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Unformatted text preview: . VM156: Natural Frequency of a Nonlinear Spring-Mass System
Reference: S. Timoshenko, D. H. Young, Vibration Problems in Engineering, 3rd Edition, D.
Van Nostrand Co., Inc., New York, NY, 1955, pg. 141. Analysis Type(s): Full Transient Dynamic Analysis (ANTYPE = 4) Element Type(s): Nonlinear Spring Elements (COMBIN39)
2-D Spar (or Truss) Elements (LINK1)
Structural Mass Elements (MASS21) Input Listing: vm156.dat Test Case
A mass is supported from a spring having the nonlinear characteristics shown. The mass is displaced an amount δ
from its equilibrium position and released (with no initial velocity). Find the corresponding period of vibration τ. Figure 156.1 Nonlinear Spring-Mass System Problem Sketch ANSYS Verification Manual . ANSYS Release 9.0 . 002114 . © SAS IP, Inc. 1–345 VM156
m = 1/386.4 = 0.002588 lb-sec2/in
ko = 2 lb/in Geometric Properties k1 = 4 lb/in3
see force-deflection curve in Figure 156.1: “Nonlinear Spring-Mass
System Problem Sketch” A = 0.01 in2
δ = -1 in = 100 in Analysis...
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