| A lightweight,easy-to-deploy high performance explosive protection material is essential for bomb disposal workers and battlefield explosion protection.FRP has the advantages of light weight,high strength,high energy absorption coefficiency and no secondary damage caused by bouncing,so it is an ideal choice to prepare this protective material.The aim of this paper is to design and prepare a kind of high-speed impact resistant composite material.The compound curing agent formulation of F-44 resin matrix was studied in this paper.It was found that when the mass ratio of 593 to DDM was 6:4,the curing temperature was reduced from 120?to 90?with the same curing agent dosage,and the curing time was reduced from 2h to 78min.ETBN was used to modify F-44 resin,with10wt%ETBN as toughening agent and 10wt%PEG400 as capacity enhener.Through Fourier infrared spectrum analysis,it was proved that epoxy groups at the end of ETBN molecular structure participated in the cross-linking curing of epoxy resin,while PEG400did not participate in the reaction,but only played a physical capacity enhancing role.Tensile strength increased from the original 35.6MPa to 55.3MPa,bending strength increased from 58.4MPa to 187.6MPa,and impact strength increased from 0.85 J/cm~2 to1.95 J/cm~2.It was found from the observation of the impact failure fracture of F-44 that the toughened and modified resin presented ductile phase.The addition of PEG400 could improve the interface between ductile phase and brittle phase,and the simultaneous occurrence of holes in the resin limited the mechanical properties of the composite material to some extent.In this paper,the surface modification of Kevlar fiber was studied.The chain structure of Kevlar fiber surface was damaged by ultraviolet irradiation.The results of Fourier infrared spectrum analysis showed that carboxyl and amino groups were generated on the fiber surface.SEM analysis was used to prove that uv radiation 15min introduced active groups on the fiber surface,and the surface roughness increased.A large number of AM molecular crystals were introduced into the fiber surface when the concentration of AM aqueous solution was 10%.When the concentration increased to more than 15%,AM coating layer was formed on the surface,which was not conducive to the formation of chemical bond between coupling agent and F-44 resin matrix.The dynamic contact Angle between the modified fiber and resin decreased from 87.613°to74.757°,and the interfacial shear strength increased from 46.1MPa to 88.1MPa.At the same time,the surface modification of Kevlar fiber improves the tensile strength of KFRP from 240MPa to 315MPa,and the bending property from 162MPa to 325MPa.Different composite structures were designed.When the CFRP/KFRP lamination mode was[0,90]_s,the tensile property ratio of{[0,90]/±45}_s lamination was{0,90].The tensile strength of CFRP increased from 563MPa to 571MPa,and the tensile strength of KFRP increased from 135.6MPa to 218.2MPa.Meanwhile,the tensile modulus of[0,90]_s layer is higher than that of{[0,90]/±45}_s layer.The bending performance of{0,90]/±45}s laminates was better than that of[0,90]_s laminates.The bending strength of{0,90]/±45}_s laminates was increased from 346MPa to 570MPa by resin toughening modification.When[0,90]_s was laid,the strength was increased from 263MPa to 363MPa.The mechanical properties of Hybrid Fiber Reinforced Composite(HFRP)are between the two kinds of Fiber Reinforced laminates.The mechanical characteristics of CFRP at the initial stage of loading and KFRP at the later stage can be used as the transition layer in the material structure.In this paper,the shrapnel impact composite structure of 1400m/s is simulated by finite element analysis.The composite laminated structure of K/H/C has the best impact resistance,and the addition of aluminum foam as the energy-absorbing layer can greatly improve the impact resistance of the composite.Also through the actual test 122 howitzers exploded fragment impact of composite materials,use of depth of field microscope and SEM analysis of fragment impact on composite material damage,KFRP as the first layer of shock effect is good,the various failure modes,fiber appeared three failure modes,can effectively absorb the kinetic energy,reduce the fragment velocity,the CFRP as the first layer of impact damage fracture surface smooth,not fully absorb kinetic energy,fiber shear failure is flat and level.Aluminum foam after the impact of a deeper pit,absorb a lot of energy,while compaction burst is happening.However,the subsequent material was not damaged,so the composite material can fully resist the high-speed impact of more than 1400m/s. |
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