Quantitative evaluation of accelerated stress testing based on SSI

In conducting accelerated stress testing (AST), to quantitatively evaluate reliability with respect to time by use of stress-strength interference (SSI) model, stochastic processes were introduced to describe stress and strength. Firstly, It was assumed that strength degradation and stress variation is drift and symmetric Brownian motion, respectively. Brownian motion SSI established by Basu involved reliability equals 1 when time equals zero. To overcome this problem, from engineering view, reliability of product was regarded as the result, which inherence reliability determined by design and manufacturing is in series with operation reliability decided by experiments and operation. Based on the traditional SSI and Basu's model, time-dependent interference model of strength degradation I (IMSD I) was derived. With the combination of AST and accelerated degradation testing (ADT), data collection method in AST was improved. Finally, simulation example verified the correctness and applicability of the methodology proposed.