超声冲击消除高强钢焊接残余应力的数值模拟研究

Numerical simulation on ultrasonic impact treatment on welding residual stress of high strength steel

焊接残余应力会对结构的力学特性带来不利的影响,而超声冲击能较有效地消除大型焊接结构残余拉应力,起到大幅增加结构疲劳强度的作用。该文首先采用热弹塑性方法对超声冲击前的高强钢平板焊接残余应力进行分析,然后采用瞬态动力学方法对焊接残余应力的超声冲击消除进行三维仿真研究,最后对超声冲击前后残余应力的数值计算结果与试验结果进行对比分析研究。由分析结果可知:超声冲击前高强钢平板焊缝附近存在较大的残余拉应力,呈双峰分布;超声冲击后较大的残余拉应力转化为残余压应力;数值模拟结果与试验结果相一致。并且,平板厚度方向的应力经过超声冲击后表现为应力的均匀化。文中研究结果可为高强钢大型焊接结构超声冲击消除残余应力进行合理评估和后续进行相关力学特性研究提供理论基础和技术支撑。

Welding residual stress is a deficiency for mechanical properties of structure. Ultrasonic impact treatment(UIT) could eliminate welding residual tensile stress effectively, so it might largrly increase fatigue strength of structure. In this paper, the welding residual stress of a welding plate of high strength steel before UIT is calculated using the thermal elastic-plastic method, and then a 3D simulation of eliminating welding residual stress with UIT is studied by transient dynamic analysis method. Finally, it is compared with experiment results before and after UIT. The results show that it exist large residual tensile stress near the welding line before UIT, and it presents double peak value. After UIT the large residual tensile stress changes to residual compressive stress, and the results of simulation agrees with those of experiments.Moreover, it presents tendency of stress equalization. These results would provide a theretical basis and technical method for reasonable assessment of eliminating welding residual stress with UIT and follow-up study of relative research of mechanical properties.