Bearing failure prognostic model based on damage mechanics and vibration monitoring

Bearing failure is one of the foremost causes of breakdown in rotating machinery. In this paper, a stiffness-based life-signal prognostic model of a bearing system based on vibration response analysis and damage mechanics is proposed. When a bearing system is simplified as a Single-DOF vibration system, the natural frequency of the system is proportional to the system stiffness, and the amplitude of acceleration response at the natural frequency is opposite to the system stiffness. Meanwhile, for the rules of dam age mechanics, the relationship among failure lifetime, running time and variations of stiffness of a bearing system can be established. With the combination of above two relationships, the natural frequency and the amplitude of acceleration response at the natural frequency are related to the running time and failure life time. Thus, the failure lifetime of a bearing system can be predict ed via vibration signals from an accelerometer, which is attached to the bearing housing. The resulting model is calibrated by parameter identification approach. Failure life tests of taped roller bearing are performed for verification of this analytical model. The experimental results indicate that this model can effectively trace and evaluate the failure lifetime and the remaining life of a bearing system.