The effect of a spew fillet on adhesive stress distributions in laminated composite single-lap joints

A laminated composite single-lap joint without a spew fillet, subjected to tensile loading, is investigated experimentally and numerically. By directly comparing the experimentally- and numerically-determined deformations of the single-lap joints with and without a fillet, the effect of a spew fillet on adhesive stress distributions is discussed. Moiré interferometry is used to measure the in-plane surface deformation of the overlap region of the test specimens. The deformation interactions of the laminated adherends, adhesive layer and a fillet are documented in the form of orthogonal components of the displacement fields (u and v). Two-dimensional, geometrically linear and nonlinear finite element analyses are performed to simulate the mechanical response of the laminated composite single-lap joint and the effect of a spew fillet. Experimental and numerical results indicate that the adhesive shear and peel strain (stress) concentrations can be reduced greatly by introducing a fillet at the end of the overlap, and these concentrations are affected by the geometrically nonlinear deformation of the single-lap joint.