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 co-incident and separated modes are found. Frequencies and mode shapes are reported in tabular and graphical form.

MASS DISTRIBUTION

Analysis model member cross-sectional 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 non-structural 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 cut-off 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