Interfacial Enhancement And Mechanical Properties Of Steel/GFRP Co-Cured Hybrid Structures

Composite is widely used in the marine field due to its advantages of designability,corrosion resistance,electromagnetic insulation and high fatigue life.At present,small and medium-sized ships have achieved full composite manufacturing,but the composite structures of large ships still have problems such as insufficient rigidity,insufficient connection strength,and equipment matching.Therefore,metal/composite hybrid structures are proposed.Among them,metal is mainly used to improve the rigidity and assembly of ship structures.The advantages of composite structures are to reduce the weight of ships and improve electrical insulation performance.The connection strength between metal and composite is particularly important in hy brid structures.In the dissertation,steel/GFRP(Glass Fiber Reinforced Plastic)co-cured hybrid structures were prepared based on the co-curing(Comeld)hybrid connection technology.The interfacial reinforcement and mechanical properties of the steel/GFRP hybrid structure were studied by a combination of experiments and numerical simulations.the specific research contents are as follows:To study the effect of surface grooves of steel members on the properties of steel/GFRP hybrid structure,six interfacial groove structures with different topological patterns were proposed,and corresponding steel/GFRP co-cured hybrid structural specimens were prepared.Through the double cantilever beam and shear experiments,the influence law and mechanism of the surface topography of the steel member on the mechanical properties of the hybrid structure are revealed.The experimental research shows that the groove structure of steel members significantly affects the fracture toughness,peel strength and shear strength of the steel/GFRP hybrid structure,and the groove structure of ±45° is the best.At the same time,a numerical model of a hybrid structure with a groove structure of ±45° was established,and the Weibull stochastic method and Cohesive element were introduced to study the influence of the uneven bonding strength of the adhesive layer resin due to defects on the mechanical properties of the hybrid structure.The structural strength and failure mode are in good agreement with the experimental results,which verifies the feasibility of the simulation method and the reinforcement scheme of the groove structure.For the ±45° groove structure,the representative volume element(RVE)model of the steel/GFRP hybrid structure was established,and the shear and peeling simulation of the hybrid structure was completed.The equivalent model of the steel/GFRP hybrid structure is established;the influence law of the groove parameters on the mechanical properties of the hybrid structure is given,and the experimental verification is completed.L-shaped hybrid structures with diferent geometric parameters were fabricated by the cocuring process,and the effects of bonding length and other parameters on the properties of Lshaped hybrid structures were studied.Through the compression experiment and numerical simulation,the ultimate load,displacement and failure mode of the L-shaped hybrid structure compression experiment and simulation are obtained,and the prediction diagram of the failure load,displacement and failure mode is given.According to the prediction graph,the following conclusions are drawn:when the bonding length is 100.00 mm,the steel/GFRP L-shaped hybrid structure has better mechanical properties;The performance of the/GFRP L-shaped hybrid structure was evaluated,and its fatigue failure mode and expected fatigue life were given.