Non-steady, periodic behavior in the dynamic fracture of PMMA

Abstract

A crack moving dynamically through a sheet of Polymethylmethacrylate at high average velocity is found in reality to propagate in a non-steady, periodic, and perhaps discontinuous fashion. The spatial period of the fracture process in the direction of travel, or banding morphology, is of millimeter size and is consistent both in magnitude and discontinuous nature with a crazing mechanism proposed in fatigue settings. The band size in both the dynamic and fatigue environments scales with the applied stress intensity. This commonality has importance in modeling. It suggests that a single mechanism is fundamental in both dynamic and fatigue loading regimes.