Abstract
Several researchers have proposed some repair method for damaged machines. It is well known that the stop drilling holes is useful and practical method for fatigue damages. Moreover, the relaxation effect of the stress concentration can be increased by adding notches, holes and so on to the stop drilling holes. The stress concentration of the crack with the stop drilling hole can be relaxed by adding two holes near the crack tip as the holes face with each other symmetrically. Then, it has been reported that the additional holes are effective in the fatigue crack extension. However, the influence which the additional holes have on retardation of the fatigue crack initiation and propagation is not clarified. In this paper, the fatigue tests of the cracked plated with the stop drilling holes and additional holes were carried out on the low carbon steel S45C changing spatial and dimensional relations between the stop drilling hole and the additional holes. The relations suitable for repairing the fatigue crack are examined.
