Test Design for Combining Tests at Multiple Product Levels

SUMMARY & CONCLUSIONSIn reliability validation test practice, the component of same type can be tested at multiple product levels such as component, subsystem, system, and product. All those tests contribute something to the component reliability validation. Instead of treating these tests completely independent, there are significant benefits to combine these tests together for the test design and the component reliability performance evaluation. [1] provides a method with the underlying assumption that the same stress level is applied to the component in both component level test and system level test. This paper extends the results in [1] to much general and useful cases in practice. First, consider the components of same type are tested at two product levels in component and system separately with the stress of same type applied for the targeted failure modes. However, the stress levels and therefore the acceleration factors in two tests are different. The goal is to validate the overall reliability requirement with the tests at the component level and the system level combined. The equations for the life test designs are derived and the test design methods are described. Then, the result for the tests at the two product levels is extended to the more general case with more than two product levels. Examples are given to illustrate the developed methods.