Weibull Lifetime Model Considering Stress-Dependent Parameters  
Author J. Juskowiak

 
Co-Author(s) M. Bartholdt; B. Bertsche

 
Abstract Different Weibull lifetime models are presented whose scale, shape and minimum lifetime parameters are stress-dependent. This allows to describe and predict the lifetime of products with a Weibull distribution more accurately wherever stressdependence applies to the failure mechanism as is the case in e.g. failures due to fatigue on which this paper focusses. The proposed procedure encompasses a two-step maximum likelihood estimation and a Fisher matrix confidence bounds calculation followed by a model evaluation. This model evaluation is conducted by means of a general plausibility check, likelihood ratio test and Bayesian information criterion. Their applicability to accelerated life test data is discussed and validated using test data.

 
Keywords Stress-dependent Weibull Parameters, Non-constant Shape Parameter, Accelerated Life Test, Maximum Likelihood Estimation
   
    Article #:  21261
 
Proceedings of the 21st ISSAT International Conference on Reliability and Quality in Design
August 6-8, 2015 - Philadelphia, Pennsylvia, U.S.A.