Define Dynamic Loads
Dynamic (time-dependent) loading on boundaries (vertices, edges and faces) can be defined in terms of displacement, force, velocity or acceleration versus time.
Project Settings
Ensure that the Dynamic Analysis checkbox is enabled in Project Settings 
and enter the dynamic setup parameters.
Add Dynamic Load
To define dynamic loads on boundaries:
- Select the Dynamic workflow tab
- Select Define Dynamic Loads
from the toolbar or the Dynamic menu. - You will see the Dynamic Load Properties dialog. To edit an existing load click on the load name in the list at the left of the dialog. To define a new load select the Add
button. To delete a load, select the Delete 
button. You may enter or edit the load name or use the default name (e.g. Dynamic Load 1). - Select the load Type. There are five possible dynamic load types:
- Force
- Displacement
- Velocity
- Acceleration
- Choose the load direction(s):
- Custom - X, Y or Z axis directions
- Normal (to boundary)
The dynamic load may be defined independently in the X, Y and Z directions or the load may be applied in the direction perpendicular to the boundary it will be applied on. Select the appropriate direction option, whether it is normal, or a combination of X, Y and Z directions.
- Select the Define button beside the X, Y, Z or Normal option, and you will see another dialog which allows you to enter the time-dependent load information. Enter the Time and Load values in the data columns (at least two points must be defined).
- You can also Import
or Export 
comma, tab or space delimited text files to add or extract load function data. - Furthermore, you can select the Power Spectrum option to filter input data with a defined frequency range. See the topic for more details.
- Select Show Chart
to plot the function in the chart area at the right. Select the Copy Chart button to copy the chart image onto the Microsoft clipboard. - Use the available editing tools on the right of the table to select all, cut, copy, paste from clipboard, insert, delete, append data values.
- Select OK in the Define Dynamic Load dialog when you have entered your load function.
- Select OK in the Dynamic Load Properties dialog to save the dynamic load(s).
After defining dynamic loads, they can be applied to the model with the Add Dynamic Loads option.
Drift Correction
The Drift Correction option is only applicable for Velocity or Acceleration load types. Selecting this will ensure that the displacement that is applied to the nodes will start and end at zero. See the Dynamic Analysis Theory document for details.
Compliant Base
The Compliant Base option is only applicable for Velocity or Acceleration load types. Since a rigid base will null the effects of the absorb boundary conditions, in order to absorb outgoing waves from the model (to avoid the reflection of those waves back to the model), the motion restraint is transferred to stresses and applied to the boundaries. This option can only be applied to Velocity or Acceleration loads applied to a horizontal and planar face that lies on the XY plane and is at the base of the External geometry.