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ID:32691375
大小:2.76 MB
页数:54页
时间:2019-02-14
《lng低温储罐用9ni钢焊接残余应力的数值模拟》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、中文摘要随着世界经济与工业生产的飞速发展,人们对洁净能源——液化天然气(LiquefiedNaturalGas---LNG)的需求越来越大。然而,LNG的广泛应用需要建设大型的低温储罐。由于大型低温储罐焊接残余应力的存在严重威胁着低温储罐的使用寿命,并具有较大的安全隐患,这使储罐结构的安全性成为人们十分关注的问题。因此,宏观把握焊接工艺参数与残余应力之间的关系对于控制低温储罐的焊后接残余应力具有十分重要的意义。本课题以液化天然气低温储罐用9Ni钢焊接残余应力的数值模拟为对象,利用SYSWELD有限元软件动态模拟焊接的全过程,定量分析焊后残余应力的分布和大小,通过对不
2、同焊接线能量和层间温度下焊接过程的数值模拟,分析焊接线能量和层间温度对焊接残余应力的影响,为LNG低温储罐的实际应用提供理论依据。利用SYSwELD焊接有限元分析软件,选择双椭球焊接热源模型,模拟了LNG低温储罐用9Ni钢的焊接过程,获得了五组不同工艺参数下焊接粗晶区的焊接热循环曲线,并分析讨论了线能量和层间温度对热循环参数的影响。应用SYSWELD软件进行数值模拟时,考虑了材料热物理性能与温度的非线性关系,以及相变潜热对温度场的影响,实现温度场和应力应变场的耦合计算,获得了多层焊焊接头残余应力的分布规律。关键词:低温储罐;残余应力;SYSWELD;数值模拟ABST
3、RACTWiththerapiddevelopmentofwordeconomyandindustrialmanufacture,thedemandforcleanenergysources(LiquefiedNaturalGas--LNG)becomesmoreandmoreconsiderable.However,thewidelyuseofLNGneedstoconstructlarge—scalecryogenicstoragetanks.Becausetheexistenceofweldingresidualstressesseriouslythreate
4、nsalarge-scalecryogenicstoragetank’Sservicelifeandevenmightresultinseveresecuritydisaster,thesecurityofstoragetanks’structurebecomesaproblemthatpeoplepayincreasinglyattentionto.Therefore,macroscopicallygrasptherelationshipbetweenweldingtechnologicparametersandweldingresidualstresses,ha
5、vingimportantsignificanceforthecontrolofweldingresidualstresses.Thispaperfocusesonthenumericalsimulationofweldingresidualstressin9Nisteelcryogenicstoragetanks,whereSYSWELD(afiniteelementsoftware)isutilizedtodynamicallysimulatetheentireweldingprocessandtoquantitativelyanalyzethedistribu
6、tionofweldingresidualstressesandtheirvalues.Theinfluenceofweldinglineenergyandinterpasstemperatureoverweldingresidualstressesisexaminedthroughthesimulationofweldingprocesseswithdifferentweldinglineenergyandinterpasstemperature.TheapplicationofLNGcryogenicstoragetanksinpracticalmanufact
7、uringwillbetheoreticallybasedonsuchanexamination.TheweldingprocessofLNGcryogenicstoragetanksissimulatedwithSYSWELD,whereamodeliSappliedintheformofdoubleellipsoidheatsource.Curvesofweldingheatcirculationincoarsegrainzoneareattainedunderfivedifferentweldingtechnologicparameters,whoseim
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