Heuristic Degradation Test Plans for Reliability Demonstration

Reliability demonstration is an important task in the product development process. The commonly used reliability demonstration test methods include bogey test, life test, and degradation test, among which the degradation test is known to be most efficient. However, its application in industry is still limited primarily due to the lack of appropriate test plans. This paper presents heuristic reliability demonstration test plans for the products whose performance characteristics can be modeled with the Weibull distribution. In particular, the paper describes degradation models, test method, test termination rules, and the calculation of reliability and confidence interval from degradation data. The paper delineates test plan models, which are solved for optimal sample size and test time using the proposed heuristic algorithm. The algorithm results in the lowest test cost and the shortest test time for the products that are expected to pass or fail the test at a high degree of confidence. A case study is presented to illustrate the proposed method, and shows that the heuristic test plan reduced the test time, and cost by 27%, and 29%, respectively. The paper also numerically compares the three test methods, and concludes that the degradation test method is most efficient in terms of test time, cost, and sample size.