OS-V: 0415 Deep Simply-Supported Beam

Test No. FV5 OptiStruct tests the repeated eigenvalues, shear deformation, and rotary inertia. The possibility of missing extensional modes is also investigated.



Figure 1. FE Model with Boundary Conditions and Loadcases

Benchmark Model

The 2-node beam elements are used to model the simply-supported beam which consists of five elements. The displacements in x, y, and z direction, as well as the rotation in x direction are fixed at the end A. In addition, the displacements in y and z direction are constrained at end B.

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.
f*
Closed form solution.
Modes 1 and 2 Flexural Mode 3 Torsional Mode 4 Extensional
f*

CBEAM

42.649 Hz		 42.649 Hz

1.0124

 f*

CBEAM

77.542 Hz		 77.542 Hz

0.9157

 f*

CBEAM

 125.00 Hz

1.0000
Modes 5 and 6 Flexural Mode 7 Torsional Modes 8 and 9 Flexural
f*

CBEAM

42.649 Hz		 148.31 Hz

1.0409

 f*

CBEAM

 233.10 Hz

0.8840

 f*

CBEAM

 284.55 Hz

1.0725

Model Files

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

The model file used in this problem includes:

fv5.fem

Reference

NAFEMS R0015 - Selected benchmarks for natural frequency analysis