Dynamic Event

Use the Dynamic Event tool to define a dynamic (Modal Transient (MTRAN)) loadcase to solver and analyze squeak and rattle occurrences.

From the SnRPre ribbon, Setup group, select the Dynamic Event tool from the Dynamic Event tool group.

Figure 1.
Optional: From the guide bar, click to define loadcase options.
In the modeling window, select one or more nodes where the load should be applied.
In the microdialog, select the required load type.
For Load Curve, select a curve type.
- Sine Sweep: Defines a SineSweep curve.
- From File: Import a load curve data in time domain from an external file.
- From PSD: Select a PSD curve and SnRD will convert it to time-domain.
- From Curve: Select curve(s) TABLED1, which already exists in session.
Optional: To visualize curves, click to open the Curve Editor dialog.
Click Load Direction(s).
Optional: Click to define scaling and other options.
From the guide bar, complete one of the following options:
- Click to create the dynamic event and remain in the tool.
- Click to create the dynamic event and exit the tool.
- Click to exit the tool without creating the dynamic event.

A dynamic event loadcase is created at the selected node. All the relevant cards are automatically created and listed in the Model Browser.

For more information, see Linear Transient Analysis in the OptiStruct User Guide and EIGRA in the OptiStruct Reference Guide.

Dynamic Event Options

Description of Dynamic loadcase options.

Load Curve

Sine Sweep: Sinusoidal or Sine sweep is a sine function that gradually changes frequency over time.; Displacement and Acceleration load types are supported.
From File: Use this option to import a file containing the load time history. SnRD supports loading either one, two, or three directions.; Note: When more than one load direction is created at the same time, SnRD will automatically create one Loadcase for each direction and one with all directions combined. Example: Applying a load on one node in three directions at the same time will create four loadcases.

Figure 2.
From PSD: PSD: Power Spectral Density; An Input PSD curve (Acceleration vs Freq) is converted into a signal in timedomain depending on the selection of loadtype and Time length.
From Curve: Use already existing curves (TABLED1) in session as load curves. You will be prompted to select which curve is used for which direction.

Undo Dynamic Event ()

Reverts the recently created dynamic event.

You can revert the creation only if Curve Editor (

) is chosen.

Curve Editor ()

Launches the Curve Editor after creation of loadcase which allows for preview of the imported load curve(s).

Modes

Defines data for Eigenvalue analysis (EIGRL/EIGRA)

Method: Select Eigenvalue method, Lanczos or Amses.; Defines data required to perform real eigenvalue analysis (vibration or buckling) with the Lanczos Method.
Frequency Range: Define which frequency range to consider in evaluation.
No of Modes to Extract: Set the number of modes to extract. If set to blank all modes in Frequency range are extracted.

Damping

Defines damping parameters (TABDMP1)

Damping: Define damping factor as constant over all frequencies or through a table.
Method: Set damping method.

Time Step

Defines Time Step Parameters (TSTEP)

Auto Time Step: Automatically extracts Time Step based on load curve.
Auto No of Time Steps: Automatically extracts number of time steps based on load curve.
Output frequency: Defines the output frequency of the results at the respective time steps.

Output

The Supported format for loadcurve data is CSV and TXT and columns in file should be organized depending on your selection as shown below:

One direction-: TIME, DIR1; One direction sample file is shown below-; Figure 3.
Three Directions-: TIME, X, Y, Z; Three directions sample file is shown below-
Figure 4.
Two Directions XY-: TIME, X, Y; X,Y direction loading sample file is shown below-; Figure 5.
Two Directions XZ-: TIME, X, Z; X,Z direction loading sample file is shown below-; Figure 6.