A three-level offshore platform located in the Helang Oilfield
area has a 1500 kg floor
steel grating supported at each level. The structure sometimes is
subjected to a vertical
oscillation movement during rough sea waves given by function of
?(?) = ? sin ??.
If the steel grating only moves in the vertical direction and is
supported by one
equivalent spring and damper at each steel grating pole level with
stiffness, k1 = (600) N/m, k2 = (400) N/m and k3 = (200) N/m while
damping, c1 = (105)
Ns/m, c2 = (70) Ns/m and c3 = (35) Ns/m, respectively, as
simplified in Figure
Q1. Neglect the effect of gravitational force.
mz 4 W an ya TF20 m2 wy, F70) ( m; k; W Figure Q1
b) Determine the equation of motion in a matrix form using Newton's second law, [m]y+ [c]y +[k]y=F. c) By omitting the damping and external force parameter, deduce and express the general solution in the form of ([k] - w?[m]){Y} = 0. d) Analyze the maximum vertical displacement at each floor when the system's natural frequency is equal to the external stimulation frequency. Assume nontrivial solution and F1.2,3(t) exhibits harmonic oscillation of sin 0.02t. e) Describe an eigenvector using a three-degree-of-freedom system's mode form as an illustration for wl, w2> wl and w3 > w2>wl.
mz 4 W an ya TF20 m2 wy, F70) ( m; k; W Figure Q1 b) Determine the equation of motion in a matrix form using Newton's
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mz 4 W an ya TF20 m2 wy, F70) ( m; k; W Figure Q1 b) Determine the equation of motion in a matrix form using Newton's
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