Sample Size Equation of Mechanical System for Parametric Accelerated Life Testing

Abstract

This chapter proposes how to decide the sample size. Due to cost and time, it is unfeasible to carry out the reliability testing of product with many samples. More studies on testing methods should explain how to decrease the sample size. To provide the accurate analysis for product reliability in the bathtub curve, Weibull distribution is chosen. Based on Weibayes method, we can derive the sample size equation from the product BX life. As the reliability of product is targeted and the limited sample size is given, we can determine the mission cycles from new sample size equation. Thus, by applying the accelerated loading to mechanical product, we can reveal the design failures of product and confirm if the reliability target is achieved. Comparing conventional sample size equation, this derivation of sample size equation is helpful to evaluate the lifetime of mechanical product and correct its design problems through parametric accelerated life testing (ALT). This equation also might be applicable to develop the test method of all sorts of structure in the civil engineering.