激光冲击7075-T6铝合金焊缝的残余应力场数值模拟

Numerical Simulation of Laser Shock Peening on Residual Stress Field of 7075-T6 Aluminum Alloy Welding

针对激光冲击强化铝合金焊缝过程中存在多场耦合导致残余应力变化幅度大、实时表征难的问题,采用ABAQUS非线性有限元软件建立了激光冲击强化7075-T6铝合金板材焊接件的有限元模型,模拟计算焊缝在激光冲击强化前后的残余应力场分布,重点分析了激光冲击强化对焊缝的横、纵向残余应力场的影响规律,并对焊缝的激光冲击强化工艺参数进行优化。研究结果表明,焊缝表面为残余拉应力场并且分布不均,激光冲击强化使得焊缝的拉应力状态转变为高幅压应力状态;优化激光冲击强化工艺参数(如激光能量、激光光斑尺寸、搭接率),可以明显改善焊缝区域和热影响区的残余应力分布;当激光光斑搭接率为50%至70%时,残余应力分布趋于均匀,可以有效消除"残余应力洞"现象。

Due to the significant fluctuation and the real-time measurement difficulty of residual stress, a finite element model of laser shock peening （LSP） on residual stress field of Al alloy welding has been developed in ABAQUS. The residual stress fields of 7075-T6 Al alloy welding are computed and compared before and after LSP, and special attentions are paid to the effects of LSP on residual stress field of 7075-T6 Al alloy welding. Subsequently, the processing parameters of LSP on Al alloy welding are also optimized. Results show that LSP causes the residual stress evolution from tensile residual stress to high-level compressive residual stress on the Al alloy surface. Residual stress distributions can be clearly improved by optimizing the processing parameters （including laser pulse energy, spot size and overlapping rate）. When the overlapping rate is between 50% and 70%, residual stress tends to a more uniform residual stress field, which can effectively eliminate “residual stress hole”.