Abstract
Uniaxial tension cyclic loading and creep tests were carried out on Inada granite aiming to clarify effects of stress amplitude and loading rate on fatigue behavior. Relationship between fatigue life, deformation behavior and AE activity were also examined. It was found that time to failure in cyclic loading test became shorter than that in creep test for low applied stress. This indicates stress amplitude has a significant effect on fatigue failure. The amount of fatigue damage per cycle increased with decrease in loading rate when the same maximum stress was applied. This is thought to be cause of decrease in fatigue life with decrease in loading rate. On the other hand, the amount of fatigue damage per cycle and fatigue life did not depend on loading rate when the same maximum stress ratio, which was normalized by the uniaxial tensile strength at each loading rate, was applied. Fatigue life of a specimen showing less strain increment tended to be longer and the relationship between the minimum value in the strain increment and fatigue life was represented by a line regardless of loading rate and maximum stress. AE event rate as well as strain increment was inversely proportion to life expectancy before failure. Ratio of AE event rate in unloading to loading began to increase just before failure. These results show that strain increment and AE event are useful parameter to predict fatigue failure.
