354 – 354 - Experimental Design and Reliability
Design Optimization for the Step-Stress Accelerated Degradation Tests Based on Exponential Dispersion Process
David Han
The University of Texas at San Antonio
In order to assess the lifetime characteristics of highly reliable products, the step-stress accelerated degradation test (ADT) is a practical and effective solution, especially when there are very few items available for testing. During the past decades, the step-stress ADT has been studied by many researchers based on the assumption that the underlying degradation path follows one of the well-known but restricted stochastic processes such as Wiener, gamma, and inverse Gaussian. In practice, however, the degradation path of a product/device may not follow these specific processes, and the researchers are calling for a more flexible but unified approach toward generalized degradation models. To address this issue, the exponential dispersion process has been proposed, which is a generalized stochastic process including Wiener, gamma, and inverse Gaussian processes as special cases. In this work, we develop the step-stress ADT of products/devices when the underlying degradation path follows a class of the exponential dispersion processes. Based on this framework, the design optimization for the step-stress ADT is formulated under the C-optimality. Under the constraint that the total experimental cost does not exceed a pre-specified budget, the optimal design parameters such as measurement frequency and test termination time are determined via minimizing the approximate variance of the estimated mean time to failure of a product/device under the normal operating condition.