Vibro-Acoustic Studies of Transmission Casing Structures

Abstract

Abstract Automotive transmission casing plates of irregular shape, with complex boundary conditions and non-uniform material properties, are experimentally and computationally studied to acquire a fundamental understanding of their dynamic and acoustic radiation characteristics. A modified flat cover is designed which simplifies the geometry while providing uniform thickness and material properties. Both covers (“real-life” and “laboratory”) are studied with free and bolted boundary conditions. In particular, the free boundary conditions are useful because they eliminate the cover-housing interaction allowing for a more detailed analysis of the cover plate. Finite element models for both covers under the free boundary conditions are developed and refined. Predicted natural frequencies and mode shapes are in excellent agreement with measured modal data. Then the finite element models are coupled with boundary element models to predict acoustic radiation properties. Predictions match well with measured acoustic directivity at resonant frequencies.