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Unformatted text preview: ting frequency f is equal to the resonant frequency fn,
the force F1 = muω2 = 2.4 lb where ω = ωn = sqrt(k/m) = 34.0294 rad/sec is the resonant circular frequency. When
f >> fn, it is assumed that f = 100 fn = 541.5947 Hz and the corresponding force F1 = 24000 lb. Results Comparison
0.60000 0.60000 1.000 angle, deg
f =100 fn Ratio Amp, in f = fn ANSYS -90.000 -90.000 1.000 0.080000 0.080008 1.000 -180.00 -179.92 1.000 Amp, in
angle, deg 1. Based on f = ∞ ANSYS Verification Manual . ANSYS Release 9.0 . 002114 . © SAS IP, Inc. 1–201 VM89: Natural Frequencies of a Two-mass-spring System
Reference: W. T. Thomson, Vibration Theory and Applications, 2nd Printing, Prentice-Hall,
Inc., Englewood Cliffs, NJ, 1965, pg. 163, ex. 6.2-2. Analysis Type(s): Mode-frequency Analysis (ANTYPE = 2) Element Type(s): Spring-Damper Elements (COMBIN14)
Structural Mass Elements (MASS21) Input Listing: vm89.dat Test Case
Determine the normal modes and natural frequencies of the s...
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