Simulation of gearbox structure borne noise using a detailed multi-body dynamics gear contact

Gear rattle and whine are undesired noise and vibration issues, which frequently arise in automotive transmissions. Although the excitation source itself is dedicated to the gear contact properties, other adjacent components, like rolling element bearings, shafts and housing play an important role, too. Acting as transmitters/amplifiers in the acoustic transfer path, their dynamic behaviour is crucial from a whine/rattle noise perception point of view. Focusing on the product development process, a clear tendency towards so called virtual design methods is evident. Consequently, it becomes increasingly important to virtually predict the gear noise behaviour not only from the pure gear mesh point of view, but also by incorporating the vibratory response of the whole system. Beside the ability of depicting relevant physical phenomena, the applied software tools must be in agreement with the requirements of the development process in terms of data availability and computational effort. The paper addresses a detailed gear contact model, which is embedded into a flexible multi-body dynamics (Flexible-MBD) framework [1]. Numerical aspects, like state events, which are caused by gear rattle impacts as well as the handling of large flexible structures as a precondition for efficient structure borne noise simulation, are outlined. The practical relevance of the proposed approach is shown by applications to gear whine as well as gear rattle with special focus on gearbox structure borne noise properties. Experimental data gained from gear whine/rattle test rigs is finally used to compare the approach against measurements.