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How to Define Event Curves in Timeline

When setting up a time-based event, you must specify how loads change over time. For example, you might want to define a cyclical load based on a sine wave or ramp up a load logarithmically.

You can use the Timeline graphical utility to specify and visualize time-based event curves. Timeline enables you to produce multiple and complex time-based event curves within FEMPRO, which can help you to more quickly perform transient analyses. It graphically plots curves based on your time-dependent variable inputs, making it easy to catch setup errors prior to analysis by simply viewing the resulting curves and how they interact throughout an event.

Timeline consists of two components -- an event editor and an event viewer -- and features:

  • the ability to click and drag points on a plot display;
  • a built-in equation editor for creating event curves using mathematical expressions;
  • depiction of various event curves on a single plot or multiple plots;
  • presentation support, including capabilities to save curves as images for reports;
  • a library for saving commonly used curves; and
  • the ability to exchange curve data with Microsoft Excel or other applications through the use of a comma-separated value (CSV) file.

Defining an Event Curve with the Timeline Event Editor

To define a time-based event curve using Timeline, you must first add a load to the model in the FEA Editor environment. Then, in the dialog for adding the load, a number is specified in the "Load Case/Load Curve" field and the "..." button is clicked to access the Timeline Event Editor (see Figure 1).

Figure 1: After specifying a load curve number, the "..." button is used to access the Timeline Event Editor.

With the editor, you enter curves into a spreadsheet-style dialog to define individual events or loads. Curves can also be imported from a CSV file or generated using the equation editor.

If, for example, you wanted to define an event curve that could be expressed as a sine wave, you would click on the equation editor toolbar icon to access the "Equation Editor" dialog. The equation editor:

  • supports a single variable (x);
  • includes 20 built-in functions that will perform mathematical operations such as sine, logarithm, etc.; and
  • includes support for the constant PI.

As shown in Figure 2, the start time, end time, interval and equation are specified to define the event curve in the equation editor.

Figure 2: The "Equation Editor" dialog of the Timeline Event Editor enables you to define event curves by entering an equation.

Viewing Event Curves with the Timeline Event Viewer

The viewer enables you to view the timelines that have been defined for each load, which can help you validate setup by displaying curves and seeing how loads will act on a model during analysis -- their activation and deactivation times and how their magnitude changes over time. To access the Timeline Event Viewer, right click on "Analysis Parameters" in the tree view and choose "View Timelines...". As shown in Figure 3, two additional timelines were defined for our example model, which can be displayed either all together or in separate windows.

Figure 3: The "Timeline Event Viewer" dialog enables you to view the timelines that have been defined for each load either all together (left) or separately (right).

You can double-click on a graph to access the Timeline Event Editor and modify the event curve.

Thus, Timeline provides convenience and flexibility by enabling you to manage time-dependent input parameters through a graphical user interface.

For more information about Timeline, click here or see the ALGOR User's Guide.

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