Planning Optimal Degradation Tests in Consideration of Budget and Statistic Accuracy on Different Stress Levels  
Author Zeljana Beslic
Co-Author(s) Peter Müller; Shuang Yan; Bernd Bertsche
Abstract Degradation testing is a useful technique to demonstrate the process of failure over time. The challenges for planning a test are how many test units should be examined, how long the test should run to get enough data, to reach the predefined reliability targets within the provided and/or available test budget. In this paper, a strategy workflow to identify the sample size and the number of measurements during each test run to determine the degradation characteristics in consideration of the accuracy will be purposed. The number of sample size and the testing time are constantly adapted until the predetermined requirements are met. The presented work results in a treatment of a mechanical failure mode: pitting of transmission gears. We apply this degradation model to degradation signals obtained through the relatively time-consuming and cost-intensive accelerated testing of gears on a testing bench. The results contain the optimal sample size, the number of inspections for each sample and the asymptotic lifetime and its variance coefficients.
Keywords Degradation tests, test plan, statistic accuracy, test expense
    Article #:  23-108
Proceedings of the 23rd ISSAT International Conference on Reliability and Quality in Design
August 3-5, 2017 - Chicago, Illinois, U.S.A.