Numerical study to understand thermo-mechanical effects on a composite-aluminium hybrid bolted joint

Abstract

Hybrid bolted joints, where carbon fiber reinforced polymers and metallic plates are clamped using bolts, are widely used in aircraft structures. During operation, aircraft experience extreme temperatures that can adversely affect the response of an hybrid joint. On account of the lack of understanding on this aspect, we analyzed a representative carbon-aluminum single lap shear bolted joint using a 3D numerical model. A parametric study varying the temperature, friction coefficient, bolt clamping force, bolt-hole clearance, and thickness of the metallic plate, provided insight into their effect on the stiffness stages of the mechanical response of the joint, as well as the contact evolution among the different elements. Bolt-hole clearance was one of the parameters that most influenced the joint stiffness and bolt bending. Temperature excursions induced sliding between plates and significantly altered the clamping load of the bolt, i.e., a 40% reduction and an 18% increase for a negative and positive thermal jumps, respectively. This clamping load variation entails undesirable bolt loosening or even yielding. Therefore, this work sheds light on the detrimental effects of temperature on hybrid joints, thus providing background for a safer structural design.