激光冲击718镍铬合金残余应力场试验及有限元分析

Experimental investigation and finite element analysis on residual stress field in LSP Inconel 718

为提高718镍铬合金的疲劳强度,采用Nd:Glass强脉冲激光对其表面进行冲击强化处理.经X射线应力仪测试冲击区的残余应力场,利用Abaqus有限元软件,以Johnson-Cook(JC)模型作为本构关系,对其残余应力场进行分析计算.通过试验结果与仿真分析的对比,说明激光冲击能形成残余压应力层、提高疲劳寿命,选择JC模型作为本构关系是可行的,但由于应变率的差异,必须对JC模型材料参数数值进行优化,才能取得较精确的结果,并从激光冲击次数对残余应力场的分析进一步加以验证.结果表明,所提的JC模型材料参数优化方法简单易行.

To improve the fatigue strength of Inconel 718, Nd： Glass pulse laser was used to shock the surface of Inconel 718. X -ray stress analyzer was used to test the residual stress of the shocked area, and calculation was done by finite element software Abaqus that Johnson -Cook（JC） model was select- ed as constitutive. By comparison of simulation and experimental data, it shows that the JC constitutive model is feasible in finite element analysis and compressive residual stress can form on the Inconel 718 target surface and the fatigue life can be improved after LSP. However, due to differences in the strain rate, the JC model material parameters must be optimized in order to obtain more accurate results and that is further verified by multiple laser shock on the residual stress field analysis. The results show that this is a simple and feasible method which can optimize the JC model material parameters.