DynamicResponseAnalysisofCoupledTrain-Track-GroundSystemUnderNon-SymmetricalDynamicInteractionConditions

Abstract

Railwaysareoneofthemostcommon,economicandefficientmeanoftransportation,whichcanofferasuitablealternativetotrafficcongestioninbigcities.However,inpopulatedareas,groundvibrationsinducedbymovingtrainmaycauseseriesdiscomforttonearbyresidentsandleadtostructuredamage.Thevibrationsfrommovingtrainsatthecontactpointofthewheelandtherailareduetotheself-weightofthetrain(quasi-staticloading)anddynamicinteractionforcesinducedbytrackirregularities.Therefore,theanalysisofthedynamicresponsesofthetrain-track-groundsystemunderquasi-staticloadinganddynamicinteractionloadinginducedbytrackirregularitieshasbecomeafundamentalconcerninrailwayengineeringandplaysanessentialroleintheoptimalrailwaydesign. Inthisthesis,anewsolutionprocedurefortrain-trackinteractionproblemwasinspiredfromtheshortcomingsoftheexistingintersystemiterationmethod.Theproposedmethodwasdevelopedbasedonrigidbodymovement,parallelspatialforcetheoremandalreadyexistingintersystemiterationmethod.Inpredictingthetrack-groundvibrationsinducedbymovingtrains,itisgenerallyassumedthattheirregularitiesoftworailsofatrackareidenticalandfullycorrelated.Thisassumptionleadstoidenticalcontactforcesatthecontactpointofwheelsandrails.Inthepresentwork,theuncorrelatedprofileofthetworailsisconsideredtoinvestigatetheirinfluenceonthetrain-track-groundvibrations.Forthispurpose,athree-dimensional(3D)finiteelementmodelcapableofsimulatinginteractionsbetweenthe3DtrainandthetrackbyusinganonlinearHertzcontactmethodisdeveloped.NonlinearHertzcontactisrepresentedbythetensionlessstiffnessbetweenthewheelsandtherails.Therailsaremodeledas3DEuler-Bernoullibeamelements.Solidbrickelementsrepresentthemodelcomponents,suchasthetrack(otherthanrail)andground. Adetaileddescriptionofaniterativenumericalalgorithmispresentedtoestablishtheintegrationsofthetrainandtracksystem.Thisiterativenumericalalgorithmcancalculatetheresponsesandforcesattheinteractionpointbetweeneachwheelandrailtoincorporatetheuncorrelatedprofileoftworails,insteadofonlyconsideringtheinteractionatthecentroidofthewheelsetaxleandatthecenterofthetrack.Acomparativestudyisconductedbyconsideringvarioustrainspeedsandthreedifferenttrackcases.Theresultsshowthatanincreaseintrainspeedcausesanincreaseingroundvibrationinthecaseofuncorrelatedprofilesoftworailsofatrack.Moreover,theeffectsofcorrelatedanduncorrelatedprofilesoftworailsofatrackareinvestigatedintermsofthetrain-track-groundresponses.