The effect of infiltration induced crack closure on crack growth retardation

It is now well known that extra materials on the flanks of a fatigue crack will cause premature crack closure and a reduction in crack growth rate. These extra materials may be residual plastic wake, corrosion/oxidation products, phase transformation and fluid. Micro-roughness of the fatigue fracture surface is also capable of bringing about premature crack closure. The phenomenon of crack growth retardation following a single tensile overload has been attributed to some of these crack closure mechanisms. Considerable amount of research has been carried out on the mechanisms and effects of naturally occurring crack closure on fatigue crack growth. By contrast, relatively little attention has been given to artificially induced crack closure. Recently, it has been noted that artificially created crack closure may lead to the development of practical fatigue crack repair methods. This work presents the preliminary results on the effects of using alumina powder reinforced epoxy resin infiltration to induce crack closure.