Experimental and Numerical Studies of a Laminated Composite Single-Lap Adhesive Joint

Abstract

The problem of a single-lap bonded joint with laminated polymeric composite adherents and with a spew fillet, subjected to tensile loading, is investigated. Experimental and numerical analyses of this problem are presented to address the mechanics and deformation of such material and bonding configuration. Strain gages are employed to record the geometrically nonlinear deformation of the specimen. Full-field moiré interferometr is used to measure the surface deformation of the adherends and adhesive (including a spew fillet). A geometrically nonlinear, two-dimensional finite element analysis is performed to check the mechanics assumptions by comparing with the experimental measurement. A good correlation between experimental and numerical solutions is obtained. It is observed that the composite single-lap joint deforms nonlinearly when subjected to tensile loading. The resulting displacement and strain fields for the adherend and adhesive layer are also presented. The moire results show that the transverse normal and shear strains, but not the longitudinal stain, for composite adherents on the free surface suffer from the fire edge effect, anticlastic as well as bending-twisting coupling effects. For the adhesive strains, the transverse normal (peel) component on the free surface is compressive throughout all the bond line except for a small region near the tip of the spew fillet, wile this component in the interior becomes tensile near the end of the overlap. The adhesive longitudinal strain in the spew fillet is insensitive to the three-dimensional defamation effect, but not the adhesive shear strain in the spew fillet. The adhesive longitudinal strain is not small enough to be neglected in the stress analysis.