On the estimation of Kt at a bottom of a grind-out cavity after one-sided patching

An unsupported plate containing an embedded grind-out cavity repaired with a reinforcement bonded on one side may experience a considerable out-of-plane bending near a cavity due to the load-path eccentricity even when the geometrically nonlinear effect is taken into account. This out-of-plane bending causes stresses in the plate near the bottom of the cavity vary significantly through a remaining plate’s thickness with inner wall fiber stresses in some cases at 20–30% higher than the corresponding plane-stress type results, i.e., those without considering the out-of-plane deflections. A plane-stress type analysis of a repair over a corrosion cavity had been presented in a previous paper by Duong et al. [Theoretical and Applied Fracture Mechanics 36 (2001a) 187] for a constant depth cavity repaired with an elliptical patch and most recently by Duong and Yu [International Journal of Engineering Science 40 (2002a) 347] for a spherical depth cavity repaired with a polygonal patch. Extension of these methods to include the effect of out-of-plane bending therefore will be delineated in the present paper.