Mechanical Characterization Of Steel/CFRP Double Strap Joints At Elevated Temperatures And Its Numerical Simulation Study

Carbon Fiber Reinforced Polymer(CFRP)is widely used in the field of reinforcement and repair of civil engineering structures due to its light weight,high strength,fatigue resistance and durability.The performance of the bonded CFRP-steel system is very sensitive to temperature.In the past,the system was considered as a whole,and the temperature was less studied from its specific material and structure.Moreover,previous studies rely entirely on a large number of experiments to describe the mechanical performance of the system,and the research cost is large.Based on the high temperature resistant adhesive developed by the research group and the commonly used structural adhesives,the thermodynamic performance of the adhesive and the temperature mechanical properties of the bonded CFRP-steel structure were studied and simulated.The specific work is as follows:1.The quasi-static tensile and dynamic thermodynamic properties of four epoxy adhesives at different temperatures were tested.The temperature influence law of static and dynamic mechanical properties of epoxy adhesives and the evaluation method of high temperature resistance were studied.2.The thermodynamic properties and high-efficiency curing system of high-performance high-temperature epoxy adhesive HJY adhesive were obtained through experiments.The tensile test of HJY bonded CFRP-steel double-shear joint specimens under different temperature conditions was carried out,and the mechanical properties at different temperatures were obtained.It was proved that the HJY bonded CFRP-steel system has good high temperature resistance.It can be applied in civil engineering structiUres that need to withstand high temperatures.3.Based on the field of composite materials and the results of continuous damage mechanics,considering the damage and failure of different materials and structure composition of bonded CFRP-steel joints,the damage mechanics simulation method was studied.Based on ABAQUS/Explicit platform,the damage mechanics finite element model of bonded CFRP-steel joint is established and calculated.The simulation results are in good agreement with the test results,which verifies the validity of the whole process damage mechanics simulation method of bonded CFRP-steel joint.4.The high temperature mechanical behavior of bonded CFRP-steel joint was simulated,and the influence law of working temperature and curing conditions on the high temperature mechanical properties of bonded CFRP-steel joint was obtained:as the test temperature increased,the surface strain distribution of CFRP would become wider,and the peak interface shear stress would decrease,and the mechanical properties of the joint would deteriorate Increasing the curing temperature and the curing time at high temperature can increase the peak shear stress and increase the interface force transfer efficiency.The research results can provide reference for the design of bonded CFRP-steel structure.