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TEST CASE 2.1 EIGENFREQUENCIES 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 sketch:

Fig. 2.1

Type of created problem:

Flat plate or grillage ( Z , UX , UY).

Input data:

; ;

Material properties:

Isotropic elastic: ; ;

Problem description:

System was modeled using finite elements of thin plate (FE 19).

Mesh: 20x20 FE - classic analysis; 10x10 FE - analysis using finite elements with intermediate nodes.

Modal analysis has been performed to solve the problem.

Calculation results:

Table 2. 1

# of mode

Frequency, Hz

Deviation, %

Analytical solution

Solution results by LIRA 10.4

4

33.7119

33.6624 (33.6544)

0.15 (0.14)

5

49.4558

48.9696 (48.9608)

0.98 (1.0)

6

61.0513

60.6587 (60.6399)

0.64 (0.67)

7

87.5160

86.9481 (86.9483)

0.65 (0.65)

8

87.5160

86.9481 (86.9483)

0.65 (0.65)

- solution results using finite elements with intermediate nodes are specified within the brackets.