Optimization of the test stress levels of an ADT

In order to predict the reliability of the product with high reliability and long life, the accelerated degradation test (ADT) is commonly applied. However, in the studies of optimizing the ADT plans, there is nearly no researches on how to select the test stress levels. In this paper, the drift Brownian motion is selected as the degradation model. The optimization of the selection of the stress levels in a step stress accelerated degradation test (SSADT) is studied. The objective is to minimize the mean square error (MSE) of the prediction of the product operation reliability under the cost constraints. Through a Monte Carlo simulation method, the optimal stress levels and related sample size and test time are obtained. At last, the robustness of the results is shown through the sensitive analysis.