Optimal design of cyclic-stress accelerated life tests for lognormal lifetime distribution under type I censoring

Abstract

In this paper, optimal ALT plans are developed under the assumptions of cyclic-stress loading, Type-I censoring, lognormal lifetime distribution, log-linear relationship between the scale parameter of the lifetime distribution and stress variable, and the cumulative exposure model for the effect of changing stress levels. In particular, the common floor level of, and the proportions of units allocated to two cyclic-stress conditions are determined such that the large-sample variance of the maximum likelihood estimator of the q-th quantile of the lifetime distribution at the use condition is minimized. In addition, a sample size determination method is developed for the practical use.