Fiber architecture

The premise that discontinuous short fibers such as floating catalyst VGCF can provide structural reinforcements can be supported by theoretical models developed for the structural properties of paper Cox [36]. This work was recently extended by Baxter to include general fiber architecture [37]. This work predicts that modulus of a composite, E can be determined from the fiber and matrix moduli, Ef and E, respectively, and the fiber volume fraction, Vf, by a variation of the rule of mixtures,... 

Another major drawback of polysaccharides is their hydrophilic nature leading to low degrees of adhesion between fiber and matrix [11]. Moisture absorption takes place by three types of mechanisms namely diffusion, capillarity, and transport via micro cracks [2]. Among the three, diffusion is considered to be the major mechanism. Water absorption largely depends on the water-soluble or hygroscopic components embedded in the matrix, which acts as a semipermeable membrane. While, fiber/matrix adhesion and fiber architecture also affect the moisture absorption. The results of the water sorption experiment showed an interesting trend. The extent of water uptake was not very significant and also did not increase linearly with amount of filler (Table-2). 

Chemical Vapor Infiltration (CVI). Recall from Section 3.4.2 that CVI is primarily nsed to create ceramic matrix composites, CMCs. Fabrication of CMCs by CVI involves a sequence of steps, the first of which is to prepare a preform of the desired shape and fiber architecture. This is commonly accomplished by layup onto a shaped form of layers from multifilament fibers using some of the techniques previously described, such as filament winding. 

Continuous strand mats are approximately isotropic and have almost the same permeability in all directions (in the plane of the fabric). Many other fabrics, however, are strongly anisotropic and have different permeability in different directions. Gebart [18] proposed a model for this class of fabrics derived theoretically from a simplified fiber architecture. The model, which is valid for medium to high fiber volume fractions, was developed for unidirectional fabrics, but it can also be used for other strongly anisotropic fabrics. In this model the permeability in the high permeability direction (which is usually, but not always, in the direction of the majority of fibers) follows the Kozeny-Carman equation (Eq. 12.2). In the perpendicular direction, however, it is ... 

Fig. 11 Fiber architecture of a 3D orthogonally woven structure for cartilage tissue engineering, (a) Interlocking multiple layers of two sets of in-plane fibers (x- and y-direction). (b, c) Third set of fibers in the -direction cross-sectional views are of the Y—Z plane (b) and X-Z plane (c).

All of the CMC properties that govern structural utility and life depend upon the constituent properties (fibers, matrix, interfaces), as well as the fiber architecture. Since the constituents are variables, optimization of the property profiles needed for design and lifing become prohibitively expensive if traditional empirical procedures are used. The philosophy of this article is based on the recognition that mechanism-based models are needed, which allow efficient interpolation between a well-conceived experimental matrix. The emphasis is on the creation of a framework which allows models to be inserted, as they are developed, and which can also be validated by carefully chosen experiments. 

CMCs with 2-D fiber architecture are susceptible to interlaminar cracking in various component configurations (Fig. 1.38). In such cases, as the crack extends through the component, conditions range from Mode I to Mode II. Tests and analyses are needed that relate to these issues. Most experience has been gained from polymer matrix composites (PMCs).99 The major issue is the manner whereby the interlaminar (transverse) cracks interact with the fibers. In principle, it is possible to conduct tests in which the cracks do not interact. In practice, such interactions always occur in CMCs, as the crack front meanders and crosses over inclined fibers.100,101 These interactions dominate... 

As mentioned previously, the heat flow through C/C composites by conduction can be controlled by the design of the fiber architecture. The most suitable design method is by using the functionally graded fiber arrangement technique. 

Carbon-carbon composites made with the functionally graded fiber arrangement technique present the opportunity to tailor thermo-physical properties into carbon materials. In this paper, the changing of the fiber architecture is the method for FGM. Fibers or matrices are other options for FGM. This functionally graded fiber arrangement technique can be applied to a wide range of materials processing. 

Coated woven glass cloth and fiber Architectural fabrics, gaskets and laminates, electrical insulation, release sheets, hoses... 

Reese, T.G., et al.. Imaging myocardial fiber architecture in vivo with magnetic resonance. Magn Reson Med, 1995. 34(6) p. 786-91. 

Fung, Y.C. (1981). Biomechanics Mechanical Properties of Living Tissues. Springer-Verlag, New York. Cans, C. (1982). Fiber architecture and muscle function. Exerc. Sport Sci. Rev. 10 160-207. 

Stress-free and unloaded reference configurations Muscle fiber architecture Connective tissue organization Pericardium, epicardium, and endocardium Coronary vascular anatomy... 

Birkefeld K, Roder M, Von Reden T, Bulat M, Drechsler K. Characterization of biaxial and triaxial braids fiber architecture and mechanical properties. Appl Compos Mater... 

Designs and fiber architectures that obviate the delamination sensitivity of the critically important joints and attachments should be used (as they are in PMCs). 

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