Normal Distribution or a Weibull Distribution for Fatigue Lives

摘要

The results of six series of 18 to 30 similar fatigue tests on three types ofspecimens were used to check the applicability of the normal distribution function and the three parameter Weibull distribution function: unnotched, edge notched, and riveted lap joint. A least square procedure was adopted to obtain the three parameters of the Weibull function. Comments are made on the results obtained. On average, the Weibull distribution function agreed equally well or better with the test data in comparison to the normal distributiuon function. The data confirm relatively more scatter for higher endurances. The practical significance of statistical analysis of large test series should be considered with extreme caution in view of possible sources of scatter in laboratory tests, which may be irrelevant in practice.