An interval estimate of mean-time-to-failure for a product with reciprocal Weibull degradation failure rate

To meet increasing competition, get products to market in the shortest possible time, and satisfy demanding customer expectations, products are made more robust while few failures are observed in a short development period it now takes to design and produce a product. In this circumstance, assessing product reliability based on degradation data at high stress levels becomes necessary. This data is typically generated through accelerated degradation tests (ADT). There is a need to scientifically design these test plans as a good test plan can save time and expense and provide more accurate estimates of reliability for the same number of test units and test time. Extracting reliability information from degradation data is different from extracting reliability information from use stress level, which makes degradation test planning more difficult. But, when carrying the accelerated degradation tests several decision variables such as inspection frequency, the sample size, and the termination time at each stress level are important. An optimal plan is proposed for the design of accelerated degradation test (ADT) using reciprocal Weibull degradation data based on the minimization of the mean time to failure (MTTF) criterion. A LED example is used to illustrate the proposed method.