Meta-structuredconcretefabricationandradiatedsoundanalysisofrollingnoiseforcomplexpolymerconcreteslabrailway

Abstract

Trainsystemisessentialtransportationduetoitshighspeedandlargescalecomparingwithvehicle.Althoughtrainsystemhasmanybenefitasabove,radiatedsoundfromtrainmakeannoyancetoresidentsnearrailroad.Thetrainnoisemainlyconsistsofaerodynamicnoise,drivingnoisefrompowersources,rollingnoisefromwheel,railtrackandsleepers.Whentrainrunningfasterthan300km/h,theaerodynamicnoisebecomesdominantcomponentofthetrainnoise.However,rollingnoisecontributestrainnoiseoverallspeedrange.Toreducerollingnoise,thewebdamperinstalledonthetrackandthehighdampingpadunderthetrackhavebeeninvestigated.Thewebdampercoversonlylowfrequencyrangeandrailpadcauseshighmaintenancecost.Cementconcretesleeperofhighspeedrailwayismajorcomponentoftherailsystem.Duetoflexuraldeflectionoftrainandrailtrack,elasticcharacteristicsofconcretesleeperaffectsvibrationofrailsystem.Highdampingconcretesleepersareneededtosolvethenoiseprobleminducedfromrollingnoise.Radiationcharacteristicsofrollingnoisewaspredictedbyapplyingmovingloadtheorem.Runningtrainonrailtrackismodeledasmovingloadoninfinitebeam.Relationshipbetweenthelossfactorofsupportingstiffnessandtherailvibrationwasanalyzed.Radiatedsoundpoweranddirectivityofrollingnoisefromrailvibrationwereidentifiedwithdifferenttheloadvelocity. Concretecementhasbeenwidelyusedasamaterialincivilengineeringstructuresduetoitsflexibilityandloadholdingcapabilities.However,Portlandcementconcreteshaveexhibitedproblemsarisingfromexcessivenoiseandvibrationgenerationduetotheirlowdamping.Inthispaper,polymerconcretesmadewithanepoxyresinwerestudiedandtheirabilitytoreducenoise/vibrationinaconcreteslabtrackwasexamined.Thepolymerconcreteswerefabricatedwithdifferentmixingratiosoftheepoxyresin/aggregateandaggregatesofdifferentsizes.Theeffectsofthesevariablesonthecompressiveandflexuralstrengthsofthepolymerconcretesweremeasuredtostudythemechanicalreliabilityunderwaterabsorptionenvironments.Also,thefrequencydependentvariationsofstiffnessanddampinginthepolymerconcreteswereobtainedbyimpactvibrationteststostudytheirabilitytoreducevibrations. Thefatiguetestsoftheconcreteswereperformedbyapplyingperiodicloadforbendingtests.Toinvestigatethereductionofstiffnessduetofatiguedamage,thefrequencydependentvariationsofthedynamicstiffnessandthelossfactorofthepolymerconcretes(amixtureofepoxyresin,carbonfiberandaggregates)wereobtainedbyimpacttests.Thevariationofthedynamicpropertiesbeforeandafterthefatiguetestswasmeasured.Theseparatedbeammethodwasusedtoidentifythestiffnessdistributionalongtheconcretespecimen.Thismethodanalyzedthebeamvibrationusingevenlyspacedbeamelements.Theboundaryconditionsofdisplacementandslopecontinuityatendofeachelementwereimposed.Theleastsquaremethodwasappliedtoestimatethedynamicpropertiesofthebeamelementsfromthemeasuredvibrationresponse.Thisprocedurewasrequiredtoidentifysmallchangeinthedynamicpropertiesinducedduringfatiguetests.Consequently,thedurabilityofthecarbonfiberreinforcedpolymerconcreteswasvalidatedbycomparisonwithnormalpolymerconcretes.Apipestructurewasembeddedinpolymerconcretespecimens.Thefrequency-dependentvariationsofthedynamicstiffnessandthelossfactorsofthespecimensweremeasuredbythevibrationtestmethodsothatthedampingenhancementfromtheembeddedstructurecouldbeidentified.Theweightreductioneffectofepoxyresinusagewascomparedafterpipeembedment.Impactdamperswereappliedtothepipe-embeddedpolymerconcretestoimprovetheirvibrationalenergydissipation.Theimpactdamperswerefabricatedthroughtheinsertionofimpactballsintothepipestructures.Thedynamicpropertiesoftheimpact-damper-positionedpolymerconcreteswereobtainedbyvibrationtests.Thedampingperformancewasinvestigatedaccordingtothegapsizebetweentheimpactballandthepipe.Ananalyticmodelwasusedtopredictthevibrationalbehaviorofthepolymerconcretewhentheimpactdamperswereapplied.Consequently,theeffectonvibrationdampingwasidentifiedfordifferentmassratiosandgapstofindoptimalconstruction. Asanotherwaytoimprovedampingperformanceoftheconcretesleeper,complexconcretewhichispolymerconcretewasinsertedincementconcretewasfabricated.Theadhesionforceattheinterfacebetweenthepolymerconcreteandthecementconcretewasinvestigatedfromimpacttest.Acylindricalembedmentstructurewasfabricatedbyusingasiliconmoldandtheembedmentwasplacedindirectionoflengthandheight.Fromthecylindricalembedment,moresuitableembedmentshapewasdeterminedbymeasuringtheflexuralstrengthandthelossfactor.Awavetypeembedmentstructurewasdesignedinordertoimprovetheperformanceofthecomplexconcrete.Withthelongitudinaldirection,theheightofthepolymerconcretechangecontinuously.Theresponsesofthecomplexconcreteswerealsomeasuredusingaccelerometersbyimpactexcitation.Thecharacteristicsofthemetamaterialwasidentifiedfromtheperiodicnonlinearinterface.Ananalysismodelconsideringtheclassicallaminatetheoremtoinvestigatethedampingeffectofwavetypeembedmentwasimposed.Toverifythedampingperformanceofmeta-structuredconcrete,actualsizemeta-structuredconcretesleeperwasfabricated.Theaveragedlossfactorofthecomplexsleeperinfrequencyrangefrom50Hzto3.2kHzwascomparedwiththatofthecementconcretesleeper.Itwasfoundthatthemetastructureusingthepolymerconcretewavepatternisalsoeffectiveinimprovingdampingperformanceofanactualconcretesleeper.Lastly,thedynamicpropertiesofthemeasuredcomplexconcretewereappliedtotherollingnoiseanalysismodel.Therollingnoiseformrailwayinvelocityof300km/hwasanalyzed.Usingmeta-structuredconcretesleeper,theradiationoftherollingnoisewasreducedeffectively.Thisinvestigationonthecharacteristicsofconcretesleeperembeddingwavetypepolymerconcretecontributestostudyofcomplexslabrailwaystructurestominimizethevibrationandnoisegenerationfromrunningtrains.