In the present report, we describe the results of the fatigue strength of the spring steel (Sup 3) under the stress waves which are composed of superposition of the two stress waves, with the mean stress 40kg/mm2.
The primary waves are about 70cpm and the secondary ones about 730cpm. The former has a large amplitude and the latter a small one (the ratio: 0-0.8). The specimens which have been treated in ordinary heat-treated conditions are tested in the full size.
We have summarized the results of this experiment as follows:
1) Designing the laminated spring, we should pay attention to the frequency of the fatigue test.
2) When the secondary waves are superposed on the primary ones in such an extent as described in this report, we can estimate the fatigue strength as the following, that is, a) the stress amplitude is of the primary stress waves superposed on the secondary ones, b) the cycle of the repetition is that of the primary waves.