Stress distribution in laminated composite tubular joints with damaged adhesive layer under torsion

Abstract

ABSTRACT This study investigates the effect of geometric and mechanical properties of the adherends and adhesive layer on the shear stress distribution in a damaged adhesively bonded tubular lap joint (laminated composite to steel) under pure torsion. Using first-order shear deformation theory, the equilibrium equations are deduced and solved by the generalized differential quadrature (GDQ) method, results of which were compared and verified with those of finite element solution. Results show that for the steel and [±15]10 composite adherends, increasing the elastic modulus of the adhesive layer increases the maximum shear stresses in the adhesive layer while increasing the joint length beyond its so-called effective bond length has no additional effect on the peak shear stress in the adhesive. Additionally, selecting a quasi-isotropic lamination setup instead of [±15]10 reduces the peak shear stress, where the use of an orthotropic tube with the lamination sequence of ±45° further reduces this magnitude. Additionally, depending on the size and location of a void or debond in the adhesive layer, the peak shear stresses can gain higher values, with almost similar behaviors for the two defects. Nonetheless, for defects far enough from the adhesive ends, their effects on the adhesive peak shear stress seemed to be negligible.