VM-LSDYNA-SOLVE-057
VM-LSDYNA-SOLVE-057
Pin-Ended Double Cross: In-Plane Vibration
Overview
| Reference: | Abbassian, F., Dawswell, D. J., & Knowles, N. C. (1987). Free vibration benchmarks - NAFEMS. Dept. of Trade and Industry, National Engineering Laboratory. |
| Analysis Type(s): | Modal Analysis |
| Element Type(s): | 1D Beam Element |
| Input Files: | Link to Input Files Download Page |
Test Case
Eight beams, each 5 m long, are joined at the center and arranged radially at equal angles. The beams are constrained in the x and y direction at all 8 beam endpoints. Modal analysis is performed on the model.
The model is composed of 8 beams. Each beam is divided into 40 elements. Boundary conditions are defined using the keyword *BOUNDARY_SPC_SET.
| Material Properties | Geometric Properties | Loading |
|---|---|---|
| E = 200 x
109 N/m2
ρ = 8000.0 kg/m3 | L = 5 m | ux = 0, uy = 0 at beam endpoints |
Results Comparison
Results are compared with published benchmark results in the following table. Excellent agreement validates the results.
| Result Frequency | Target NAFEMS Manual | LS-DYNA | Error (%) |
|---|---|---|---|
|
MODE 1 (Hz) MODE 2,3 (Hz) MODE 4,5,6,7,8 (Hz) MODE 9 (Hz) MODE 10,11 (Hz) MODE 12,13,14,15,16 (Hz) |
11.336 17.709 17.709 45.345 57.390 57.390 |
11.330 17.663 17.691 45.252 56.907 57.211 | 0.052928723 0.2597549270.101643232 0.205094277 0.841610037 0.311901028 |