In-Depth PHEV Driveline Torsional Vibration Induced Vehicle NVH Response Study by Integrated CAE/Testing Methodology 2020-01-1507
In this paper, a 1-D refined driveline model in AMESIM was built up, for a P2.5 topology PHEV. The model includes detailed engine, damper, dual clutch transmission, differential, motor, half-shaft, wheel, body, suspension, powertrain mounting and powertrain rigid body, The objective of the simulation is to predict torsional vibration induced vehicle NVH response under different driving scenarios. Firstly, the torsional vibration modes were predicted, and the critical modes were identified. This enabled a good understanding of modal alignment, identification of countermeasures and provide feedback to other engineering teams in the early stages of vehicle development. Secondly, the holistic operational testing, which included a plenty of measurement points at various locations, partly intended for later model calibration, partly for extracting mandatory excitation input, and partly for the reference of next optimization stage, was implemented on vehicle chassis dyno in a hemi-anechoic chamber. As it was merely centered on torsional vibration induced scenarios, the intake system / exhaust system/engine radiation noise contribution was excluded by specific measures during the testing. Thirdly, the NTF/VTF from the mount / suspension attachment points to vehicle response points were measured on the trimmed body using hammer impact testing, to create structural TPA model, that way, each transfer path contribution to the response point could be predicted and overall response could be synthesized from all paths. Fourthly, the above-mentioned driveline model, combining the excitation on each cylinder due to gas pressure, inertial forces and motor average torque, was well calibrated to predict the critical rpm fluctuation / vibration / cabin noise and vibration. Finally, it was validated that CAE results correlated very well to measurement data for defined loadcase. This approach can be adapted to PHEV driveline/vehicle NVH development from the early stages of vehicle development as well as NVH tuning / refinement stage to expedite HEV/PHEV NVH developing process. This paper was a part of the whole study, including analyses of all loadcases corresponding to various driving scenarios followed by driveline design / calibration parameter sensitivity study to improve the torsional vibration induced vehicle NVH response.