Finite element simulation of the film spallation process induced by the pulsed laser peening

The laser spallation technique for measuring the interface strength between a coating and a substrate is similar to laser shock peening, in which the stress wave induced by laser shock cause debond on the interface between a hard coating with micron thickness and a metal substrate. According to the modified experiment setup of the laser spallation technique, finite element analysis simulated the process of the film spallation by taking the laser loading as a direct input. We presented a numerical model of finite element that the laser spallation process includes two related, but uncoupled procedures. One was transient heat transfer in a two-layer medium. The other was the related transient elastic wave propagation in the same two-layer media, which was the result of the thermal misfit by transient heating. Based on the threshold of film spallation, we analyzed the process of laser shocking to study the propagation of stress wave and evaluate the spall resistance of sputtered films. The analysis result showed the dynamic adhesive strength of the interface between the TiN coating and the 304 stainless steel substrate was 193.0 MPa. (C) 2003 American Institute of Physics.