OS-V: 0450 Free Cylinder: Axisymmetric Vibration
Test No. FV41 A free cylinder with axisymmetric 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
Model Files
Before you begin, copy the file(s) used in this problem
to your working directory.
Benchmark Model
The 1st order and 2nd order triangular axisymmetric 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 |
Reference
NAFEMS R0015 - Selected benchmarks for natural frequency analysis