OS-V: 0435 Clamped Thick Rhombic Plate

Test No. FV22 The behavior of distorted, thick elements in normal modes analysis is examined using OptiStruct.


fv22
Figure 1. FE Model with Boundary Conditions and Loadcases

Benchmark Model

The 4-node quad elements with 10x10 mesh configuration are used to model the thick rhombic plate. The x-translation, y-translation displacements, and z-rotational displacements are fixed for all of the nodes. In addition, the z-translation, x-rotational and y-rotational are fixed for the nodes along the four edges.

The material properties are:
Property
Value
E
200 x 109 N/m2
υ
0.3
ρ
8000 kg/m3

Modal Analysis Results

The frequency of each targeted mode is normalized with the closed form solution. The closed form solution is not available for mode 6, the target value for H.O.E. should be used instead.
f*
Closed form solution
Mode 1 Mode 2 Mode 3
fv22a fv22b fv22c
f*

CQUAD4

 133.95 Hz

0.9937

 f*

CQUAD4

 201.41 Hz

1.0382

 f*

CQUAD4

 265.81 Hz

1.0633
Mode 4 Mode 5 Mode 6
fv22d fv22e fv22f
f*

CQUAD4

 283.68 Hz

1.0006

 f*

CQUAD4

 334.45 Hz

1.1073

 F[HOE]

CQUAD4

 386.62 Hz

1.0403

Model Files

Refer to Access the Model Files to download the required model file(s).

The model file used in this problem includes:

fv22.fem

Reference

NAFEMS R0015 - Selected benchmarks for natural frequency analysis