Getting started with the Correlation solution process

Estimated time to complete: 20–30 minutes

In this tutorial, you will correlate the results from a structural analysis solution with results from the test solution.

1: Workflow for correlation of analysis results with test results

Step

Summary

1.

Import test model and results.

In the Pre/Post application, you will insert a new modal test data solution into an existing analysis simulation.

2.

Align test geometry with analysis geometry.

You will align the test geometry with the analysis geometry.

3.

Create the Correlation.

You will insert the Correlation simulation process. Specify the Test Solution for the reference solution and the Analysis Solution for the work solution.

The software automatically creates mode pairs between reference and work solutions. You can view the pairs, and change the method the software uses for pairing.

4.

Manage sensors.

For the test solution, you will activate or deactivate DOFs and sensors that will be used for correlation.

You will generate a simulation DOF set that matches the test sensor locations.

5.

Post process work and reference solution modes and mode pairs.

You can visualize different correlation metrics to evaluate the degree of correlation between the work and reference solutions.

You can also export them to Excel and CSV files.

6.

Modify the analysis solution

You will modify and resolve the Analysis Solution.

7.

Update the correlation

You will update the Correlation solution process and post process the correlation results.

2: Open the Simulation file

  1. On your desktop or the appropriate network drive, create a folder named correlation_airplane.

  2. Click the link below:

    Download the part

  3. Extract the part files to your correlation_airplane folder.

  4. Start Simcenter 3D or NX.

File

  • Open

  • Look in

    correlation_airplane

  • Files of type

    Simulation Files (*.sim)

  • File name

    airplane_sim.sim

  • OK

     

Note the following nodes are created in the Simulation Navigator.

 airplane_sim.sim

 airplane_fem.fem

 CSYS

 Selection Recipes

 Groups

 Fields

 Modeling Objects

 Regions

 Simulation Object Container

 Constraint Container

 Load Container

 Solver Sets

 Analysis Solution

 Temperatures

 Simulation Objects

 Constraints

 Results

 Structural

3: Reset dialog box memory

The options you select in dialog boxes are preserved for the next time you open the same dialog box within a given session. Restore the default settings to ensure that the dialog boxes are in the expected initial state for each step of the activity.

File

Preferences→User Interface

  • Options

  •   Reset Dialog Memory

  • OK

     
4: Create the test solution

You create the test solution by importing the geometry and mode shape data from UNV files. Optionally, you can also import frequency response function data.

If your UNV file contains both geometry and mode shape data, enter the path and name of the UNV file in the Geometry File box and leave the Modes File box empty.

Note:

If necessary, right-click in the Ribbon bar area and turn the Correlation tab on.

Correlation

  • New Test Reference Solution (Correlation group)

  • Name

    Test Solution

  • Solver

    Modal Test Data

  • Browse (Geometry File)

  • Look in

    correlation_airplane

  • File name

    airplane_geom.unv

  • OK

     

  • Browse (Modes File)

  • Look in

    correlation_airplane

  • File name

    airplane_shapes.unv

  • OK

     both dialog boxes

Note the following nodes are created in the Simulation Navigator.

 Test Solution

 Test Model 1

Modes

FRFs

5: Display test model and sensors

Simulation Navigator

  • Test Model 1

  • Show

  • Fit (Top Border bar→View Fit Drop-down list)

  • Simulation Navigator

  • Modes

  • Initial Sensors [30]

  • Show Sensors

  • Initial Sensors [30]

  • Hide Sensors

You hide the sensors for easier selection in the next step.

6: Align the test and analysis solutions

Simulation Navigator

  • Test Models

  • Test Model 1

  • Alignment

  •  

  •   Preview

  • to select the reference node on the test model as the common origin for the test and analysis models.

  • to select the working point on the analysis model as the common origin.

  • Add Pair

     Test Model Alignment dialog box

  • to select the reference node on the test model as the first axis node.

  • to select the working point on the analysis model as the first axis node.

  • Add Pair

  • Align

  • OK
7: Create a Correlation solution process

New Correlation (Correlation group)

  • Reference Solution (Test or Analysis)

    Test Solution — Test Solution

  • OK

     Correlation dialog box

Note the following nodes are created in the Simulation Navigator.

 Correlation 1

  Test Solution

  Modes [10]

  Analysis Solution

  Modes [10]

  Node Map [30]

Mode Sensor Sets

Initial  Sensors [30]

 Mode Pairing

 Mode Pairs [8]

  Mode Correlation Metrics

Note:

The Correlation solution process automatically pairs test and analysis modes. Eight pairs were created. This is indicated by Mode Pairs [8].

8: Inspect the mode pairs

In this step, you will display the mode pairs 5 and 8. These pairs were chosen at random. You can select any other pair.

Simulation Navigator

  • Mode Pairs [8]

  •  

Notice the detailed information on the correlation mode pairs in the Correlation Details View subpanel.

Pair

Ref

Frequency

Wrk

Frequency

MAC

Freq.% Error

1

1

100.3

1

93.93

0.998

6.3838

2

2

146.5

3

141.5

0.978

3.38212

3

4

296.7

5

287.9

0.711

2.97164

4

5

405.7

6

373.6

0.988

7.92817

5

6

474.5

8

448.8

0.983

5.415

6

7

487.8

7

441.3

0.965

9.52281

7

8

521.3

9

485.3

0.839

6.90096

8

9

582.7

10

535.5

0.975

8.10604

  • 5 from the Pair column

  • Side-by-Side Display

  • 8 from the Pair column

  • Side-by-Side Animation

  • any row in the Correlation Details View subpanel.

  • Single View (Result tab).

Return to Model (Context group)

9: Plot the MAC matrix

Plot MAC (Correlation group)

  • the main graphic window

  • Probing Mode (XY Graph group)

  • in the R8W5 cell of the MAC matrix

    Note:

    In the MAC matrix, the R values indicate the reference (test) mode shapes and the W values indicate the work (analysis) mode shapes. The R8W5 cell stores the MAC value for the 8th test mode shape and the 5th analysis mode shape.

    Inspect MAC values for other test and analysis mode pairs.

Return to Model (Context group)

10: Manage test sensors

You will deactivate a sensor, change the direction of one of the sensor’s axis, and enable another sensor’s axis.

Simulation Navigator

  • Initial Sensors [30]

  • Clone

    Mode Sensor Sets

    Initial  Sensors [30]

    Copy of Initial  Sensors 1 [30]

  • Copy of Initial  Sensors 1 [30]

  • Show Sensors

  • Edit

  • Name

    Test Sensors

  • DOF3 for the Sensor 5

  • Apply

     Sensor Set dialog box

  • Note:

    The change is shown in the graphics window.

  • DOF2 for the Sensor 2

  • Apply

  • Selected Rows (Edit in Place group)

  • sensor 7 row

  • Clear All DOFs

  • OK
Note:

Notice the icon in front of the Mode Pairs [8] node in the Simulation Navigator. It indicates that you need to update the mode pairing.

 Mode Pairing

 Mode Pairs [8]

  Mode Correlation Metrics

11: Update the mode pairs

You will update the mode pairs to see how the changes to the sensors influence the mode pairing.

Refresh Correlation Results (Correlation group)

Note:

The change in the sensor configuration found an additional mode pair. Nine mode pairs now exist. The Simulation Navigator displays Mode Pairs [9]. The update icon is no longer displayed.

 Mode Pairing

 Mode Pairs [9]

  Mode Correlation Metrics

Simulation Navigator

  • Mode Pairs [9]

Note:

In the Correlation Details View subpanel, notice that the additional mode pair is mode pair 3. Also notice the values of the existing mode pairs after you modify the sensors. Only the values in the MAC column are different. All the other values remain unchanged.

  • Initial Sensors [30]

  • Make Active

Note:

You activate the sensors with their original configuration that was imported from the UNV file. In the next step, you will generate a DOF set that matches this original sensor configuration.

12: Generate the matching DOF set

You will generate a DOF set that matches the sensor configuration. You will then use this DOF set to modify the analysis solution to solve for the results that contain the reduced mass (Mr) matrix.

Simulation Navigator

  • Initial Sensors [30]

  • Create DofSet

  • Create DOF Set Only

    (Create DOF Set) dialog box

  • Solver Sets

  • 1 – Created from SensorSet 'Initial Sensors'

13: Modify the analysis solution

You will set the analysis (ASET) DOF to be the generated matching DOF set.

Simulation Navigator

  • Analysis Solution

  • Edit

  • General

  •  

  • Solution Process

    Correlation

  • Correlation Database Generation

    Delivery Database

  • Bulk Data

  •  

  • Analysis (ASET)

    Created from SensorSet 'Initial Sensors'

  • OK

     Solution dialog box

14: Solve the analysis solution

  Simulation Navigator

  •   Analysis Solution

  •   Solve

  • OK

     Solve dialog box

  • Wait for Completed to display in the Analysis Job Monitor dialog box and for the command window to close.

  • No

     Review Results dialog box

  • Information window

  • Cancel

      Analysis Job Monitor dialog box

15: Update the Correlation solution process

Notice the update icons in front of the Node Map [30] node. It indicates that you need to update the Correlation solution process.

 Correlation 1

 Test Solution

 Modes [10]

 Analysis Solution

 Modes [10]

 Node Map [30]

Mode Sensor Sets

Initial  Sensors [30]

Test  Sensors [28]

 Mode Pairing

 Mode Correlation Metrics

Refresh Correlation Results (Correlation group)

  • Reload Now

     

Additional nodes are created in the Simulation Navigator under the Analysis Solution Results node: A–Set DOF [60] and Mr [60 x 60].

The Nastran solver performed the Guyan reduction to obtain the reduced mass matrix Mr.

Correlation 1

 Test Solution

  Modes [10]

  Analysis Solution

 A–Set DOF [60]

 Mr [60 x 60]

 Modes [10]

 Node Map [30]

Mode Sensor Sets

Initial  Sensors [30]

Test  Sensors [28]

  Mode Pairing

  Mode Pairs [8]

Mode  Correlation Metrics

16: Plot the MAC and X_Ortho matrices

Plot MAC (Correlation group)

  • the main graphic window

  • Probing Mode (XY Graph group)

    Note:

    Inspect values of the MAC matrix by clicking on the cells.

  • in the R8W5 cell of the MAC matrix

  • Plot Mode Shapes

  • Layout

    Side-by-Side

  •  

  •   Keep Visible

  • OK

     Plot Mode Shapes dialog box

    Note:

    You can compare MAC quantitative correlation with qualitative mode shape in a single layout for a single mode pair.

  • Single View (Result tab).

  • Return to Model (Context group)

  • Plot X-Ortho (Correlation group)

  • the main graphic window

    Note:

    Because the reduced mass matrix Mr exists in the Analysis Solution results, notice that the Plot X-Ortho command is now available from the Correlation toolbar. The reduced mass matrix Mr is necessary for calculating the cross-orthogonality (X-Ortho) matrix.

  • Probing Mode (XY Graph group)

    Note:

    Inspect values of the X-Ortho matrix by clicking on the cells.

  • Return to Model (Context group)

17: Plot the CoMAC matrix

  Simulation Navigator

  •   Mode Correlation Metrics

  •   Correlate Modes

  • Method

    COMAC

  • Show Matrix

  •  the main graphic window

Note:

The CoMAC values that approach 1.0 indicate that these particular degrees-of-freedom have good correlation across the set of mode pairs. The column indicates the sensor’s degree-of-freedom and the row indicate the sensor’s number. You can display the sensor’s number in the graphics window using the Show Sensors command.

Notice that most of the cells with green and orange colors are in the X column indicating that these particular sensors have poor correlation between the set of mode pairs in the X degree-of-freedom.

18: Generate and display CoMAC results

 Simulation Navigator

  •  Mode Correlation Metrics

  •   (1 – COMAC)

    In the Simulation Navigator, a (1 – COMAC) node is created under the Mode Correlation Metrics node.

    Mode  Correlation Metrics

     (1 – COMAC)

  • (1 – COMAC)

  •   Post Processing Navigator

  • Correlation 1

    In the Post Processing Navigator, notice the Correlation 1 result nodes.

     Correlation 1

     (1 – COMAC), X Component - Nodal

     (1 – COMAC), Y Component - Nodal

     (1 – COMAC), Z Component - Nodal

  • (1 – COMAC), X Component – Nodal

Note:

A degree-of-freedom displayed with a large red sphere indicates that its (1 – COMAC) value approaches 1.0. The value indicates that the degree-of-freedom has poor correlation across the set of mode pairs.

Notice the spheres on the fuselage. They are located at the sensors which had the cells with green and blue colors in the X column of the CoMAC matrix on the previous page. Compare the colors of the displayed spheres to the color spectrum to find the values for the degrees-of-freedom.

Explore (1 – COMAC) results for the Y and Z components.

19: Save and close

Save and close your files when you are finished.

File

  • Save→Save All

File

  • Close→All Parts