对流换热系数对熨平板焊接变形和应力的影响

Influence of convective heat transfer coefficient on welding deformation and stress of screed

采用有限元模拟不同对流换热系数下熨平板的焊后变形和应力分布,并采用塞尺和X射线法进行试验验证。结果表明:整体变形趋势为U形板呈"鼓泡"状,左连接板伸出端向x正向收缩变形,两侧板自由边向内收缩变形。最大变形位置出现在连接板伸出端最上端,对流换热系数为采用曲线加载时,变形误差为34.3%,系数为0.02时,误差为17.1%;不同对流散热系数对残余应力峰值影响很小,应力分布与对流换热系数为0.02时趋势一致,误差为32.6%,采用曲线加载,不考虑低应力区结果,误差为21.1%,均满足工程应用要求,证明了模拟结果的准确性。两种加载方式均满足焊接变形预测要求,在焊缝较多、应力分布复杂的情况下,应力预测建议采用曲线加载方式,反之则采用系数为0.02加载。

The finite element is used to simulate postwelding deformation and stress distribution of screed with diffelent convection heat transfer coefficients. And the results are verified by using feeler gauges and x ray method. The results show that overall deformation trend is bubble shape of U-shaped plate,and the extended end of the left connecting plate shrinks and deforms along the forward direction of x axis. And the free edges of two side panels are concave. The maximum deformation position appears on the tip of the connecting plate extended end. When the convective heat transfer coefficient loads temperature change curve, the deformation error is 34.3%. When the coefficient is 0.02,the error is 17.1%. Different coefficients have little effect on the peak values of the residual stress. The trend of stress distribution is consistent with that when the convective heat transfer coefficient of 0.02 and the error is 32.6%. Using curve loading and without considering low stress zones, error is 21.1%. All of them meet the requirements of engineering application, which proves that accuracy of the simulation results. Two loading nmdes can predict welding defi）rmation. Under the circumstance of many welds and complicated stress distribution, the curve loading method is recommend, otherwise the loading method with coefficient of 0.02 are recommend.