Eigenvalue Calculation Parameters

The eigenvalue analysis extracts eigenvalues (frequencies) for a system. Lanczos method from solution of eigenvalue problems is applied. See the users manual for details.

All cross-sections in the model must have a mass and radius of gyration larger than zero.
The results are printed on the sima_eigmod.res file placed in the Results/Eigenvalue/ folder.

1. Parameters

1.1. Free vibration options

  • Number of eigenvalues: Number of eigenvalues and eigenvectors to be calculated

For details, see Free vibration options.

1.2. Computation parameters

  • Max. relative error: Maximum acceptable relative error in computed eigenvalues (default: 1.0e-10)

  • Number of Lanczo Steps: Maximum number of Lanczos steps (vectors) to be used

For details, see Lanczos eigenvalue computation parameters.

1.3. Storage

  • Store visualization responses: Option to store eigenvectors for visualization. If not selected, only eigenvalues will be stored.

    • Visualization scaling: Scaling of eigenvectors for visualization purposes. This does not affect the eigenvalues or the physical interpretation of the modes, but can be used to enhance the visibility of mode shapes in post-processing. Increasing this value will amplify the mode shapes, while decreasing it will reduce their amplitude in visualizations.

2. References

  1. Nour-Omid, B., Parlett, B.N., Taylor, R.L. (1983): Lanczos versus Subspace Iteration for Solution of Eigenvalue Problems. International Journal for Numerical Methods in Engineering, Vol. 19, pp. 859–871.

  2. Parlett, B.N. (1980): The Symmetric Eigenvalue Problem. Prentice-Hall.