Accelerated life testing under variable synthetic stresses for hydraulic pump

Life testing is an important technique to assess the reliability and lifetime of components with long life and high reliability. To some expensive products, it is difficult to supply a large of samples and long test time to carry out the life testing, so this paper investigates the accelerated model and presents statistical method based on hybrid Weibull distribution under variable synthetic stresses. Based on the cumulative exposure theory, the failure probability can be cumulated with transform rate that can convert the fault proportion at certain stress into another stress. Using the genetic algorithm, the parameters of accelerated model can be estimated according to the accelerated stress profile. Then the lifetime at normal stress can be calculated with accelerated life model under normal stress profile. Application of hydraulic pump indicates that this method can reduce test time and test samples greatly.