Optimal Design for Accelerated Life Tests Under Progressively Type-II Hybrid Censoring

Abstract

This paper presents the constant-stress and step-stress accelerated life tests model with two stress levels under the progressively Type-II hybrid censoring. The optimal test design plans for accelerated life tests are studied. It is assumed that the lifetime of the items follow the exponential distribution. The explicit conditional density functions of order statistics under progressively Type-II hybrid censoring scheme are given to obtain the expected Fisher information matrix. The optimal test design plan with the minimum asymptotic variance of the mean life under the use stress level is determined. The test units allocated to each stress in constant-stress accelerated life test and the changing time to severer accelerated stress in step-stress accelerated life test are obtained. Finally, a numerical example is presented by the Monte Carlo simulation to illustrate the optimal test design plan. It is shown that the step-stress accelerated life test is a better choice