钢桥面横隔板弧形切口残余应力分布特性研究

Residual Stress Distribution Characteristics of Arc Notches ofSteel Bridge Transverse Diaphragms

为研究正交异性钢桥面横隔板过焊孔及弧形切口处残余应力分布特性,建立了顶板、纵肋、横隔板焊缝连接的三维有限元模型,基于热弹塑性有限元方法对焊接动态过程进行数值模拟,分析了温度场和应力场的动态变化过程,并通过实测数据验证了有限元计算的正确性。研究结果表明:纵肋-横隔板焊缝距起弧端20 mm范围内,横向残余应力受顶板-纵肋焊缝初始残余应力影响显著,与初始角焊缝距离越远初始应力对残余应力影响越小;纵肋-横隔板焊缝采取间接焊法产生的残余应力振幅小;弧形切口0~180°测点的切向应力分布趋势符合余弦函数在一个周期内变化规律,其中法向与纵肋平行测点的切向应力值最大;横隔板厚度变化对过焊孔位置残余应力变化不明显;顶板下表面过焊孔处残余应力极值点、应力梯度极值点分别位于横隔板起弧端焊趾、焊根部位;在不影响钢桥面板构造完整性的基础上,可以增大过焊孔半径以降低开口残余应力。

To study the distribution characteristics of residual stress at welding holes and arc-shaped incisions of orthotropic steel bridge diaphragms,a three-dimensional finite element model of the weld joints of the roof,longitudinal ribs and transverse diaphragms was established.Based on the thermo-elastic-plastic finite element method,the numerical simulation of welding dynamic process was carried out,the dynamic change process of temperature field and stress field was analyzed,and the correctness of finite element calculation was verified by the measured data.The results show that the transverse residual stress is significantly affected by the initial residual stress of the roof and longitudinal rib weld within 20 mm of the weld seam distance from the arc starting end,and the farther the weld distance is from the initial fillet weld,the less the initial stress influences the residual stress.The residual stress amplitude of longitudinally ribbed diaphragm weld by indirect welding is small.The distribution trend of tangential stress at the measuring points of 0~180°in arc-cut conforms to the law of cosine function change in a period.Among them,the tangential stress at the measuring points parallel to the normal and longitudinal ribs is the largest.The variation of diaphragm thickness has no obvious effect on the residual stress of the welded hole position.The extreme values of residual stress and stress gradient at the through welding hole on the lower surface of top plate are located at the welding toe and welding root of the arc starting end of the diaphragm respectively.Without affecting the structural integrity of steel bridge panel,the radius of through welding hole can be increased to reduce the opening residual stress.