TEST CASE 2.1 NATURAL FREQUENCIES OF FREE SQUARE PLATE
Reference:
M.V. Barton, “Vibration of rectangular and skew cantilever plates”, Journal of Applied Mechanics, vol. 18, 1951, p. 129 – 134.
Problem description:
Determine the natural frequencies of a restraint-free square plate.
Problem sketch:
Type of created problem:
Flat plate or grillage (Z, UX, UY).
Geometric characteristics:
a = 1 m; t = 0.01 m.
Material properties:
Elastic modulus: E = 2.1·1011 Pa;
Poisson’s ratio: μ = 0.3;
Density: γ = 7800 kg/m3.
Boundary conditions:
Elastic links of low stiffness in all nodes of the calculation scheme: RZ = 0.001 N/m.
Loads:
Dead load.
Model description:
The system is modeled using 400 finite elements of thin plate (FE type is 19). To solve the problem, a modal analysis was performed.
Calculation results:
Form № |
Frequency, Hz |
Deviation, % |
|
Analytical solution |
LIRA 10 |
||
4 |
33.7119 |
33.6624 |
0.15 |
5 |
49.4558 |
48.9696 |
0.98 |
6 |
61.0513 |
60.6587 |
0.64 |
7 |
87.5160 |
86.9481 |
0.65 |
8 |
87.5160 |
86.9481 |
0.65 |