MICRO-MECHANISM OF DYNAMIC CRACK PROPAGATION IN BRITTLE MATERIALS

Micro-mechanism of dynamic crack propagation is experimentally studied. A running crack experiment in brittle PMMA plates is conducted under constant velocity condition by the use of a fixed grip apparatus. The fracture surface is microscopically observed. Analysis of parabolic patterns on the fracture surface shows the process of micro-crack initiations, propagations and their coalescences to the global crack propagation. The condition of the micro-crack initiation at the nuclei is obtained from the examination of the patterns and the dynamic stress analysis.