OS-V: 0450 Free Cylinder: Axi-symmetric Vibration
Test No. FV41 A free cylinder with axi-symmetric vibration. OptiStruct is used to investigate the rigid body mode, close eigenvalues, and the coupling between axial, radial and circumferential behavior.
Figure 1. FE Model with Boundary Conditions and Loadcases
Benchmark Model
The 1st order and 2nd order triangular axi-symmetric elements (CTAXI) are used to model the cylinder. The cylinder is unsupported.
The material properties are:
- Property
- Value
- Young's Modulus
- 200 x 109 N/m2
- Poisson's Ratio
- 0.3
- Density
- 8000 kg/m3
Modal Analysis Results
Mode shapes predicted by OptiStruct.
Figure 2.
Figure 2.
The frequency of each targeted mode is normalized with the NAFEMS closed form
solution.
| Mode | ||||||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | |
| NAFEMS | RBM | 243.53 Hz | 377.41 Hz | 394.11 Hz | 397.72 Hz | 405.28 Hz |
| HOE (8×1) | RBM | 243.34 Hz | 372.14 Hz | 374.18 Hz | 378.22 Hz | 396.00 Hz |
| Normalized | 1 | 1.000780801 | 1.014161337 | 1.053263135 | 1.051557295 | 1.023434343 |
| HOE (16×3) | RBM | 243.46 Hz | 377.15 Hz | 393.2 Hz | 394.6 Hz | 400.97 Hz |
| Normalized | 1 | 1.000287522 | 1.000689381 | 1.002314344 | 1.007906741 | 1.010748934 |
| LOE (8×1) | RBM | 242.45 Hz | 376.02 Hz | 379.86 Hz | 389.83 Hz | 426.92 Hz |
| Normalized | 1 | 1.004454527 | 1.003696612 | 1.037513821 | 1.020239592 | 0.949311346 |
| LOE (16×3) | RBM | 243.28 Hz | 377.69 Hz | 391.42 Hz | 395.54 Hz | 423.00 Hz |
| Normalized | 1 | 1.001027622 | 0.999258651 | 1.006872413 | 1.005511453 | 0.958108747 |
Model Files
The model files used in this problem include:
<install_directory>/hwsolvers/demos/optistruct/verification
- /FV41HOEC.fem
- /FV41HOEF.fem
- /FV41LOEC.fem
- /FV41LOEF.fem
Reference
NAFEMS Ltd, The Standard NAFEMS BENCHMARKS TNSB Rev. 3, NAFEMS Ltd, Scottish Enterprise Technology Park, Whitworth Building, East Kilbride, Glasgow, United Kingdom, 1990.