Statistical planning and evaluation of fatigue tests. A survey of recent results

Abstract

The great scatter of fatigue test results demands special planning and evaluation. A development of the Wöhler diagram is presented which splits up the fatigue ranges into ones of finite endurance, transition and infinite endurance. The two types of the Wöhler diagram with this conception are shown. Reasons are given why ranges rather than distinct divisions should be defined. The favorable values of probability of fracture P_F are discussed. Experiences with the mathematical functions are reported. For the transition range the classical evaluation is explained; the boundary technique is recommended, and the staircase method and the Prot and the Locati methods are not recommended. Some recommendations are given for planning tests expected to lie within the range of finite fatigue life.