Generic Methodology for Vibration and Wear Analysis to Understand Their Influences in an Electric Drivetrain 2020-01-1506
The prime factor which influences noise and 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 Noise Vibration and Harshness (NVH) models of the drive unit. The vibration domain model, initially, focuses on the calculations of mechanical excitations at the gear shafts which are generated via a nonlinear dynamic model. Furthermore, the bearings are studied for the influences on their stiffness and eventually their impact on the harmonics of the drivetrain. Later, free and forced vibrations of the complete drivetrain are simulated via a steady-state dynamic model. Consequently, the paper concentrates on the abrasion calculations at the gears. Wear is a complex process and understanding it is essential for determining the vibro-acoustics characteristics. As part of wear modeling, a finite element static model used for abrasion calculations is described. The special subroutines developed aid in the coupling of the wear equations, various contacts and friction formulations to the numerical model. The abraded solution model is then inputted into the vibration module for further analyzing changes in the velocities of the housing surfaces. As part of the method validation, a drivetrain with a three-stage (gear) drivetrain 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 an optical microscope and laser vibrometer, respectively. Finally, it is shown that the developed simulation method allows for a better comprehension of the influences of abrasion on the vibro-acoustics of drive units.