67 巻 (2001) 660 号 p. 1372-1377
The fatigue test of surface crack propagation was conducted on the plate specimen with a small hole at a notch root. The cyclic strain at a notch root was measured by a strain gage and the cyclic strain behavior has been shown as the relationship between the strain and the number of cycle. The propagation rate of the surface fatigue crack at a notch root was found from crack length curves. It is found that the propagation rate of surface fatigue crack is expressed as the mth power of the range of strain intensity factor. The strain intensity factor is defined as the parameter multiplied the cyclic strain range at a notch root by root of the half length of a surface crack length. The value of m is 2 in the middle and is more than 2 in the edge of the plate thickness.