The selective laser melting (SLM) process involves irradiation from a high-power laser to melt and sinter powdered material. The high temperature gradient near the laser spot generates high residual stress that can lead to failure of fabricated parts. Estimation of the residual stress for real transient SLM processes by simulation involves considerable computation effort which makes its application in real industrial SLM processes rather difficult. To tackle this challenge, a two-stage coupled transient thermomechanical model with a quasi-transient heat source was developed. In the first stage, a transient thermal analysis was performed to acquire temperature distribution of the full SLM process. The temperature distribution serves as thermal loading input for subsequent transient thermal stress analysis. This quasi-transient thermomechanical model can provide residual stress data consistent with that of a conventional full transient model in 68% less computation time. The data provided by the new model also includes the dynamic stress release due to re-heating and re-melting in overlapped laser scanned regions which was in close confirmation with experimental results. This efficient quasi-transient model is useful for rapid analysis and optimization of SLM processing parameters.

选择性激光熔化 (SLM) 工艺涉及来自高功率激光的辐射以熔化和烧结粉末材料。激光光斑附近的高温梯度会产生高残余应力，从而导致制造零件的故障。通过仿真估计实际瞬态 SLM 过程的残余应力涉及大量计算工作，这使得其在实际工业 SLM 过程中的应用相当困难。为了应对这一挑战，开发了一种具有准瞬态热源的两级耦合瞬态热机械模型。在第一阶段，进行瞬态热分析以获取整个 SLM 过程的温度分布。温度分布用作后续瞬态热应力分析的热负载输入。这种准瞬态热机械模型可以提供与传统全瞬态模型一致的残余应力数据，计算时间减少 68%。新模型提供的数据还包括在重叠的激光扫描区域中由于重新加热和重新熔化而导致的动态应力释放，这与实验结果非常吻合。这种高效的准瞬态模型对于 SLM 处理参数的快速分析和优化很有用。