Abstract:

In order to make inference about problems of accelerated life test plan under different experiments, a stepstress accelerated life test model of units based on Weibull lifetimes is given. For this model, the maximum likelihood estimates of the parameters in normal stress level are derived under TypeII censoring. The NewtonRaphson method is using to solve the likelihood equations, and a simplified estimator is presented, which is used as an initial estimate in the iterative process. Bootstrap confidence intervals for the parameters are provided. Some numerical results for solid tantalum electrolytic capacitor are discussed to illustrate validity of this model.