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Powertrain units such as engine and gearbox are important components affecting the noise and vibration performance of a vehicle. This paper presents a unique technique that uses structural shape optimization together with an acoustic transfer vector (ATV) technique to minimize the noise radiated from a gearbox casing. The ATVs relate the normal velocities of the gear case surface to the sound pressure at points in the acoustic field around the structure. The ATVs are calculated once only in an initial step using a boundary element method (BEM). By integrating the pre-calculated ATVs into the structural model as a frequency-dependent constraint relationship, the sound pressure at any position in the acoustic domain can be obtained as a response quantity in the FEM calculation. This makes it possible to use the standard structural optimization tools available in advanced FEM software to minimize the radiated noise.

Today, time available for production development is shorter and good quality development is required. Using the finite element method is a mean of meeting this requirement. This method of analysis is very adaptable to many fields and can predict static stress, strength, endurance, resonance, dynamic stress, thermal conductivity, convection, radiation, the optimum design, sound, fluid behavior, and electromagnetics in a short period. Furthermore, finite element methods are becoming more practical because of increased speed by computer vector operations and the main memory expansion of computers. This paper outlines an analytical model for studying vibration characteristics including amplitude, modal shapes and stress while a variable displacement compressor is operating. Finite element analysis reveals the dynamic behavior of the mounts and body of this compressor.