Effect of wood species and glue type on contact stresses in a mortise and tenon joint

Abstract

New technologies for wood building construction continue to employ various profile-adhesive joints, with mortise and tenon joints being the most popular. Their strength depends both on the wood species and type of the applied glue, as well as the execution accuracy of individual elements. The aim of the performed experiments was to determine the size of normal stresses in places of mutual pressures of the tenon and mortise and the impact of the change of wood species and the type of glue (or lack of glue) applied to the joint on the value of those stresses. It was established, on the basis of numerical calculations, that the phenomena of the tenon and mortise contact are caused both by the bending of the tenon as well as by the torsion of the glue bond. Stresses in the direction perpendicular to the fibre course generating pressures exceeding wood compression strength turned out to be the most dangerous for the tenon and mortise joint. The value of the linear elasticity modulus of the glue bond exerts a decisive influence on the stress values caused by the mutual pressures of the elements of the examined joint.