Planning step-stress test plans under Type-I censoring for the log-location-scale case

Abstract

In this paper, we consider a k-level step-stress accelerated life-testing (ALT) experiment with unequal duration steps τ=(τ₁, …, τ _k ). Censoring is allowed only at the change-stress point in the final stage. A general log-location-scale lifetime distribution with mean life which is a linear function of stress, along with a cumulative exposure model, is considered as the working model. Under this model, the determination of the optimal choice of τ for both Weibull and lognormal distributions are addressed using the variance–optimality criterion. Numerical results show that for a general log-location-scale distributions, the optimal k-step-stress ALT model with unequal duration steps reduces just to a 2-level step-stress ALT model.

Keywords:

• accelerated life
• reliability
• censored data
• distributed computations
• Weibull and similar distributions
• maximum likelihood
• optimization

Acknowledgements

We express our sincere thanks to the editor and the referee for their valuable comments and suggestions. The first author thanks the National Science of Council of Taiwan (NSC Grant Number 99-2118-M-032-011-MY3) for funding this research, while the third author expresses thanks to the Natural Sciences and Engineering Research Council of Canada.