Abstract Understanding the thermal distortion induced by arc welding, laser, or induction heating is a challenge in academia and industry. This study presents the artificial thermal strain (ATS) method which was modified from strain as boundary (SDB) method, based on inherent strain theory, and its equivalent mechanical model to analyse the distortion mechanism. Experiments and numerical simulation of multi-pass laser bending of alloy 304 L were conducted, wherein the various kinds of inherent strain distributions and the boundary of effective inherent strain were examined. Further, the mechanism of bending angle reduction under lower line energy was evaluated by considering the inherent strain redistribution at each pass. The results indicate that the bending angle reduction in multi-pass laser scanning is determined by the size of the inherent strain area at low line energy. Moreover, a simplified plastic finite element model based on the ATS method was developed to predict the welding deformation of plate curvature induced by parallel laser scanning. Additionally, only 210 elements and 7 s was cost to perform with the deformation analysis, which indicates that the ATS model is effective in predicting thermal distortion. Meanwhile, the ATS method can provide theoretical guidance and fast prediction for the actual thermal processing in large welded structure and additive manufacturing in the future.

中文翻译：

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人工热应变法：一种热畸变分析与快速预测的新方法

摘要 了解弧焊、激光或感应加热引起的热变形是学术界和工业界的一个挑战。本研究基于固有应变理论，提出了由应变边界法（SDB）改进而来的人工热应变（ATS）法及其等效力学模型来分析变形机理。对304L合金进行了多道次激光弯曲实验和数值模拟，研究了各种固有应变分布和有效固有应变边界。此外，通过考虑每道次的固有应变重新分布，评估了较低线能量下弯曲角减小的机制。结果表明，多道激光扫描中弯曲角的减小由低线能量下固有应变区域的大小决定。此外，建立了基于ATS方法的简化塑性有限元模型，以预测平行激光扫描引起的板曲率焊接变形。此外，变形分析只需要 210 个单元和 7 秒的成本，这表明 ATS 模型在预测热变形方面是有效的。同时，ATS方法可以为未来大型焊接结构和增材制造中的实际热处理提供理论指导和快速预测。建立了基于ATS方法的简化塑性有限元模型，用于预测平行激光扫描引起的板曲率焊接变形。此外，变形分析只需要 210 个单元和 7 秒的成本，这表明 ATS 模型在预测热变形方面是有效的。同时，ATS方法可以为未来大型焊接结构和增材制造中的实际热处理提供理论指导和快速预测。建立了基于ATS方法的简化塑性有限元模型，用于预测平行激光扫描引起的板曲率焊接变形。此外，变形分析只需要 210 个单元和 7 秒的成本，这表明 ATS 模型在预测热变形方面是有效的。同时，ATS方法可以为未来大型焊接结构和增材制造中的实际热处理提供理论指导和快速预测。