Crack resistance of RT-PMMA under impact loading

Analysis of failure mechanisms under high strain rate loading in engineering materials is a key point for the design of structures submitted to accidental overloads. We are here interested in the crack arrest capability under impact loading of polymers used as structural and/or protection materials. In the present work, crack arrest capability is defined by how an engineering structure which is initially weakened by a pre-crack behaves when dynamically reloaded. The Kalthoff and Winkler (KW) impact test, consisting in impacting the edge of a double notched plate, is retained for that purpose. An experimental investigation of the dynamic crack arrest capability of shock-resistant PMMA under high strain rate loading is presented, evidencing the brittle feature of the material failure. A high-speed camera is used to record the chronology of the failure mechanisms. It is notably shown that the higher the impact velocity (in the range 50-100 m/s) the larger the number of fragments. Moreover, depending on the impact velocity, changes in the crack path and thus in the mechanisms controlling the PMMA dynamic fracture can be seen.