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Old Feb 25th 2017, 03:10 PM   #1
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Join Date: Feb 2017
Posts: 7
Determine the natural frequency 2

The question is:

Determine the natural frequency of the rotor shown below given the following data:
Moment of inertia of rotor Jr=0.6 kgm^2
Diameter of shaft d=38.0mm
Length of shaft L=189.0 mm
Material of shaft Steel Modulus of Rigidity 82 GPa

My solution is:


The correct answer should be 61.2 what am I doing wrong?
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Old Mar 8th 2017, 10:57 AM   #2
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Determine the natural frequency 2

J=PI()/32*(38*10^-3)^4= 2.04708E-07 m^4
G = 82000000000 GPa
L = 0.189 m
I = 0.6 kg * m^2

ω=((J*G)/(I*L))^0.5 = 384.740176 Rads / sec
F = W / (2*pi) = 61.23 Hz
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