Numerical Analysis of the Influences of Wear on the Vibrations of Power Units

Numerical Analysis of the Influences of Wear on the Vibrations of Power Units 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 The prime factor, which influences vibrations of electro-mechanical drives, is wear at the components. This paper discusses the numerical methods developed for abrasion, vibration calculations and the coupling between wear and NVH models of drive unit. Wear is a complex process and understanding it is essential for vibro-acoustics. The paper initially depicts finite element static model used for wear calculations. The special subroutines developed, aids in coupling the wear equations, various contact and friction formulations to the numerical model. The vibration domain model initially, focuses on calculations of mechanical excitation's at the gear shafts, which are generated via a nonlinear dynamic model. Furthermore, the bearings are studied for the influences on its stiffness and eventually its impact on harmonics of the drive trains. Later, free and forced vibrations of the complete drive train are simulated via steady-state dynamic model. The abraded solution model is then inputted to the vibration module for further analyzing changes in velocities of the housing surfaces. As part of method validation, a drive train with a three stage gear model is developed. The simulation model allows studying the influences of wear at the gear components and its impact on the vibrations of the whole structure. Eventually, the experimental calculations for wear on the gear surfaces and surface vibrations of housing are performed with optical microscope and laser vibrometer respectively. Finally, it is shown that the developed simulation method allows for better comprehension of influences of abrasion on the vibro-acoustics of drive units.