Numerical analysis of stresses in double-lap adhesive joint under thermo-mechanical load

Abstract

A numerical study for the double-lap adhesive joint made of similar adherends subjected to tensile and thermal loads is presented. A novel displacement coupling conditions which are able to correctly represent monoclinic materials (off-axis layers of composite laminates) are used to build a comprehensive numerical model. Two types of double-lap joints are considered in this study: metal–metal and composite-composite. In case of composite laminates, four lay-ups are evaluated: unidirectional ([08]T and [908]T) and quasi-isotropic laminates ([0/45/90/−45]S and [90/45/0/−45]S). The effect of different parameters (adherend stiffness, ply stacking sequence, adherend thickness, one-step or two-step manufacturing of the joint) on peel and shear stress distribution in the middle of the adhesive is studied. The comparison of the behaviour of single-lap and double-lap joint in relation to these parameters is made. The maximum peel and shear stress at the ends of the overlap with respect to the axial modulus of the adherends are presented in a form of the master curves. The analyses of results show that: the maximum peel and shear stress concentration at the overlap ends is reduced with the increase of the axial modulus of the adherend; the stress distribution in the adhesive layer can be improved (lower stress concentrations and level-out the curve) by changing the fibre orientation (which affect the stiffness) in plies connected to the adhesive layer.