Abstract
Fatigue property in gigacycle regime is focused as an important subject in recent years. In such a long life region, a tremendous long period is required to perform fatigue tests. In order to overcome this difficulty, a multi-type rotating bending fatigue testing machine of cantilever type has been developed. It is known that this type of fatigue machine can be performed much quickly comparing with the tension and compression fatigue testing machines, and the fatigue dates are matched with many experimental dates in the past though the dates of an ultrasonic fatigue testing machine are unclear. Researchers would like to carry out fatigue tests at the rotating speed as fast as possible, but the maximum speed of a rotating bending fatigue test are limited because of the heat generation caused by the cyclic plasticity work and the clamping area of a specimen. Each maximum loading frequency may as well be limited by each raised temperature to affect the fatigue properties of base materials. However each appropriate limited loading frequency is unclear because it is very difficult to measure the temperature of the fracture portion of a specimen precisely during the rotating bending fatigue test. The measuring technique of the temperature near the fracture portion in a specimen during the rotating bending fatigue test of cantilever type is proposed, and the maximum speed of a rotating bending fatigue testing machine is discussed about the validity in this study.
