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1) Consider a truss of constant cross section, section the truss in 5 segments and a) calculate the first and second mode both analytically and b) with FEA methods

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1) Consider a truss of constant cross section, section the truss in 5 segments and a) calculate the first and second mode both analytically and b) with FEA methods. c) Calculate the ratio of first to second mode found by FEA methods. d) State clearly your mass and stiffness matrix(s). e) Attach your scilab script or equivalent used to make the calculations. f) Explain how large the error of the frequencies calculated by FEA with 5 sections is.

2. Consider a non-uniform truss cross section A(x) = A₀Ö1 – (x/L)⁶ and redo point 1 FEA (not analytical). State if the frequencies are higher or lower, if these results are expected and state the ratio of the first mode frequency to the second mode frequency. Please include a plot for your cross section.

Material properties:

E = 10 GPa

Ay = 10 mm²

L = 100 mm

P = 1800 kg/m³