In order to investigate the fatigue life of notched specimens under combined bending and torsion which were acting at different frequencies, a testing machine was deviced, and some experiments were carried out on three types of notched carbon steel specimens.
In the same way as that proposed in the previous paper, a modified Findley equation including the correction factor of different frequencies R1/t was used as the criterion of fatigue life, (σ/σN)1/ψN+(R1/t·τ/τN)2=1
where σN, τN=fatigue strengths at N cycles
ψN=τN/σN
R=the frequency ratio of torsion to bending
t=the gradient of the S-N diagram of torsion
It was found that the method was applicable to the notched specimens also.
