Two-step simulation approach for laser shock peening


Laser shock peening (LSP) is a surface modification technique to introduce compressive residual stresses (RS) with a high magnitude in the near surface region of the material. Due to non‐linear interactions (e.g. laser absorption by plasma, shock wave propagation, etc.) and a high number of parameters, it is difficult to study and optimize the process based on experiments alone. Therefore, a two‐step simulation approach is proposed in this paper, where two models are combined, because one model of the complete process is difficult to derive, due to the different characteristics of the plasma formation and the shock wave propagation in the material. On one hand, a global model including plasma and shock wave descriptions is applied for the LSP of an aluminium sample with water confinement. The numerical solution of this model, applied for a 3×3 mm2 focus size, 5 J and 20 ns (full width at half maximum (FWHM)) laser pulse, allows to determine the temporal plasma pressure evolution on the material surface. On the other hand, a finite element simulation is used to calculate the RS distribution within the target material, where the plasma pressure is applied as a surface loading for the aluminium alloy AA2198‐T3. The simulated residual stresses are fitted to measurements via parameter variation of the global model. The identified values and the two‐step simulation approach can be used in future work to predict stress states of materials after LSP for various process parameters variations.
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