Study Of Mechanical Properties Of Hybrid Modified Resin And Fiber Reinforced Composites

The epoxy resin composites that with the advantages of high strength,strong designability,simple preparation process and easy to industrialization et al.have been widely used in aerospace,shipbuilding,automobile,building,supplies and so on.and.Resin matrix composites are usual consists of two parts:matrix and the reinforced phase.The epoxy resin composites are widely used in various fields.However,poor interlaminar toughness of fiber reinforced epoxy resin is due to the high cross-linked structure of epoxy resin matrix and the load-bearing capacity will be limited.In addition,the resin matrix composites show different mechanical properties for that are prepared with different component,served in different environment temperature and loading conditions during the actual using process.t.In this paper,firstly,the quasi-static mechanical properties of epoxy resin that modified with single and hybrid particles have been analyzed.Secondly,the dynamic mechanical properties of epoxy resin that modified with single and hybrid particles have been test on the split Hopkinson pressure bar.Finally,mechanical properties,interlayer toughening mechanism of single and hybrid particles modified fiber reinforced polymer composites that served in different temperature conditions have been discussed.The main contents of this thesis include the following aspects:（1）The different mechanical test specimens of epoxy resin matrix and fiber reinforced epoxy resin composites that modified with different particles,which are prepared by dispersing technology of nanoparticle,vacuum assisted resin infusion,vacuum hot pressing molding technology and son on.The mechanical tests were based on the GB and ASTM standards.Meanwhile,the dynamic fracture and compression properties of particle reinforced epoxy resin tested with the two-dimensional digital image correlation technique and the split Hopkinson pressure bar technique.（2）Quasi-static tensile and fracture behaviors of epoxy resin modified with 50nm,100nm,200nm Al₂O₃ are studied by experiment.The toughening mechanism of particle size effect on modified epoxy were studied by micromechanics of continuous progressive damage model.At the same time,particles size effect on the dynamic fracture properties of epoxy resin that modified with 50nm,100nm,200nm Al₂O₃ particles are studied by the split Hopkin pressure bar and digital image correlation technology.The results show that the tensile strength and fracture toughness of epoxy resin modified with nano-Al2O3 particles increase more than 80%.Under quasi-static loading,the smaller the particle size,the greater the tensile strength and fracture toughness,but under dynamic loading condition,the fracture toughness increases with particle size.（3）Quasi-static tensile and fracture properties of epoxy resin reinforced with coupling agent modified 50nm,1μmAl2O3 particles,multi walled carbon nanotubes that in single or hybrid mode are studied.It was found that epoxy resin modified with particle size mix,the quasi-static fracture toughness of epoxy resin can be improved e effectively.（4）The dynamic compression properties of epoxy resin reinforced by coupling agent modified 50nm,1μmAl2O3 particles,multi walled carbon nanotubes that in single and hybrid mode have been conducted on split Hopkinson pressure bar with the loading strain rate of800/s,1200/s,1500/s,respectively.The experimental results show that the stress-strain curves nonlinear stage of epoxy resins modified with different particle types decreases with the strain rate.The dynamic compressive strength and failure strain will be different for the same specimen under different strain rate.（5）Tensile,compressive and flexural properties of epoxy vinyl resin modified with50nm,1μm Al2O3 and short carbon fiber in single and hybrid mode are studied experimentally.It was found that the tensile,flexural and compressive properties of epoxy resin modified with Al2O3/SCF could be improved effectively.The toughening effect was obvious when the epoxy resin modified with hybrid particle and mixed size particles.（6）The mechanical properties and interlaminar fracture properties of carbon fiber reinforced thermoplastic matrix and glass fiber reinforced epoxy matrix composites that modified with nanoparticles have been investigated experimentally.It is found that the interfacial strength can be effectively improved when the nanoparticles are dispersed uniformly on the fiber surface.While the interfacial strength will be reduced for the fiber surface with particle agglomeration.At the same time,the energy dissipation mechanism will be affected by the dispersion degree of particles on the fiber surface during the specimen failure process.（7）Mechanical properties of glass fiber reinforced polymer modified with nano-Al2O3particles in low temperature and high-low cycle temperature service environment are studied experimentally.The temperature effect on mechanical properties of composite laminates are characterized with modulus damage coefficient,strength attenuation coefficient.It is found that the mechanical properties of GFRP in low temperature service environment can be greatly improved,when nanoparticles mass fraction is less than 1%.The tensile and flexural properties of modified and unmodified GFRP decrease with the increase of temperature cycles.However,low cycle times（less than 25 cycles or less）,the residual stress which formed during the preparation process can be eliminated and the mechanical properties can be improved.