CFRP构件垫圈/衬套铆接损伤及拉剪性能试验研究

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

碳纤维增强复合材料(CFRP)易发生铆接损伤,通过试验方法开展垫圈/衬套铆接损伤行为及其拉剪性能研究,研究结果表明:镦头不均匀膨胀及下压会导致净铆接和衬套铆接出现不同程度、多损伤模式铆接损伤,而垫圈/衬套铆接后并未出现明显损伤。净铆接试件与垫圈/衬套铆接试件的拉剪力-位移响应呈现出明显的线性、渐进损伤和失效破坏的特征,而衬套铆接由于减小了镦头与层板的有效紧固面积,衬套铆接试件拉剪力-位移响应仅包含线性和失效破坏阶段,其拉剪峰值载荷亦最低。净铆接试件和垫圈/衬套铆接试件的拉伸失效模式均为层板剪切与铆钉拉脱耦合失效,拉脱失效模式为层板铺层断裂和分层,且伴有层板弯曲变形;衬套铆接试件拉剪过程中均发生铆钉直接拉脱破坏。

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.