DocumentCode :
1435097
Title :
Optimum Degradation Tests for Comparison of Products
Author :
Yang, Guangbin
Author_Institution :
Americas Product Development Quality, Ford Motor Company,
Volume :
61
Issue :
1
fYear :
2012
fDate :
3/1/2012 12:00:00 AM
Firstpage :
220
Lastpage :
226
Abstract :
Life tests are often conducted to compare products, designs, or processes to select the one that has the highest reliability. To make a sound decision, engineers may require the tests to continue until all or most of the test units fail. As such, the test time is often excessive, especially when we test high-reliability products. For some products, a failure is said to have occurred when a performance characteristic reaches a specified threshold. For these products, reliability is defined by the performance characteristic. Then comparing the reliabilities of two products can be turned into comparison of their performance characteristics. During testing, it is possible to measure the performance characteristics at different times. Measurement data can be employed to predict whether or not the performance characteristics of the two products will be significantly different at the time of interest, e.g., design life, warranty time, or specified test time. When there are sufficient data to make such a prediction with a high degree of confidence, the test can be terminated. As a result, the test time is reduced. This paper presents a method for comparing the performance characteristics of two products with a reduced test time, where the log performance characteristics are -normally distributed with a mean as a (transformed) linear function of time, and a constant standard deviation. In particular, the paper describes a test method, test termination rules, and degradation modeling. Then we develop an overlap probability as a metric to measure the difference between two products. The confidence interval for the overlap probability is calculated. The reliability and its confidence interval are computed from the degradation data. The paper also delineates optimum test plans which choose sample size and test time to minimize the variance of an estimate related to the overlap probability, and simultaneously satisfy the constraints on test budget and available sample size. The - est plans are robust against the pre-estimates of model parameters. The proposed method is illustrated with a practical example. The application shows that the method is effective at reducing test time.
Keywords :
production testing; reliability; confidence interval; degradation modeling; high reliability products; measurement data; optimum degradation test; optimum test plan; overlap probability; performance characteristic; sound decision; test budget; test termination rules; test time; Degradation; Extraterrestrial measurements; Maximum likelihood estimation; Reliability; Size measurement; Testing; Time measurement; Degradation test; optimum test plan; overlap probability; sample size; sensitivity analysis; test time reduction;
fLanguage :
English
Journal_Title :
Reliability, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9529
Type :
jour
DOI :
10.1109/TR.2011.2182257
Filename :
6142138
Link To Document :
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