Chapter 16: Problem 23
Cite the distinction between carbon and graphite.
Chapter 16: Problem 23
Cite the distinction between carbon and graphite.
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Get started for free\(16.14\) A continuous and aligned fiber-reinforced composite having a cross- sectional area of \(1130 \mathrm{~mm}^{2}\left(1.75 \mathrm{in} .^{2}\right)\) is subjected to an \(\mathrm{ex}\) ternal tensile load. If the stresses sustained by the fiber and matrix phases are \(156 \mathrm{MPa}\) \((22,600 \mathrm{psi})\) and \(2.75 \mathrm{MPa}(400 \mathrm{psi})\), respectively; the force sustained by the fiber phase is \(74,000 \mathrm{~N}\left(16,600 \mathrm{lb}_{6}\right)\); and the total longitudinal strain is \(1.25 \times 10^{-3}\), determine (a) the force sustained by the matrix phase, (b) the modulus of elasticity of the composite material in the longitudinal direction, and (c) the moduli of elasticity for fiber and matrix phases.
16.7 (a) For a fiber-reinforced composite, the efficiency of reinforcement \(\eta\) is dependent on fiber length \(l\) according to $$ \eta=\frac{l-2 x}{l} $$ where \(x\) represents the length of the fiber at each end that does not contribute to the load transfer. Make a plot of \(\eta\) versus \(l\) to \(l=40\) \(\mathrm{mm}\) (1.6 in.), assuming that \(x=0.75 \mathrm{~mm}\) \((0.03 \mathrm{in} .)\) (b) What length is required for a \(0.80\) efficiency of reinforcement?
Estimate the maximum and minimum thermal conductivity values for a cermet that contains 85 vol \(\%\) titanium carbide (TiC) particles in a cobalt matrix. Assume thermal conductivities of 27 and \(69 \mathrm{~W} / \mathrm{m} \cdot \mathrm{K}\) for \(\mathrm{TiC}\) and \(\mathrm{Co}\), respectively.
16.8 A continuous and aligned fiber-reinforced composite is to be produced consisting of 30 vol \(\%\) aramid fibers and 70 vol\% of a polycarbonate matrix; mechanical characteristics of these two materials are as follows: \begin{tabular}{lcc} \hline & Modulus of Elasticity [GPa (psi)] & Tensile Strength \([\) MPa (psi)] \\\ \hline Aramid fiber & \(131\left(19 \times 10^{6}\right)\) & \(3600(520,000)\) \\ Polycarbonate & \(2.4\left(3.5 \times 10^{5}\right)\) & \(65(9425)\) \\ \hline \end{tabular} Also, the stress on the polycarbonate matrix when the aramid fibers fail is \(45 \mathrm{MPa}\) (6500 psi). For this composite, compute (a) the longitudinal tensile strength, and
16.5 Cite one similarity and two differences between precipitation hardening and dispersion strengthening.
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