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Numerous authors have previously published on the effects of system dynamics on gear noise in automotive applications [1,2]. It is now widely understood that the torsional compliances and inertias of propeller shafts and pinion gear sets are a controlling factor in final drive gear noise for rear wheel drive vehicles. Considerable progress has been achieved in using finite element simulations of the driveline dynamics to improve the system in regards to gear noise. However very few published results are available showing the application of dynamic simulation methods to automatic transmissions which require considerations of the complications due to epicyclical gear sets. This paper documents the successful application of finite element dynamics modeling methods to the prediction of gear noise from the gear set in a rear wheel drive automatic transmission. The model was used to investigate the effects of component inertias, stiffnesses, and resonances.

The design of Front Wheel Drive transmission side covers is primarily driven by packaging concerns, and secondarily by structural durability requirements. While the side cover design is a very important element in the NVH performance of a transaxle, there has historically been little consideration of this concern at the design stage. The typical approach to NVH considerations on a side cover is to start with the initial prototype hardware and add any stiffening features in order to reduce the cover vibration or radiated sound. A preferred approach would be to factor the NVH considerations into the initial design. Through consideration of the packaging constraints and a goal of maximizing the fundamental natural frequency of the side cover, it is possible to select from various alternative geometries the one which best meets these objectives.

The design of Front Wheel Drive transmission side covers is primarily driven by packaging concerns, and secondarily by structural durability requirements. While the side cover design is a very important element in the NVH performance of a transaxle, there has historically been little consideration of this concern at the design stage. The typical approach to NVH considerations on a side cover is to start with the initial prototype hardware and add any stiffening features in order to reduce the cover vibration or radiated sound. A preferred approach would be to factor the NVH considerations into the initial design. Through consideration of the packaging constraints and a goal of maximizing the fundamental natural frequency of the side cover, it is possible to select from various alternative geometries the one which best meets these objectives.

Powertrain noise is often dominated by the radiation from individual panels or covers. A structural side cover for a front wheel drive transmission represents a complex noise and vibration design problem. Amongst the NVH concerns are the radiation of structural borne sound and the sound transmission loss characteristics. This paper addresses the use of acoustic boundary elements and structural finite elements to predict the radiation of noise from a structural side cover. A comparison is made to experimental measurements, and discussion provided for practical application of these modeling methods to total side cover design.