Expanding vibration measurements to a mesh workflow

Performing a Simcenter 3D Noise and Vibration Modal Expansion solution is a two-step process. You start with an assembly FEM that contains a mode set of the structural mesh.

It is presumed:

• The mode set has enough detail to properly represent the mode shapes and frequency characteristics.

• The measured vibrations are detailed enough to represent an accurate structural behavior.

To create a Modal Expansion solution, do the following:

1. Create a Model and Load Pre-processing solution to perform Mesh Mapping.

2. Create a Modal Expansion solution.

Model and Load Pre-processing Workflow
Step	Summary	Detailed help topic
1.	Open or create a Simulation file of an assembly FEM.	Open or create a Simulation file of an assembly FEM containing a mode set representation of the FEM file.	Alternate representation (standalone FEM file)Mode Set / Frequency Response Function Set / Acoustic Transfer Vector Set / Vibro-Acoustic Transfer Vector Set dialog box
2.	Create an MLPP solution.	In the Simulation Navigator, right-click the Simulation file and choose New Solution Process→Model and Load Pre-processing.(Optional) In the Model and Load Pre-processing dialog box, type the name that you want to appear in the Simulation Navigator for the solution process.Click OK.	Modal Expansion Output Requests dialog box
3.	Add the input file to the solution.	Choose Add Load → Input File to select the desired mesh input file.Then refresh the data table and deselect any undesired inputs.
4.	Edit the mesh mapping.	In the Simulation Navigator, right-click the Mesh Mapping node and choose Edit.	Solution Step dialog box (Modal Expansion)
5.		In the Simulation Navigator, right-click the Mesh Mapping node, and choose Add Operations → mesh Mapping.	Mesh Mapping dialog box
6.	Name the file to export the mesh mapping matrix and compute the mapping matrix.	Name the file of the Export Mesh Mapping Matrix.Enable Export Mesh Mapping Matrix.
7.	Specify the mesh mapping	In the Simulation Navigator, right-click Mesh Mapping Data and choose Edit.Select the Mapping Method and then select:Maximum DistanceConservative Maximum DistanceNearest NeighborNote: Select Nearest Neighbor if there is a one-to-one correspondence between the measurement data and the mesh.If you select Maximum Distance or Conservative Maximum Distance, specify the Maximum Distance to search between nodes.
8.	Perform the mesh mapping.	Select the Transfer From (source mesh) and the Transfer To (destination mesh) entities.If there is a one-to-one correspondence between the source and destination mesh, select Same as Source.
9.	Solve the MLPP solution to compute the mesh mapping.	Right-click the MLPP solution and choose Solve.
10.	Post-process the results with Post-Processing Scenario to examine the mesh mapping results.	Right-click the solution Results and choose Post-Processing Scenario	Scenario-based post-processing

Modal Expansion Workflow
Step	Summary	Detailed help topic
1.	Create a Modal Expansion solution.	Set the Solver to Simcenter 3D Noise and Vibration.Set the Analysis Type to Structural.The Solution Type is automatically set to Modal Expansion.Click Create Solution.
2.	Edit or create forcing frequencies.	Click Create Forcing Frequencies . If you do not define any frequencies the input load or analysis frequencies are used.
3.	Edit or create the output requests.	Right-click the Modal Expansion solution and choose Edit.Enable Displacement, Velocity, and/or Acceleration as output.Enable Modal Participation Factors.	Modal Expansion Output Requests dialog box
4.	Set singular value decomposition.	Set Relative Threshold for Singular Values % to filter the modal data.
5.	Edit the solution subcase.	Right-click Subcase – Modal Expansion and choose Edit	Solution Step dialog box (Modal Expansion)
6.	Edit the vibration file.	Edit or Create the Reduced Vibration Set
7.	Edit the vibration and mesh mapping files.	Specify the Vibrations or Mode Shapes.Vibrations file types:Simcenter Testlab Project File (.lms)Nastran Results Files (.op2)Simcenter HDF5 Data File (.sc_h5) I-deas Results Files (.unv)Mode Shapes file types:Nastran Results Files (.op2)Simcenter HDF5 Data File (.sc_h5) Specify the Mapping Table from the following file types:Simcenter HDF5 Data File (.sc_h5) Test Files (.txt)Comma Separated Values (.csv)	Reduced Vibration Set dialog box
8.	Select the degrees of freedom to use.	Select theDegrees of Freedom to be used:Translation and RotationTranslationRotationSelect Skip Missing DOFs to ignore missing degrees of freedom, such as measurements that do not include some of the possible DOFs, such as rotations.
9.	Solve the solution.	Right-click the Modal Expansion solution and choose Solve.	Solve dialog box
10.	Post-process the results with Post-Processing Scenario.	Right-click Results and choose Post-Processing Scenario.	Scenario-based post-processing

Learn more

Mapping measured or computed modes to a mesh

Expanding mode shapes to a mesh workflow

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Expanding vibration measurements to a mesh workflow, Simcenter 3D 2021.1 Series

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