ApplicationofNumericalSimulationsforRailandWheelWearManagementonLightRail

NetworksProf. MaksymSpiryagin

CentreforRailwayEngineeringCentralQueenslandUniversityRockhampton QLD Australia

THE4THANNUALLightRail201721- 22February2017

Introduction

Main components involved in vehicle dynamics studies from a modellingpoint of view are:

• LightRailVehicle(includingmechanical,electricalandothersubsystems)• Track• Wheel/RailInterface• CatenaryandPantograph• DriverBehaviour

Wheel-railcontact&damageestimationusedinnumericalstudiesincludes:• WearModelling• RollingContactFatigue (RCF)

ThisPresentation

• Vehicle Dynamics of Light Rail Vehicle Approaches:• ModelDevelopmentProcess• ModellingofWheel-RailContact• ModellingofTractionControl• MultibodySoftware

• Wear&RCFModelling• ExampleofModelling• TransitiontoPracticalApplications:• TrackDamage• MaintenanceChallenges• CostModelling

Major Standard Tasks in this Process:• ModellingofRailVehicleElements• ModellingofWheel-RailContact• TrackModelling• NumericalIntegrator

Nowadays the multibody modelling approach isgenerally used for vehicle dynamic studies.

A multibody system is a collection of mechanical subsystems called bodies,components or substructures. The motions of the subsystems arekinematically constrained because of joints and connections.

VehicleDynamics:ModelDevelopmentProcess

VehicleDynamics:ModelDevelopmentProcessAdvanced Tasks in this Process:

• ModellingofTractionPowerSystems• AdvancedModellingofWheel-RailContact• ValidationofModels

The traction power system consisting of anadhesion/traction control and power plant arecommonly modelled with either simplified or advancedapproaches.Advanced wheel-rail contact modelling requires themodelling of the real behaviour that accounts for thefrequent traction and braking modes, using a dynamic(rather than static) friction coefficient because thefriction coefficient is largely affected by materialproperties and surface conditions.Validation of light rail vehicle models should beperformed through physical testing due to the lack ofrelevant Australian standards. Current AS7509 –Railway Rollingstock Dynamic Behaviour does not coverlight rail networks.

VehicleDynamics:ModellingofWheel-RailContactWheel-rail contact can be formulated as a rolling contact problembetween two nonlinear profiles in the presence of friction.The main task of wheel-rail contact modelling algorithms is to delivervalues of forces and moments acting at the contact points.

Normal Problem• Hertz Theory• Multi-Hertzian• Semi-Hertzian• Non-Hertzian

Tangential Problem• Kalker’s Linear Theory• FASTSIM• Pre-Calculated Tables• Shen-Hedrick-Elkins

• Polach• Modified versions ofFASTSIM• Kalker’s Exact Theory

VehicleDynamics:ModellingofWheel-RailContactTangential problem analysis is very important for the modellingbecause it also has an influence on traction control modelling.

Our Centre uses the followingalgorithms for traction and brakingstudies:

• POLACH• ModifiedFASTSIM• ExtendedCONTACT

All of these algorithms require theintroduction of experimental dataparameters into a wheel-rail contactmodel.

0

0.1

0.2

0.3

0.4

0 1 2 3 4 5 6 7 8 9 10sx [%]

f x

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k = 1.0 k = 0.2 k = 0.05

Longitudinal creepage

Adhe

sion c

oeffic

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Typical measurement

AB

Modellingofcreepforcecharacteristicusingdynamic(falling)frictioncoefficientanddifferentreduction

factorsk.Thereisdisagreementbetweenthemodelledcreepforcecharacteristicshapeanditstypicalshapefrommeasurementsonwetrail.[1]

[1]M.Spiryagin,O.Polach,C.Cole,CreepforcemodellingforrailtractionvehiclesbasedontheFastsimalgorithm,VehicleSystemDynamics,51(11),2013,pp.1765-1783.

VehicleDynamics:ModellingofTractionControlThree types of traction power systems for rail vehicles arein use for light rail networks:• Conventional Wheelsets

• Bogie Traction Control• Axle Traction Control

• Independently Rotating Wheels (IRWs)

Two statements about IRWs implementations can beobserved from the literature:

• IRWscansignificantlyimprovethelifecycleofwheels• IRWscangivehigherwearratesduetothelossofself-steeringability

This might be related to how fast and robust is the tractionsystem controlling the traction torque of IRWs, whichmeans that wear numerical studies cannot be performedwithout a proper modelling of traction control systems.

VehicleDynamics:ModellingofTractionControl

A simplified approach is commonly used because it allows significant reductions incomputation time. It can also be easily implemented if co-simulation is not used formodelling of traction control algorithms and the algorithm is created inside the multibodycode as a subroutine or function.An advanced approach requires that the whole electric traction system (adhesion/tractioncontrol, power equipment, traction motors) are fully modelled in Matlab/Simulink or othersimilar packages.

Two approaches for the modelling of the traction power system are in use:• Simplified Modelling Approach• Advanced Modelling Approach

Advancedapproachformodellingoftractioncontrolsystem

VehicleDynamics:MultibodySoftwareMultibody Dynamics Software for Vehicle Dynamics studies that are in use bythe Centre for Railway Engineering:

• GENSYS (Sweden)• SIMPACK (Germany)• VAMPIRE (UK)• In-HousePackages

Why do we use these software products in our research and commercialprojects?

Dynamic behaviour simulation software shall be an industry-recognised kinematic tool,shall include the validated modelling of the behaviour of the wheel-rail interface (asevidenced by peer review in technical publications) and shall have been validated asbeing suitable for simulation of railway vehicle dynamic performance.(quoting the NEW AS7509 Standard that has now completed the Public Consultation stage)

Wear&RCFModelling:GeneralTerminologyBoth wear and RCF estimation approaches are in use to assess damage of material in thewheel/rail contact zone.The wear models relate the quantities in the contact surface to a wear depth on the profiles andwear distributions.There are two principal methods to predict wear indexes/wear rates:

• Sliding(Archard)Model• FrictionEnergyModel

Rolling Contact Fatigue (RCF) occurs in the form of head checks (shallow cracks), shelling at the railsurface and similar cracks on the wheel tread.Threefatigueindexesareincommonuse:

• Surface Fatigue Index• Subsurface Fatigue Index• Deep Defects Fatigue Index

What are the current limitations in Wear and RCF simulations?• Amajorlimitationoftheexistingmethodologiesisthehighrelianceon

dataaccuracy• WearratesofAustralianrailsteelshavenotbeendocumented

Wear&RCFModelling:Howdoesitwork?

WheelProfile

RailProfile

Driver’sBehaviour

TractionControl

TrackData

FrictionConditions

Wear&RCF SimulationsinMultibody Software

VariableWeight

DataBank

ExampleofModelling:CaseStudyTheneedformodellingcommonlyariseswhenitisnecessarytoinvestigatewearindicesfordifferenttypesofrunninggear.Let’sassumethatthetaskrequirestobefocusedonthestudyofLRVbehaviourforrighthandcurvesofradius90metres.Thetrackiseitherdryorlubricated.TheLRVspeedis30km/handitrunsundertractionconditions.

ExampleofModelling:SimulationScenarioSimulationCaseNo.

LightRailVehicle

DesignFeaturesof LeadingBogie Friction ConditionsattheWheel-RailInterface

1 Type1 Conventionalwheelsets,axletractioncontrol Dry

2 Type2 Independentlyrotatingwheels Dry

3 Type3 Independentlyrotatingwheels+Steering control Dry

4 Type 1 Conventionalwheelsets,axletractioncontrol Lubricated

5 Type2 Independentlyrotatingwheels Lubricated

6 Type3 Independentlyrotatingwheels+Steeringcontrol Lubricated

ExampleofModelling:DryFrictionConditions

ExampleofModelling:LubricatedFrictionConditions

TransitiontoPracticalApplication:TrackDamageStage1–Collectinformation

Stage2-Conductvehicledynamicsandtrackdamage

simulations

Stage3-Determinearelationshipbetweensimulation

resultsandtrackdamage

Stage5–Confirmengineeringratesandindexes

Stage4–Validationoftrackdamagesimulationresults

TransitiontoPracticalApplication:MaintenanceChallengesStage1–Collectinformation

Stage2-Conductvehicledynamicsandtrackdamage

simulations

Stage3-Determinearelationshipbetweensimulation

resultsandtrackdamage

Stage4–Validationoftrackdamagesimulationresults

Stage6–Confirmresultsandmaintenancemodels

Stage5-Determinearelationshipbetweentrack

damageandtrackmaintenanceCurrentmaintenancepractice

Recommendationsonmaintenanceschedule

TransitiontoPracticalApplication:CostModellingStage1–Collectinformation

Stage2-Conductvehicledynamicsandtrackdamage

simulations

Stage4-Determinearelationshipbetweensimulation

resultsandtrackdamage

Stage5–Validationoftrackdamagesimulationresults

Stage7–Confirmresultsandcostmodels

Stage6-Determinearelationshipbetweentrack

damageandmaintenancecosts

Stage3–Determinemaintenancecosts

Thankyou!!!

Questions