同轴送粉激光增材制造Al-Zn-Mg-Cu合金应力场数值模拟

Numerical simulation of stress field of Al-Zn-Mg-Cu alloy laser additive manufacturing based on coaxial powder injection under different processes

采用Ansys软件建立了同轴送粉激光增材制造Al-Zn-Mg-Cu合金的有限元模型,对该模型进行了试验验证,模拟分析了不同激光功率和扫描速度单层单道成形过程中的温度场和应力场。结果表明,模拟得到的应力与试验结果误差约为5.2%,验证了模型的准确性。激光成形过程中,激光作用产生“端部效应”,熔池前端的温度梯度大,后端的温度梯度小。随着激光功率的增加和扫描速度减小,熔池温度增加,激光功率的影响更加显著。随着激光功率与扫描速度的增加,沉积层的三向应力也随之增大,最大Von mises等效应力与垂直于扫描方向的应力σ_(y)呈“W”形分布,沿扫描方向的应力σ_(x)先增大后减小,且σ_(x)>σ_(y)。当沉积层冷却至室温时,其表面残余应力主要为拉应力,且沉积层中部位置的残余应力高于边缘位置的残余应力。

The finite element model of Al-Zn-Mg-Cu alloy fabricated by laser additive manufacturing with coaxial powder injection was established by Ansys software and verified by experiments.The temperature field and stress field of single-layer single-track forming process under different laser power and scanning speed were simulated and analyzed.The results show that the error between the simulated stress and the experimental results is about 5.2%,which verifies the accuracy of the model.In the process of laser additive manufacturing,for the single-layer single-track forming process,under the action of laser,end effect will be generated,the temperature gradient at the front end of the molten pool is large,and the temperature gradient at the back end is small.With the increase of laser power and the decrease of scanning speed,the temperature of molten pool increases,and the influence of laser power is more significant.With the increase of laser power and scanning speed,the three-dimensional stress of the deposition layer also increases,the maximum Von mises equivalent stress and the stressσ_(y) being perpendicular to the scanning direction are distributed in a‘W'shape,the stressσ_(x) along the scanning direction first increases and then decreases,andσ_(x)σ_(y).When the deposition layer cooled down to room temperature,the surface residual stress is mainly tensile stress,and the residual stress in the middle of the deposition layer is higher than that at the edge.