Abstract
To obtain long life fatigue properties of various materials within a reasonable time, intermittent ultrasonic loading method is a promising one. The signal pattern of the intermittent ultrasonic loading method consists of a block of duty period and pause period. However, no systematic work of the effect of duty period on the S-N diagram has been done. In the present study, various duty periods were applied to SNCM 439 temperd at high or low temperature and the difference in their fatigue properties was studied. No practical difference was observed, and as long as the fundamental condition that the intermittent method is applied for suppressing the heat generation by internal damping is maintained, any combination of the duty and pause period can be used to obtain the reasonable fatigue data.
