Introduction to Reliability Demonstration Testing of Nonelectronic Components

摘要

This report is intended as an instructional manual in demonstration testing of nonelectronic components. Primary emphasis is upon truncated tests. Starting from a basic binomial model, the trade-offs between sample size, consumer risk, rejection number and the expected probability of failure are explored. The Weibull distribution is a flexible model for representing mechanical failure modes where reliability degrades with time (a hazard rate that increases with time). The time of test termination follows from the appropriate failure model and the desired reliability. Techniques are presented for analyzing truncated failure data to determine an appropriate failure model. The problems and advantages of using current military test specifications, designed for an exponential failure model, when testing mechanical components, are discussed in detail. The Probability Ratio Sequential Test (PRST) is discussed as an alternative to the truncated test. A variety of PRSTs for different failure models are presented. The Weibull PRST and the exponential PRST are compared.