You can specify a load by entering a mathematical function.
Specifying a Load with a Mathematical Function
To define a function load:
In the Details pane, click Magnitude (or Displacement) and select from the fly-out menu.
Enter a function, such as =1000*sin(10*time). Note that the values you are evaluating can exceed the final time value by as much as one time step.
The Graph window displays the variation of the load with time. Annotations in the Geometry window display the current time in the Graph window along with the load value at that time.
Supported Mathematical Functions
The following functions are supported:
|
|
Note: When you specify a Magnitude as a , the integer Modulus (%) operator is not supported.
Spatial Load and Displacement Function Data
When using spatial varying loads or displacements, selecting Function as the input option in the Details pane presents an editable function field. Enter a mathematical expression in this field. Expressions have the following requirements:
For a Pressure load, the Define By option must be set to Normal To.
For a Line Pressure load, the Define By option must be set to Tangential.
You can use the spatial variation independent variables x, y, or z, and time (entered in lowercase) in the definition of the function.
For Line Pressure loads in a 3D analysis or Pressure loads in a 2D analysis, you can also use the variable s. This allows you to define pressure as a function of the distance along a path whose length is denoted by s. When defining a path length, valid primary variables you can enter are s alone or s combined with time, for example, s*time, or s*sin(time/s). Load values are sent to the solver for each element on the defined path based on a first-order approximation.
Define only one direction, x, y, or z, or path length, s. After entering a direction or path length, the Graph Controls category (see above) displays.
Properties of Mathematical Function Loads
When the Details pane property Magnitude is set to Function, the following categories automatically display.
- Function
Properties include:
Unit System: The unit system that defined when you select the Function option. As a read-only property, the unit system does not change.
Angular Measure: The angular measure that is used to evaluate trigonometric functions. As a read-only property, the angular unit does not change.
Note: The application uses the currently selected Unit System and Angle when you specify the Function option for the Magnitude. This setting does not change even if you manually change the Unit System and/or Angle.
- Graph Controls
Properties include:
X-Axis: This provides options to display time or the spatial independent variable in the graph. When set to Time you can activate and deactivate the load at a solution step.
Alternate Value: If the function combines time and a spatial independent variable, one of these values (alternate) must be fixed to evaluate the function for the two dimensional graph.
Range Minimum: If the X-Axis property is set to a spatial independent variable, this is the minimum range of the graph. For time, this value defaults to 0.0 and cannot be modified.
Range Maximum: If the X-Axis property is set to a spatial independent variable, this is the maximum range of the graph. For time this defaults to the analysis end time and can’t be modified.
Number of Segments: The function is graphed with a default value of two hundred line segments. This value may be changed to better visualize the function. The function can be graphed with up to 100,000 segments.
Caution: Specifying a large number of points may slow the response time of Mechanical.