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Acoustic field in a cased well with a sectorial crossing channel
  • 简介:Tostudythepossibilityofdetectingthecrossingchannelbyusingatraditionalloggingtool,acousticfieldgeneratedbyamonopolesourceinacasedwellwithacrossingchannelofvariousanglesissimulatedby2.5-DFiniteDifferenceMethod(FDM).Snapshotsofnormalstressandsynthetictime-domainwaveformsaredisplayed.Thetwo-dimensionalspectruminwave-numberandfrequencydomainsisalsocalculated,wheretheinfluenceofthechannelisclearerthanthatinthewaveforms.Numericalstudydemonstratedthatacrossingchannelcanbedetectedandsizedifitsangleisgreaterthan30degree,andlargerspacingandlowerfrequencysourcearefavorabletodetectandsizethecrossingchannel.

  • 标签: 声场 交叉管 有限微分理论 实轴积分理论 FDM 数值模拟
Residual stress profiling of an aluminum alloy by laser ultrasonics
  • 简介:Aresidual-stressprofilealongthethicknessofanaluminumalloysheetisdeterminedbylaser-ultrasonictechnique.SurfaceacousticwavesaregeneratedbyaNd:YAGpulselaseranddetectedbyaHeterodyneinterferometeronalateralfreesurfaceofthesheet.Thedistributionofresidualstressisdeterminedbymeasuringtherelativevariationofthewavevelocitiesatdifferentlocationofthesamplealongitsthickness.Thistechniqueisvalidatedbythreedifferentresidualstressprofilesobtainedexperimentally.

  • 标签: 铝合金 残余应力剖面 激光超声技术 声表面波 激光脉冲 外差干涉计
Evaluation of corrosion damage of aluminum alloy using acoustic emission testing
  • 简介:Currentstudiesareaimingatmonitoringcorrosiondamageofaircraftmainstructuresbyusingacousticemission(AE)techniqueandatsupplyingusefuldatafordeterminingcalendarlifeoftheaircraft.ThecharacteristicsofAEsignalsproducedduringacceleratingcorrosionprocessaredescribed,andmethodsforevaluatingcorrosiondamagesanddeterminingremaininglifeofmainstructuresofaircraftusingAEtestingareoutlined.ExperimentalresultshaveshownthatAEtechniquecandetectcorrosiondamageofaluminumalloymuchearlierthanconventionalnon-destructivetestingmeans,suchasultrasonictestingandeddycurrenttesting.RelationshipbetweencorrosiondamageandAEparameterswasobtainedthroughinvestigatingcorrosiondamageextentandchangesofAEsignalsduringacceleratingcorrosiontest,andshowingthatAEtechniquecanbeusedtodetectearlycorrosion,investigatingcorrosiondevelopingtrend,andinmonitoringandevaluatingcorrosiondamages.

  • 标签: 铝合金 声发射 腐蚀损伤 航空材料 涡流测试 腐蚀测试
An improved method for measuring the surface sound energy diffusion coefficient in a room
  • 简介:Thepartlyspecularreflectionandpartlydiffusionreflectionmodelisaconvenientwaytoexpressthephenomenaofsurfacesoundenergyscatteringinroomacoustics.Soundenergydiffusioncoefficientbecomesakeyfactortostudysurfacescattering.Buttherehavebeenveryfewmethodsfordeterminingtheaveragesoundenergydiffusioncoefficient.Vorliinderproposedsuchaneasyonebasedonthecorrelationprinciple.However,hismethodignoredthecorrelationfromdirectsound,inwhichdefectispresent.Anewapproximatemethodforcalculatingsoundenergydiffusioncoefficient,includingdirectsoundandfirststrongreflectionsispresented.Therefore,Vorlaender''''''''sdefectisovercome.Inaddition,withtheaidofdigitalmeasuringtechnology,arelevantmeasuringsystemwasdeveloped.TheexperimentresultshowsthatthemethodisimprovedthanVorlaender's.

  • 标签: 室内声学 建筑声学 表面声能散射 声能传播系数 声散射模型
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