针对高强铝合金薄板结构焊接时存在的焊后残余应力及变形大的缺点,采用施加一不大于材料屈服强度σs的纵向预置拉应力的方法降低其残余应力与变形,对此平板对接焊的残余应力与变形进行了数值模拟.结果表明:该方法可以改善残余应力的分布状态,显著降低焊后残余应力的峰值,预置应力越大,残余应力越低;从而减小了焊接件的变形;随着预应力的增加变形相应减小,0.5σs和0.7σs的预置应力下的最大变形挠度由常规焊的38 mm分别降至18 mm和7 mm,降至原来变形的17%左右;试验结果验证了模拟结果的准确性.

The serious residual stress and distortion are the weld defects associated with welding thin plate structure of high strength aluminum alloys.By applying a longitudinal tensile stress less than yield strength of the material,the residual stress of the flat butt welding was analyzed by the ellipsoidal heat source model.The results show that it can improve the residual stress distribution of welded joint and the peak value of the residual stress reduced evidently.The greater the pre-stress,the lower the residual stress.So welding distortion reduced.The values of deflection between conventional welding and welding with pre-stress were compared.It is found that the deflection reduced with the increase of longitudinal pre-stress.The maximum deflection of thin plate decreased from 38 mm under the condition of conventional welding to 18 mm and 7 mm respectively when 0.5σs and 0.7σs were applied.The value decreased to 17% of that in conventional welding.The reliability of numerical simulation results is proved by the experimental results.