基于无损检测的结构钢机械性能退化分析

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1、ABSTRACTNondestructiveevaluation(NDE)，alsoknownasnondestructivetesting，lSanimportanttechnologyinindustries．TKStechnologyiSusedtodetectstructurematerialundertheconditionofkeepingtheirphy’sicalandchemicalpropertiesandgeometricalintegrity．BecauseNDEdoesnotpermanen

2、tlyalterthearticlebeinginspected，itisahighlyvaluabletechniquethatcansavebothmoneyandtimeinproductevaluation，troubleshooting．andresearch．Witlltllehelpofmagnetic，optical，electrical，acousticandthermalresponsefromthestructuralmaterials，wecanthusdeterminetheexistenc

3、eofinternaldefects．andevaluatethefeaturesofdefect，theservice1ife，etc．ConventionalNDTmethodsincluderadiographictesting，magneticparticletesting，eddycurrenttestingpotentialdifferencedetection，etc．ultrasonictesting，penetrationtesting，andmetalmagneticmemorytestingan

4、dInthispaper,thenonlinearultrasonictechnique(NUT)andmetalmagneticmemory(MMM)techniqueareemployedtoevaluatethemechanicaldegradationoftheLZ50axlesteelandQ235steel．Theresearchresultsshowthat：1．Intensileloadingmode，studiesbasedonnonlinearultrasonictestingshowsthatt

5、hereisnotobviouschangeforthenonlinearcoefficientwhenthestressislessthantheyieldingstress．Changeappearswhenthestressreachestheyieldingstressforthespecimen．Afterslowdecreasewiththeincreaseoftheloadingstress，nonlinearcoefficientincreaseswiththeloadingstress．Itincr

6、easesquicklybeforeenteringtheneckingstress；2．Infatigueloadingmode，studiesbasedonnonlinearultrasonictestingshowsthatthenonlinearcoefficientinitiallyincreasesfastwiththecycleoffatigueload．However,thenonlinearcoefficientdoesnotchangesignificantlywiththeincreaseint

7、henumberoffatigueloading；3．Intensileloadingmode，studiesbasedonthemetalmagneticmemorytechniqueshowsthatthenormalleakagemagneticfieldvarieslinearlyalongtheloadlineinelasticdeformationstage．Themagnitudeoftheslopeincreaseslinearlywiththestress·Therearenonlinearchan

8、gesforthenormalleakagemagneticfieldwhenlocalplasticdeformationappears．ThenormalleakagemagneticfieldincreasessignificantlywhenVll北京交通大学硕士学位论文ABST彤忆Tmacroscopiccrackappears．Th