Optimal Designs For Accelerated Life Tests Of Competitive Failure Products Under Cost Control

The Step-Stress ALT (accelerated life test) is the most important method in reliability statistics. The problem of optimal design for Step-Stress ALT has been proposed early in the 60s of 20st century. Miller, Nelson(1983) and Bai,Kim, Lee(1989), applying the theory of maximum likelihood estimator(MLE) respectively, discuss the optimal design problem for exponential distribution with two stress. Cheng Yim-ing(1994) generalized the result to the condition of k parameters and k stresses. This paper, under the condition that the number of stress and parameter is not equal, using the principal of minimal MLE asymptotic variance,and applying the theory of Moore-Penrose inverse, solves the optimum design for exponential distribution. This paper also generalizes the result to optimal design for step-stress ALT with competing causes of failure and step-stress ALT under linear restrict. Practical data simulations show that the proposed method is feasible and effective.