Composite Undirectional

Assume that the conductivity of a undirectional, continuous fiber-reinforced composite is a summation effect just like elastic modulus and tensile strength that is, an equation analogous to Eq. (5.88) can be used to describe the conductivity in the axial direction, and one analogous to (5.92) can be used for the transverse direction, where the modulus is replaced with the corresponding conductivity of the fiber and matrix phase. Perform the following calculations for an aluminum matrix composite reinforced with 40 vol% continuous, unidirectional AI2O3 fibers. Use average conductivity values from Appendix 8. 

Figure 16. The deformation behavior of PVC composite reinforced undirectionally by the prepregs. 

Mobility of the ions implies that their association with the PAc chains is weak (or at least not strongly directed). As the weak or undirected bonding limit of the two sublattices is approached, there is no reason to expect the periodicity of the ions along the channel to be compatible with that of the polymer. The resulting sublattices would be incommensurate, and as found in the simulations, they might exhibit a composition and dopant ion periodicities that need not be described by PAKl, PAK2, or any other commensurate structure. 

It is instructive to consider the calculation of the elastic constants for an undirectional fibre composite consisting of perfectly aligned fibres of infinite length. It is assumed that there is excellent adhesion between the fibres and the matrix. 

D 3355 Fiber Content of Undirectional Fiber/Polymer Composites... 

Continuous-filament glass is widely used, alone or in hybrid composite structures with other fibres, in epoxy, unsaturated polyester, phenolic and melamine resins. Techniques for composite formation have already been outlined. In undirectional composites requiring high tensile strength and modulus, S-glass may be used because of its additional contribution to these properties. 

The most recent development is the sharp increase during the past decade in the use of non-metallic composites as structural components. These materials are prepared from so-called prepregs based on undirectional or woven fabrics composed of aramid, glass, or carbon fibers, and for the most part impregnated with thermosetting epoxy formulations. To keep pace with this development, compatible adhesives have been designed that can be either (1) co-cured with the prepegs, or (2) used to bond cured composite to itself, to metallic substrates, or to honeycomb. 

Figure 16.16 Lay-ups (schematics) for laminar composites, (a) Undirectional (b) cross-ply (c) angle-ply and (d) multidirectional. (Adapted from ASM Handbook, Vol. 21, Composites, 2001. Reproduced with permission from ASM International, Materials Park, OH, 44073.)...

Fig. 7. At test temperature 77 K, fractographs of (a) a carbon-fiber-epo composite with (0°, 45°, 90°) cross-ply. The load is applied in the vertical direction (b) an undirectional...

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