Optimum Step Stress Accelerated Life Testing for Mukherjeeislam Failure Model

Abstract

Step stress accelerated life testing model is presented to obtain the optimal hold time at which the stress level is changed. A Mukherjee-Islam Failure model is assumed for the failure time at any constant stress level and a cumulative exposure model is assumed. The scale parameter of the Mukherjee-Islam Failure model at constant stress levels is assumed to be a log-linear function of the stress level. The maximum likelihood function is given for the step stress accelerated life testing. Optimal SSALT plan is proposed by minimizing the Asymptotic Variance (AV) of the desired life reliability estimate. Fisher information matrix is obtained. An optimal test plan with the minimum asymptotic variance of reliability estimate at time τ is determined.