抄録
Effects of the crack velocity a^^· and the crack acceleration a^^&lo;··&gut; on the dynamic stress intensity factor Kd of Humility-100 were studied. Evaluations of Kd, a^^· and a^^&lo;··&gut; during dynamic crack propagation were made by using the method of caustics in combination with high-speed photography. The relation between Kd and a^^·, i. e. Kd(a^^·), showed that it is not a unique function of a^^· and that the decelerating cracks have larger values of Kd(a^^·) than the accelerating cracks for the same velocities. It is found that Kd(a^^·) for a constant acceleration, i. e. Kd(a^^·, a^^&lo;··&gut;=cost), becomes a unique function with respect to a^^·.
