Multi-domain NVH Model for the Complete Electro-mechanical Power Unit

Multi-domain NVH Model for the Complete Electro-mechanical Power Unit Yashwant Kolluru, Rolando Doelling eBike Department Robert Bosch GmbH Kusterdingen, Germany yashwant.kolluru@de.bosch.com rolando.doelling@de.bosch.com Lars Hedrich Institute of Informatics Goethe University Frankfurt Frankfurt, Germany hedrich@em.informatik.uni-frankfurt.de Acoustics and vibrations are amongst the foremost indicators in perceiving the quality of power units. Analyzing these factors is vital to improve the performances of electro-mechanical systems. This paper deals with development of a generic simulation method enabling the multi-domain vibro-acoustic modelling for the drive trains. Excitation's for these systems majorly arise from the electric motor and mechanical gears. The paper initially depicts a flexible gear model for gear whining, which are generated for reasons like gear tooth bending. The forces generated from gear mesh (lumped parameter model) to gear components (multi-body model and nonlinear static model) and the excitations resulting from motor model are coupled for the frequency domain analysis of complete drive train. Additionally, paper discusses the influences of these forces on bearings (dynamic implicit model) and effect of bearing deformations on the harmonics of drive unit. Furthermore, velocities on the housings are calculated via steady-state dynamic model generated. Later, acoustical characterizations like pressures and intensities for variants are studied using acoustic infinite elements. For method verification, a three stage gear model of an electro-mechanical drive train is developed. The simulation model allows studying rotational oscillations of the shafts, three-dimensional vibrations of gear parts and peripheral components, surface vibrations of housings and pressure fluctuations of surrounding fluids. Eventually, the experimental validations for exterior vibrations and acoustical fluctuations are performed with aid of laser vibrometer and acoustic camera. Finally, it is depicted that the developed simulation method allows for better comprehension of vibro-acoustics of drive units.