NASA Reference Publication, Volume 1254
United States. National Aeronautics and Space Administration. Scientific and Technical Information Office
National Aeronautics and Space Administration, Scientific and Technical Information Office, 1977 - Astronautics
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addition Advanced alignment applications approach approximately architecture bonding braid bundle CC composites Ceramic chemical coating compressive containing continuous cracks crystallites cycles density depending deposition direction effective elastic engine exhibit fabric failure final flow fraction geometry glass graphite heat high temperatures higher impregnation improve increase interface internal isotropic knit laminate layer less limit lower Manufacture material matrix mechanical properties mesophase metal method microstructure modulus obtained orientation outer oxidation oxygen percent performance pitch pitch-based carbon fibers planes precursor fiber preform pressure produce protection range References regions reinforced resin resistance result shape shear shown in figure shows similar solutions Space stiffness strain stress structure studies substrate surface techniques temperature tensile strength thermal expansion thickness treatment typical unit cell values vapor volume weave woven yarn yield
Page 102 - Processing-Proceedings of 1987 International SAMPE Metals Conference, August 18-21, 1987. Bibliography A. Chou, TW; and Ko, FK: Textile Structural Composites . Elsevier, 1988. B. Hearle, JWS; Grosberg, P.; and Backer, S.: Structural Mechanics of Fibers, Yarns nd Fabrics. John Wiley & Sons, 1969. C. Kaswel, ER: Wellington-Sears Handbook of Industrial Textiles. West Point Pepperell, Inc., 1963. D. Klein, AJ: Which Way to Weave. Adv. Mater. & Process., vol. 2, no. 3, 1986, pp. 40-43.
Page 72 - On the basis of structural integrity and fiber linearity and continuity, fiber architecture can be classified into four categories: discrete, continuous, planar interlaced (2-D), and fully integrated (3-D) structures. In table I, the nature of the various levels of fiber architecture is summarized (ref.
Page 8 - In the thermal gradient technique (fig. 9), the part to be infiltrated is supported by a mandrel that is inductively heated. Therefore, the hottest portion of the substrate is the inside surface, which is in direct contact with the mandrel. The outer surface of the low-density substrate is exposed to a cooler environment and results in a temperature gradient through the substrate thickness. Surface crusting is eliminated because the deposition rate is greater on the heated fibers near the mandrel,...
Page 14 - Bokros, JC: Deposition, Structure, and Properties of Pyrolytic Carbon.
Page 84 - Brochier (ref. 12), and SEP (ref. 13) and in Japan by Fukuta of the Research Institute for Polymers and Textiles (refs. 14 and 15). The structural geometries resulting from the various processing techniques are shown in figure 15 (ref. 16). Figures 16(a) and 16(b) show the single bundle XYZ fabrics in a rectangular and cylindrical shape. Figure 16(c) demonstrates the multiple-yarn bundle possibilities in the various directions; figure 16(d) shows the multidirectional reinforcement in the 3-D structure...
Page 95 - In this way, four inclined, unidirectional laminae formed a unit cell. Using classical laminate theory, the elastic moduli then can be expressed in terms of the laminae properties. From the preform processing science aspect, Ko et al. (ref. 45) developed a fabric geometric model (FGM) based on the unit cell geometry shown in figure 26. The stiffness of a 3-D braided composite was considered to be the sum of stiffnesses of all its laminae. The unique feature of the FGM is its ability to handle 3-D...
Page 73 - A discrete fiber system such as a whisker or fiber mat has no material continuity; the orientation of the fibers is difficult to control precisely, although some aligned discrete fiber systems have recently been introduced. The structural integrity of the fibrous preform is derived mainly from inter-fiber friction. The strength translation efficiency, or the fraction of fiber strength translated to the non-aligned fibrous assembly of the reinforcement system, is quite low.
Page 88 - The major distinctions of these fabrics are the linearity of the bias yarns, the number of axes, and the precision of the stitching process.
Page 251 - ... to 1 14). Figure 14 shows the type of forced-flow thermal gradient arrangement currently being used for rapid CVI within deposition chambers at General Atomics. Temperature Limitations Current Coatings Although actual temperature limitations on the coatings currently being used for CC oxidation protection will vary depending on specific operating conditions and component performance requirements, general guidelines can be established based on experimental observations and the known thermochemical...