Nonlinear finite element analysis of stress and strain distributions across the adhesive thickness in composite single-lap joints

A geometrically nonlinear, two-dimensional (2D) finite element analysis has been performed to determine the stress and strain distributions across the adhesive bond thickness of composite single-lap joints. The results of sim ulations for 0.13 and 0.26 mm bond thickness are presented. Using 2-element and 6-element mesh schemes to analyze the thinner bond layer, good agreeme nt is found with the experimental results of Tsai and Morton. Further mesh refinement using a 10-element analysis for the thicker bond has shown that both the tensile peel and shear stresses at the bond free edges change sign ificantly across the adhesive thickness. Both stresses became increasingly higher with distance from the centerline and peak near but not along the ad herend-adhesive interface. Moreover, the maximum shear and peel stresses oc cur near the overlap joint corner ends, suggesting that cohesive crack init iation is most likely to occur at the corners. The dependence of stress and corresponding strain distributions on bond thickness and adhesive elastic modulus are also presented. It is observed that the peak shear and peel str esses increase with the bond thickness and elastic modulus. (C) 1999 Elsevi er Science Ltd. All rights reserved.