机械毕业设计外文翻译岩土材料的摩擦声波Word文档下载推荐.docx
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学院:
机械工程学院
专业:
机械设计制造及其自动化
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外文出处:
TylerTJ,HillR,LaiE.Frictiongeneratedultrasoundfromgeotechnicalmaterials[J].Ultrasonics,2004,42
(1):
169-172.
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1、外文原文;
2、外文资料翻译译文。
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Frictiongeneratedultrasoundfromgeotechnicalmaterials
TJTyler,RHill,ELai
Abstract
Drillingisaprocessinvolvedwithproductmanufacturingandforcivilengineers,sitepreparation.Theusualrequirementisforefficientmaterialremoval.Inthisstudy,thefrictionpairinteractiongeneratedbyadrillingprocessprovidesultrasoundinformationrelatedtoparametersforthegeotechnicalmaterialbeingdrilled,wherethedrillbithasnon-degradingultrasoniccharacteristicsandnoessentialrequirementformaterialremoval.Thisstudyhasconsideredmonitoringtheultrasonicsignalgeneratedbydrillingprocess,withaviewtocharacterisingtheparametersofthegeotechnicalmaterialbeingdrilledandprovidesanovelmethodtoidentifyorcharacterisegroundstructures.Drillingofgeotechnicalmaterialsystems,typicallyinvolvetheinteractionofarotatingprobeandagranularcompositemedium.Theappliedloadandangularvelocityaremeasuredtodeterminetheirrelevancetotheultrasonicsignal.Samplesofgranularmaterialshavebeengradedintocontrolledgrainsizeranges.Attentionhasbeenfocusedondeterminingtheeffectsontheultrasoundsignalofgrainsize,bulkdensityandthewatercontentofthegranularmaterial.Acomparisonbetweenthevariousgranularsamplesofthedifferentgrainsizes,density,watercontentandtheassociatedultrasonicsignalhasbeendone.Theeffectofeachvariable,andexistingtheoryfortheseeffectsiscommentedupon.Thebroadaimofthisresearchistoevaluateultrasonicmonitoringofdrillingandassessitspotentialforreal-timegeotechnicalgroundconditionmonitoringapplicationsandofferitasanalternativetoexistingmethods._2004PublishedbyElsevierB.V.
1.Introduction
Theultrasoundgeneratedfromasolid–solidfrictionpairhasbeenthemainfocusofresearchconcerningfriction-generatedultrasound,mainlyassociatedwithrotatingandreciprocatingmachines.Africtionalprocessdevelopedduringrelativemovementbetweencontactingmaterialshasaninherentlevelofwearthateventuallywouldresultinfailure.Monitoringtheultrasonicsignalgeneratedfrommachineryhasbecomeanalternativecondition-monitoringtool,asthegeneratedsignalcontainsinformationrelatedtothemicroconditionofthefrictionpair.Itispossibletodetectwhencomponentsofamachinearebecomingwornandathusreducetheriskofcatastrophicfailureleadingtoproductiondowntime.HolroydandRandall[1]discussedthesensitivityofusingacousticemission(AE)fordetectingchangesinlubrication,overloading,wearandreviewanumberofdifferenttechniquesusedtoanalysetheacousticsignature.FurthermethodologiesforanalysingthefrictiongeneratedacousticsignatureswerediscussedbyBukkapatnametal.[2]andprovideanovelanalysistechniquebasedonchaostheory,waveletsandneuralnetworks.Muchoftheresearchconcerningconditionmonitoringfocusesonthechangesinthesignalduetowear,butsomeresearchhavealsofocusedontheparametersassociatedwiththegeneratedacousticsignal.WorkbyDiei[3]monitoredtheacousticemissiongeneratedbytoolwearduringfacemillingandproposedapowerfunctionrelationshipbetweentheAERMSvoltageandtherateoffrictionalenergydissipationgivenbyAERMSekgssAaVTm=2e1TwherekandmareconstantsthatdependontheAEmeasuringsystemandthematerialpropertiesofthefrictionpair,gisafunctionofsurfaceroughnessandelasticpropertiesofthefrictionpair,ssistheshearstrengthoftheinterfacialmaterial,AaisthevisibleareaofcontactandVistheslidingvelocity.TheparametersgandAaessentiallydefinetherealareaofcontactandtherefore,theAERMSisafunctionoftherealareaofcontact,theshearstrengthandtheslidingvelocity.ResultsobtainedbyDiei’sworkalsoindicatedalinear
relationshipbetweentheAERMSandtheslidingvelocity.JiaaandDornfield[4]monitoredtheAEgeneratedbyapinondiskexperiment,highlightingthattheAEiscausedbyimpulsiveshockduetoasperitycollisionsandmicro-vibrationsexcitedbystick–slipphenomena.TheresearchshowsthattheAERMSincreaseswithloadwhilealinearrelationshipexistsbetweentherelativesurfacevelocityandtheAERMS.SarychevandShchavelin[5]describethefrictionalprocessandthegeneratedacousticemissionassociatedwithit.Twogeneralruleswereestablishedrelatingtherateofcountingtheacousticpulses(countrate)totheslidingspeedofthefrictionpairandtheappliedload.
ThegeneralruleforthedependenceofthecountrateN_ontheslidingvelocityisintheform:
N_AtBvXe2TwhereAandBareconstantsandXP1.Asimilarrelationshipalsoappliesforthedependenceoftheloadonthecountrate,buttheexponentX61.AfurtherrelationshipwasexpressedrelatingtheAEactivitytotheregimeoffrictioninelasticcontact:
N_akN0:
71h0:
71A0:
71cr0:
90R1:
60aVe3TwhereNisthenormalload,hthegeneralisedelasticmodulus,Acthecounterareaofcontact,rthesurfaceasperitytipradius,Raisthesurfaceroughnessandkisacoefficientofproportionality.FurtherworkbyBaranov[6]producedtwomodelsrelatingthefrictionalparametersofthefrictionpairtotheacousticparameters;
countrateandacousticenergy.Themodelforthecountrateisbasedontheassumptionthattherateofcountingacousticpulsesisdirectlyproportionaltothenumberofcontactpointsformedperunittime.WorkbyHenriqueetal.[7]studiedparticlecollisionsdownaninclinedslopeandthenumberofacousticeventswereusedtomonitorthenumberofcollisions(contacts)generatedwhenaballwasrolleddowntheslope.Themodelfortheacousticenergyrelatesthemechanicalpotentialenergygeneratedduringtheelasticdeformationofacontactingasperitytotheamplitudedistributionoftheacousticsignal.TheenergymodeldoesnottakeintoconsiderationtheeffectsofwearandisbasedontheAEgeneratedduetoelasticcontact.
Currentstudiesinfriction-generatedacousticshaveshownthattheacousticsignalscontaininformationrelatingtothematerialparametersofthefrictionpair.Theworkinthisstudyusestheacousticsignalasatooltocharacterisethematerialpropertiesofthefrictionpair.TheideaforthisstudyoriginatesfromastudybyHill[8]forScientifics,whenitbecameapparentthatmonitoringtheultrasoundgeneratedbyadrillingprocessprocesshadpotentialforgroundconditionmonitoring.Theoverallaimofthisworkistodevelopamethodofcharacterisinggeotechnicalmaterialsusingatypicaldrillingprocessandmonitoringtheultrasoundgeneratedduetotheinteractionbetweenthedrilltipandthegeotechnicalmaterial.
2.Experimentaldesign
Asimplifieddrillingarrangementhasbeenconstructedwherearotatingprobeisusedtomaximisethefrictionattheprobe-tip–granularcontact.Theprobestringisdesigned,usingasuitablecouplingdevice,sothattheultrasonicsignalistransmittedfromtheprobetiptoastationarypiezoelectricsensor.Thesignalisamplifiedby60dBandfilteredbetween250and500kHz.Thecapturedsignalisthereforeinthemid-ultrasonicrangeandrelatestothetransducermonitoringfrequencyused.AschematicdiagramoftheexperimentalarrangementcanbeseeninFig.1.Theproberotates,whilebeingsubmergedinagranularmediumofcontrolledparticlesize,initialdensityandwatercontent.Thefeedrateandangularvelocityweresettoaconstant
valueandtheappliedload,countrateandultrasonicenergyweresimultaneouslymonitored.Theeffectsoftheparticlesize,densityandwatercontentontwoultrasonicparameters(countrateandenergy)havebeeninvestigatedandthesystemaimstobeafutureoptionforgroundconditionmonitoring.
3.Results
TheeffectofloadonthecountratecanbeseeninFig.2a.Thesignalvaluesontheleftofthefigurecorrespondtotheprobetipnotbeingincontactwiththegranularmedium.Whentheprobeispushedintothegranularmaterialtheloadincreases.Thedatahighlightsastabilizatio(reduction)inthecountrateandisreferredtoasthe‘‘characteristiccountrate’’foraparticularfrictionpair.Thestabilisationofthecountratemeansthatnomoreoscillationsarebeingproducedduetoanincreaseintheloadandthereforethesignalamplitudeisonlysubjecttoamplitudeincrease.Differentgradesofparticulatematerialhavebeenusedandthecharacteristiccountratemonitored.Theresultsindicatethatalowercharacteristiccountrateoccursastheaverageparticlesizeisincreased.EightsamplesofsandwereusedandthecharacteristiccountrateiscomparedwiththeparticlesizeinFig.2b.LargerparticlesizesproducefewercontactsandthereforetheresultsagreewiththeassumptionstatedbyBaranovetal.[6]that,therateofcountingisproportionaltothenumberofcontactsformedperunittime.TheresultsinFig.2crevealthatthewatercontenthaslittleeffectonthecharacteristiccountrate.Fourrangesofgrainsizehavebeenusedandthecountrateisplottedagainstthemasspercentagewatercontent.Thereisasmallvariationinthecountratebuttheseparationinthesignalsgeneratedbythe
differentparticlesizesstillexist.Resultshaverevealedthatthecountratevaluedoesnotsignificantlychangeduetotheadditionofwaterandthatthecountratesignalismainlydependentonthenumberofcontactsformed.Therefore,regardlessofthewatercontentof