2001 Volume 44 Issue 3 Pages 431-437
Dynamic crack propagation and unloading behaviors of epoxy and PMMA were studied using the method of caustics. Single-edge-cracked tensile specimens were pin-loaded so that cracks could undergo both the acceleration and the deceleration process in one fracture event. The effect of loading position H1 was examined by measuring the stress intensity factor KID, crack velocity a and load P as a function of time t. Unloading rate P, time derivative of P, was also evaluated to examine correlation with the time variations of KID and a. The results showed that H1 was an important factor in the change of behaviors of KID, a, P and P.