Dynamic Event

Define a Modal Transient (MTRAN) loadcase.

Using the Dynamic Event tool, you can setup a dynamic (Modal Transient) loadcase to solve and analyse squeak and rattle problems.
  1. From Setup group, select Dynamic Event.
    Figure 1.
  2. Optional: On the guide bar, click to define Load Case Options
  3. Select a node(s) where the load should be applied to in the graphics area.
  4. Use the Load Type drop down menu on the microdialog to select the required load type.
    Available load types are-
    • D- Displacement
    • V- Velocity
    • A- Acceleration
    • F- Force
  5. Select a curve type from Load Curve list.
    Available load curve types are-
    • 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
  6. Optional: Select Curve Editor option to open the Curve Editor window.
    Once a load is created, the Curve Editor window appears where all the loads are displayed as curves. You can choose the listed curves and view them in time v/s displacement plots.
  7. Select Load Direction(s).
  8. Optional: For SineSweep and PSD use to view more options.
    Note: Input Type activates only for From PSD curve type.
  9. Click .
    This will create a Dynamic event loadcase at the selected node and all the relevant cards are created and listed in the model browser automatically. Refer to Linear Transient Analysis Optistruct page .
    Below is an example-
    Figure 2.
    For more details refer to Optistruct Manual.

Dynamic Event Options

Description of Dynamic loadcase options.

Below are the options available for dynamic loadcase setup.
Load Curve
Sine Sweep
Sinusoidal or Sine sweep is a sine function that gradually changes frequency over time.
Only Displacement load type is supported.
From File
Use this option to import a file containing the load time history. SnRD supports loading either one, two or three directions.

Refer From File options.

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 4 loadcases.
Figure 3.
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.

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
(EIGRL/EIGRA) – Defines data for Eigenvalue analysis
Method
Select Eigenvalue method, Lancos 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
(TABDMP1) – Defines damping parameters
Damping
Define damping factor as constant over all frequencies or through a table
Method
Set damping method
Time Step
(TSTEP) – Defines Time Step Parameters
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
Displacement
Output displacement on all E-lines
Velocity
Output Velocity on all E-lines

Note: 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 4.
Three Directions-
TIME, X, Y, Z
Three directions sample file is shown below-
Figure 5.
Two Directions XY-
TIME, X, Y
X,Y direction loading sample file is shown below-
Figure 6.
Two Directions XZ-
TIME, X, Z
X,Z direction loading sample file is shown below-
Figure 7.