多点激光冲击强化50CrVA合金钢残余应力场的数值模拟

Numerical Simulation of Residual Stress Field of 50CrVA Alloy Steel Strengthened by Multi-point Laser Shock Processing

基于ABAQUS/Explicit软件模块的显示动态分析方法,建立50CrVA合金钢激光冲击强化的有限元模型,对单点圆形光斑下松弛持续时间的收敛性进行研究,确定松弛持续时间,采用有限元模拟方法研究了圆形光斑多点激光冲击强化后冲击区域的残余应力分布,并与试验结果进行对比;采用该模拟方法分析了圆形和方形光斑单点激光冲击强化过程中应力波的分布与强化后残余应力的分布,以及多点激光冲击强化时激光功率密度、光斑形状对残余应力场的影响。结果表明:确定的松弛持续时间为0.0001 s;模拟得到圆形光斑多点激光冲击强化后残余压应力随深度的增大而减小,变化趋势与试验结果基本吻合,最大残余压应力的相对误差为6.8%,验证了有限元模型的准确性;在相同能量输入条件下,光斑的形状不会影响单点激光冲击强化后的残余应力场;随着平均激光功率密度的增加,最大残余压应力均增大;方形光斑多点激光冲击强化后的最大残余压应力(704 MPa)略高于圆形光斑多点激光冲击强化(692 MPa),方形光斑和圆形光斑多点激光冲击强化后的表面残余应力波动率分别为10.9%,12.9%,方形光斑多点激光冲击强化后的残余应力分布更均匀。

Based on the display dynamic analysis method of ABAQUS/Explicit software module,a finite element model of 50CrVA alloy steel laser shock processing was established.The convergence of relaxation duration under single-point round spot was studied to determine the relaxation duration.The distribution of residual stress in the shock region after round spot multi-point laser shock processing was studied by finite element method and compared with the test results.The distribution of stress waves during strengthening and residual stress after strengthening of round and square spot single-point laser shock processing,and the effects of laser power density and spot shape on the residual stress field during multi-point laser shock processing were analyzed by this simulation method.The results show that the determined relaxation duration was 0.0001 s.The simulated surface residual compressive stress decreased with the increase of depth after round spot multi-point laser shock processing,and the trend was in good agreement with the test results;the relative error of the maximum residual compressive stress was 6.8%,which verified the accuracy of the finite element model.Under the same energy input condition,the shape of the spot did not affect the residual stress field after single-point laser shock processing.With the increase of the average laser power density,the maximum residual compressive stress increased.The maximum residual compressive stress(704 MPa)after square spot multi-point laser shock processing was slightly higher than that after round spot multi-point laser shock processing(692 MPa).The surface residual stress fluctuations of square spot and round spot multi-point laser shock processing were 10.9%and 12.9%,respectively,indicating that residual stress distribution after square spot multi-point laser shock processing was more uniform.