预拉伸控制铝合金筒体环焊缝焊接残余应力及变形的数值模拟

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1、摘要摘要本文是在铝合金平板对接焊缝预拉伸焊接试验的基础上，提出预拉伸对铝合金筒体环焊缝焊接残余应力和残余变形影响的数值模拟研究设想。文中通过对有限元分析方法介绍，通过实体建模法建立模型，采用表面均匀热源模型，采用自由网格划分法划分网格，在柱状坐标体系下通过循环语句实现热源移动，依靠数值分析理论处理7075铝合金热物理性能参数材料,对有无预拉伸应力条件下铝合金筒体环焊缝对接焊接过程中焊接区域温度场、应力应变场进行了三维实时动态模拟分析，探讨了筒体焊接过程中应力及变形的变化规律，和预拉伸应力对铝合金筒

2、体的焊接应力及变形的影响特征。数值模拟分析结果表明，预拉伸焊接法可以有效控制铝合金筒体环焊缝焊接残余应力和残余变形，预拉伸应力为90%σ0.2时焊接，其焊后残余应力峰值最小，筒体断面上纵向残余应力分布曲线平缓，残余应力降低了50%左右；采用预拉伸焊接法可以有效控制铝合金筒体环焊缝焊接残余变形，筒体焊缝及近缝区的纵向挠曲变形，当预拉伸应力σp=90%σ0.2时，施加预拉伸焊接焊缝的残余变形下降了30%左右；焊件结构对焊接残余变形的影响不同于焊接残余应力，平板的残余变形除了塑性外还有弹性挠曲，筒体由于

3、是回转体不具备挠曲结构条件，因此筒体的焊接残余变形小于平板接残余变形，由于筒体的焊接残余变形较小，预拉伸焊接减小焊接残余变形的幅度小于预拉伸焊接减小焊接残余应力的幅度。关键词：数值模拟；有限元；筒体结构；温度场；残余应力；残余变形；预拉伸IAbstractAbstractBasedontheexperimentofaluminumalloyplatebuttweldingseamwithpretension,numericalsimulationresearchabouttheinfluenceo

4、fresidualstressandstrainwithpre-drawingstressappliedtobarrelweldingseamisassumed.IntroducingFEM(FiniteElementMethod),buildingmodelwithsolidmodelbuildingmethod,uniformsurfaceheatsourcemodelandfreemeshgridwayareused.Themovementofheatsourceisachievedthro

5、ughtheloopsentenceincylindricalsystem.Numericalanalysisisappliedtodealwiththermalphysicalparametersof7075aluminumalloy.Regionaltemperatureandstrain-stressinweldingareaofaluminumalloybarrelaresimulatedwith3-Dreal-timedynamicsimulationanalysismethodwhen

6、theseamwasappliedrespectivelywithpretensionandnot.Thedisciplineofstrain-stressdistributingintheprocessofaluminumalloybarrelweldingisdiscussed.Theinfluenceofstress-straininbarrelweldingwithpretensionisalsodiscussed.Withtheresultofnumericalsimulationana

7、lysis,it’sclearthattheresidualstressandresidualstrainwerecontrolledeffectivelywithpre-drawingstressinaluminumalloybarrelwelding.Thepeakofresidualstressisdeclinedwhenpre-stressis90%σ0.2.Verticalresidualstressdistributedcurveisflattenedinbarrelfracturep

8、laneandtheresidualstressdroppedby50%.Weldingwithpre-stressisaneffectivewaytocontrolresidualstressanddeflectiondeforminaluminumalloybarrelwelding.Theresidualstrainofweldingseamwithpre-stressdeclined30%.Theinfluenceofweldingstructureonweldingres