NVH optimization of vehicle powertrain

The noise and vibration performance of powertrain is main contributor for vehicle NVH (Noise, Vibration and Harshness) issue. To achieve better NVH performance, it is critical to conduct NVH optimization during the powertrain initial design stage. This paper presents an investigation of optimize vehicle powertrain NVH performance via modification of excitation-radiation system of powertrain. To minimize excitation force of the gearbox with special focus on gear pair dynamic characteristics via the gear profile modification, and to reduce transmission housing noise radiation via enhance its stiffness, are the main objective of optimization. The excitation forces are analyzed by Multi Body Dynamics (MBD) method, considering different excitation mechanisms of the powertrain. The vibro-acoustic behavior of powertrain is obtained by FEM/BEM coupled analysis. The acoustic transfer vector (ATV) calculation is used to predict the powertrain sound power level (SPL) and panel contributions. Based on the acquired NVH data of the powertrain, the optimization which couples the transmission gear profile modification for attenuating gear system excitation and the structure stiffness modification for reducing transmission housing noise radiation is proposed. Experiment validation is conducted in order to evaluate the modified results. The evaluation shows that the optimization can effectively reduce powertrain noise and vibration.