Fatigue testing and test interpretation

Various material factors and testing conditions which contribute to the scatter found in fatigue data are reviewed in a general manner. The inadequacies of conventional procedures for planning and interpreting fatigue tests are discussed and various application of statistical theory are considered. An attempt is made to derive the cumulative frequency distribution function of fatigue life, at any particular stress amplitude, from considerations of statistical theory. The theoretically derived distribution is shown to approximate the results of rotating-beam and reversed torsion fatigue tests on steel, aluminum and copper. A possible means is suggested for estimating the endurance limit of some metals through analysis of statistical data.Office of Naval Research, U. S. Navy, Contract N6-ori-71, Task Order IV; Project NR-031-00