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


Model Files

Before you begin, copy the file(s) used in this problem to your working directory.

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

Reference

NAFEMS R0015 - Selected benchmarks for natural frequency analysis