Health index extracting methodology for degradation modelling and prognosis of mechanical transmissions

Failure caused by severe wear of friction couplings, which is the primary failure mode of mechanical transmissions, has an adverse influence on vehicle reliability that may have catastrophic consequences. Therefore, the wear in a mechanical transmission should be monitored regularly to avoid possible unscheduled maintenance, and proactive maintenance should be implemented in a timely manner to extend the period during which the transmission is in a healthy state. Currently, the condition monitoring (CM) and prognostics of a mechanical transmission, which uses CM data to evaluate the residual life before wear failure of friction couplings and provides a vital foundation for condition-based maintenance, has attracted considerable attention in research and plays a key role in industries [3,7]. CM data (e.g., vibration, temperature and oil analysis data) that are measured during machine operation, which can characterize the severity of underlying degradation and failure processes, are typically regarded as degradation data. A typical assumption is that the machine failure will occur when the degradation data cross a threshold that is usually prescribed by practitioners [14,19]. Therefore, the degree of degradation and the residual life of a machine can be determined by comparing the degradation data with the predetermined failure threshold. With the residual life evaluated, condition-based maintenance Shufa YAn Biao MA Changsong Zheng