1967 年 16 巻 163 号 p. 234-239
One of the authors previously reported the results of the repeated tensile impact test on carbon steel and copper having notches with various fillet radii ρ to find the effect of notches on impact fatigue curves and cleared up the crossing of plastic fatigue curves.
In this paper, the results of experiment are reported on the specimens having notches with constant radius ρ and various ratio of notch d/D where d is the diameter of root of notch and D is the diameter of the parallel part of the specimens.
From the results of experiments, the following conclusions are obtained;
(1) The impact value at N=1 decreases when the diameter ratio of notch d/D becomes smaller.
(2) In the diagram of the relation between the repeated impact energy E and the number of repetitions of impact to failure N, the plastic fatigue curves start from the impact value at N=1 for each type of the specimen. Unlike the case with various fillet radii in the previous paper, they go down abreast to each discontinuous point, and do not cross each other. This seems to depend upon the fact the deformation preventing effect is almost identical in the low energy range of plastic fatigue, because the sharpness of the root of the notch is kept constant.
(3) There was observed the changes of elongation φ and contraction of area ψ with impact energy.