Abstract:

This paper presents the optimal design for accelerated life testing (ALT) experiments when step-stress plans with Type I censoring are performed. We adopt a generalized Khamis-Higgins model for the effect of changing stress levels. It is assumed that the lifetime of a test unit follows a Weibull distribution, and both its shape and scale parameters are functions of the stress level. The optimal plan chooses the stress changing time to minimize the asymptotic variance (AVAR) of the Maximum Likelihood Estimator (MLE) of reliability at the use stress level and at a pre-specified time.