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

Abstract

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.

A non-oscillatory method for spallation studies

“…They obtained the displacements of several points in the crater region which are in accord with the measured displacements. Finite element simulations have also been used to study the film spallation process induced by the pulsed laser peening [6]. In addition, molecular dynamics has recently been applied to analysis of the mechanical behaviour of materials, including spallation.…”

Grains Ultra-Refinement of Materials Imposed by Pulse Laser

“…B.P.Fairand [6] and R.Fabbro [7] comparatively earlier and systematically researched and applied LSP technique to modify and strengthen materials surfaces. Besides the application of materials strengthening, the novel technique is also employed in other domains, such as shock deformation of metal plate and the measurement of adhesion strength of materials interfaces [8,9].However, up to now, no researches about micro/nanocrystalline synthesizing by LSP technique have been reported.…”

Fundamentals of Laser Ablation of the Materials Used in Microfluiducs

“…In addition, there are several secondary processes which can arise due to the steep temperature gradients which are produced. If the laser beam is composed of short, high-intensity pulses, as would be typical for Q-switched systems, then the adiabatic heating of the substrate can cause sufficiently high temperature gradients for which differential thermal expansion and acoustic shock can produce surface cracking or spalling of the substrate (Zhou et al, 2003). Micron-sized flakes of the substrate can be explosively ejected from this process without requiring the additional thermal energy to fully vaporize the material.…”