Correlations among dynamic stress intensity factor, crack velocity and acceleration in brittle fracture

Abstract

Dynamic fracture in PMMA was studied to determine the correlations among dynamic stress intensity factor K _ID, crack velocity $\dot a$ and acceleration ä. Specimen geometry, a single-edge-cracked tensile plate with two circular holes, was employed to obtain the crack acceleration, deceleration and re-acceleration process in a single fracture event. K _ID was evaluated using the method of caustics in combination with a Cranz-Schardin high-speed camera and correlated with $\dot a$ and ä. The behaviors of K _ID $\dot a$ and ä in a SEN specimen were also examined, and the following correlations were obtained: (1) K _ID was an increasing function of $\dot a$, but their relation was not unique. (2) K _ID for a constant velocity $\dot a$ was larger when the crack was decelerated than when it was accelerated. (3) K _ID was dependent on both $\dot a$ and ä, and K _ID for ä=constant could be uniquely related to $\dot a$.