资源描述:
《基于应力转换的内螺纹高周疲劳强度分析方法.pdf》由会员上传分享,免费在线阅读,更多相关内容在行业资料-天天文库。
1、第52卷第21期机械工程学报Vol.52No.212016年11月JOURNALOFMECHANICALENGINEERINGNov.2016DOI:10.3901/JME.2016.21.166*基于应力转换的内螺纹高周疲劳强度分析方法1,212111龙旦风黄成海向东徐卫国王一江江伟(1.一汽解放汽车有限公司无锡柴油机厂无锡214026;2.清华大学机械工程系北京100084)摘要:螺纹具有特征尺寸小、结构复杂的特点,其非线性接触的有限元分析具有很高的难度,因此机械零件强度仿真分析时螺纹通常被忽略,只根据经验对螺
2、纹作保守设计。事实上承受循环重载的零件极容易从螺纹部位发生疲劳断裂,在设计阶段有必要进行疲劳强度校核。针对此问题,提出了一种基于应力转换的内螺纹高周疲劳强度分析方法。此方法把螺纹根部应力分解为近源应力和远源应力两部分,通过无螺纹简化模型仿真获得螺纹接触压力和摩擦力之后转换为近源应力和远源应力并叠加得到螺纹根部最大应力,最后考虑应力梯度、存活率和表面粗糙度等因素的影响系数,借助Haigh图计算各扣内螺纹的疲劳安全系数。把这种方法与带螺纹的细节模型有限元仿真和疲劳强度分析结果进行对比,所提方法的安全系数结果与细节模型的
3、相应结果相差–7.6%;把这种方法应用于某型号缸体主轴承壁,其分析结果与疲劳试验结果相差–8.2%,证明了它的可行性。关键词:内螺纹;应力集中;疲劳强度;安全系数中图分类号:TH123Stress-conversion-basedApproachofHigh-cycleFatigueStrengthAnalysisforInternalThreads1,2121LONGDanfengHUANGChenghaiXIANGDongXUWeiguo11WANGYijiangJIANGWei(1.WuxiDieselEng
4、ineWorks,FAWJiefangAutomotiveCompanyLtd.,Wuxi214026;2.DepartmentofMechanicalEngineering,TsinghuaUniversity,Beijing100084)Abstract:Threadsaresmallinsizeandcomplicatedinstructure,andcausegreatdifficultyinfiniteelementanalysisofthenonlinearcontactinteraction.Fort
5、hisreason,threadsareusuallyneglectedduringthestrengthsimulationanalysisofmechanicalparts.Infact,partsbearingheavycyclicloadsusuallyfatigueandfracturefromtheinternalthreads,thustheirfatiguestrengthisnecessarytobecheckedinthedesignstage.Tosolvethisproblem,anappr
6、oachbasedonstressconversionisproposedtoanalyzethehigh-cyclefatiguestrengthoftheinternalthreads.Inthisapproach,thestressatthethreadrootsisdecomposedintonear-sourcestressandfar-sourcestress.Thecontactpressureandfrictioncalculatedfromsimplifiedmodelwithoutthreads
7、areconversedintonear-sourcestressandfar-sourcestressandthensuperposedintothemaximumstressofthreadroots.Afterwards,takingtheinfluenceofstressgradient,survivalprobabilityandsurfaceroughnessintoaccount,thefatiguesafetyfactoroftheinternalthreadsarecalculatedemploy
8、ingHaighdiagram.Comparisonisconductedbetweentheproposedapproachandthefinite-elementsimulationandfatigueanalysisofdetailedmodelwiththreads,andshowsthesafetyfactorresultoftheproposed