Lap shear testing is used where an adhesive bond joins flat surfaces.
The required surfaces may be profiled, single, double or multiple, but standard test methods focus on a single joint.
Lap joint strength is a function of the materials used, including their absorbency to adhesive, relative elastic properties, and the cohesive properties of the bonding material.
Standard test methods are usually tensile, but materials like wood are tested under compression.
Being able to analyse test result characteristics in fine detail is important where shear failure may occur in either the bonding or bonded layers or both (adhesion and cohesion).