激光选区熔化增材制造TC4钛合金典型结构变形的数值模拟研究

Numerical Simulation of Deformation of Typical Parts in Selective Laser Melting Additive Manufacturing

激光选区熔化(selective laser melting,SLM)增材制造过程中,由高温梯度诱导的高热应力引起零件发生变形,严重影响SLM成形零件的尺寸精度,已成为阻碍其工程应用的主要障碍。基于等效层思想并考虑随温度变化的热物性参数,建立了SLM成形大尺寸热-结构间接耦合有限元数值模型,研究了SLM成形典型结构的变形分布。研究结果表明,薄板、倾斜板、方块、圆柱和三棱柱等典型结构均呈现内凹陷变形,并且最大内凹变形量位于零件侧边中部位置。模型预测变形结果与试验吻合良好,两者误差小于±20μm。研究结果可为SLM成形的变形和尺寸精度控制提供理论指导。

In selective laser melting(SLM) additive manufacturing, the high thermal stress induced by the high temperature gradient causes the deformation of the parts, which seriously affects the dimensional accuracy of SLM parts and has become the main obstacle to its engineering application. In the study, a large-scale thermo-mechanical indirect coupling finite element numerical model is developed to study the deformation distribution of the typical parts fabricated by SLM. The results indicate that the typical parts, such as the thin-walled part, incline-walled part, block, cylinder, and tri-prism, show an internal concave deformation. The maximum deformation occurs at the middle of the side of the parts. The simulated deformation results are in good agreement with the experimental data, and the error is less than ± 20 μm. The results provide the theoretical guidance for the deformation and accuracy control in SLM.