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ABSTRACT
A simple method of repairing fatigue cracks using stop-holes reinforced with wedge members has been newly proposed. By using this method, the stress range at the stop-hole edge is expected to be drastically reduced by the wedge load effect of the wedge member. 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 even after the structure around the stop-hole is subjected to some excessive tensile loads and the stop-hole is plastically deformed. Specifically, slope-type wedge members have been newly designed and optimized, and an adaptive mechanism of the wedge member has been devised using a pulley, a string and a weight. Static loading tests and fatigue tests were performed on a steel plate specimen with a slit and a drill hole, and validity of the above repair method was experimentally examined using both of simple and adaptive wedge members. FE analyses using contact elements were also carried out for a comparative study. As a result, it was found that the stress range at the stop-hole edge is reduced by more than 60 % and the fatigue life is prolonged more than 20-fold by application of the adaptive wedge member as compared with those in the case of the conventional stop-hole. It was also shown that application of the simple wedge member is limitedly effective when the wedge part is held on the specimen and the applied load range is lower than a certain level.