Precision of the one-dimensional solutions for bonded double lap joints

The solutions that have been proposed for the stress state in bonded joints inevitably adopt a simplified description. By comparison with finite element results, it can be noticed that the analytical solutions reproduce in general terms the stress field, but in the end zones of the overlap mismatches are frequently observed. The present paper focuses the attention on the double lap joint. The classical solutions found by Volkersen (Construction métallique 4, 1965) and Hart-Smith (Technical Report NASA CR-11234, 1973) are compared with a solution, developed in this work, which accounts for bending in the external adherends and axial stiffness imbalance. Several cases of adherend to adhesive elastic modulus ratio, thickness and overlap length are considered; finite element results are taken for reference. It is found that the analytical solutions give acceptable results when the elastic modulus of the adhesive is much lower than that of the adherends. The Volkersen's solution, although it fulfils the zero-traction boundary condition, does not give better results than the others and often underestimates the peak values. It is likely that a better description of stress variation through the adhesive thickness could improve substantially the situation.