EXPERIMENTAL AND NUMERICAL-STUDIES OF A LAMINATED COMPOSITE SINGLE-LAP ADHESIVE JOINT

The problem of a single-lap bonded joint with laminated polymeric comp osite adherends and with a spew fillet, subjected to tensile loading, is investigated. Experimental and numerical analyses of this problem a re presented to address the mechanics and deformation of such material and bonding configuration. Strain gages are employed to record the ge ometrically nonlinear deformation of the specimen. Full-field moire in ter-ferometry is used to measure the surface deformation of the adhere nds and adhesive (including a spew fillet). A geometrically nonlinear, two-dimensional finite element analysis is performed to check the mec hanics assumptions by comparing with the experimental measurement. A g ood correlation between experimental and numerical solutions is obtain ed. It is observed that the laminated composite single-lap joint defor ms nonlinearly when subjected to tensile loading. The resulting displa cement 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 strain, for composite adherends on the free surface suffer from the free edge effect, anticlastic as well as bending-twisting coupling effects. For the adhesive strains, the t ransverse normal (peel) component on the free surface is compressive t hroughout all the bond line except for a small region near the tip of the spew fillet, while this component in the interior becomes tensile near the end of the overlap. The adhesive longitudinal strain in the s pew fillet is nsensitive to the three-dimensional deformation effect, but not the adhesive shear strain in the spew fillet. The adhesive lon gitudinal strain is not small enough to be neglected in the stress ana lysis.