Fatigue damage repair: a comparison of some possible methods

When a fatigue crack is discovered in an engineering component, some expeditious temporary repair may be needed before more thorough treatment is available. Conventional repair methods, such as grinding removal of the crack and stop drilling, are often employed. In this work, the method of drilling crack-flank holes near to but not at the crack tip has been studied. It was found that retardation still occurred. Moreover, if the holes were drilled a small distance ahead of the tip, the crack was likely to grow into the hole, achieving a considerable amount of life extension. The effects of inducing artificial crack closure by infiltrating epoxy resin, alumina powder and a mixture of both have also been investigated. These were compared with the effect of overload-induced retardation. In all the methods studied, different degrees of crack growth retardation have been achieved, and they have the potential to be developed into practical fatigue crack repair methods.