爆炸消减钢桥面顶板-纵肋焊接残余应力的模拟分析

已有研究表明焊接残余应力会严重影响正交异性钢桥面的疲劳强度和使用寿命。爆炸处理方法已在冶金设备、压力容器及海上采油设施等大型焊接结构的残余应力消减中得到了应用，本文提出了焊接-爆炸处理全过程数值模拟流程，分析了顶板-纵肋焊接连接残余应力变化过程，考察了爆炸处理对钢桥面板顶板-纵肋焊接残余应力的消减效果。首先，采用热-结构间接耦合分析方法模拟了顶板-纵肋焊接连接的焊接过程，使用生死单元法模拟焊缝金属的填充及热源输入过程，得到了动态温度场和应力场。然后，采用LS-DYNA显式动力分析软件，基于任意拉格朗日-欧拉法和流固耦合算法模拟了爆轰波与顶板-纵肋焊接连接的相互作用过程。分析结果表明，焊接过程在焊趾处引起的横向残余应力高达112 MPa，纵向残余应力高达117 MPa；爆炸处理后焊趾处横向残余应力消减幅度达159 MPa，纵向残余应力消减幅度达278 MPa。表明该方法可使焊接区域残余应力产生重分布，从而有效消减残余应力。本文分析结果可为类似桥梁的残余应力消减处理提供技术参考。

Numerical Analysis on Welding Residual Stress Reduction for Rib-Deck Connection in Orthotropic Steel Deck via Explosion

The existing research have indicated that the fatigue strength and service life of the welded structure are seriously affected by the welding residual stress. Explosion method is widely used in the reduction of residual stress in large welded structures such as metallurgical equipment, pressure vessels and offshore oil extraction facilities. The numerical simulation procedures of full processes including welding and explosion treatment is proposed, the changing process of the residual stress in the deck-rib welding connection is analyzed, and the effect of the explosion treatment on the reduction of the residual stress in the deck-rib welding connection is studied. First, the welding process of the deck-rib was simulated by the thermal-structure coupling analysis method. The weld metal filling and the heat source inputting of the welding process were simulated by the element birth-death method. The temperature and stress fields of welding were obtained. Then, the interaction between detonation wave and the deck-rib was simulated by the arbitrary Lagrange-Euler algorithm and the fluid-structure interaction method in the explicit dynamic analysis software LS-DYNA. The results show that the welding transverse residual stress at weld toe is 112MPa, and the welding longitudinal residual stress at weld toe is 117MPa. The reduction amplitude of the transverse residual stress at weld toe is 159MPa, and the reduction amplitude of the longitudinal residual stress at weld toe is 278MPa. The residual stress of the welded structure can be redistributed and effectively reduced by the explosion method. The conclusion of the numerical simulation is supposed to provide technical reference for the residual stress reduction of similar bridges.