焊接数值模拟

材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity1焊接过程的数值模拟•概述–焊接过程数值分析的内容–焊接过程的特点–焊接过程中温度－应力和变形－组织转变的关系–焊接过程数值分析的主要困难材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity2焊接数值分析的内容•焊接熔池中的流体动力学和热过程•热源与金属的相互作用–焊接电弧物理，焊接电弧的传热与传质•电弧作用于熔池表面的热能和压力分布•熔池表面的变形•液态金属的蒸发•氢及氮氧等在熔池及环境之间的分配•焊接冶金和焊接接头组织性能的预测，包括相变过程•焊接应力与变形•焊接过程中的氢扩散•特种焊的数值模拟–电阻点焊–陶瓷－金属的焊接–激光焊的熔化和凝固–瞬态液相连接（过渡液相焊）–搅拌摩擦焊•焊接接头的力学行为－－焊接裂纹–热裂纹，冷裂纹，裂纹的形成和扩展，–焊接接头的不均匀性–焊接断裂力学材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity3焊接数值模拟的研究：电弧焊•电弧部分–流场、温度场、电场–研究各种工艺参数（电流、电压、弧柱气氛，电极伸出长度等等）对温度场，电流密度，压降分布以及熔滴过渡过程的影响规律•熔池部分–熔池形状–流场、温度场，主要研究成分和工艺因素对熔池形状的影响，针对焊缝形状控制–冶金过程熔池中气体的吸收各种氧化物氮化物的形成及其作为非均质核心的可能凝固－熔质元素分布（偏析）凝固组织大小，结晶路径，BTR区间等•结构部分–热过程－温度分布，预测热影响区大小，冷却时间，Tmax，th，t8/5等–力过程－应力应变过程，残余应力和变形，预测裂纹，控制残余应力和变形–冶金过程－晶粒长大，相变，氢扩散，接头组织性能预测，冷裂敏感性预测等–接头性能与服役行为－不均质、存在缺陷、残余应力－断裂行为（韧性，强度，疲劳性能等）与可靠性分析等等材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity4焊接数值模拟：其他焊接方法•电阻点焊–熔核的形成与控制，性能预测与分析•扩散焊–过程模拟，温度，压力对界面接合的影响；TLP过程的模拟•钎焊–SMT焊点形态模拟，焊点服役过程中的热应力应变循环，寿命估计等等•激光焊接–焊接温度场模拟与接头的形成及预测，激光相变硬化时的三维温度场模拟与处理材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity5焊接数值模拟：其他加热工艺•热处理–包括焊后热处理等对应力和变形的影响等等•热校核–焊后产生变形，用局部加热的方法校正，研究加热部位，加热量等因素的影响•热成形–确定加热部位，热源强度，加热时间等等；可以实现变形的精确控制材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity6IndustrialweldingprocessesElectronbeamweldingspotweldingMIGweldingMultipasssubmergedarcweldingLaserweldingGTAwelding材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity7MultipasssubmergedarcweldingComparisonoftransverseresidualstressesbetweensimulationandX-Raydiffraction材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity8AluminiumweldingofBMWsuspensionpartsAtBMW,SYSWELDisusedtopredictdistortionsandresidualstressesonweldedaluminumframeparts.AnexampleisthewingoftherearaxissystemofaBMWseries5.Thewingismadeoutofthreehydroformed,thick-walledaluminumpartswhichareweldedtogetherby8weldingjointsinacertainsequence.Figure:BMWseries5rearsuspensionsystem材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity9HypermeshmodelingofthewingofrearaxlesystemTominimizetheinservicemodelingtime,HypermeshhasbeenchosentomeshtheIDEASCADmodel.SYSWELDcanbeinterfacedtoHypermeshusingthePAMCRASHfileformat.Inthenextimage,theHypermeshmodelofthewingoftherearaxlesystemcanbeseen.Figure:SolidHypermeshmodelofthepart材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity10SimulationofweldingdistortionandresidualstressesThesimulationgivesexcellentresultsondistortionsandresidualstresses,incomparisonwithalargeseriesofmeasurements.Thepredicteddistortionshavebeenwithintherangeofthedistortionsaccessedattheproduction.Figure:Distortionsafterunclamping,valuesstronglyamplified材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity11MonteCarloSimulationofGrainGrowthinMetals•2-Dsimulation•3-Dsimulation材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity13NeuralNetworkforPulsed-LaserWeldingProcess•Therearefourvariablesthatappeartocontroltheweldpoolshapearelaserpower,weldingspeed,laserpulsepowerandlaserpulseduration.Theinteractionbetweenthesevariableswereexperimentallystudiedandanartificialneuralnetworkwasconstructed.Typicalcalculationsfromtheneuralnetwrokareshownbelow.•Effectofweldingspeed•Effectoflaserpower•Effectoflaserpulseenergy•Effectoflaserpulseduration材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity14ResistanceWeldingTemperatureDistribution(thermal-electricalinteractions)Thefollowingquicktimemovieshowstypicalheatingandcoolingduringresistanceweldingprocessinasteelsheet.Themovieshowsonly1/4thofthegeometryduetosymetry.ResistanceWeldingTemperatureDistribution–Basedontheworkof•BernieRiemer(423)574-6502•[e-mail]材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity15Thermal-Electrical-MechanicalInteractionsofRSWThreewaycoupledmodelallowsonetodepicttheeffectsofelectrodecurvatureonthewelddevelopment.Observation:•Toillustratethiswehavemadethreequicktimemoviesofwelddevelopmentforthesamesteelmaterialwithdifferentelectroderadius.Thewelddevelopmentarefoundtobegreatlydifferentifweuseflatelectrodecomparedtoaelectrodewithcurvature.•SimulationwithflatelectrodeSimulationwithradiusofelectrode=156mmSimulationwithradiusofelectrode=35mmSimulationwithradiusofelectrode=35mm(butwith0.1timescontactresistance)Implications•Theobservedresultsareindeedconsistentwiththeindustrialpractice,wheretheelectrodesareusuallydressedtoobtainconsistentweldquality.Ourresultssuggestthatbyusingflatelectrode,theweldzonedevelopmentsaredelayedincomparisontotheelectrodeswithcurvature.材料加工的计算机模拟与仿真2019/10/14ZhaoHaiyan,DepartmentofMechanicalEngineering,TsinghuaUniversity16Performaceofresistancesteelspotweld