Topic: Material Science
A composite material consists of 60% by volume of fibre (modulus 200 GPa) and 40% by volume of matrix (modulus 5 GPa). What is the approximate modulus of the composite (using rule of mixtures)?
- A. 122 GPa
- B. 82 GPa
- C. 42 GPa
- D. 22 GPa
Answer: A. 122 GPa
Explanation: According to the rule of mixtures for the longitudinal elastic modulus of a composite (Voigt bound): $E_c = V_f E_f + V_m E_m$, where $V_f$ and $V_m$ are volume fractions of the fibre and matrix respectively.
$E_c = (0.60 \times 200) + (0.40 \times 5) = 120 + 2 = 122$ GPa.