Numerical Investigation of the Rivet Installation in an Adhesively Bonded Joint and the Load Transfer in a Bolted/Bonded Hybrid Joint 2014-01-2242
Hybrid (bolted/bonded) joining is becoming one of the innovative joining processes for light weight structures in the transport industry, especially in the aerospace industry where weight reduction and high joining requirements are permanent challenges. Combining the adhesive bonding with the mechanical joining -riveting for instance- can lead to an enhancement of the properties of the joint compared to the wide established riveting, as a result of a synergistic load bearing interaction between the fastener and the adhesive bondline. The influence of the rivet installation process on a hybrid joint regarding the joint stress state, the change of the bondline thickness as well as its effects on the joint performance and load transfer are some of the factors that drive the users to a better understanding of the hybrid joining process. This paper deals therefore on one hand with the numerical simulation of the rivet installation process in an adhesively bonded joint to understand the phenomena occurring during the installation process and on the other hand with the investigation of the load transfer depending on the joint parameters.
In order to simulate the rivet installation in adhesively bonded aluminium (2024-T351) adherends, two models have been developed. One for a solid rivet specified by the European standard EN6081 another for a Lockbolt specified by the standards ASNA2041/ASNA2045. The developed simulation model for the rivet installation process has been validated by comparing the simulation results with experiments regarding the qualitative change of the bondline thickness depending on the adhesive's Young's modulus and on the rivet type. The experimental rivet installation process for the validation of the simulation model takes place in a fully automated C-frame riveting machine with all-electric drilling and riveting operations aptitude. A generic numerical study to determine the effects of the adhesive's Young's modulus on the joint stress state and the effect of the rivet installation on the adhesive bondline has been carried out.
In order to determine the load transfer behaviour in a hybrid joint, a single lap joint model for the above mentioned and aluminium (2024-T351) adherends has been developed. A generic study to investigate the effect of the rivet installation and the adhesive Young's modulus on the load transfer has been carried out. To validate the simulation model for the single lap shear test, the simulation results have been compared with the experiments regarding the force displacement curves.