Electromagnetic Riveting Process And Service Performance Of Carbon Fiber Composite-aluminum Alloy Joint Under Various Working Conditions

Automobile lightweight is one of the significant ways to realize energ y saving and emission reduction.The most effective way to realize lightweight is to use lightweight materials instead of original steel.Carbon fiber reinforced plastic is one of the most potential lightweight material.It not only has excellent specific strength and specific stiffness,but also has good load-bearing and energy-absorbing properties.So this material can lose weight and improve strength at the same time.In addition,carbon fiber is a non-metallic material,which has outstanding corrosion r esistance and anti-aging properties,so as to cause long service life.While it is expensive.So it is often employed with low-cost,high-plasticity aluminum alloys.However,there are tremendous differences in physicochemical properties between the two ma terials,and the current welding technique used cannot realize efficient connection.Electromagnetic riveting has the characteristics of fast riveting speed,large riveting force,stable deformation of rivet and less damage to composite.It can realize the reliable connection between carbon fiber composite and metal materials.In this pa per,T300 carbon fiber composite and 5182 aluminum alloy are taken as the research objects.Firstly,according to the principle of electromagnetic riveting,the riveting platform was built,and the performance of electromagnetic riveted joints under differ ent technological parameters was studied.Secondly,the plastic deformation of rivet,sheet warping,carbon fiber composite damage and joint stress concentration after electromagnetic riveting were analyzed by finite element method.Finally,the service performance?fatigue,dynamic and corrosion resistance?of the joint under different working conditions was comprehensively investigated.The main research work and results of this paper are as follows:?1?The relationship between the technological parameters of electromagnetic riveting and deformation of driven head,microstructure and mechanical properties was revealed.The size of driven head conforming to the national standard was obtained through a lot of process tests.The dimensionless parameter?D/D₀?about dimension of driven head was defined,which made the research results more applicable.Interference measurement,microscopic observation and mechanical property test were carried out on the joints with qualified driven head dimensions.The most sui table technical parameters for this hybrid structure were obtained,and the failure mechanism of the joints under different technical parameters was revealed.?2?The damage model of carbon fiber composite was established.The accuracy of the finite element model was verified by punch speed and rivet deformation?dimensions of driven head and interference?.Through this simulation model,the plastic deformation of rivets and the warping law of sheet metal during electromagnetic riveting process were revealed.The damage mechanism of carbon fiber composite and the stress concentration phenomenon of joint after riveting were analyzed.These results can provide guidance for the subsequent service performance analysis.?3?The fatigue failure model of carbon fiber composite-aluminum alloy electromagnetic riveted joint was established.The fatigue data of the joint were firstly obtained through fatigue test.And then the fatigue data were fitted with the two-parameter weibull distribution to obtain the S-N curve of the joint under high safety factor.It could predict the fatigue life of the joint under different stress levels and provide a design standard for the use of electromagnetic riveting technology.Finally,through hysteresis loop and fatigue fracture analysis,the fatigue failure mechanism of electromagnetic riveted joint was revealed.?4?The dynamic failure mechanism of carbon fiber composite-aluminum alloy electromagnetic riveted joint was revealed.The deformation behavior and joint failure mode of joints with different carbon fiber laminate's thickness during high-speed loading were obtained by full-field strain analysis and failure fracture observation.The mechanical response and failure mechanism of electromagnetic riveted joints under different loading rates were revealed through various tensile velocity tests.The analytical model of maximum shear load of joints was established,which could predict the failure load of joints under high-speed loading.?5?The corrosion characteristics of carbon fiber composite-aluminum alloy electromagnetic riveted joint and the joint strength degradation law in severe environment were revealed.The corrosion failure model of joint was established.The electrochemical properties and mutual corrosion mechanism of th e components were obtained by electrochemical testing.In addition,salt spray accelerated corrosion was carried out,and the microstructure evolution and mechanical property degradation of the joint were revealed.The fatigue fracture was observed and the mechanism of fatigue after corrosion was analyzed...