Characterization of fatigue crack growth in aluminium panels with a bonded composite patch

Abstract

This study introduces an analytical procedure to characterize the fatigue crack growth behavior in an aluminium panel repaired with a bonded composite patch. This procedure involves the computation of the stress intensity factor from a two-dimensional finite element method consisting of three layers to model cracked plate, adhesive and composite patch. In this three layer finite element analysis, as recently introduced by the authors, two-dimensional Mindlin plate elements with transverse shear deformation capability are used. The computed stress intensity factor is then compared with the experimental counterpart. The latter was obtained from the measured fatigue crack growth rate of an aluminium panel with a bonded patch by using the power law relationship (Paris Law) of an unpatched aluminum panel. Both a completely bonded patch (with no debond) and a partially bonded patch (with debond) are investigated in this study. This procedure, thus, provides an effective and reliable technique to predict the fatigue life of a repaired structure with a bonded patch, or alternatively, it can be used to design the bonded composite patch configuration to enhance the fatigue life of cracked structure.