One of the main objectives of the automotive industry is to build more fuel efficient cars. The most dominant factor, among the many that determine fuel efficiency, is the weight of the vehicle. Any overall attempt to reduce weight involves all areas of the vehicle. Over the years the industry has addressed this need by developing new or modified materials and innovative production processes, combining these with one another and transforming them into viable production solutions.
A very successful approach among the many things done is the use of structural metal adhesives, which have brought significant improvements in body shell rigidity and crash behavior. Traditionally, aluminum, steel and other metal parts were joined together with mechanical or thermal methods, such as rivets or resistance welding. But, structural adhesive is now an alternative that engineers consider very seriously.
With any adhesive joint, the goal is to achieve as uniform a stress distribution as possible. The difference of structural and thermal properties between the base materials and the adhesives provide unique challenges in adhesive joint design. Adhesives fail by creep mechanisms that are time-dependent, while mechanical fasteners usually fail by fatigue mechanisms that are cycle-dependent.
The objective of this paper is to present three-dimensional stress analysis of adhesive joints, which are placed under in-plane loads. Analysis of stresses at the joint interface reveals high levels of stress concentration, especially at the edges. These stress concentrations may be reduced by joint redesign. In this paper the simplest form of joint redesign, through the addition of fillets, is explored and its influence on changes in stress levels is reported.