(a) 23.4
The fiber-to-matrix load ratio is given by
![\frac{F_f}{F_m}=\frac{E_f V_f}{E_m V_m}](https://tex.z-dn.net/?f=%5Cfrac%7BF_f%7D%7BF_m%7D%3D%5Cfrac%7BE_f%20V_f%7D%7BE_m%20V_m%7D)
where
is the fiber elasticity module
is the matrix elasticity module
is the fraction of volume of the fiber
is the fraction of volume of the matrix
Substituting,
(1)
(b) 44,594 N
The longitudinal load is
F = 46500 N
And it is sum of the loads carried by the fiber phase and the matrix phase:
(2)
We can rewrite (1) as
![F_m = \frac{F_f}{23.4}](https://tex.z-dn.net/?f=F_m%20%3D%20%5Cfrac%7BF_f%7D%7B23.4%7D)
And inserting this into (2):
![F=F_f + \frac{F_f}{23.4}](https://tex.z-dn.net/?f=F%3DF_f%20%2B%20%5Cfrac%7BF_f%7D%7B23.4%7D)
Solving the equation, we find the actual load carried by the fiber phase:
![F=F_f (1+\frac{1}{23.4})\\F_f = \frac{F}{1+\frac{1}{23.4}}=\frac{46500 N}{1+\frac{1}{23.4}}=44,594 N](https://tex.z-dn.net/?f=F%3DF_f%20%281%2B%5Cfrac%7B1%7D%7B23.4%7D%29%5C%5CF_f%20%3D%20%5Cfrac%7BF%7D%7B1%2B%5Cfrac%7B1%7D%7B23.4%7D%7D%3D%5Cfrac%7B46500%20N%7D%7B1%2B%5Cfrac%7B1%7D%7B23.4%7D%7D%3D44%2C594%20N)
(c) 1,906 N
Since we know that the longitudinal load is the sum of the loads carried by the fiber phase and the matrix phase:
(2)
Using
F = 46500 N
![F_f = 44594 N](https://tex.z-dn.net/?f=F_f%20%3D%2044594%20N)
We can immediately find the actual load carried by the matrix phase:
![F_m = F-F_f = 46,500 N - 44,594 N=1,906 N](https://tex.z-dn.net/?f=F_m%20%3D%20F-F_f%20%3D%2046%2C500%20N%20-%2044%2C594%20N%3D1%2C906%20N)
(d) 437 MPa
The cross-sectional area of the fiber phase is
![A_f = A V_f](https://tex.z-dn.net/?f=A_f%20%3D%20A%20V_f)
where
is the total cross-sectional area
Substituting
, we have
![A_f = (340\cdot 10^{-6} m^2)(0.3)=102\cdot 10^{-6} m^2](https://tex.z-dn.net/?f=A_f%20%3D%20%28340%5Ccdot%2010%5E%7B-6%7D%20m%5E2%29%280.3%29%3D102%5Ccdot%2010%5E%7B-6%7D%20m%5E2)
And the magnitude of the stress on the fiber phase is
![\sigma_f = \frac{F_f}{A_f}=\frac{44594 N}{102\cdot 10^{-6} m^2}=4.37\cdot 10^8 Pa = 437 MPa](https://tex.z-dn.net/?f=%5Csigma_f%20%3D%20%5Cfrac%7BF_f%7D%7BA_f%7D%3D%5Cfrac%7B44594%20N%7D%7B102%5Ccdot%2010%5E%7B-6%7D%20m%5E2%7D%3D4.37%5Ccdot%2010%5E8%20Pa%20%3D%20437%20MPa)
(e) 8.0 MPa
The cross-sectional area of the matrix phase is
![A_m = A V_m](https://tex.z-dn.net/?f=A_m%20%3D%20A%20V_m)
where
is the total cross-sectional area
Substituting
, we have
![A_m = (340\cdot 10^{-6} m^2)(0.7)=238\cdot 10^{-6} m^2](https://tex.z-dn.net/?f=A_m%20%3D%20%28340%5Ccdot%2010%5E%7B-6%7D%20m%5E2%29%280.7%29%3D238%5Ccdot%2010%5E%7B-6%7D%20m%5E2)
And the magnitude of the stress on the matrix phase is
![\sigma_m = \frac{F_m}{A_m}=\frac{1906 N}{238\cdot 10^{-6} m^2}=8.0\cdot 10^6 Pa = 8.0 MPa](https://tex.z-dn.net/?f=%5Csigma_m%20%3D%20%5Cfrac%7BF_m%7D%7BA_m%7D%3D%5Cfrac%7B1906%20N%7D%7B238%5Ccdot%2010%5E%7B-6%7D%20m%5E2%7D%3D8.0%5Ccdot%2010%5E6%20Pa%20%3D%208.0%20MPa)
(f) ![3.34\cdot 10^{-3}](https://tex.z-dn.net/?f=3.34%5Ccdot%2010%5E%7B-3%7D)
The longitudinal modulus of elasticity is
![E = E_f V_f + E_m V_m = (131 GPa)(0.3)+(2.4 GPa)(0.7)=41.0 Gpa](https://tex.z-dn.net/?f=E%20%3D%20E_f%20V_f%20%2B%20E_m%20V_m%20%3D%20%28131%20GPa%29%280.3%29%2B%282.4%20GPa%29%280.7%29%3D41.0%20Gpa)
While the total stress experienced by the composite is
![\sigma = \frac{F}{A}=\frac{46500 N}{340\cdot 10^{-6}m^2}=1.37\cdot 10^8 Pa = 0.137 GPa](https://tex.z-dn.net/?f=%5Csigma%20%3D%20%5Cfrac%7BF%7D%7BA%7D%3D%5Cfrac%7B46500%20N%7D%7B340%5Ccdot%2010%5E%7B-6%7Dm%5E2%7D%3D1.37%5Ccdot%2010%5E8%20Pa%20%3D%200.137%20GPa)
So, the strain experienced by the composite is
![\epsilon=\frac{\sigma}{E}=\frac{0.137 GPa}{41.0 GPa}=3.34\cdot 10^{-3}](https://tex.z-dn.net/?f=%5Cepsilon%3D%5Cfrac%7B%5Csigma%7D%7BE%7D%3D%5Cfrac%7B0.137%20GPa%7D%7B41.0%20GPa%7D%3D3.34%5Ccdot%2010%5E%7B-3%7D)