超声冲击处理对高强钢焊接接头残余应力影响的数值模拟

Numerical simulation on residual stress distribution of high-strength steel welded joints treated by ultrasonic impact

超声冲击处理(UIT)是一种有效的焊后改善焊接接头疲劳性能的工艺措施,其借助机械撞击和超声振动的共同作用,使焊趾表面产生塑性变形从而引入有益的压缩残余应力。为评价UIT技术对焊接接头残余应力的影响,该文提出了一套新的数值分析方法,包括焊接数值模拟及随后的超声冲击处理过程的动态弹塑性有限元分析。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。以船用高强钢AH36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与实验结果进行对比,两者有较好的吻合。在此基础上,探讨了静态预载荷对超声冲击处理态残余应力再分布的影响。

Ultrasonic impact treatment （ UIT） is an efficient post-weld fatigue improvement technique, which applies mechanical impacts in combination with ultrasonic oscillations into weldedjoints and plastically deforms the weld toe, consequently introducing beneficial compressive residual stress in the region of the weld toe. In order to evaluate the effect of UIT on welding residual stress, a novel 3D numerical analysis approach including thermo-mechanical welding simulation and dynamic elastic-plastic FE analysis of ul-trasonic impact treatment process for weldedjoints was proposed. In the FE model, the actual process pa-rameters and ultrasonic-induced material softening, which was appropriately adjusted to fit experimental re-sults, were considered. The predicted residual stress distributions before and after UIT in the non-load-car-rying cruciformjoints of AH36 shipbuilding high-strength steel were compared with experimental results,showing a fairly good agreement with each other. In addition, the influence of static preloads on the re-distribution of UlT-induced residual stress was also discussed.