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TEST CASE 2.5 NATURAL FREQUENCIES OF THE ROUND PLATE HINGE-SUPPORTED 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 a round plate, hinge-supported 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 = 0.

 

Loads:

Dead load.

 

Model description:

The system is modeled using 1152 finite elements of thin plate (FE type is 19), splitting in the radial direction with a step of 0.03125 m and in the tangential with a step of 5°. To solve the problem, a modal analysis was performed.

  

Calculation results:

Form №

Frequency, rad/sec

Deviation, %

Analytical solution

LIRA 10

1

306.0

306.0

0.00

2, 3

861.8

861.8

0.00

4, 5

1588.2

1589.4

0.08

6

1842.9

1843.1

0.01

7, 8

2477.7

2481.4

0.15

9, 10

3006.1

3008.1

0.07

11, 12

3524.6

3531.6

0.20

13, 14

4347.8

4362.0

0.33

15

4598.3

4597.0

0.03