Stress, damage, and fatigue performance analysis of CFRP/Al double-sided countersunk riveted joints with variable rivet-hole clearance

Abstract

The CFRP/Al countersunk rivet joints are one of the most fatigued dangerous points of the aircraft fuselage. To deeply investigate the failure mechanisms of the riveted joint structures, this paper utilizes electromagnetic riveting technology to prepare single-lap joint specimens and investigates the quasi-static tensile and fatigue failure behaviours of the joints under different rivet-hole clearances and stress levels. In addition, to assist this investigation, a three-dimensional finite element model, combining riveting and fatigue loading, is developed. This model takes into account the strain rate effects during riveting process and progressive failure behavior of various typical damage modes in CFRP laminates. The results indicate that Aluminum alloy sheets fracture dominates the fatigue failure of the joints. Increasing the clearance can reduce the stress amplitude on the shear plane and further enhance the fatigue life of the joints. Furthermore, all additional CFRP damage during the loading process is the growth of the initial riveting damage, and the damage-induced fibre bearing capacity decrease is considered the reason for the increase in stress amplitude of the Al sheet. Last, excessive clearance enlargement does not appreciably diminish the initial riveting damage, instead, it could result in a joint strength reduction.