Mechanical characterization of a modern epoxy adhesive for automotive industry

Adhesives have become a key technology in the automotive industry, since they can join numerous materials such as steel, aluminum and fiber-reinforced plastics. A modern structural adhesive must work in various temperatures and stress levels without the joint failure. In order to properly design adhesive joints, it is necessary to know the mechanical properties of the adhesives. In this study, the mechanical characterization of a new modern epoxy adhesive for automotive industry was done. Tensile bulk tests were performed to determine the tensile properties of the adhesive as a function of temperature (the Young's modulus, the ultimate tensile stress and the failure tensile strain). Fracture tests (Double-Cantilever Beam test as a function of temperature, and the End Notched Flexure test at room temperature) were performed in order to get the fracture toughness of the adhesive in pure mode I and pure mode II. Finally, single lap joints were fabricated using two different adhesive layer thicknesses and three overlap lengths and tested as a function of temperature to assess the adhesive performance in a joint. The results found fully characterize the adhesive, which combines good mechanical strength and high toughness with ductility, being suitable for automotive industry.