FATIGUE CRACK-GROWTH RETARDATION BY BONDING PATCHES

A method for fatigue crack growth retardation by bonding patches to cracked surfaces is presented. In an effort to see how fatigue crack growth retardation is affected by some of the patch variables, several experiments are conducted to see their effects. These include different patching configurations, patch thicknesses and surface quality, and finally number of patches applied, one face versus both faces of a through thickness cracked surface. Compact tension specimens are precracked and patches are bonded to their surfaces. Effects of the above mentioned variables on fatigue crack growth rate are then studied. Testing for fatigue crack growth rate is conducted in accordance with the ASTM standard. Within the limits of the experimental constraints of this study, it is seen that fatigue crack growth rates of patched specimens are sensitive to some of the above mentioned variables. Recommendations on how to retard crack growth by bonding patches to cracked surfaces along with suggestions on future work for the purpose of improving the bonding technique are also made.