Transmission Side Cover Design Optimization for NVH Part 1: Shell Curvature Studies

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. Present day geometry optimization algorithms available in high-end Computer Aided Design packages provide an automated process of achieving this goal.

This paper presents the first phase in addressing this design goal through a consideration of alternative methods for stiffening a flat panel in order to raise the fundamental natural frequency. The results show the dramatic benefits afforded through the use of panel curvature and form the basis for the consideration of the geometric optimization of the side cover design through the use of variational geometry.