Prognostics of Health Measures for Machines With Aging and Dynamic Cumulative Damage

Modern engineering components generally work under aging and dynamic cumulative damage processes. To prevent failures of such components, the proportional hazards model (PHM) was proposed to integrate both processes for health prognostics. However, the existing PHMs use constant damage rate within monitoring intervals for machine health estimation and still lack consideration of dynamic operational conditions, which fails to model the practical degradation situations. This article presents a prognostic model using a new PHM to consider aging and environment-varying cumulative damage for engineering machines. A dynamic multistate process with practical transition mechanisms under varying operational conditions is presented to model the cumulative damage progress. To address the difficulties in prognostics with PHMs, a matrix-based approximation method with low computational load is developed to compute important health measures such as conditional reliability, mean residual life (MRL) and residual life distribution. A prognostic scheme featuring online prediction and dynamic updating is presented. The particularity of the proposed model is that it considers dynamic environments and can be applied to a large number of deteriorating states. The proposed approach is illustrated using a case of pump under different operating environments, and comparison with other advanced PHM is given to validate the applicability and effectiveness of the proposed approach.