Abstract
As one of the important friction components of internal combustion engine, the main bearing is exposed to complex dynamic loads and is prone to wear during long-term operation. It is of great significance to study the wear condition monitoring of main bearing. Time domain analysis and wavelet packet decomposition (WPD) are carried out to analyze the block vibration signals under different working conditions. The influence of engine speed, torque, oil temperature and main bearing clearance on the block vibration is analyzed. On this basis, the characteristic parameters reflecting the main bearing state are extracted to form the input vector and the support vector machine (SVM) model is established. Then the key parameters of the SVM, including penalty factor and kernel function parameter are optimized by grid search method and gray wolf optimizer (GWO). The optimized diagnosis model is used to identify the wear state of main bearing. The result indicates that the recognition accuracy and the running time of the model optimized by GWO is 97.22% and 9.13 s respectively. So GWO-SVM diagnosis model can effectively recognize the main bearing wear state, mitigating the risks of unplanned downtime and secondary damage caused by main bearing failure.
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