Natural frequency of steel bar given by a. (58554 mathrm{rad} / mathrm{s}) lumped-mass matrices b. (33806 mathrm{rad}
Question:
Natural frequency of steel bar given by
a. \(58554 \mathrm{rad} / \mathrm{s}\) lumped-mass matrices
b. \(33806 \mathrm{rad} / \mathrm{s}\) consistent-mass matrices
c. \(33758 \mathrm{rad} / \mathrm{s}\)
d. \(58471 \mathrm{rad} / \mathrm{s}\)
Assume a fixed-fixed bar with one middle node:
Element matrices: \([k]=\frac{A E}{l}\left[\begin{array}{rr}1 & -1 \\ -1 & 1\end{array}\right],[m]_{c}=\frac{ho A l}{6}\left[\begin{array}{ll}2 & 1 \\ 1 & 2\end{array}\right],[m]_{l}=\frac{ho A l}{2}\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]\)
Steel bar: \(E=200 \times 10^{9} \mathrm{~Pa}, ho=7800 \mathrm{~kg} / \mathrm{m}^{3}, l=0.3 \mathrm{~m}\)
Aluminum bar: \(E=72 \times 10^{9} \mathrm{~Pa}, ho=2800 \mathrm{~kg} / \mathrm{m}^{3}, l=0.3 \mathrm{~m}\)
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