Using modal participation factors in a load recipe

You can create a load recipe from Modal Participation Factors (MPFs) in Simcenter 3D Noise and Vibration. For example you can use spectra, waterfall or order cut data to create a load recipe which contains all the excitations across a range of frequencies. Creating the load recipe from the MPFs will create the subcases and loads efficiently.

You can create a load recipe from the MPFs, which you can then use in a vibro-acoustic solution to compute how a structure excites an acoustic fluid and radiates noise to the environment. The MPFs contain the contributions of each mode and the applied forcing frequencies. The software multiplies MPFs by the mode shapes and outputs the responses.

To generate MPFs when the solver is Simcenter Nastran, enable the SDISPLACEMENT output request in a:

• SOL 108 Direct Frequency Response solution with a pre-computed Mode Set.

• SOL 111 Modal Frequency Response solution

You solve a structural analysis under operating conditions, such as loads or RPMS, and solve for the corresponding MPFs. You can also obtain the MPFs from other types of analysis, such as Simcenter 3D Motion.

In a typical workflow:

You solve a structural analysis under operating conditions, such as frequencies or RPMS, and solve for the corresponding MPFs and mode shapes. The MPFs can also be obtained from other types of analysis, such as Motion.

In Simcenter 3D the MPFs are then used as input in the Simcenter 3D Noise and Vibration MATV Response solution.

You will have:

• An assembly FEM in which:A structure is represented as a Mode Set. The Mode Set contains mode shapes at different eigenfrequencies. The modes should be computed up to 1.5 to 2 times the highest frequency of the solution.An acoustic fluid is represented as an ATV Set. The ATVs are over computed over a frequency range, at a fine frequency step.

• MPFs as loading. The MPFs act as loads under a forced response over a frequency range, typically matching the ATV Set frequency range, but at a finer frequency step.

For more information, see Create a solution from a load recipe.

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Using modal participation factors in a load recipe, Simcenter 3D 2021.1 Series

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