predictive evaluation of fuel economy vs. nvh trade-off ... · pdf filepredictive evaluation...

Predictive evaluation of fuel economy vs. NVH trade-off using co-simulationPresented at NAFEMS World Congress 2015
Mario Felice, Jack Liu, Imad Khan (Ford Motor Company)Jonathan Zeman, Llorec Gomes (Gamma Technologies)Wulong Sun (MSC Software)Michael Platten (Romax Technology)

Copyright 2015Slide 2CONFIDENTIAL
Introduction Study of the fuel economy vs. NVH (Noise Vibration and Harshness) trade-off of a 4 cylinder AWD vehicle with a
6 speed automatic transmission integrating technology from 3 partner software suppliers
o Gamma Technologies for Engine and Torsional Damper
o MSC Adams for 3D Driveline and Chassis
o RomaxDESIGNER for Transmission and PTU (Power Take-off Unit)
Four main aims:
o Predictively quantify fuel economy penalty for slipping TCC (Torque Convertor Clutch)
o Predictively quantify transmission torsional vibration and seat track acceleration amplitudes for locked and slipping TCC
o Predictively quantify drivetrain lugging and rattle NVH responses under damper designs and slipping TCC
o Evaluate other damper technologies as an alternative to TCC slip
o Understand details and benefits of software co-simulation and model reduction

Software usage overview
Adams full vehicle and driveline mode

Engine Behavior Predictive GT-POWER engine gives physically accurate engine torque and fuel consumption output as a function of engine rpm and load request

GT-Suite damper models Models of three common used damping technologies to reduce the oscillatory
characteristic of the engine torqueo Conventional Damper
Controlled slip from 0-60RPM in 10RPM increments
o Series Double Damper
o Centrifugal Pendulum Absorber (CPA)
Modeled with 1D+2D planar components
Conventional Damper
Series Double Damper
Pendulum Absorber

GT-Suite damper models
Steady-state damper isolation performance curves

Dynamic FUSION Workflow
6F35 with PTU in RomaxDESIGNER
Dynamic FUSION discretizes and exports a time-domain 1D/3D MBD model
Visualization of Adamsformat of Romaxmodel
Dynamic FUSION can export a native 3DAdams file, or generic XML file, which canbe read by GT-SUITE to create a 1Dtorsional-only model

Model setup and co-simulation
Merged chassis, transmission and driveline models
Dynamic engine speed sweep from 800-3000 RPM at full load with Rear Differential Unit (RDU) clutch locked
GT-SUITE co-simulates with Adams, exchange transmission input shaft speed and torque data Adams Vehicle Model Romax Trans/PTU Model
Adams Drivetrain Model
GT Engine ModelRomax/Adams Model
Co-simulation

Co-simulation results: TCC slip
Transmission Output Shaft RMS Speed Amplitudes Conventional Damper with Slip

Co-simulation results: Damper types

Co-simulation results: Damper mode resonance
Baseline Lugging Limit
CPA Lugging Limit

Co-simulation results: Seat track vibration
Seat Track Acceleration: Damper DesignSeat Track Acceleration: TCC Slip

Co-simulation Results: PTU rattle
Baseline (0 TC slip)
RDU Open (7Nm constant drag) Gear Lash in Driveshaft: 2 Degree Full Throttle, 5th gear position Various TCC Slip (0 60 rpm)
Vehicle Model Setup Model Outputs PTU rattle torque Drivetrain torsional vibration Drivetrain torsional modes Seat track vibration
Relative Gear Displacement
Rattle Rattle
Torque on Gear
Rattle Rattle

Co-simulation results: PTU rattle
Driveshaft Torsional Mode at Rattle ~59Hz
Baseline (0 TCC slip) Linear Mode Animation
Time domain + FFT
Rattle
59 HzRattle Peak

Co-simulation results: PTU rattle
TCC Slip reduces PTU rattle response
Relative Gear DisplacementTorque on Gear
0 rpm30 rpm60 rpm
0 rpm30 rpm60 rpm

Co-simulation results: PTU rattleRelative Gear Displacement
Torque on Gear
0 rpm40 rpmDoubleCPA
0 rpm40 rpmDoubleCPA

Co-simulation results: Fuel economy
TCC slip has negative impact on fuel economy
Damper design has negligible effect on fuel economy

Conclusions
This paper performs the FE evaluation based on special driving maneuverso Lugging results show a high fuel economy penalty for TCC slip
o However, a complete certification driving cycle will not exhibit the same penalty
FTP75 HFET US06 NEDC
Modified Slip Map 1.5% 0.22% 1.4% 0.30%
Fuel Economy Penalty vs. Driving Cycle

Conclusions
This paper demonstrates a powerful method in evaluating predictive tradeoff of fuel economy and NVH
o An optimal design best balancing fuel economy and NVH can be analytically determined before prototypes are built
This method is also applicable for predicting tradeoff of cost vs. performance, and fuel economy

Predictive evaluation of fuel economy vs. NVH trade-off using co-simulationIntroductionSoftware usage overviewEngine Behavior GT-Suite damper modelsGT-Suite damper modelsDynamic FUSION WorkflowModel setup and co-simulationCo-simulation results: TCC slipCo-simulation results: Damper typesCo-simulation results: Damper mode resonanceCo-simulation results: Seat track vibrationCo-simulation Results: PTU rattleCo-simulation results: PTU rattleCo-simulation results: PTU rattleCo-simulation results: PTU rattleCo-simulation results: Fuel economyConclusionsConclusionsSlide Number 20

predictive evaluation of fuel economy vs. nvh trade-off ... · pdf filepredictive evaluation...

Documents