针对金属材料的激光立体成形 (MLSF)工艺,利用大型有限元分析工具Ansys的二次开发语言APDL,开发了成形过程温度场、应力场的参数化有限元模型。该模型综合考虑了随温度变化的材料非线性、高斯激光能量分布、对流/辐射换热边界条件、相变以及自由变形约束等一系列问题。通过使用过渡网格划分技术,在提高计算精度的基础上,大幅减少了单元数目,从而实现了金属激光立体成形过程的整体建模。采用移动热源和单元生死技术,对激光成形过程热应力场进行了有效仿真,在准确计算温度场演化规律的基础上,揭示了塑性压缩区、塑性拉伸区、卸载区等热应力场产生的原因。使用该参数化模型便于研究金属激光立体成形工艺条件、不同材料等对成形过程热应力场的影响。

Based on Ansys secondary development language APDL,a parametric temperature/stress finite element model for metal laser solid forming (MLSF) process was developed. The model allows for non-linear behavior of material properties,Gaussian distribution of laser energy,thermal convection and radiation boundary condition,phase change,free deformation constraints condition et al. A full finite element model of MLSF process is established by transition mesh technology. Accuracy of simulation is improved and the element number is reduced under the model. The temperature/stress evolution of MLSF process is simulated based on moving laser beam and element birth and death technology. On the basis of the temperature distribution is evolution,the reason of inducing the compress plastic stress,tensile plastic stress and unloading zones is analyzed. The influence of MLSF process conditions on temperature/stress can be studied by utilizing the parametric finite element model in order to optimize the MLSF process.