Influence of the Spew Fillet and other Parameters on the Stress Distribution in the Single Lap Joint

Even the most recent closed form analyses of single lap joints assume that the adhesive terminates in a square end. In practice a fillet of adhesive (hereafter called the spew) usually forms at the overlap ends. This spew can considerably reduce peak adhesive stresses and so strengthen the joint. An investigation has been made into the role of the spew for a wide range of joint parameters. The stress distribution across the adhesive thickness was also considered, and was found to be essentially uniform over a large part of the overlap length. However, near the overlap end, the stress variation across the thickness can be high, resulting in higher stresses and so lower strengths than would be expected considering average stress levels in the joint, but even after including the effect of this variation the maximum adhesive stresses have usually been found to be considerably lower than corresponding peak values predicted by closed form analysis of square ended joints.