Use of the moving cepstrum integral to detect and localise tooth spalls ingears

The objective of this paper is to propose a new indicator for the vibratory diagnosis of gear systems. This indicator is deduced from the power cepstr um of the accelerometer signal. A model aimed at simulating the contributio ns of local tooth defects such as spalls to the gear dynamic behaviour is s et-up. The pinion and the gear of a pair are modelled as two rigid cylinder s with all six degrees of freedom connected by a series of springs which re present gear body and gear tooth compliances on the base plane. It permits us to foresee the shape of the excitation induced by the presence of spalls . From an analytical analysis of the equations of motion, a detection techn ique based upon the acceleration power cepstrum is proposed. The identifica tion of the spalls is provided by the fact that the power cepstrum of the e xcitation that it generates is strictly negative, in contrast to that of a normal excitation. A tool of detection and localisation, using this propert y, has been defined. It is first tested on acceleration signals simulated b y numeric integration of the model, then on real signals. (C) 2001 Academic Press.