1999 Volume 48 Issue 6 Pages 375-381
With the aim of studying the fracture dynamics of environmentally assisted fractures in thin plates, we developed a new source simulation method of the zeroth-order symmetric (or S0-) Lamb wave using the experimental overall-transfer function of the system. The transfer function was determined by the time-domain deconvolution of detected S0-Lamb component by the artificial fracture source of a compression-type PZT element whose vibration kinetics was previously monitored by a laser interferometer. The fracture kinetics was estimated by the iteration so that the S0-waveform computed to the assumed fracture kinetics best represents the S0-waveform detected. Hydrogen induced blistering was found to be caused by the succession of fast Mode-I fracture with source rise times from 0.6 to 1.0μs. The crack volume estimated by the source simulation corresponded to that of fine blistering with an opening displacement of 5μm. As the estimated fracture kinetics of hydrogen blistering coincide with those of delayed fracture of high tension low alloy steel under tensile loading, the kinetics of first and micro-fractures and blistering induced by hydrogen gas precipitation appears to be independent on the hydrogen solubility and strength of steels, the applied stresses and the orientation of cracks.
