くさび補強型ストップホールを用いた疲労き裂の簡易補修法

－ コンパクト型適応くさび部材の適用および変動振幅荷重の影響 －

抄録

A simple repair method of fatigue cracks using stop-holes reinforced with slope-type wedge members, which was previously proposed by the author, has been examined for the case of reinitiated cracks. By using this method, the stress intensity factor range around a reinitiated crack tip is expected to be reduced by the wedge load effect of the wedge members. The chief advantages of this method are that the repair work can be easily performed from only one side of a cracked structure, and that the wedge member can be set so adaptive as to maintain the wedge load automatically and effectively as the reinitiated crack grows. In addition to the conventional adaptive wedge member using a pulley and a wire-type displacement meter, a compact adaptive wedge member with a reverse slope and using elastic bands has been newly proposed and comparatively tested with the conventional one. Fatigue tests both under constant and variable amplitude loads were performed on a steel plate specimen with a drill hole and a notch, and validity of the above repair method was experimentally examined using both of conventional and compact adaptive wedge members. As a result of the fatigue tests under constant amplitude loads, it was found that the strain range on the specimen side is reduced to 40.7% and the fatigue life is prolonged by 26.1 times by application of the compact adaptive wedge member as compared with the case of the conventional stop-hole. Under variable amplitude loads, both of the conventional and the compact adaptive wedge members reduced the strain range on the specimen side and prolonged the fatigue life, however, the efficacy of the former was even stronger (30.6～27.8 times in fatigue life as compared with the case of the conventional stop-hole).