Development of a Numerical Model to Simulate Laser-Shock Paint Stripping on Aluminum Substrates

Abstract

An explicit 3D Finite Element (FE) model was developed in the LS-Dyna code to simulate the laser shock paint stripping on aircraft aluminum substrates. The main objective of the model is to explain the physical mechanisms of the laser shock stripping process in terms of shock wave propagation, stress and strain evolution and stripping shape and size and to evaluate the effects of laser and material parameters on the stripping pattern. To simulate the behavior of aluminum, the Johnson–Cook plasticity model and the Gruneisen equation of state were applied. To simulate stripping, the cohesive zone modeling method was applied. The FE model was compared successfully against experiments in terms of back-face velocity profiles. The parameters considered in the study are the aluminum thickness, the epoxy paint thickness, the laser spot diameter, the fracture toughness of the aluminum/epoxy interface and the maximum applied pressure. In all cases, a circular solid or hollow stripping pattern was predicted, which agrees with the experimental findings. All parameters were found to affect the stripping pattern. The numerical results could be used for the design of selective laser shock stripping tests.

Keywords

• laser shock
• paint stripping
• numerical simulation
• finite element analysis
• cohesive zone modeling
• shock wave propagation