Model Correlation - Display Tab

The NVH-Utilities tab > Display tab, allows you to filter MAC results and select various plotting options using the MAC and COMAC sub-tabs.

nvh_mac_display_tab_mac_and_comac_tabs_hv

Model Correlation Utility - Display tab - MAC sub-tab

MAC Results Filtering

MAC results can be filtered based on the MAC threshold or frequency range, and the resulting table can be copied to be pasted into a document or exported into a .csv for further processing.

nvh_model_correlation_mac_example_hv

Frequency Difference

Plots the difference in the frequency values for matching mode pairs.

nvh_model_correlation_frequency_diff_example_hv

Partial MAC (Submodels)

MAC values based on submodels (partial MAC) can be useful in determining which part of the structure is responsible for poor correlation.

nvh_model_correlation_partial_mac_example_hv

Shape Difference Contour Plots

Shape difference is calculated by subtracting the results of the selected pair of modes. Higher values indicate bigger differences between the two vibration shapes.

nvh_model_correlation_shape_diff_example_hv

CoMAC Contour Plots

Coordinate Modal Assurance Criterion (CoMAC) is a measure of correlation at the individual node level:

nvh_mac_comac_equation_hv

The lower value of CoMAC indicates a relative lack of correlation.

nvh_model_correlation_comac_contour_example_hv

MAC Sensitivity Contour Plots

Coordinate Modal Assurance Criterion (CoMAC) for a particular node pair with low MAC.

nvh_model_correlation_low_comac_contour_example_hv

MAC Modification Studies

Nodal sensitivity to MAC can be studied by excluding nodes with low CoMAC values. This can be done either by unchecking individual nodes in the CoMAC node table, or by filtering using the submodel filter. The resulting MAC is then calculated and compared to the original MAC.

nvh_mac_low_comac_example_hv

nvh_mac_updated_mac_example_hv

To activate the Display tab (and the MAC and COMAC sub-tabs), you must first load a file and select options from the Load tab.

MAC Tab

nvh_mac_display_tab_mac_tab_hv

Sub Model

Use the drop-down menu to select a partial MAC (submodel) or the entire model for the corresponding plot.

filter

Displays the Filter Submodels dialog, which can be used to hide/show various submodels/components.

You can select items from the list by selecting them with your mouse or the arrow keys. Multiple submodels from the tree structure can be selected using the CTRL and SHIFT keys.

Use the Add Selected Path Contributors and the Remove Selected Path Contributors buttons, to add or remove the desired submodel(s).

Submodels in each listing can be quickly selected/deselected using the Select All , Select None , or Select Reverse buttons.

MAC Threshold >

Enter a MAC threshold into the field (if desired). The default value is 0.6.

Start Freq

Enter the starting frequency into the field.

End Freq

Enter the ending frequency range into the field.

Scan

Click the Scan button to execute a scan of the filtered MAC results and display those results in a table.

MAC Table

Contains a list of mode pairs with the following information displayed in the table:

•

Reference

•	Correlation

•	Freq Diff %

•

MAC

•	Modified MAC

A check mark indicates that the item/mode pair will be included in the scan. You can also use the Select All, Select None, and Select Reverse buttons to quickly select/deselect items (see below).

Select All

Selects all items in the table.

Select None

Clears all items currently selected.

Select Reverse

Reverses the selection for each item. For example, a selected check box is deselected.

Save

Click the Save button to export the table into a .csv file for further processing.

Copy

Click the Copy button to copy and paste the table into a document.

3d Bar

Select one of the 3D bar chart plotting options below:

MAC

Activate this option to plot the MAC.

Partial MAC

Activate this option to plot the Partial MAC. This is useful in determining which part of the structure is possible for correlation.

Modified MAC

This option is automatically activated whenever the Update MAC option is used in the COMAC tab.

Display

Click the Display button to plot the MAC, Partial MAC, or Modified MAC.

Contour

Select one of the contour plotting options below:

COMAC

Activate this option to plot a COMAC contour. See the COMAC tab below.

MAC Sensitivity

Activate this tab to plot a COMAC contour for a particular node pair.

Shape Diff

Activate this option to plot a shape difference contour. calculated by selecting results from the filter mode pair. in the resulting contour plot, higher values indicate a bigger difference between the two vibration shapes.

Display

Click the Display button to plot a Shape Difference or COMAC contour plot.

Note - You can adjust the Shape Difference and CoMAC contour plots displayed in HyperView by moving the contour value slider located in the Iso panel.

Bar Plot

Select one of the bar chart plotting options below:

Partial MAC

Activate this option to plot the Partial MAC.

Mode Pairs

Activate to plot the Mode Pairs contained in the entries selected in the table.

highest/lowest

Use the drop-down menu to plot the mode pairs with the highest or lowest MAC numbers.

value

The value of the highest or lowest MAC number.

Display

Click the Display button to plot the bar chart.

2D Line Plot

Freq Diff

Plots the difference in the frequency values for matching mode pairs.

COMAC Tab

nvh_mac_display_tab_comac_tab_hv

Sub Model

Use the drop-down menu to select a partial MAC (submodel) or the entire model for the corresponding plot.

filter

Displays the Filter CoMac Submodels dialog, which can be used to include/exclude submodel nodes.

nvh_mac_comac_tab_filter_comac_submodels_dialog_hv

You can select items from the list by selecting them with your mouse or the arrow keys. Multiple submodel nodes from the tree structure can be selected using the CTRL and SHIFT keys.

Use the Add Selected Path Contributors and the Remove Selected Path Contributors buttons, to add or remove the desired submodel node(s).

Submodel nodes in each listing can be quickly selected/deselected using the Select All , Select None , or Select Reverse buttons.

Threshold <

Enter a COMAC threshold into the field (if desired). The default value is 1.0.

Show

Use the drop-down menu to select None or Node Pair.

COMAC Node Table

Contains a list of nodes with the following information displayed in the table:

•

Reference

•	Correlation

•

COMAC

•

Submodel

A check mark indicates that the item/mode pair will be included in the scan. You can also use the Select All, Select None, and Select Reverse buttons to quickly select/deselect items (see below).

Display All

Selects all items in the table.

Display None

Clears all items currently selected.

Reverse Display

Reverses the selection for each item. For example, a selected check box is deselected.

Scan

Click the Scan button to execute a scan of the filtered COMAC results and display those results in a table.

lowest COMAC

Allows you to plot the node pairs with the lowest COMAC. Click the drop-down menu to select a desired setting.

Display

Click the Display button to plot the COMAC.

Update MAC

It is also possible to study nodal sensitivity to MAC by excluding/filtering nodes with low COMAC values. Uncheck the boxes next to the Nodes in the table with low COMAC values, and also use the filter if desired, then click on the Update MAC button. The MAC tab is automatically displayed with the Modified MAC option activated.