Shigen-to-sozai, Vol.116, No.2, pp.111-118.
Estimation of the Fatigue Strength of Granite Subjectedto Long-period Cyclic Loading
Jun-ichi KODAMA1 Yoshio ISHIZUKA2, Tohru ABE3 ISHIJIMA4 and Tatsuhiko GOTO5
| 1. Research Associate, Dr., Muroran Institute
of Technology, 27-1, Mizumoto-cho, Muroran-shi,
Hokkaido 050-8585 Japan 2. Dr., Shimizu Corporation 3. Shimizu Corporation 4. Professor, Dr., Graduate School of Engineering, Hokkaido University 5. Professor, Dr., Muroran Institute of Technology |
| The effects of excitation frequency on fatigue
life and fatigue damage were investigated
by carrying out a series of cyclic loading
tests at high stress levels on Inada granite.
An attempt was made to estimate fatigue strength
under long-period loading based on the experimental
results. The amount of fatigue damage per
cycle and fatigue life decreased with increases
in the excitation frequency at the same maximum
stress. On the other hand, they did not depend
on the excitation frequency between 2.5×10-4
Hz and 0.5 Hz when the same maximum stress
ratio,which was normalized by the static
strength under a strain rate corresponding
to the excitation frequency, was applied. Cyclic fatigue tests at the frequency of 0.5 Hz were performed under several stress ratios. It was clarified that : (1) there is no fatigue limit within 4×104 cycles of loading, (2) the relationship between stress ratio S and fatigue life Nf can be represented by S = A-B log Nf (S-Nf curve), (3) fatigue strength increases with increases in confining pressure, and (4) fatigue strength decreases in the presence of water. Estimation of fatigue strength under long-period loading might be possible using both the S-Nf curve and the relationship between static strength and strain rate. |
| KEY WORDS: Fatigue Life, Granite, Excitation Frequency, Long-period Loading, Fatigue Strength |