On the correlations among dynamic stress intensity factor, crack velocity and acceleration in fast fracture

The method of caustics in combination with a Cranz-Schardin high-speed camera was utilized to study dynamic crack propagation in PMMA. Stress intensity factor K_ID was evaluated in the course of crack propagation which included crack acceleration, deceleration and re-acceleration in one fracture event. Crack velocity á and acceleration ä were also measured to correlate with K_ID, and the following findings were obtained: (1) K_ID was an increasing function of á, but their relation was not unique. (2) For a constant velocity á. K_ID was larger when the crack was decelerated than when it was accelerated. (3) K_ID was dependent on both á and ä, and K_ID for a constant acceleration ä could be uniquely related to á.