Study On Mechanical Properties And Failure Mechanism Of Hybrid Bond-riveted Joints

With the development of automobile lightweight,the usage of aluminum alloy is increasing.The bond-riveted joint has the advantages of adhesive joint and rivet joint,and it has excellent performance and bearing capacity.In this paper,through the experimental method,the mechanical properties of the riveted hybrid joint are studied.The main research contents are as follows:(1)The whole process from selecting materials to completion of joint fabrication,detailed steps of quasi-static tensile test method of single/double lap joints and observation methods of scanning electron microscope are introduced.Six groups of the load-displacement curves and mechanical properties(peak load,strength and energy absorption)of single/double adhesive joints,rivet joints and bond-riveted joints are compared.It can be concluded that hybrid bondriveted joint can increase the failure test force of adhesive layer and rivet to a certain extent,increase the failure displacement,effectively extend the bearing time of joint,and greatly increase the energy absorption of bearing.After the failure of bond-riveted joint can continue to play the role of connection,prevent the joint from being completely destroyed due to the failure of adhesive layer,effectively extend the service time of the joint,enhance the bearing capacity,and improve the safety and reliability of the joint.(2)Double rivets of single/double lap joints are taken as the research object to study the influence rule of different rivet arrangement,adhesive layer thickness and lap joint mode on the mechanical properties of the joint.Its mechanical properties are measured by quasi-static tensile failure test.The joint failure modes of single lap joint and double rivet in transverse/longitudinal arrangement are all that the adhesive layer has cohesive failure first,and then the rivets drawing failure occurs,but the failure load and failure strength of the adhesive layer in transverse arrangement are higher than those in longitudinal arrangement.The second peak load,the rivet failure load is not affected by the arrangement.The joint failure mode of double lap joints with double rivets in transverse/longitudinal arrangement is irregular disconnection of aluminum alloy plate in the middle of the specimen.The failure load of horizontal joint is higher than that of vertical joint.The thickness of adhesive layer has no effect on the failure load,failure strength and failure mode of rivets and aluminum alloy plates.(3)Different forms of artificial defects are introduced in adhesive layer of hybrid bondriveted single and double lap joints,simulating defects in the adhesive layer during the manufacture process,to study the effect of local defect on the lap shear mechanical performance of hybrid joint.The bond-riveted single and double lap joints are manufactured with 6061-T6 aluminum alloy as the adherend,and the artificial defects using Teflon spacer with different thicknesses,areas,shapes and locations are placed in the inner region of the adhesive layer before adhesive curing.Quasi-static tensile testing is then conducted on the ready-cured hybrid joint,and macroscopic observation and scanning electron microscopy are used to analyze the failure modes on the failure surface.The experimental results of this paper can provide a reference for the design and application of bond-riveted joint on the body.