抄録
The machine parts or the members of structures are generally subjected to complex stress waves in the service. It is considered that this service stress which varies usually at random consists of continuously varying stress amplitude and continuously varying mean stress.
In this study a statement is made of the tests that were carried out of varying stress amplitude fatigue under constant mean stresses and varying mean stress fatigue under constant stress amplitudes on coiled springs because they are among the most important mechanical elements.
We not only counted the number of stress cycles to failure under the pulsating compression stress, but also investigated the change in residual deflection due to fatigue stressing, and obtained the relation of the residual deflection to the fatigue life.
From these results, it is found that the fatigue life is more dependent upon the stress amplitude than upon the mean stress, and also that the residual deflection is more influenced by the mean stress than by the stress amplitude. On the basis of these experimental results the fatigue life under repeated varying stress has been estimated by application of Miner's linear damage law.
The authors have succeeded in estimating the fatigue life with considerable accuracy for a certain region of the number of stress cycles by introducing the correction factor e-α.
