scope:

Purpose.

This standard provides instructions and guidelines for implementing Degradation Analysis, as part of a Weibull analysis, to determine product reliability. In Degradation Analysis, the performance or condition of each part is measured repeatedly throughout the test, with the time to failure (defined as the performance/condition degrading to some specified allowable limit of acceptability) being predicted for any parts that have not failed by the end of testing. These predicted failure times are included along with any actual failure times in the Weibull analysis. Using these predicted times to failure provides more information to the Weibull analysis than does calling these unfailed parts right censored (or suspended) at the point they were taken off test.

Degradation Analysis may be used for both Development and Validation of a product. It is primarily used in a Test-to-Failure validation plan, where, in effect, it increases the number of failure points, and thus improves the Weibull analysis. Both time and cost can be minimized while still implementing a Test-to-Failure plan, because prediction of future failure times reduces the number of actual failures needed to get a good Weibull analysis and reliability assessment. Degradation Analysis may also be used for a Success Test plan, as the measured performance and predicted lives add valuable information about the product and its capabilities, as well as giving an early warning of impending failures.