激光冲击强化残余应力场的数值仿真分析

Numerical Simulation of Residual Stress Field for Laser Shock Processing

有限元分析(FEM)是预测激光冲击强化处理(LSP)后材料的残余应力场、合理优化冲击参数非常有效的方法。通过对材料冲击响应过程的分析,建立了激光冲击强化处理的有限元分析模型,实现了激光冲击强化处理残余应力场的数值仿真。根据显式分析得到的材料内部各种能量变化过程,结合应力波理论,验证显式分析过程的正确性,提出显式分析求解时间的选择方法;分析了单次和多次冲击下材料内部的残余应力场分布,分析结果与实验结果非常接近。数值分析结果表明,表面残余应力在冲击区域内分布比较均匀,表层的残余应力梯度较小;多次重复冲击后,材料的残余压应力明显增加,残余压应力影响深度也显著加深;随着冲击次数的增加,材料的残余应力场趋于饱和。

Finite element method （FEM） simulation of laser shock processing （I.SP） is an effective method to predict the residual stress field and optimize the laser shock parameters. The FEM is applied to attain the numerical simulation of residual stress field of material treated by laser shock processing. The history of energies during explicit dynamic analysis is discussed and is well correlated with the result derived by shock wave theory. The method of solution time choosing for explicit analysis is presented based on the history of energies. Residual stress distribution of single and multiple laser shock is analyzed and validated by experimental result. The analysis results indicate that compressive residual stress of material is uniform on surface and the stress gradient in depth is small. Compressive residual stresses and plastically affected depth are extensively increased and gradually reach the saturated state by multiple laser shock.