Ultra-High Cycle Fatigue Properties of High Strength Steel Fratigue crack initiation mode transition from surface to inside found in Giga cycle fatigue of high strength steel has been examined. A special interest is paid to clarify how the internal crack initiates and grows up to fish eye type marking. To uderstand the meaning of fatigue damage random fatigue tests have been done and the fatigue damage were correlated with the small crack growth behavior. Same approach has been also applied to the fatigue of combined fatigue stressing. Then, the method is applied to estimate the effects of variable stress amplitudes and loading rate.
Further application is at present being undertaken.
Evaluation of Fatigue Strength of Short Carbon Fiber-Reinforced Thermo Plastics by Monitoring Temperature Rise in Fatigue Process Trans. A special attention is paid to understand how the stress state affects the nano-scale fracture process. The Sakko-kai Paper Award, Japan Society for Mechanical Engineers, April 1985. 2000 Kyushu Institute of Technology. All rights reserved.