Research On Optimal Design Method Of Test Profile For Accelerated Life Test

The accelerated life test is often used for evaluating the reliability of high reliability and long life products in engineering practice.The accelerated life test can get the life information of such products faster than the traditional environmental test and has the significant advantages of reducing test time,lowering test cost and improving test efficiency.The optimal design of test plan is to further improve the accuracy of reliability evaluation and test efficiency.In order to realize a fast and accurate reliability evaluation of high-reliability and long-life products at normal stress level.The three-parameter Exponential-Weibull distribution is took into account,which can better characterize the complexity of such products and the multi-factor of the failure mechanism.The optimal design of a three-step accelerated life test profile is discussed,which based on the three-parameter ExponentialWeibull distribution,stress transition time and stress level are used as design variables,minimize the asymptotic variance of the logarithmic median life of the product at normal stress levels is used as the optimization criteria.The main research contents of this article are as follows:(1)The optimal design of the three-step stress Type-I censored accelerated life test plan was performed based on a three-parameter Exponential-Weibull distribution,stress transition time and stress level are used as design variables,minimize the asymptotic variance of the logarithmic median life of the product at normal stress levels is used as the optimization criteria.The comparison between the optimized test plan and the traditional uniform design test plan shows that the optimized test plan has higher accuracy of estimation.(2)The BP neural network is used to train the implicit asymptotic variance expression to further improving the optimized test plan for making fast estimation without losing the estimation accuracy.The results show that the 3-layer BP network has better fitting prediction ability than the 2-layer BP network.(3)Simulate and evaluate three test schemes,including the traditional uniform test plan,the optimized test plan in this paper and the BP improved test plan.Comprehensively evaluate the advantages and disadvantages of the test plan from the three aspects of accuracy,stability and fastness.The results show that the BP improved test plan takes less time than the other two test plans while satisfying the accuracy and stability.It is the best test plan among the three.