Use the minEnvelope function to operate on two or more previously saved X–Y data objects (each object is a collection of ordered pairs) to produce a new X–Y data object. The new X–Y data object has as its X-coordinates all X-coordinates of the input data objects and any additional X-coordinates needed for alignment of the input data objects. ABAQUS/CAE computes additional X–Y data pairs by interpolation and extrapolation. The new data object has as its Y-coordinates the minimum Y-coordinate of all input X–Y data objects at the current X-coordinate. The arguments of this operation are commutative.
Figure 29–28 illustrates the type of X–Y plot that can be produced by using the minEnvelope function.
For information on how to find the current minimum of a single X–Y data object, see “Finding the current minimum of an X–Y data object,” Section 29.4.32.
To find the current minimum of two or more X–Y data objects:
Locate the Operate on XY Data dialog box.
From the main menu bar, select Tools
XY DataCreate. Click Operate on XY data in the dialog box that appears; then click Continue. The Operate on XY Data dialog box appears.
From the Operators listed, click minEnvelope(A,A,...).
The minEnvelope function appears in the expression window.
From the XY Data choices, click the names of two or more X–Y data objects on which to operate and click Add to Expression. Choices include all previously saved X–Y data objects, which are listed alphabetically.
The X–Y data object names appear, separated by commas, within the minEnvelope function parentheses in the expression window.
To continue to build your expression, position the cursor in the expression window and type in or select the functions, operators, and X–Y data you want to include.
To evaluate and display your expression, click Plot Expression.
To save your new X–Y data object, click Save As and then provide a name in the dialog box that appears.
Saving your data object makes it available for future operations within this session and for inclusion in X–Y plots containing multiple data objects.
When you are finished, click Cancel to close the dialog box.
