Abstract

Recently the requirement of system analysis is increasing drastically especially for dynamic simulation, where the driving system with high-speed electric motor is widely used. A rotating gear in a driving system generates specific frequency caused by gear and its pair, and it is called gear mesh frequency (GMF). This GMF is likely to cause system resonance, especially when driving speed varies. To find some problematic resonance in a system, numerical system modeling and simulation for the whole system is needed. In the meantime, electric motors may also be excessively vibrating at certain speed zone connected with gearboxes, so that, upfront design review of an entire assembly is more essential to avoid undesired system resonance. This presentation introduces a process of system modeling in terms of a driving system using two engineering software - RecurDyn and KISSsoft, and shows NVH result of a combined assembly. RecurDyn is a dedicate software for dynamic simulation and KISSsoft is an engineering software for gear design. By defining a gearbox system containing multiple gears and bearings using above software, GMF characteristics can be viewed and compared between simulation results and theoretical values. Since gears accelerate with linear or nonlinear slope profiles, system’s specific GMF as well as side frequency along with speed change was seen and checked. And, to derive system vibration characteristics from the system both from views of time-domain and frequency-domain at the same time, the gearbox was designed and defined with two different FEM methods, one is nonlinear flexible modeling for shafts and the other is linear flexible modeling for a housing. For higher reliability and accuracy of simulation result, an electric motor and an inverter model were also applied to the gearbox as an extra boundary condition. Torque ripple by electric motor is one of important excitation factors to the system vibration characteristic of gearbox. In order for understanding specific resonance in a complex system, a waterfall diagram (Campbell diagram) was used.