| There are three main stays of science and technology in modern times: Material, energy sources and information. With the development of productive force and the improvement of standard of living, the material is transiting from meta, inorganic compound and macromolecule to composites. The natural resources are becoming shortage because beings are consuming more structural materials, then the composite emerges now and then, thermoplastic composites have been studied a lot during the recent a few years. Compared with thermosetting plastics, the molten viscosity of thermoplastic resin, particularly high performance thermoplastic resin is high, which creates difficulty in impregnation into fiber bundles, but, thermoplastic composites offer a number of important advantages over thermosetting plastics, such as unlimited shelf-life, better toughness/damage tolerance, high recycle ability, chemical and environmental resistance, etc.Using simply fabric(woven, braided fabric, knitted fabric, non-woven fabric) to be combined with resin to make laminated plate is the most widely used to manufacture textile composites at present, i.e. interlaminar binding and reinforcing strength, what is made is two-dimensional textile composite. However, these composites exhibited poor impact resistance, interlaminar shear strength, when they are bent and shorn, the phenomenon of delamination occurs. In order to conquer the poor interlaminar shear strength shortcoming of two-dimensional textile composites,3D whole textile composites are developed.In this paper, micro-braided yarn is taken as the medium, the study show that the core-spun yarn made by micro-braiding technology , and the reinforcing fiber can be protected effectively in the following process, and the yarn can get good impregnation, at the same time micro-braided yarn meet for the requirement of rapid, uniform impregnation and harsh 3D cubic weaving condition, this opens up new prospect for weaving of 3D and producing of thermoplastic composites. And, the process technique, the structure as well as the determination of structuralparameters for micro-braided yarn are illustrated and analysed in this article.This article mainly studies the structure of 3D woven, and the unit cell model of 3D woven structure is established in this paper. By means of observing the section of 3D woven and assuming micro-braided yarn section as racetrack shape, yarn configurations as an assemblage of linear and arc sections for binders and warps, and straight form for stuffers and wefts, the unit cell model of 3D woven structure is established in this study. On the basis of the model mentioned above, the length of constituent yarns inside the cell and the orientation angle of binders and warps as well as the fiber volume fraction are calculated. The calculated fiber volume fraction is compared with test results from selected samples of 3D woven composites .A good agreement is demonstrated between the theoretic predictions and the experiment results, this indicates that the unit cell model of 3D woven structure established above is right. This thesis also discusses the process producing of the 3D weaving.Meanwhile, the study sums and talks about the problems of the weaving process as well, and find out the treatment to deal with them.During the process of the consolidation molding consolidation, this paper adopts three schemes to make a kind of samples, while it gives and studies the molding temperature as well as adopts the molding pressure, analyzing the relationship between the molding pressure and the molding thickness.In this paper, the tensile property and bending property among the basic mechanics performance of 3D woven are tested, furthermore, the composite void content indicating compound quality is determine. Through measuring the tensile performance value(tensile strength and tensile modulus), the bending value (flexural strength and flexural modulus)and the composite void content of the specimens, this article analyzes and discusses the factors which influence the... |
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