Demonstrates the use of Pre-loading with Normal Mode Analysis. The
Pre-Loaded analysis is a type of structural analysis performed on a structure under prior
loading (Pre-Loading).
The response of a structure is affected by its initial state and this is in turn affected
by the various preloading applied to the structure, prior to the analysis of interest. Here,
do a comparison study the normal model analysis, with and without pre-load effect using a
chair frame. Figure 1. FE-Model
Model Description
This example of the chair frame is solved for Pretension in the first subcase and then
followed by a Modal Analysis (with pre-loading).
FE Model
Element Types
CTETRA
CBEAM
CQUAD
RBE2
The linear material properties are:
MAT1
Young’s Modulus
2.1E5 MPA
Poisson's Ratio
0.3
Initial Density
7.85E-9 Mg/mm3
Results
In Figure 2, the displacement plot from the first subcase (Pretension) and also the
Eigen mode from the second subcase (Modal). Figure 2. Displacement Contour and Eigen Mode Plot
Figure 3. Six Mode Shapes Contour
Figure 4 shows the comparison of the Frequencies from the Normal Model Analysis,
with and without pre-load effect. Figure 4. Comparison of the Frequencies
