Mechanical properties analysis of carbon fiber composite bond-rivet hybrid joints of maglev train body in different service environments

Abstract Carbon fiber reinforced composites have the advantages of high specific strength and stiffness, which are widely used in rail vehicles. As one of the most commonly used connection forms for maglev train bodies, it is important to ensure the strength and reliability of the joint under different temperatures. Therefore, the paper takes the perspective of carbon fiber composites in the lightweight application of high-speed train bodies. The optimal geometric parameters (end-diameter ratio e/D, width-diameter ratio w/D) of the bond-rivet hybrid joint connection are investigated. The influence laws on structural strength and load-bearing failure forms are found under typical temperatures such as room temperature environment, high-temperature environment, and alternating high and low-temperature environment. Failure specimens and tensile load-displacement curves were analyzed. At the three-room temperatures, the joint structure with an end-diameter ratio e/D of about 3:1 and a width-diameter ratio w/D of about 6:1 had the highest strength, and the failure form was the ideal extrusion damage around the nail hole. The high-temperature environment has little effect on the overall load-bearing capacity of the connected structure in a short period, but it changes the morphology of the adhesive layer. The structure is more prone to shear and peel failure of the adhesive layer. The strength of the alternating high and low-temperature treated joints is slightly higher than that of the untreated specimens when tensile at room temperature. The epoxy resin and carbon fibers are more closely fitted by the environment, enhancing the ability of the composite laminate to withstand tensile and torsional loads.