Dual-Impulse Response Model for the Acoustic Emission Produced by a Spall and the Size Evaluation in Rolling Element Bearings

The size of the spalling area has a significant influence on the operation performance and the remaining useful life of rolling element bearings. Therefore, spall size estimation is of great importance to the bearing performance degradation assessment and the life prediction. In this paper, the acoustic emission (AE) signal is used to evaluate the size of a single spall, considering the sensitivity of the AE signal to the incipient fault detection. First, based on the hypothesis that the AE signal is composed of two events for each passage of the rolling element across the spall, an analytical model, named as dual-impulse response model, is developed to describe the AE signal. Then, an averaged dual-impulse interval determining method is proposed to evaluate the spall size. Finally, simulations and experiments are carried out to validate the proposed model and method. It is indicated that the proposed model describes the collected AE signals more satisfactorily than the traditional vibration model involving only a single-impulse response. Compared with the method performed by averaging real cepstra of the dual-impulse segments, the proposed method is more powerful in the inner and outer spall size estimation tests.