多軸載荷下疲勞裂紋擴(kuò)展壽命分析方法研究.pdf

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