The Influence of the Use of Fasteners with Different Stiffness in Hybrid Joints Subjected to Complex Mechanical Loads

Abstract

To this day, most of the papers related to hybrid joints were focused on single and double lap joints in which shear deformation and degradation was the dominant phenomenon. However, in real constructions, complex state of loads can be created by: a) torsion with shear, b) bending with shear, c) torsion with tensile. Analytical and numerical computation for simple mechanical joints is known, however, the introduction of an adhesive layer to this joint makes the load transferred both through: (1) the adhesive and (2) mechanical fasteners. There is also an interaction between the amount and stiffness of mechanical fasteners and the strength of the adhesive layer. The paper presents the results of numerical calculations for the bending with shear type of load for the hybrid structural joint and corresponding simple joints by: (1) pure adhesion and (2) rivets with different quantity maintaining the same cross-sectional area. A total of 9 simulations were performed for: (1) 4 types of pure rivets connections, (2) pure adhesive joint and (3) 4 kinds of hybrid joints. The surface-based cohesive behavior was used for creation of the adhesive layer, whereas the rivets were modelled by connector type fasteners, which simplify complexity of the numerical model. The use of connectors allowed for effort assessment taking into account damage in both types of connections. Application of connector elements can be useful for larger structures modelling, e.g. aircraft fuselage, where the number of mechanical joints is significant and complex load conditions occur.

Keywords

• hybrid joining
• fasteners
• adhesive
• mechanical loads
• numerical modelling