Accelerated Life Test Models and Data Analysis

Document Type

Article

Publication Date

1-1-2006

Abstract

Todayʼs consumers demand high quality and reliability in the products they buy. Accelerated accelerated tests life tests (ALT) are commonly used by manufacturers during product design to obtain reliability information on components and subsystems in a timely manner. The results obtained at high levels of the accelerating variables are then extrapolated to provide information about the product life under normal use conditions. The introduction and Section 22.1 describe the background and motivations for using accelerated testing. Sections 22.2 and 22.3 discuss statistical models for describing lifetime distributions in ALT. Commonly used ALT models have two parts: (a) a statistical distribution at fixed levels of the accelerated variable(s); and (b) a functional relationship between distribution parameters and the accelerating variable(s). We describe relationships for accelerating variables, such as use rate, temperature, voltage, and voltage rate. We also discuss practical guidelines and potential problems in using ALT models. Section 22.4 describes and illustrates a strategy for analyzing ALT data. Both graphical and numerical methods are discussed for fitting an ALT model to data and for assessing its fit. These methods are thoroughly illustrated by fitting an ALT model with a single accelerating variable to data obtained from an actual ALT experiment. Extrapolation of the results at accelerated levels to normal use levels is also discussed. Section 22.5 presents statistical analysis of a wider variety of ALT data types that are encountered in practice. In particular, the examples involve ALTs with interval censoring and with two or more accelerating variables. Section 22.6 discusses practical considerations for interpreting statistical analysis of ALT data. This Section emphasizes the important role of careful planning of ALT to produce useful results. Section 22.7 discusses other kinds of accelerated tests often conducted in practice. Brief descriptions of each and specific applications in industry are also provided. Section 22.8 reviews some of the potential pitfalls the practitioner of accelerated testing may face. These are described within practical situations, and strategies for avoiding them are presented. Section 22.9 lists some computer software packages that are useful for analyzing ALT data.

Publication Source (Journal or Book title)

Springer Handbooks

First Page

397

Last Page

426

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