超声冲击处理改善焊接接头疲劳性能的数值研究

超声冲击处理（UIT）作为一种有效的焊后改善焊接接头疲劳性能的工艺措施，近年来在国内外船舶行业受到了广泛关注。为评价UIT技术对焊接接头疲劳强度的影响，提出一套新的数值分析方法，包括焊接数值模拟、超声冲击处理过程的弹塑性动态有限元分析，以及基于断裂力学的疲劳强度评估。在有限元模型中考虑了实际的工艺参数和超声促成的材料软化效应。以非承载十字焊接接头为研究对象，将预测的超声冲击处理前后的残余应力分布及疲劳强度与实验结果进行对比，两者吻合较好。

Numerical study on fatigue properties of welded joints improved by ultrasonic impact treatment

Ultrasonic Impact Treatment(UIT) has recently attracted considerable attention in the ship industry as an effective post-welding improvement method for welded joints. In order to evaluate the effect of UIT on the fatigue properties of welded joints, we propose a novel numerical analysis approach including welding simulation, dynamic elastic-plastic Finite Element Analysis(FEA) of the UIT process, and the evaluation of the fatigue strength of welded joints based on fracture mechanics. In the FEA model, the actual process parameters and ultrasonic-induced material softening, appropriately adjusted to fit the experimental results, are considered. The predicted residual stress distributions and fatigue strength of non-load-carrying cruciform joints before and after UIT are compared with the experimental results, and show a fairly high level of agreement.