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Quantitative diagnosis of a spall-like fault of a rolling element bearing by empirical mode decomposition and the approximate entropy method

ShuanFeng Zhao, Lin Liang, GuangHua Xu, Jing Wang, WenMing Zhang, Mechanical Systems and Signal Processing, October 2013, Volume 40, Issue 1, pp 154-177.

Abstract

Spalling or pitting is the main manifestation of fault development in a bearing during the earlier stages. Previous studies indicated that the vibration signal of a bearing with a spall-like defect may be composed of two parts; the first part originates from the entry of the rolling element into the spall-like area, and the second part refers to the exit from the fault region. The quantitative diagnosis of a spall-like fault of the rolling element bearing can be realized if the entry–exit event times can be accurately calculated. However, the vibration signal of a faulty bearing is usually non-stationary and non-linear with strong background noise interference. Meanwhile, the signal energy from the early spall region is too low to accurately register the features of the entry–exit event in the time domain. In this work, the approximate entropy (ApEn) method and empirical mode decomposition (EMD) are applied to clearly separate the entry–exit events, and thus the size of the spall-like fault is estimated.

How Multibody Dynamics Simulation Technology is Used

RecurDyn is used to simulate the dynamic effects of rolling element bearings with spall-like faults. A variety of spall widths and bearing speeds were tested without the cost and time associated with physical prototypes.