翘曲变形是影响复合板激光弯曲成形精度的重要因素。基于ANSYS软件和电子探针面扫描实验, 建立了含结合面的不锈钢-碳钢复合板激光弯曲有限元模型, 对一次扫描过程中产生的翘曲变形进行数值模拟。通过模拟激光作用下复合板的温度场、应力场及残余应力分布, 结合自由端的变形, 分析了翘曲变形产生的过程及原因。模拟结果表明: 激光扫描过程中, 受初始温度及边界效应的影响, 扫描线上各点最高温度分布的不均匀百分比为18.33%。经0.2 s热传导及热量散失的共同作用后, 扫描线中间区域出现热累积现象, 热应力增大, 产生了翘曲变形。对扫描线到自由端整体区域进行残余应力模拟分析可知, 板材在其区域内部产生了翘曲作用力与区域周边约束反作用力, 其大小和方向与翘曲的变形吻合。对比实验数据和模拟结果, 翘曲线最大误差为3.90%, 其中, 弦高误差为3.33%, 为复合板激光弯曲成形的角度控制提供了计算依据。

In laser bending forming, the warping deformation influences the forming accuracy. Based on ANSYS software and electron microprobe, process of the warping deformation for stainless steel-carbon steel composite plate including interfaces bended by pulsed laser was simulated using a multi-layered finite element model (FEM) in single-pass scanning. By simulating temperature field, stress field, residual stress distribution and the free end deformation of the composite plate, the process and the reason of warping deformation were analyzed. The results show that during laser scanning, the uneven rate of the highest temperature on the scanning line is 18.33%, which is influenced by initial temperature and edge effect. After 0.2 s heat conduction and heat loss, heat accumulation phenomenon appears in middle area, which leads to warping deformation caused by increased thermal stress. Simulation results of the residual stress from scanning line to free end show that, warping force within the region and constraint counterforce at the edges of the region are produced, warping deformation matches both the magnitude and direction of the simulation result. The max error of warping line between the experiment and simulation is 3.90% and the error of chordal height is 3.33%, which provids the calculation basis for better bending angle control of the composite plate.