Abstract:

This paper deals with the design of Optimal Step-Stress Partially Accelerated Degradation Test (PADT) using Wiener Process for modelling degradation paths. In partial step-stress loading, the unit is tested at usual stress for some time and then stress is accelerated. This helps in preventing over-stressing the test specimens. Failure occurs when the performance characteristic crosses the critical value the first time. The first passage time follows Inverse Gaussian Distribution. The optimal plan consists in determining the optimal test duration, and number of inspections at each intermediate stress level by minimizing asymptotic variance of MLE of quantile of the lifetime distribution at use condition subject to the constraint that total testing or experimental cost does not exceed a pre-specified budget.