Compressive Properties Of Carbon Fiber Composite Curved Honeycomb Structure

With the depletion of terrestrial resources,the detection and development of marine resources has become one of the effective ways to solve the resource shortage.The development of marine resources is inseparable from deep-sea equipment,which usually provides buoyancy with lightweight materials.At present,glass beads/epoxy composite materials are mostly used for lightweight materials,but their density is high,water pressure resistance is poor,and the buoyancy is small,which is difficult to meet the technical requirements of deep sea equipment.Therefore,designing a buoyant structure that combines low density and high load bearing performance is an urgent problem to be solved.The composite honeycomb structure is a lightweight sandwich structure with excellent mechanical properties and strong designability,and has received extensive attention and in-depth research from scholars at home and abroad.However,the existing honeycomb structure is a straight wall configuration,and the honeycomb wall is prone to buckling failure and the bearing capacity is not high.In order to solve this problem,this paper proposes a curved wall honeycomb topological strengthening method,designs and prepares a carbon fiber composite curved wall honeycomb structure,studies the out-of-plane compression and hydrostatic compression properties of the structure,and reveals its failure mode and failure mechanism.Firstly,the failure strength of the honeycomb structure is predicted theoretically,and an optimized design method and preparation process are proposed.In order to slow the buckling failure,it is an effective way to increase the section moment of inertia of the honeycomb structure.Considering the complexity of the process and the difficulty of assembly,the honeycomb structure is finally designed as a curved-cut curved wall structure.Then,the carbon fiber curved wall honeycomb structure was prepared by the molding method,and the carbon fiber curved wall honeycomb sandwich structure was obtained by bonding the solidified honeycomb structure and the carbon fiber panel with the structural adhesive filmSecondly,through the simulation and experiment,the out-of-plane compression performance of carbon fiber curved wall honeycomb structure is studied.According to the above configuration design and preparation process,two kinds of carbon fiber honeycomb structures,unidirectional and braided,were prepared,and the damage process and compressive strength were simulated.The simulation found that the honeycomb structure was damaged due to buckling failure,and the effects of radius of curvature,cell wall thickness and relative density on the strength and modulus of the honeycomb structure were studied experimentally.The experimental results show that the carbon fiber curved wall honeycomb structure has excellent out-of-plane compression performance compared with the existing aluminum honeycomb structure.When the density is 0.2 g/cm3,the out-of-plane compressive strength is 87 MPa,which is the about 5 times strength of the existing aluminum honeycomb structure;the specific strength is 416 × 103 m2/s2,which is about 4 times the specific strength of the existing aluminum honeycomb structure.In conclusion,carbon fiber curved wall honeycomb structure has excellent compression performance outside the plane,which provides technical support for its engineering application.In order to study the application potential of carbon fiber honeycomb structure in deep-sea equipment,this paper further studies its mechanical properties under hydrostatic pressure.Firstly,the mechanical response,hydrostatic compression strength and failure mechanism are studied through simulation analysis.Considering the density and strength of honeycomb structure comprehensively,the honeycomb configuration with a relative density of 10%was determined to be a hydraulic model.The simulation results showed that,compared with the experimental results of external compression,the hydrostatic compression strength decreased somewhat.Failure process analysis,and surface compression failure process is different,the honeycomb sandwich structure under the hydraulic load,the panel will happen in the region of the honeycomb supports large deformation,lead to the area of contact with the core end to form a surface,core end under complex load,the stress concentration problems,eventually leading to cellular sandwich structure failure in advance.At last,the hydrostatic compression property of the hydrostatic specimen is tested.The experimental results show that the failure modes of the specimens are consistent with the simulation results.The experimental result is 36MPa,which is consistent with the simulation strength.Glass microbeads with the same density can only withstand the water pressure of about 6MPa,while the curved wall honeycomb structure of carbon fiber composite designed in this paper can withstand the water pressure of 36MPa,which is 6 times better than that.It indicates that the application of carbon fiber composite curved wall honeycomb structure with excellent mechanical properties in deep-diving equipment can greatly improve the mechanical properties of buoyancy structure,reduce weight and volume at the same time,enable it to carry more payload and improve its comprehensive performance.