Damage behavior and mechanical property investigation of CFRP/CFRP washer-bushing riveted joints

Abstract

Carbon fiber reinforced composites (CFRP) are prone to occur riveting damage. Therefore, the damage behaviors and mechanical properties of CFRP/CFRP washer-bushing riveted joints were investigated experimentally in this paper. Results showed that due to the uneven expansion of rivet shank and local pressure caused by upsetting head, CFRP/CFRP riveted joints occurred multiple damage modes by using net riveting method and bushing method. The damage was mainly located in the layer around the CFRP hole near the upsetting head. However, washer-bushing riveting method effectively limited the uneven expansion and the local pressure of upsetting head, and no obvious damage was observed. Load-displacement curves of direct riveted joints and washer-bushing riveted joints exhibited obvious linear stage, progressive damage stage and final failure stage in both tensile shear and pull-off tests. However, the bushing reduced the effective fastening area of upsetting head, and load-displacement curves of bushing riveted joints only included linear and failure stages. Besides, the tensile shear and pull-off peak load were also the lowest. Tensile failure modes of both net riveted joints and washer-bushing riveted joints were dominated by the coupling failure mode of shear failure and rivet pull-off. The CFRP connecting hole was observed with obvious shear damage and extrusion deformation area. Besides, pull-off failure modes were laminate fracture and ply delamination, and also accompanied by laminate bending deformation. In contrast, bushing riveted joints failed by rivet pull-off in both tensile shear and pull-off tests.