STATISTICAL ANALYSIS FOR ACCELERATED LIFE TESTS BASED ON DIFFERENT CENSORING SCHEMES

Abstract

Due to the rapid development of the advanced technology, the products and devices today become more and more reliable, and the products' life gets longer and longer. For such highly reliable products, it is quite hard or even impossible to obtain the failure information under normal conditions. Therefore, accelerated life testing (ALT) is the most common way to obtain enough failure time data in a short period. Under such test settings, products are tested at higher than usual levels of stress to induce early failures. The failure time data collected from such accelerated tests are analyzed and extrapolated to estimate the life characteristics under normal operating conditions. The stress loading in ALT is applied using di erent ways. Commonly used methods are constant-stress, step-stress, progressive-stress, cyclic-stress and random-stress. Here, we discuss the constant-stress, step-stress and progressive-stress models to obtain information about the parameters of the lifetime model more speedily than under normal operating conditions. The thesis consists of six chapters: Chapter 1 This chapter is considered as an opening chapter. It includes de nitions and basic concepts that are used throughout this dissertation. A survey of the previous studies is presented such as accelerated life testing, statistical models for acceleration, constant-stress models, step-stress models, progressive-stress models, lifetime data, Bayesian analysis, and goodness of t test. At the end of this chapter, a literature review of the previous studies is presented. xii SUMMARY Chapter 2 In this chapter, we consider constant-stress ALT to