Experiment and simulation study on bonded, bolted and hybrid bolted/bonded joints of textile CFRP using bimodulus constitutive model

Tensile tests on bonded, bolted and hybrid bolted/bonded carbon fibre reinforced polymer (CFRP) joints were designed with four stacking sequences. The force-displacement curves, failure modes, and bolt hole strains were recorded. A bimodulus orthogonal anisotropic constitutive model (BAM) of CFRP was proposed, and this was applied to the joint simulation through the secondary development of ANSYS/LSDYNA combined with a cohesive element. The force-displacement curves, macro and micro failure modes, failure process, tension–compression area distribution, and variation of hole edge strain were analysed in combination with experiments and simulations. The results show that BAM can predict the mechanical properties of bonded/bolted and hybrid joints. In S1, S2 and S4, the strength of the hybrid joint increased by 185.4%, 142.3% and 121.1%, the stiffness increased by 144.3%, 111.0%, and 99.3%. The hybrid joint has a slighter failure degree without severe fastener fracture combined with bonded or bolted joint. Furthermore, hybrid joints can modify the tension–compression area distribution at the side of the bolt hole, thus making CFRP participate more in the load bearing. This is reflected in the increased bolt hole strain and better structural performance.