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TEST CASE 2.3 EIGENFREQUENCIES OF RECTANGULAR PLATE SIMPLY-SUPPORTED ON ALL EDGES

Reference : M.V. Barton, “Vibration of rectangular and skew cantilever plates”, Journal of Applied Mechanics, vol. 18, 1951, p. 129 – 134.

Problem sketch:

Fig. 2.3

Type of created problem:

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

Input data:

; ; ;

Material properties:

Isotropic elastic: ; ;

Boundary conditions:

Across perimeter: ;

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 2.3

# of mode

Frequency, Hz

Deviation, %

Analytical solution

Solution results by LIRA 10.4

1

35.63

35.573 (35.624)

0.16 (0.02)

2

68.51

68.327 (68.506)

0.27 (0.01)

3

109.62

109.381 (109.600)

0.22(0.02)

4

123.32

122.933 (123.305)

0.32(0.01)

5

142.51

141.665 (142.474)

0.6 (0.03)

6

197.32

195.591 (197.267)

0.88 (0.03)

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