| Fiber reinforced plastic(FRP)composites have numerous characteristics such as the high strength to mass ratio,high modulus to mass ratio and desirable design ability.In recent years,composite materials have achieved wide applications in aerospace industry,marine engineering and automotive areas.Resin based FRP has achieved more interests since they are low-cost and with better mechanical properties.The application of resin based FRP in the industry increases sharply.The paper focuses on the properties of both thermosetting and thermoplastic composites,and can be divided into the following aspects:(1)Based on the characteristics of thermosetting and thermoplastic composites,we investigated the processing method.The thermosetting resin is epoxy while the thermoplastic resin is cyclic butylene terephthalate(CBT).Taking VARI as an example,we introduced the manufacturing process of the composites in details.The manufacturing process was adopted in the following FEM and experimental study to investigate the failure mode of FRPs.(2)To study the effect of manufacture processing on the novel fiber reinforced CBT thermalplastic resin composite materials,this paper firstly used two approachs that named vacuum assistanted hot-press molding(VAMP)and vacuum assistanted prepreg(VAP)to manufacture unidirectional glass fiber reinforced polymerized cyclic butylene terephthalate(PCBT)composites(GF/PCBT).Subsequently,the effect of manufacture processing on the interlaminate properties of the obtained composites was analyzed by double cantilever beam(DCB)test.FEM technology was further used to analysis the stress distribution in the material in DCB experiments.The experiment results show that compared with VAP,composites obtained by VAMP that use the limit displacement method has better interlaminate peoperties.Compared with VAP processing,VAMP processing could avoid the appearance of poor adhesive in the composites effectively.The obtained composite laminates in VAMP have better interlaminate strength,and the Mode-I strength increased by 35% while the failure displacement decreased by 40%.Simulation results show that the initial crack in the material has a limited value,and the specimen will completely damaged by delamination once the crack tips formed with increasing of loading time.(3)Hybrid composite laminates with shape memory alloy(SMA)and glass fiber(GF)as the reinforced phase,and epoxy resin as the host material,were manufactured by vacuum-assisted resin injection(VARI)processing.The SMA wires were embedded into the GF/epoxy composites with three kinds of modes.The effect of SMA content and the position on the flexural,low-velocity impact performance of the hybrid composite laminates was investigated.It was found that the bonding performance between the SMA wire and the host material is the key factor that determined the final overall performance of the hybrid composite laminates in both the static and dynamics tests.Based on these experimental phenomenon,we further carried out the fiber pull-out experiment to improve the interfacial shear strength between the SMA and epoxy resin.It was found that the interfacial performance could be enhanced significantly by adding nanoparticles in the interface phase.(4)To study the response of glass/carbon/epoxy hybrid composites under low-velocity drop weight impact,the finite element model of five different kinds of laminates in ABAQUS were built.By using the VUMAT subroutine,simulations of the five kinds of laminates under impact were performed,respectively.The results shows that addition of glass fiber could enhance the toughness of composites significantly compared with pure carbon fiber reinforced epoxy material.Different laminates with different hybrid methods absorbed various energy,it is showed that when glass fiber lay near the surface of the material,the energy absorbed by the composites is the largest and the performance of the composites to bear impact is the best.(5)Tensile properties of epoxy casts together with shape memory alloy(SMA),glass(GF)and carbon(CF)woven fabric reinforced epoxy matrix super hybrid composites were respectively investigated.In order to enhance the mechanical strength of this advanced material,two categories of modifications including matrix blending and fiber surface coating by nano-silica were studied.Scanning electron microscope(SEM)and fiber pull-out tests were conducted to complement the experimental results,respectively.Experimental results revealed that the toughness of epoxy matrix is enhanced significantly by adding 2wt.% nano-silica.The failure mechanism of SMA reinforced hybrid composites is different from that of GF/CF/epoxy composites.The matrix modified by nano-silica could enhance both tensile strength and toughness of all the composites,while the fibers modified by coating nano-silica on the surface have better tensile performance.Fiber pull-out tests were also performed and the results showed that the ultimate pull-out strength of the modified SMA fiber was enhanced significantly,which indicated that composites with fiber surface modification have better interfacial performance. |
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