Abstract: Optimal design of accelerated degradation test plan could raise the estimation precision, so the rule and method of optimal design based on constant-stresses accelerated degradation test is proposed when there is a need for considering products of the degradation of multiple performance parameters and the dependence. Under given normal working stress level, the aim is to minimum the variance of reliability estimates when products reach required life. Given the normal working stress level, the highest test stress level, test truncation time under each stress level, performance parameters degradations and testing number of times and so on, considering the test stress level and the ratio of the sample as design variables, apply maximum likelihood estimation theory, established mathematical model of accelerated degradation test plan optimal design, which based on multiple performance parameters. The result about accelerated degradation test plan optimal design of application of nitrile butadiene rubber O-ring on the electro-hydraulic servo mechanism, shows that optimized test plan can raise estimation precision of reliability and that the numbers of test samples also could be cut down under the same degree of confidence.

Key words: Accelerated degradation test, Constant-stresses, Multiple performance parameters, Optimal design