Presentation on theme: "Numerical simulation for improving the design of running gear – Part 1: improvement of vehicle dynamic behaviour Paolo BELFORTE, S. BRUNI (Politecnico."— Presentation transcript:
1 Numerical simulation for improving the design of running gear – Part 1: improvement of vehicle dynamic behaviourPaolo BELFORTE, S. BRUNI (Politecnico di Milano - Department of Mechanical Engineering)Michael JÖCKEL (Fraunhofer Institute for Structural Durability and System Reliability - LBF)LBF!!
2 MODTRAIN ProjectMODTRAIN project“ Innovative modular vehicle concepts for an integrated European railway system “6th FRAMEWORK PROGRAMME PRIORITY 6.3 – Transport4 Years Project – Started January 2004Modular approach to train designInteroperability: new generation rolling stockHarmonised European criteria for rolling stock homologation
3 It consist of five different sub-projects: MODTRAIN ProjectIt consist of five different sub-projects:MODBOGIEMODCONTROLMODPOWERMODLINKMODUSER
4 SubProject leader is ANSALDOBREDA MODBOGIE SubProjectModBogie Subproject has 11 partners:S.I.: ANSALDOBREDA / ALSTOM / BOMBARDIER / SIEMENS;Wheelset manufacturer: LUCCHINI SIDERMECCANICA;Operators: DB / TRENITALIA / SNCF;Research Institutes / Universities: POLIMI / LBF-IWM / D2S.SubProject leader is ANSALDOBREDAModBogie SubProject is dedicated to the optimization of the bogie, leading to:improved performances in terms of energy efficiency;enhanced bogie design for fulfill more demanding operational requirements;wider dynamic performances with reduced environmental impact and maintenance costs.
5 INTRODUCTION: NUMERICAL SIMULATIONS TOWARDS “VIRTUAL HOMOLOGATION” In last years, the improved calculation technologies allowed the development of more detailed and accurate numerical models of rail vehicle dynamics, which can be used as a very useful tool for the design and development of a railway stock.With the development of new generations of HS trains, numerical simulations can give an important contribution in order to raise service speed and satisfy operators requirements which claims always for improved performance in terms of comfort and safetyThis work targets the capabilities of multi body simulation models in the design and verification phase of the railway running gear.
7 Vehicle model: HS concentrated power locomotive REFERENCE SYSTEMSVEHICLE SCHEMATISATIONLoco of a concentrated power trainFixed referenceMoving reference with constant speed VMoving reference on body c.o.g .XGZGYGXoZoYoZGiYGiVsibiriCarbody with two motor bogiesTwo motors bogie-suspended by means of dedicated motor hangers per each bogieOnly rigid modes also for the wheelsets problem confined to low frequencyThe equation of motion Lagrange equationsVehicle inertiaW/R contact forces
8 Wheel rail contact forces model rail and wheel profilescontact geometrical parametersgeometrical analysiselastic deformation in normal direction (penetration)tangential & longitudinal creepagesgeneralized contact forcestangential & longitudinal forces (Shen-Hedrick-Elkins theory)normal forces (multi-hertzian model)
9 Straight track with concentrated track defect: COMPARISON A.D.Tre.S. – SIMPACK Eigenvalues and time histories comparisonNatural frequencies comparisonStraight track with concentrated track defect:5 mm lateral and 14 mrad roll;20 m wavelength;speed 72 km/h.Carbody natural frequencies
11 Tuning procedure by sensitivity analysis TYPE OF ANALYSIS : parametric analysis on primary suspension parameters and bogie wheel-base:straight track running behaviour -> critical speedcurve negotiation -> steady state Q (vertical force values)steady state Y (lateral force values)steady state ‘wear index’
12 Tuning procedure by sensitivity analysis: effect of wheel-base Vehicle configurationsWheelbase[m]Cz[kN/mm]CyAD31018V12.7V22.5Reducing the wheelbase the critical speed decreasesReducing the wheelbase the vehicle has a better steering behaviour
13 Cz Cy Tuning procedure by sensitivity analysis: effect of wheel-base Vehicle configurationsWheelbase[m]Cz[kN/mm]CyAD31018V12.7V22.5Radius curve [m]Reducing the wheelbase the track shift force is lightly increasedWear index is lower in case of reduced wheelbase
15 Vehicle configurations taken into account for EN14363 full analysis Analysis of technological options: ‘virtual dynamic homologation’ simulation acc. to EN14363Vehicle configurations taken into account for EN14363 full analysisVehicle configurationsBogie Wheelbase[m]Longitudinal axlebox stiffness[kN/mm]Lateral axlebox stiffness [kN/mm]Reference31018V13015V22.5Three curve ranges are considered: Small radius curve (250 – 400 m);Medium-small radius curve (400 – 600 m);Large radius curve (600 – 2500 m) .
16 Analysis of technological options: ‘virtual dynamic homologation’ simulation acc. to EN14363 For each curve ranges a number of 30 sections, is considered. Per each section, a combination of the following parameters is chosen: Curve geometric parameters such as radius curve, cant and length of transition curve;Wheel – rail profiles;Track irregularity (different small level one track irregularities);Speed, chosen randomly, imposing a cant deficiency of 110% of the admissible for at least 20% of the complete simulation set.
17 ‘Virtual dynamic homologation’ procedure: main curving indexes Main parameters are obtained for all vehicle configurationsTRACK SHIFT FORCEY/QEN14363 limitEN14363 limitEN14363 limitVERTICAL FORCE
18 ‘Virtual dynamic homologation’ procedure: critical speed and wear index. Additional information is the wear index which can be used for the evaluation of the aggressiveness of the vehicle.WEAR INDEXCRITICAL SPEED
19 Parametrical analysis results Steady state analysis CRITICAL SPEEDGUIDING FORCETRACK SHIFT FORCEWEAR INDEX
20 Sensitivity analysis and scatter prediction Numerical simulation can be used even for the evaluation of the impact of the scatter variation of vehicle’s parameters on running behaviour.
21 Sensitivity analysis and scatter prediction: effect of damper parameters Exemplary Simulation Results (12 Parameters Varied Simultaneously): example of the correlation of the damper parameters with vertical wheel/rail contact forces.Secondary suspension: vertical damper (“left”)Primary suspension: vertical damper (“left front”)Each point: Output for one sample-set (simulation)ScatterofoutputMax. normal force Fmax [N]D11 Strong correlation No correlationDamper coefficient D1 [Ns/m]Damper coefficient D2 [Ns/m]
23 Full factorial approach: Methodology for the assessment of technological options: FULL FACTORIAL APPROACHFull factorial approach:Dynamic performances analysis in straight track: vehicle stabilityDynamic performances analysis in curved track: curving performanceNine configuration are taken as reference, according to the full factorial approachNUMERICAL SIMULATIONSCURVING PERFORMANCEOPTIMIZATIONSTRAIGHT TRACKTrial and error -> procedura semplificata. Prima faccio tuning, problema di ottimo vincolato, ossi a soddisfare i limiti della 14363, andando ad tenere come parametro di ottimizzazione o l’usura o la somma pesata di stabilità ed usura
24 Evaluate the influence of a simultaneous variation of parameters Methodology for the assessment of technological options: FULL FACTORIAL APPROACHEvaluate the influence of a simultaneous variation of parametersDefinition of factor and factor levels:bogie wheelbase: 3 m m m;lateral axlebox stiffness: kN/mm;longitudinal axlebox stiffness: kN/mm.ANOVA method : distinction random and systematic variation polinomial equation of full factorial plan where coefficients a are determined applying the least square analysisReduced number of configurationsDiciamo parametri del veicolo come variabili della minimizzazione, con 3x3 casi, quindi 3 piani fattoriali diversi per i 3 passi. Wheel-base è variabile discreta.I vincoli sono il fatto di rispettare gli indici della EN14363 e che la velocità critica sia almeno 220 km/h (quando faccio solo WW).polynomial equation that describes the full factorial plan
25 Higher axlebox stiffness, leads to an increase of the critical speed RESULTS IN STRAIGHT TRACK: critical speed as a function of bogie wheelbase and axle boxes stiffness265 km/h245 km/h24%BW = 3 mBW = 2.75 mBW = 2.5 m230 km/hBW = 2.5 mHigher axlebox stiffness, leads to an increase of the critical speedHigher bogie wheelbase stabilises the vehicle running dynamics
26 Leading outer wheel frictional work: small radius curve RESULTS IN CURVEDTRACK: wear rate as a function of bogie wheelbase and axle boxes stiffnessLeading outer wheel frictional work: small radius curveBW = 3 m18 kJBW = 2.5 m14 kJ20%Reducing bogie wheelbase -> lower wear rateIncreasing axlebox stiffness -> higher wear rate
27 OPTIMIZATION: results with different optimization functions Two different optimisation functions were used.Wear index based optimisationSolutionBogie wheelbase [m]Cz[kN/mm]CyWear[kJ]Critical speed [km/h]Reference3101812300210Opt. 12.7521.512069221Reference vs. Opt.1: reduced wear 2%increased critical speed 5%Combined optimisation:SolutionBogie wheelbase [m]Cz[kN/mm]CyWear[kJ]Critical speed [km/h]Reference3101812300210Opt. 237.212578256A seconda della funzione da ottimizzare si trovano soluzioni diverse. Questa è la media pesata ??? VERIFICARE!!!!!!Reference vs. Opt. 2: increased critical speed of 16 %increased wear of 4%
28 CONCLUSIONSNumerical simulation can be used in order to complement physical testing for homologation;Montecarlo approach coupled with multi-body simulations can account for the effect of scatter in component performances on ride safety;Numerical simulations can also be used for optimising vehicle performances still meeting the constraints imposed by ride safety.
29 Thanks for your attention BOGIE ’07 Conference September 3rd - 6th, Budapest – HUNGARYPaolo BELFORTEStefano BRUNIMichael JÖCKEL
31 COMPARISON A.D.Tre.S. – SIMPACK Time domain comparison Straight track with concentrated track defect:5 mm lateral and 14 mrad roll;20 m wavelength;speed 72 km/h.The discrepancies between lateral forces computed in Simpack and ADTreS are due to the quasi elastic interpolation adopted SIMPACK and not used in the simulation algorithm by Polimi
32 COMPARISON A.D.Tre.S. – SIMPACK Time domain comparison Curved track without track defect:R=2000 m, a.n.c m/s2, speed 185 km/h;Outer wheelInner wheelSPKADTreSVertical force WS1 [N]1069561053725974461360Vertical force WS2 [N]1104461082985631558431Lateral force WS1 [N]1832019620-1941-2175Lateral force WS2 [N]212662088072506573Longitudinal force WS1 [N]70857165-7111-7165Longitudinal force WS2 [N]61633315-6166-3315
33 Methodology for the assessment of technological options: SIMULATIONS PARAMETERS STRAIGHT TRACKPer each configuration:MB simulations increasing speed (steps 5 km/h)Evaluation of rms valuesEvaluation of prescribed limits & identification of critical speedSimulation parameters:W/R profile: theo. Rail / worn wheel cant 1:40Track irreg: ERRI LOWThe overall assessment of one vehicle configuration requires at least 50 simulationsRMS calculation:Fourier trasform of the last 10 s of the simulationFrequency f0 corrisponding to the maximum spectrum value identifiedTime history filtered with a band-pass filter f0±2 Hz
34 Methodology for the assessment of technological options: SIMULATIONS PARAMETERS CURVED TRACKSimulation parametersSteady state condition for different radius curve (300 – 2500 m) – random combination ofTrack irregularityW/R profileCant deficiencyThree tests zone:small radius curves [ m];small radius curves [400 – 600m];radius curves [600 – 2500m];For each zone -> 30 sections -> data collected with simulations
35 Best vehicle w.r.t stability and wear optimisation function Methodology for the assessment of technological options: OPTIMISATION PROCEDUREBest vehicle w.r.t stability and wear optimisation functionCcs & Cww critical speed and minimum frictional worka & b weighting coefficientAll the indexes prescribed in the standard were considered as constrains
36 Leading outer wheel guiding force: small radius curve Results -- CURVED TRACK: Guiding force as function of bogie wheelbase and axle boxes stiffnessLeading outer wheel guiding force: small radius curveBW = 3mBW = 2.5mLow bogie wheelbase has positive effects on the vehicle curving behaviourLongitudinal stiffness reduces the bogie steering capability
37 Results -- OPTIMISATION Best vehicle parameters : optimisation procedure resultSolutionBogie wheelbase [m]Cz[kN/mm]CyWear[kJ]Critical speed [km/h]Reference3101812300210Opt.137.212578256Opt.22.7521.512069221Ref vs Opt.1: Increased critical speed of 16 %Increased wear of 4%Ref vs Opt.2: Increased critical speed of 16 %decreased wear of 2%high lateral stiffness and high boogie wheelbase