多軸載荷下疲勞裂紋擴展壽命分析方法研究.pdf

1、南京航空航天大學碩士學位論文多軸載荷下疲勞裂紋擴展壽命分析方法研究姓名：周超羨申請學位級別：碩士專業(yè)：航空宇航推進理論與工程指導教師：宋迎東201012多軸載荷下疲勞裂紋擴展壽命分析方法研究IIAbstractTurbofanengineintermediatecasingisanimptantloadbearingcomponenttowithsttheaerodynamicloadsthecomplexmaneuveringload

2、sfromaircraft.Intermediatecasingoftheadvancedengineismadeofbycastinginthemanufacturingprocessitisunavoidabletointroduceavarietyofcastingdefects.Toensurethesafetydurabilityitisnecessarytoconductdamagetolerancedesignanalys

3、is.Oneofthekeytechnologyisfatiguecrackgrowthanalysisundermultiaxialloading.Thenumericalsimulationmethodsofmixedmodecenterthroughcrackinplateunderconstantamplitudefatigueloadsarestudied.Anumericalsimulationprocessmethodba

4、sedonthecommercialfiniteelementcodeisproposed.Thecalculationmethodsofstressintensityfacttheionofcrackgrowthsteparestudiedevaluated.Theresultshowsthatusingsingularelementmethodabetteraccuracycanbeabtainedwithcoarsemeshthe

5、ratioofsingularelementfeaturelengthtocracksizeshouldbecontrolledat110less.Italsoshowsthatfthemixedmodecrackwhencrackpropagationstepisbetween100500ithasnosignificanteffectonnumericalsimulatedcrackpath.Thecrackgrowthproces

6、sofarectangularplatewithacentercrackof2024T3aluminumalloyaCompactTensionspecimenof6082T6aluminumalloyissimulatedbythemethodmetionedabove.Theresultsshowthatthedifferencebetweenthecrackopenanglepredictedbythemaximumtangent

7、ialstresscriteriontheminimumstrainenergydensitycriterionislittle.Therehasnoevidentdifferencebetweenthecrackpathsimulatedbythecrackgrowthmodelsevaluatedbuthassomedistinctionwiththeobservedcrackpathinfatiguetest.Thecrackgr

8、owthlifepredictedbyeffectivestressintensityfactcrackgrowthratemodelislessthanbythestrainenergydensityfactcrackgrowthratemodel.Keywds:fatiguecrackgrowthstressintensityfactmixedmodecracknumericalsimulationlifeofcrackgrowth