Dynamics of Machines - Part II - IFS.pdf

=(0.0291 +- 0.0001) % [m] width
h=(0.0011 +- 0.0001) % [m] thickness
I=(b*h^3)/12 % [m^4] area moment of inertia
% Position of the Platforms
L1=(0.122 +- 0.001) % [m] Length to Platform 1
L2=(0.123 +- 0.001) % [m] Length from Platform 1 to Platform 2
L3=(0.149 +- 0.001) % [m] Length from Platform 2 to Platform 3
L4=(0.127 +- 0.001) % [m] Length from Platform 3 to Platform 4
can be varied based on the geometry and assembly tolerances, as well as on material properties.
Changes of such parameters lead to changes in the stiffness matrix K.
11. MODEL ADJUSTMENT – After adjustment of the natural frequencies, try to adjust the
damping ratios ξi (i = 1, ...,4) of the analytical model using the experimental damping
ratios obtained via Experimental Modal Analysis. Remember that alpna and β are the
parameters to be varied, if you have proportional damping matrices D1, D2 and D3.
12. APPLICATION OF THE ADJUSTED MODEL – Consider the 5 different angular velocities,
close to the resonances of the building and among them, as following:
• 225 rpm (3,75 Hz),
• 495 rpm (8,25 Hz),
• 615 rpm (10,25 Hz),
• 900 rpm (15,00 Hz) and
• 975 rpm (16,25 Hz).
Use your adjusted analytical model to predict the vibration amplitude of the top mass, i.e.
acceleration of the top mass, when the rotor-disk operates unbalanced at the 5 different
angular velocities. Check your theoretical results comparing with the experimental results.
Explain the discrepancies between the results obtained with help of your mathematical
model and the experiments.
13. Write about your conclusions!
(Technical report until 01/04/2005)
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