Strength and failure of an aluminum/PA66 self-piercing riveted assembly at low and moderate loading rates: Experiments and modeling

Abstract

The self piercing riveting (SPR) process is increasingly used in the automotive industry due to its ability to connect multi-materials for weight reduction considerations. The strength and failure of such multi-material assemblies need to be characterized and modelled for full-scale structural computations. An aluminum/PA66 composite 2-sheet SPR assembly is characterized in pure and mixed tensile/shear single connection Arcan experiments. The peak force and dissipated energy increase with the loading angle. Neither loading velocity sensitivity in the range 0.016mm/s−100mm/s nor Pa66 composite fiber orientation sensitivity are observed. Some failure modes of aluminum-aluminum SPR are observed. Experiments are also carried out on a single hat component with multiple connections for two loading rates: 5mm/s and 1500 mm/s. The maximum forces and dissipated energies slightly increase at 1500mm/s. Both tensile and shear dominated mode mix ratio values are experienced by the connections. A 13 independent parameter SPR connector model is employed to model the metallic-composite SPR joint. It features three b-norm criteria employed for irreversible deformation, maximum force and failure. It can be generated by combining some elementary behaviors of the general connector model of Abaqus. The calibration procedure decouples the pure tensile/shear contributions from the mixed tensile/shear ones. The parameters are identified based on the Arcan tests and validated on the component experiments. The overall comparison between computations and experiments show satisfactory results.