Modeling and Acoustic Analysis of Noise Vibration in Automotive Gearbox by Non-destructive Testing

Abstract

A gearbox is used for transferring power from the engine to the wheels. Predicting the vibration and noise radiation from a dynamic system like a gearbox gives designers an insight early in the design process. It was conducted experimental and modeling of vibration and noise for magnitude and pressure level variations in a Peugeot 206 automotive 5-speed gearbox. It was extract vibration data related to different periodic processing and then the data was carried out by Fourier transform analysis for empirical work. After processing the signal, the data revealed a precise location of defects and vibration in the frequency domain. It was simulated and analyzed vibration data and acoustic analysis of noise in gearbox by COMSOL Multiphysics software. A transient multi-body analysis is performed to compute the gearbox vibration for the specified engine speed and external load. The normal acceleration of the gearbox housing is converted to the frequency domain and used as a source of noise. An acoustics analysis is then performed in order to compute the sound pressure levels in the near, far, and exterior fields. It was used 4 microphones to obtain magnitude and variations in pressure level that they have specific location for pressure analysis in gearbox. A microphone was added in the simulation to show the best state of the pressure. In order to visualize normal acceleration by time, it was selected different locations by defined microphones in gearbox housing. In order to visualize the pressure wave propagation in the air domain outside the gearbox, the time domain pressure data can be converted back to the frequency domain. The best microphone location was defined to obtain magnitude and variations in pressure level in gearbox for industrial need. It was comprised between simulation and empirical work and it was observed good accordance between them.