Mechanical Properties and Failure Characteristics of Hybrid Bonded-Bolted GFRP/Al Joints under Dynamic Tensile load

In this study, the mechanical properties and failure characteristics of bolted and hybrid bonded-bolted GFRP/Al joints under different loading speeds were investigated. The failure process and strain evolution were recorded using high-speed cameras and digital image correlation (DIC) techniques. The micro-morphology of the fracture was also investigated to explore the effect of loading speed on the fracture mode. The results showed that the peak load, failure displacement, and energy absorption for all joints were sensitive to the loading speed. The peak load and energy absorption of the hybrid joints were higher than that of the bolted joints under both static and dynamic loading. The loading speed had no significant effect on the failure mode of GFRP material in bolted joints, which were all shear-out failures. While for the hybrid joint, the addition of the adhesive layer changed the failure mode of GFRP material from shear-out failures to tension failures. As the loading speed increased, the final failure area of GFRP in hybrid joints gradually decreased. In hybrid joints, a greater amount of bearing damage preceded a final tension failure in GFRP material with the increase in loading speed. The fracture surface became flatter and the pulled-out fiber bundles were more integral due to the fact that cracks within the material could not extend sufficiently at high loading rates.