
Concept explainers
(a)
The volume fractions for the fiber and matrix in the laminate.
(a)

Answer to Problem 97SEP
The volume fractions for the fiber and matrix in the laminate are 0.29 and 0.71 respectively.
Explanation of Solution
Write the equation for the rule of mixture for the composite material.
Ec=EfVf+EmVm (I)
Here, modulus of elasticity of composite is Ec, modulus of elasticity of fiber is Ef, volume fraction of fiber is Vf, modulus of elasticity of matrix is Em and volume fraction of matrix is Vm.
Write the equation to calculate the volume fraction of matrix.
Vm=1−Vf (II)
Conclusion:
It is given that the component is suggested to be made from unidirectional carbon fiber composite. Therefore, the fiber layer will be carbon and the matrix layer will be epoxy.
Take the modulus of elasticity of carbon fiber to be 33×106 psi and the modulus of elasticity of epoxy matrix to be 0.5×106 psi.
Substitute 10×106 psi for Ec, 33×106 psi for Ef, 0.5×106 psi for Em and (1−Vf) for Vm in Equation (I).
10×106 psi=(33×106 psi)Vf+(0.5×106 psi)(1−Vf)10×106 psi=(33×106 psi)Vf+(0.5×106 psi)−(0.5×106 psi)Vf10×106 psi−0.5×106 psi=(33×106 psi−0.5×106 psi)Vf9.5×106 psi=(32.5×106 psi)Vf
Vf=9.5×106 psi32.5×106 psi=0.29
Substitute 0.29 for Vf in Equation (II).
Vm=1−0.29=0.71
Thus, the volume fractions for the fiber and matrix in the laminate are 0.29 and 0.71 respectively.
(b)
The volume fractions for the fiber and matrix in the laminate.
(b)

Answer to Problem 97SEP
The volume fractions for the fiber and matrix in the laminate are 0.29 and 0.71 respectively.
Explanation of Solution
Write the equation to calculate the percentage in weight reduction.
%Wt=ρAl−ρCρAl×100 (III)
Here, density of carbon composite is ρC and density of aluminum composite is ρAl.
Conclusion:
Refer Appendix I, "Important properties of the selected engineering materials" to obtain the densities of aluminum composite and carbon composite.
ρAl=0.0975 lb/in.3ρC=0.0553 lb/in.3.
Substitute 0.0553 lb/in.3 for ρC and 0.0975 lb/in.3 for ρAl in Equation (III).
%Wt=0.0975 lb/in.3−0.0553 lb/in.30.0975 lb/in.3×100=0.43×100=43%
Therefore, the carbon composite will be 43% lighter when compared to aluminum composite.
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Chapter 12 Solutions
Loose Leaf For Foundations Of Materials Science And Engineering
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