抄録
An X-ray study was conducted to investigate (I) the size effect of notched specimens on fatigue, (II) the surface area effect on fatigue and (III) a probability problem. The cyclically induced micro-yielding of the specimen surface, detected by X-ray, is the controlling factor of fatigue damage in the above three fatigue problems. This micro-yielding value is found to be interpretable in the same way as the plastic strain amplitude of low cycle fatigue in terms of the number of cycle to failure. Hence, X-ray observation was confirmed to be a very useful method in detecting fatigue damage in machine parts, and in picking out the parts that might suffer damage under service load.
