激光冲击参数对残余应力场影响的三维数值模拟

Numerical Simulation of Effects of Laser Shock Parameters on Residual Stress Field Induced by Laser Shock Processing

数值模拟是预测激光冲击残余应力场、研究激光冲击参数对残余应力场影响的一种有效方法。采用显式动力有限元软件ANSYS/LS-DYNA对激光冲击处理(LSP)40Cr钢残余应力场进行三维数值模拟;建立了激光冲击处理40Cr钢残余应力场有限元分析(FEA)模型,实现了激光冲击处理40Cr钢残余应力场的数值模拟;模拟研究了激光功率密度、激光脉冲持续时间、激光光斑尺寸对40Cr钢残余应力场的影响。数值模拟结果表明,残余应力模拟值与实测值之间有着较好的一致性;在激光脉冲持续时间一定的条件下,要想获得最大的表面残余压应力,存在一个最佳的激光功率密度;在激光功率密度一定并且脉宽大于45ns的情况下,表面残余压应力随激光脉冲持续时间的增加而减小;在激光功率密度、激光脉冲持续时间一定的条件下,表面残余压应力随光斑直径增大而增大。

Numerical simulation is an effective way to predict the residual stress field induced by laser shock processing （LSP） and study the effects of laser shock parameters on the residual stress field . The finite element sorftware ANSYS/LS-DYNA was applied to simulate the three-dimensional （3D） residual stress field of 40Cr steel surface layer induced by LSP. The 3D finite element model of laser shock processing 40Cr steel was built. The numerical simulation of residual stress field of 40Cr steel surface layer induced by LSP was realized. The effects of laser shock parameters, intensity, pulse width and beam spot, on the residual stress field of 40Cr steel surface layer were studied by simulation. The result of numerical simulation indicates that the value of residual stress from simulation has a good consistent with that from measurment. There is an optimum laser power density for inducing a maximum surface residual compressive stress when the duration of laser pulse was fixed. The surface residual compressive stress decreases as the duration of laser pulse prolongs while the laser power density is fixed and the pulse duration is over 45 ns; The surface residual compressive stress also increases as the size of laser beam spot increases when laser power density and duration of laser pulse are fixed.