TEST CASE 2.6 NATURAL FREQUENCIES OF THE ROUND PLATE CLAMPED ALONG THE CONTOUR
Reference:
V.N. Chelomey, Vibration in technics, Handbook in six volumes; V.V. Bolotin, Volume 1, The vibrations of linear systems, Moscow, Mechanical Engineering, 1978, p. 207.
Problem description:
Determine the natural frequencies of the round plate clamped along the contour.
Problem sketch:
Type of created problem:
Flat plate or grillage (Z, UX, UY).
Geometric characteristics:
r = 0.5 m; t = 0.01 m.
Material properties:
Elastic modulus: E = 2.06·1011 Pa;
Poisson’s ratio: μ = 0.3;
Density: γ = 7850 kg/m3.
Boundary conditions:
On the perimeter: Z = UX = UY = 0.
Loads:
Dead load.
Model description:
The system is modeled using 288 finite elements of thin plate with additional nodes (FE type is 19), splitting in the radial direction with a step of 0.0625 m and in the tangential with a step of 10°. To solve the problem, a modal analysis was performed.
Analytical solution:
Jn, In – Bessel functions.
Calculation results:
Form № |
Frequency, rad/sec |
Deviation, % |
|
Analytical solution |
LIRA 10 |
||
1 |
633.5 |
636.8 |
0.52 |
2, 3 |
1318.3 |
1324.9 |
0.50 |
4 |
2162.7 |
2173.1 |
0.48 |
5 |
2162.7 |
2173.2 |
0.49 |
6 |
2466.1 |
2477.8 |
0.47 |
7, 8 |
3164.3 |
3178.8 |
0.46 |
9, 10 |
3771.9 |
3788.1 |
0.43 |
11 |
4319.8 |
4338.6 |
0.44 |
12 |
4319.8 |
4338.7 |
0.44 |
13, 14 |
5244.8 |
5266.5 |
0.41 |
15 |
5525.2 |
5546.5 |
0.39 |