Study On The Mechanical Properties Of Multiaxial Warp-knitted Reinforced Composite Of High Performance Fibers

In modern high technology,materials technology information technology and energy technology have been considered three basis.High technology increasingly have more dependence on the new materials.The development of New materials technology has a great support to the development of many industries.The composites which are made of two or more than two materials are paid attention by many countries,for they not only improve and raise mechanical physical and chemical properties of single conventional materials,but also solve the key question which we can not settle if we use traditional materials in the engineering.Fiber reinforced composites are a new kind of materials in 20 century of materials science field,they are extensively used in aviation spaceflight traffic building materials chemical industry physical training and medical treatment and so on.The materials reinforced in the composites have developed from filaments to all kinds of fabrics,they make the processing of composites more continuous and automatic,at the same time,they increase the mechanical properties of composites and reduce the cost,flnally,they make the solid basis for the civil fields.A newtype of composite named multiaxial knitted-warp reinforced composite of high performance fibers is coming out along with the continuous research of high performance fibers and high performance resins.In this thesis,the fabrics used in reinforced composites have had a significant improvement in weave technology,they can bind seven layers reinforcement yarns into fabrics with warp yarns which move by chain stitch or tricot stitch,and the direction of any layer yarns can be changeable.Meanwhile,the high performance fibers can be Kevlar Carbon and Glass.In this paper,firstly,I introduce the manufacture of composites in detail,for example how to select the suitable resins and fix the prescription of resins;How to define the technology suitable to this structure by the characteristics of fabrics reinforced. Secondly,I discuss the tensile and bending performance of multiaxial warp-knitted reinforced composite of high performance fibers,I can see that the tensile of specific strength of Kevlar multiaxial warp-knitted reinforced composite is the great,and the tensile of specific module of Carbon multiaxial warp-knitted reinforced composite is the great in the same resin condition;Not only the tensile of specific strength but also the tensile of specific module of VE reinforced composite is the great in the same fabric.The results of tensile and bending are different along the different directions of composite,for the weft yarns are impaired easily by needles in the course of weaving.Finally,I use cross test to compare the differences of energy absorption of composites which are made of three kinds of fabrics of high performance fibers(Kevlar Carbon and Glass) and three kinds of common resins in the different of thickness and contents of volume and select the best scheme. The best scheme is Kevlar/VE composites,the contents of volume is 50%,thickness is 12.7mm,this standard composite's anti-strike is the best.Finally in this thesis,the problems of research and directions of research in the future have been outlined.