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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。
Aimed at the laser solid state forming (MLSF) process of metal materials, the parametric finite element model of temperature field and stress field in forming process was developed by using the secondary development language APDL of Ansys, a large finite element analysis tool. This model considers a series of problems such as material nonlinearity with temperature, energy distribution of Gaussian laser, boundary conditions of convection / radiation heat transfer, phase transition and free deformation. Through the use of transitional meshing technology, the number of elements is greatly reduced based on the improvement of the calculation accuracy, so as to realize the overall modeling of the metal laser three-dimensional forming process. Based on the accurate calculation of the evolution law of the temperature field, the thermal stress field in the laser forming process is effectively simulated by using the mobile heat source and the unit life and death technology. The results show that the thermal stress fields such as the plastic compression zone, the plastic stretching zone and the unloading zone are generated the reason. Using this parametric model, it is easy to study the influence of metal laser three-dimensional forming process conditions and different materials on the thermal stress field in the forming process.