Philipp Mell

Abstract

Zero Failure Tests are widely used to demonstrate the reliability requirements placed on products. The test is popular in application because it offers a number of advantages. DUTs (device under test) are tested to the service life requirement and then classified in a binary fashion, as they can only assume two states after testing - Intact or Failed. This allows test planning to be based on the binomial distribution and be handled very easily. The sample size to be tested results directly from the reliability and confidence to be demonstrated. Since parts only have to be tested up to the requirement and not beyond, the test also has advantages from a test planning point of view. In addition to cost savings, the test can be planned very well due to its fixed run times. However, there are some major drawbacks. For example, if the Zero Failure Test fails, it may be concluded that the product does need to undergo changes, in order to pass the test. However, this can be the wrong conclusion and a wrong business decision, since changes in the product are often very expensive in the late product development stages. Instead of changing the product, a change in testing can be the more efficient way of dealing with a failed test. In order to do this, a holistic view of available tests and test configuration is needed, as well as an objective measure for assessment. This tutorial provides the basics and differences of life testing strategies and a broad overview of different cases, scenarios, methods, processes and practical aspects of testing for the most important case of reliability demonstration. For several testing scenarios, it is shown how to best deal with test planning, in order to achieve the main target of testing. The tutorial also highlights the implementation practicalities, such as cost constraints, time constraints, and test capacity constraints.