抄録
The acceleration and deceleration behaviors of a semi-infinite crack in an elastic plate with a finite width, which is subjected to time-dependent loading, are analyzed and the caustic method for measuring the fast crack propagation toughness KID is simulated by using the boundary element method. It is shown that the "measured" KID depends on the shape of the specimen when the dynamic stress intensity factor KI ( t, v) and/or the crack speed v changes rapidly. The dependence is explained by the numerical results that the KI(t, v) -controlled field does not develop enough to cover the location of the initial curve of caustics, i. e., the displacement field near the initial curve is influenced not only by KI (t, v) but also by (1) the superposition of stress wave reflected at the boundary and (2) the change of the crack acceleration due to the reflected stress wave
