Probability, confidence, and sample-size in fatigue testing

Abstract

The sample size necessary for a statistically significant test has been determined, and a comparison of actual and predicted lives has been made for a desired probability of survival with given confidence level, statistical error, and coefficient of variation diffeient stress levels. This approach has been used for cases where to follow a log-normal distribution. On the basis of this approxiation, it is possible to estimate the lower tolerance limit using a minimum number of samples. It has also been concluded that, whater the sample size, the estimate always results in some error, Ro, which mainly depends on confidence level, probability of survival, and stress level, and that, beyond a specified sample size, fatigue life nation is independent of sample size.