VM-LSDYNA-SOLVE-062
VM-LSDYNA-SOLVE-062
Cantilever with Off-Center Point Masses
Overview
| Reference: | Abbassian, F., Dawswell, D. J., & Knowles, N. C. (1987). Free vibration benchmarks. NAFEMS. |
| Analysis Type(s): | Modal Analysis |
| Element Type(s): | 1D Beam Elements |
| Input Files: | Link to Input Files Download Page |
Test Case
A cantilever beam is situated horizontally with two off-center lump masses of mass M1 = 10000 kg and M2 = 1000 kg at right free ends. The beam is constrained in all DOFs at the left end. Frequency vibration analysis is performed on the model.
| Material Properties | Geometric Properties | Loading |
|---|---|---|
|
Material 1 E1 = 200 ⋅ 109 N/m2 ρ1 = 8000.0 kg/m3 ν1 = 0.3 Material 2 E2 = 1 ⋅ 1016 N/m2 ρ2 = 0 kg/m3 ν2 = 0 |
L = 10 m H = 4 m |
Applied at left beam endpoint uy = 0 uy = 0 uz = 0 Ry = 0 Ry = 0 Rz = 0 |
Analysis Assumptions and Modeling Notes
The model is composed of two beams. The left beam is 10 m long and assigned with Material 1. The right beam is 4 m long and assigned with Material 2. Boundary conditions are defined by keywords *BOUNDARY_SPC_SET.
Results Comparison
This comparison verifies the agreement for each mode between the NAFEMS manual target and the result from the LS-DYNA solver.
|
Results Frequency (Hz) |
Target NAFEMS Manual | LS-DYNA Solver | Error (%) |
|---|---|---|---|
| MODE 1 | 1.723 | 1.722 | 0.058 |
| MODE 2 | 1.727 | 1.725 | 0.116 |
| MODE 3 | 7.413 | 7.410 | 0.040 |
| MODE 4 | 9.971 | 9.960 | 0.110 |
| MODE 5 | 18.155 | 18.079 | 0.419 |
| MODE 6 | 26.957 | 26.843 | 0.423 |