Global Modes - Load

After loading an OptiStruct or Nastran modal file, the subcase and modal frequencies from the result file are loaded. The Global Modes utility attempts to automatically identify the global modes based on the criteria and advanced options.

File selection
Select a result file containing normal modes results and click Load.
Result selection
Subcase
The drop-down menu contains the subcases from the normal mode result file.
Criterion (1-100%)
Enter a criteria value within the range 1-100. Identify the percent of structural grids participating in the mode shape. 100% means that all the grids are participating and the mode is considered a global mode. The recommended default value is 85-95%.
Advanced Selections
Start and End Frequency
Select the frequency range to identify the global/local modes.
Mode Type
Select the type of modes to be identified: global or local.
Divider
The divider is the value that is used to get the threshold by diving the top magnitude of displacement. This threshold is used to identify global/local modes.
Top Magnitude
The maximum displacement value used to calculate the threshold for the identification of global/local modes.
By node count
The maximum displacement value is taken as an average of the displacements for the selected number of nodes.
By percent of nodes
The maximum displacement value is taken as an average of the displacements for the selected top percent of nodes.