolution. The Split Hopkinson Pressure Bar (SHPB) system is used to evaluate the strain hardening behavior and fracture characteristics of different materials (Epoxy, S2, S6, S10) at various strain rates.