| Fatigue cracking is one of the common diseases of steel structure.Carbon fiber reinforced polymer(CFRP)is a new,fast and durable method to reinforce cracked steel structures.The performance of adhesive has a significant influence on the bonding performance of CFRP/structure interface.At the same time,the properties of epoxy resin directly affect the properties of carbon fiber composites.Therefore,this paper aims to develop an epoxy resin adhesive with excellent performance.In the past,it was mostly experimental research,and molecular dynamics simulation was relatively rare.Considering the high cost of experimental research and the great influence of the external environment,this paper adopts the method of combining experimental research and sub-dynamics simulation(MD)to investigate the performance of epoxy resin system strengthened by nano-materials.The main research work is as follows:(1)The study of different proportion of carboxyl functionalized carbon nanotubes(TNMC1),hydroxyl(TNMH1)functionalized carbon nanotubes and graphene oxide(TNGO-10)under the room temperature curing epoxy adhesive colloid static performance and the effect of it is concluded that the optimum content of the nanometer materials,by means of scanning electron microscope(SEM)analysis of colloid tensile cross-section morphology,from micro level reveals the nanometer materials to enhance toughening mechanism of epoxy resin.(2)Different curing temperatures were used to cure TNMH1/EP and TNMC1/EP with a mass fraction of 0.2%,and the static properties of TNMH1/EP and TNMC1/EP after curing were tested.The effect of curing temperature on the epoxy resin system strengthened by carbon nanotubes was studied,and the optimum curing temperature was obtained.(3)The static properties of different adhesives and the mechanical properties of CFRP/steel double lap joints with different adhesives were compared and analyzed,and the influence of nanomaterials on composites was analyzed by the distribution of shear stress at the interface and the load displacement curve.(4)Based on the Materials studio2019 molecular dynamics simulation software introduced some basic theory and steps,and introduces the three ways to build epoxy crosslinking system,through the establishment of different crosslinking degree of epoxy resin system and the different diameter of carbon nanotubes reinforced epoxy resin system,and analyzes the different degree of crosslinking and the diameter of the free volume of carbon nanotubes on system,glass transition temperature and the cohesive energy.Furthermore,the mechanism of nano-materials strengthening epoxy resin system was discussed from the molecular level. |
