Residual stresses and distortions are major barriers to the broader adoption of wire arc additive manufacturing. These issues are coupled and arise due to large thermal gradients and phase transformations during the directed energy deposition process. Mitigating distortions may lead to substantial residual stresses, causing cracks in the fabricated components. In this paper, we propose a novel method to reduce both residual stresses and distortions by optimizing the fabrication sequence. This approach explores the use of non-planar layers, leveraging the increased manufacturing flexibility provided by robotic arms. Additionally, our method allows for the concurrent optimization of the structural layout and corresponding fabrication sequence. We employ the inherent strain method as a simplified process simulation model to predict residual stresses and distortions. Local residual stresses are aggregated using a p-norm function, which is integrated into distortion minimization as a constraint. Through numerical examples, we demonstrate that the optimized non-planar fabrication strategies can effectively reduce both residual stresses and distortions.

中文翻译：

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用于多轴增材制造的残余应力约束时空拓扑优化


残余应力和变形是更广泛采用电弧增材制造的主要障碍。这些问题是耦合的，并且是由于定向能量沉积过程中的大热梯度和相变而出现的。减轻变形可能会导致大量的残余应力，从而导致制造的部件出现裂纹。在本文中，我们提出了一种通过优化制造顺序来减少残余应力和变形的新方法。这种方法探索了非平面层的使用，利用机械臂提供的更高的制造灵活性。此外，我们的方法允许同时优化结构布局和相应的制造顺序。我们采用固有应变法作为简化的过程仿真模型来预测残余应力和变形。局部残余应力使用 p-norm 函数聚合，该函数作为约束集成到变形最小化中。通过数值算例，我们证明了优化后的非平面制造策略可以有效减少残余应力和变形。