Analytical Technique for Predicting Passenger Car Gearbox Structure Noise Using Vibration Response Analysis

The gear pair assembly remains one of the major noise and vibration sources in power transmission systems typically used in automotive, aerospace and industrial applications. The gearbox structure vibration and noise signatures are often dominated by several high-level tonal peaks that occur at the fundamental gear mesh frequency and its harmonics and other sources. In this paper, development of the concept of a method for predicting the contributions to exterior noise radiated by an original vehicle gearbox structure using measured vibration response. An idealization of the gearbox surface as a set of flat plates was used to calculate the radiation efficiency from physical properties and edge (end) constraints of each plate, and the vibration response of the gearbox structure surface was measured using accelerometers. These data were used in a simple acoustical power theory to determine 1/3-octave band sound pressure level under free field conditions for the whole and individual noise sources. Moreover, the prediction of the individual noise sources in order to pinpoint the exact problem area in the gearbox structure so that treatment or redesign can be carried out in correct way.