焊接管道“先漏后斷”評定裂紋張開面積研究.pdf

1、天津大學(xué)碩士學(xué)位論文焊接管道“先漏后斷”評定裂紋張開面積研究姓名：段鴦鐘申請學(xué)位級別：碩士專業(yè)：材料加工工程指導(dǎo)教師：張玉鳳20070101ABSTRACTWiththedevelopmentofnationalindustryandeconomythepressurevesselsandpipesarewidelyusedinthefieldofenergysources，transportandpetrochemistry，play

2、inganimportantroleinindustryproductionItmakesgreatmeaningtOassesstheirsafetiesNowadaysthemainassessmentmethod，consideringsteadyfluidleakbeforefracture，isbasedonleakbefore—breakThedissertationaimstonlakeresearchoncrackope

3、ningareatosupportthe“LBB”assessmentInthedissertation，theEngineeringstressstraingUlVesandthetheTruestressstraincurves鋤七givenbymechanicaltestandtheCODvaluesofweldmetalandHAZareobtainedaccordingtoBritishStandard，BS7448Andth

4、eParisformulaofbasemetal，weldmetalandHAZalealsogivenbyfatigueexperimentSodoesthethresholdstressintensityfactorrangeofweldedjointForthestzuctureofpipe，fatiguegrowthprocessofsurfacecrackundercycleloadisresearchedusingtheso

5、ftwareNASGROWecangaintheruleofgrowth，throughwallandshapedevelopmentofsurfacecrackwithdifferentinitialgeometryunderpuretensionandbendingloadsInadditionthemethodofascertainingsurfacecracksizeandthecomputationofconservative

6、criticalcracksizearealsoprovidedLineelasticCOAformulawhichbasesonthecomputationoflineelasticfractureparameterandstressintensityfactor，isdeducedaccordingto’SINTAPAnditsoutputisalsocomparedwithotherknownmethodsConsideringt

7、heeffectsthattheplasticityatcracktipistoincreasetheopeningofthecrackandthentheopeningareasaregreaterthanthoseinlinerelasticcase，availableanalyticmethodsareinvestigatedinthedissertationKEYWORDS：Leakbeforebreakcrackopening