Crack-front propagation during three-point-bending tests of polymethyl-methacrylate beams

Abstract

Crack front evolution in polymethyl methacrylate (PMMA) beams was measured during quasi static three point bending tests performed on a universal testing machine. A high speed camera was used to record the crack front propagation process through the specimen thickness and to determine the instantaneous crack length during the test, considering the effect of different initial notch lengths and loading point displacement rates. The average steady crack propagation speed was also calculated and correlated with the stored elastic energy, and these results have been compared with those reported by other authors for different test conditions. This experimental technique appears to be suitable to determine the influence of the test conditions on the crack propagation speed of PMMA specimens.