Superpose damping in a dynamic response analysis

This procedure shows you how to superpose structural damping with modal damping in a dynamic response analysis (linear transient or linear harmonic).

Defining the modal damping requires that you know the number of the modes to which you want to apply a critical damping rate. To retrieve these mode numbers and corresponding results, you must solve the solution and open the modal results before you set up the superposed damping.

1. In the Solution dialog box for Linear Transient Response Analysis or Linear Harmonic Response Analysis, select the Modal Superposition check box.

2. On the Output page, select the Generate Result Files for Modal Analysis check box.Selecting this check box generates the results files for the modal analysis so that you can view them in the Post Processing Navigator.

3. Right-click the solution and choose Solve.

4. To view the modal results so you can determine which modes you want to add the critical damping to, do the following:In the Post Processing Navigator, right-click Imported Results and choose Import Results.In the Import Result dialog box, click Browse to locate the modal results file, and click OK. The modal results file is named as follows:simulation_file_name-solution_name_*.dy.desIn the Post Processing Navigator, under the Imported Results node, post process the modal results to identify the modes that require critical damping.

5. In the Simulation Navigator, right-click the solution and choose Edit.

6. On the Solver Parameters page, in the Damping group, select the Rayleigh Damping check box and set the stiffness and mass coefficients.

7. Select the Modal Damping check box and specify a formula or table field with the critical damping rate for specified modes. Note: You must define a critical damping rate for each mode. In the field definition, you define sets of data—the first value is the mode number, and the second value is the damping rate.The critical damping rate must be between 0 and 1.To omit a critical damping rate for a mode, enter 0. For example, to set up a table field with the critical damping rate for specified modes as a function:For the independent domain, set the mode numbers in the abscissa of the function defined by the table field.For the dependent domain, set the critical damping rate in the ordinate of the function defined by the table field.

8. (Optional) Make the FEM file the active, and in the mesh collector, set the physical property damping values for Viscous Damping Ratio by Element (VDA) and Hysteretic Damping Ratio per Element (HDA).For information on accessing physical properties so you can set damping options, see Define physical properties.

9. Solve the solution again to use the superposed damping.

Superpose damping in a dynamic response analysis, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });