The effect of adherend alignment on the behaviour of adhesively bonded double lap joints

For an adhesively bonded double lap joint, end mismatch between the two outer adherends can not be removed completely although it can be controlled within a manufacturing tolerance. This paper shows that the end mismatch introduces local bending and, consequently, results in a significant effect on the surface normal displacement. Furthermore, the end mismatch also affects the shear and peel stresses in the adhesive. To include the end mismatch effect, a modified equation is developed to characterise the peel stress in the adhesive layer in terms of the surface normal displacement measured using the holographic interferometry technique. The surface normal displacement predicted by the FEM is validated experimentally. A good correlation is also noted between the adhesive peel stress computed using the FEM and that calculated using the modified equation and the measured surface normal displacement.