Study On Mechanical Properties Of Co-cured Composite Structure With Discontinuous Damping Film Embedded

Co-cured composite structure with discontinuous damping film embedded is a novel damping treatment.New structure has large damping and high interlayer bonding property.It has great potential for application in spacing technology,cutting-edge weapons and rapid transportation.The structure contains two forms.The one is co-cured composite with perforated fiber reinforced damping film embedded.The other is co-cured and stitched composite with fiber reinforced damping film embedded.Complex structure increases the difficulty of theoretical analysis.Unknown mechanical properties limit the development and application of the structure.Therefore,it has important academic significance and application value to investigate the mechanical properties of this novel structure.Theoretical analysis,experimental verification,numerical simulation and literature comparison are applied in the research.The in-plane equivalent elastic parameters and natural vibration properties as well as lager deformation of the structure are studied.The relationhsips of design parameters with the mechanical properties of the structure are revealed.The main innovation is as follows:(1)The ring deformation model of in-plane fibers with “resin nails” inserted is established.The expressions of the in-plane equivalent elastic parameters of perforated fiber reinforced damping film are derived.The validity of the theoretical model is verified by the in-plane shear modulus test of the perforared and fiber reinforced damping film.Compared with continuous damping film,perforated fiber reinforced damping film has higher shear modulus.The relationships of in-plane equivalent elastic parameters of perforated fiber reinforced damping film with design variables are revealed.(2)The polyline deformation model of in-plane fibers with “composite nails”inserted is proposed.The in-plane equivalent elastic parameters of stitched fiber reinforced damping film are obtained.The validity of theoretical model is verified by tensile tests and literature comparison.The superposition influences of stitch parameters on structural anisotropy are revealed.It will lay a foundation for the natural vibration and geometrically nonlinear research of co-cured composite with discontinuous damping film embedded.(3)According to energy approach and complex stiffness method,the natural vibration models of the co-cured composite plate and beam with discontinuous damping film embedded are built.The validity of the theoretical model is verified by modal tests and numerical simulation as well as literature comparison.Compared with the composite structures with continuous damping film embedded,co-cured composite with discontinuous damping film embedded shows higher bending stiffness.It will provide a new idea for the designability of mechanical properties of damping composites.(4)Combining von Karman strain theory with the principle of virtual work,the large deflection equation of co-cured composite with discontinuous damping film embedded is derived in detail.The numerical analysis of geometrical nonlinearity is completed.The validity of the equation is verified by literature comparison.The relationships of central deflection with design parameters are investigared.The research will provide a theoretical guidance for the large deformation design of composite with discontinuous damping film embedded.