High-frequency mechanical impact (HFMI) like ultrasonic peening (UP) exhibits a significant fatigue life enhancement of welded joints. Previous studies with regard to effects of HFMI mainly focus on welded components or structures of plate thickness greater than 5 mm. The study aims to develop a new numerical approach for predicting the surface state induced by UP process, and investigate the residual stress distribution of 3-mm 7075 aluminum alloy thin-walled welded joint. A novel model was developed to introduce the excitation amplitude of the ultrasonic horn as an input parameter and investigate the pin kinematics. A parametric study of the UP process parameters on aluminum alloy thin sheet welded joint was performed. The results of pin kinematics indicate that the pin is accelerated at the initial stage of peening and presents stochastic and high-frequency oscillations after the initial phase. For thin sheet welded joint, tensile transverse residual stresses are induced in the surface layer of the weld toe groove, which have negative effect on fatigue performance. The sensitivity of process parameters shows that relatively low intensity of peening, including moderate excitation amplitude and high treatment speed, is recommended to obtain desired residual stress and weld toe geometry, as well as high work efficiency in industrial application. The numerical results of pin kinematics and the surface state of welded joint after UP agree well with the experimental results.

超声波喷丸 (UP) 等高频机械冲击 (HFMI) 可显着提高焊接接头的疲劳寿命。以往关于 HFMI 影响的研究主要集中在板厚大于 5 mm 的焊接部件或结构上。该研究旨在开发一种新的数值方法来预测 UP 工艺引起的表面状态，并研究 3 毫米 7075 铝合金薄壁焊接接头的残余应力分布。开发了一种新颖的模型，将超声波变幅杆的激励振幅作为输入参数并研究销运动学。对铝合金薄板焊接接头的UP工艺参数进行了参数化研究。销钉运动学结果表明，销钉在喷丸初始阶段加速，并在初始阶段后呈现随机高频振荡。对于薄板焊接接头，焊趾坡口表层会产生横向残余拉应力，对疲劳性能产生负面影响。工艺参数的敏感性表明，建议采用相对较低的喷丸强度，包括中等的激励幅度和较高的处理速度，以获得所需的残余应力和焊趾几何形状，以及工业应用中的高工作效率。销钉运动学的数值结果和UP后焊接接头的表面状态与实验结果吻合良好。