Study On Mechanical Properties Of Composite Sandwich Structure

Fiber reinforced composite sandwich structure is an advanced structure with high specific strength,high specific stiffness,light weight,easy design,fatigue resistance,corrosion resistance and other advantages,so it is widely used in aerospace and other industrial fields.However,in practical engineering problems,it often suffers various unpredictable damages and failures,and the failure mechanism and failure mode of composite sandwich structures are very complex.Therefore,it is of great significance to study the mechanical properties and failure mechanism of composite sandwich structures.In this paper,the three-point bending performance of composite aluminum honeycomb sandwich structure and the low-velocity impact performance of carbon fiber grid structure are studied.The mechanical properties of fiber-reinforced composite aluminum honeycomb sandwich structure were studied by three-point bending test.The effects of different panel types(carbon fiber panel,glass fiber panel,carbon fiber/glass fiber panel)as well as panel thickness and core pore size on the structural failure mode,ultimate load and energy absorption were analyzed.The results show that the carbon fiber/aluminum honeycomb sandwich structure has stronger ultimate load and energy absorption than the other two structures;Thicker panels,smaller core apertures,stronger ultimate load and energy absorption of the structure;The thickness of the panel has a great influence on the energy absorption,and the diameter of the core has a great influence on the ultimate load.The finite element simulation of the carbon fiber/aluminum honeycomb sandwich structure was carried out,and the failure and deformation process were compared and analyzed,which verified the validity of the model and provided guidance and help for the design and analysis of the experiment.A low-velocity impact finite element model of carbon fiber composite grids was established by ABAQUS,and combined with the VUMAT user subprogram,the three-dimensional Hashin criterion was used to simulate the intra-layer damage failure behavior of carbon fiber composite laminates,and the quadratic stress criterion and the B-K energy criterion were used to simulate the viscosity Interlayer failure of junction-layer Cohesive elements.The effects of structural parameters such as grid aperture,grid height,grid type(quadrilateral configuration,triangular configuration,m-shaped configuration,diamond configuration)on the low-velocity impact performance of carbon fiber composite grid structure were investigated by numerical model.The results show that the triangular configuration has the strongest energy absorption,followed by the m-shaped configuration,the diamond configuration,and the quadrilateral configuration.The higher the height is,the more energy the structure absorbs,and the height of the grid has little effect on the panel stiffness and the impact resistance of the structure.