Limiting frequency response output to peak responses

In a Simcenter Nastran SOL 108 or SOL 111 structural or vibro-acoustic frequency response analysis, you can limit the output to frequencies where peak responses occur. This capability is called peakout.

Note:

Although Simcenter Nastran supports peakout for structural, acoustic, and vibro-acoustic frequency response analysis, Simcenter 3D supports peakout for structural and vibro-acoustic frequency response analysis only.

Without peakout, two solves are required for you to perform an equivalent analysis. The first solve calculates the frequency responses. From the frequency responses, you manually identify the frequencies where peak responses occur. You then solve the model at those frequencies. Thus, using peakout can save you time and reduce the chances for error.

When you use the peakout capability, the software does the following:

1. For each output request, calculates frequency responses for all the DOF where output is requested.

2. For DOF that you specify, filters the frequency responses using filtering criteria that you specify.Each response that satisfies the filtering criteria is called a peak response.

3. For the output requests to which you apply peakout, at all the DOF where output is requested, limits the output to the responses at the frequencies where peak responses occur.

Note:

When you apply peakout to multiple output requests, the software outputs the frequency response results for each output request at the frequencies where the peak responses occur. When peakout is not applied to an output request, the software outputs the frequency response results for that output request at all of the analysis frequencies.

Filtering criteria

You specify the filtering criteria when you create a peakout modeling object. The filtering criteria, in the order that Simcenter Nastran applies them, are as follows:

1. Limit the frequency range — The response at frequencies outside the range is excluded from the peak response search.

2. Response cutoff — The response within the frequency range, but below the response cutoff is excluded from the peak response search.

3. Response proximity — Responses within the frequency range and above the response cutoff are excluded from the peak response search if they are in close proximity to other responses with higher magnitude.

4. Requested number of peaks — Of the responses that remain after the software applies the first three criteria, the requested number of responses with the highest magnitude responses are the peak responses. The other responses are not considered peak responses unless they satisfy the outlier recovery criterion.

5. Outlier recovery — The outlier recovery criterion identifies as peak responses those responses that were eliminated because of the requested number of peaks criterion, but are at much different frequencies than the peak responses that the software identified after it applied the first four criteria. Thus, it is possible to have more peak responses than the number you requested.For a detailed explanation of how Simcenter Nastran applies this criterion, see the remarks for the FAR field in the PEAKOUT bulk entry.

Implementing peakout

Peakout is added to a Simcenter Nastran SOL 108 or SOL 111 structural, acoustic, or vibro-acoustic frequency response simulation by specifying:

• Which output requests to apply peakout.

• The type of frequency response results to filter.

• The DOF whose frequency responses are filtered.

• The filtering criteria.

After you solve the model, you can use the tools in the Post Processing Navigator and the XY Function Navigator to examine the results in the same way as you would for any other frequency response analysis.

Post-processing scenarios

You can also create a post-processing scenario to implement peakout.

For information on how to do so, see Peakout Frequencies Plots scenario.

Output requests that support peakout

The following table shows the Simcenter 3D output requests that support peakout.

Output request	Structural analysis	Vibro-acoustic analysis
Acceleration	X	X
Acoustic Pressure		X
Displacement	X	X
Grid Contribution		X
Modal Contribution	X	X
Panel Contribution		X
Velocity	X	X

Where do I find it?

Specify which output requests to apply peakout in a structural frequency response analysis

Application	Pre/Post
Prerequisite	Simcenter Nastran as the specified solverSOL 108 or SOL 111 as the specified solution typeStructural as the analysis type
Command Finder	Modeling Objects
Location in dialog box	Modeling Objects Manager dialog box→Type list→Structural Output Requests→Create

Specifying which output requests to apply peakout in a vibro-acoustic frequency response analysis

Application	Pre/Post
Prerequisite	Simcenter Nastran as the specified solverSOL 108 or SOL 111 as the specified solution typeVibro-acoustic as the analysis type
Command Finder	Modeling Objects
Location in dialog box	Modeling Objects Manager dialog box→Type list→Vibro-Acoustic Output Requests→Create

Specifying the type of frequency response results to filter, the DOF whose frequency responses are filtered, and the filtering criteria

Application	Pre/Post
Prerequisite	Simcenter Nastran as the specified solverSOL 108 or SOL 111 as the specified solution typeStructural or vibro-acoustic as the analysis type
Command Finder	Modeling Objects
Location in dialog box	Modeling Objects Manager dialog box→Type list→PEAKOUT Criteria→Create

Creating a Peakout Frequencies Plots scenario

Application	Pre/Post
Prerequisites	A Simulation file as the work part and displayed partSupported results
Command Finder	Scenario Setup (Results tab)

How do I

Reduce response errors with residual vectors

Learn more

Dynamic analysis

Simcenter Nastran dynamics workflow

Specifying forcing frequencies for a frequency response analysis

Assigning frequencies from all loads to subcases

Defining eigenvalue extraction data for Nastran analyses

Residual vector loads in a SOL 103 Real Eigenvalue solution

Quick links

Command reference

Pre/Post video examples

Bulk Entry Descriptions

Simcenter 3D tutorials

Browse Simcenter 3D help by product area

Limiting frequency response output to peak responses, Simcenter 3D 2021.1 Series

© 2020 Siemens

window.mainLanguage="en_US"

window.delivId=""

window.projectId=""

MathJax.Hub.Config({ TeX: { extensions: ["autoload-all.js"] }, tex2jax: { displayMath: [ ] }, "SVG": { scale: 125 } });