WinVIBE Civil Structural Engineering Vibration Analysis Software  Natural Modes SOFTWARE FUNCTION
WinVIBE is a program to calculate
natural modes of vibration and frequencies of vibration
for WinFRAM and WinFELA 2D/3D skeletal and/or plate
element structural analysis models. Structural
stiffnesses and an initial mass distribution are
calculated from the analysis model data. After adjustment
of the mass distribution, WinVIBE performs a lumped mass
analysis of this eigenvalue problem and detects all
natural modes of vibration within the specified mode or
frequency range; both coincident and separated modes are
found. Frequencies and mode shapes are reported in
tabular and graphical form.
MASS
DISTRIBUTION
Analysis model member
crosssectional areas, plate element thicknesses and
material densities are used to calculate an initial mass
distribution. This default mass distribution can be
factored for any member or element so that nonstructural
mass can be accounted for. Lumped masses at the nodes are
calculated from the factored member and element masses.
The lumped masses table allows further adjustment to be
made by addition or subtraction of masses and inertias at
any node with respect to any global direction. Suspended
masses and trolley masses can be modelled and a mechanism
is provided for suppression of modes of vibration in
chosen directions.
ANALYSIS
CONTROL
A Mode Range analysis may be
selected to determine all modes within a requested range;
a frequency cutoff point may be specified to declare no
interest in higher frequency modes. A Frequency Range
analysis may be requested to calculate all modes within a
specified frequency range. An WinVIBE analysis is an
iterative process in which each step converges towards
the frequency of a vibration mode. WinVIBE decides it has
achieved satisfactory convergence when the frequency
change between convergences step is sufficiently small.
The user may specify the change in frequency for assumed
convergence as a percentage change.
ANALYSIS
RESULTS
The Mode/Frequency Summary table
lists the calculated modes their frequencies and the node
and direction where the greatest linear motion is
occuring. The Displacement Vector tables, one for each
mode, list the normalised nodal displacements for all
nodes. The PLOT option allows the shape of each mode to
be studied graphically. Tabular results may be printed in
part or in whole to a printer, to a PDF file, to an ASCII
file, or copied to the Windows clipboard. Plot output may
be sent to printer, plotter, BMP file, DXF file, EMF file
or PDF file.
Interfacing
products:WinFRAM, WinFELA
