Three-dimensional braided fabric structures

Fujita A, Hamada H, Maekawa Z, Uozumi T, Okauji T, Ohno E, I-beam composites with three-dimensional braiding structure- fabrication and mechanical properties. Proceedings, TexComp-2, Leuven, Belgium, May 17-19, 1994. 

A liber or a filament (a continuous form of fiber) is the fundamental unit of textile materials. It has a unique combination of high strength (tensile, bending, torsional, or compression), high flexibility (i.e., low modulus), extensibility, and shows recoverability on deformation. Most of these properties are observed in one principal direction, which is known as the axis of the fiber. Since all textile structures from one to three dimensional (yam, fabric, or braids, etc.) are built using this basic structural unit, these stmctures also possess the above unique properties. 

Continuous SiC fibers contribute to the toughening of ceramics as the interface in SiC/SiC composites works effectively. Furthermore, continuous SiC fibers are formed into the SiC fiber preform composed of multidimensional woven and braided structures (two-dimensional woven cloth, three-dimensional woven fabric, complex braids shaped as the desired component and so on). The shape of the SiC fiber preform mostly determines the final shape of the SiC/SiC composites. High-performance SiC fibers supplied by Nippon Carbon Co., Ltd., Japan (Nicalon, Hi-Niealon, Hi-Nicalon Type S) (Ichikawa, Okamura, Seguchi, 1995 Takeda,... 

Due to the complex nature of the textile reinforcement since air can become entrapped in the interstices of the fabric structure. This can be particularly evident when coarse yams (or tows) are used or in complex three-dimensional (3-D) stmctures, e.g. braided or woven, and may be most prevalent at the tool/composite interface. 

Manufacturers of composite structures have traditionally used prepreg tape to manufacture structural components. Fibres are initially combined into unidirectional tows (bundles) of fibres combined into fabrics, e.g. by weaving or knitting. The vast majority of the tows employed in woven, braided or knitted reinforcements comprise low twist or untwisted continuous filament yams. Three-dimensional technical textiles can be produced by weaving [5], knitting [6] and braiding [7] or as non-crimp fabrics. 

Braids Is used to give high strength three-dimensional (3-D) reinforcement, incorporating more than one type of fiber, if required. Conventional woven fabrics are limited to providing reinforcement at orthogonal orientations, but many reinforced plastics structures are loaded in non-orthogonal fashion. Woven fabrics are, therefore, not necessarily mechanically efficient. 

A variety of shapes can be fabricated for composite applications, from hollow tubular (with in-laid, non-interlaced yams) to solid sections, including I-beams. Unlike woven fabrics, braided structures can be directly laid on a three-dimensional mandrel by passing it through the braiding ring (Fig. 1.6) and hence producing seamless, near-net shapes. For example, aircraft propeller blades are produced by using this... 

The strength and tensile behavior, at room and high temperatures, as well as the structure of three dimensional earbon fiber/SiC composites, fabricated by the slurry pulse/CVI combined process, were eharacterized by Suzuki et al [207-209]. Carbon fiber preforms, constructed with 4-step braid, 4-step/axial braid, 2-step braid and orthogonal weave, were used as reinforcements of the composites. The composites were fabrieated by a process consisting of slurry and dissolved organosilicon polymer infiltrations, followed by the application of pulse CVI. 

Textile structures can be divided into two- and three-dimensional structures. Most woven fabrics and knits as well as noncrimp fabrics, braids, and nonwovens belong in the first group (Fig. 1.13). For complex, mainly technical products, three-dimensional structures are an interesting alternative to conventional products, namely 3-D wovens, knits, and braids. 

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