Mechanical APDL Basic Analysis Guide - Ansys

Chapter 3: Using the Function Tool
• Function -- A set of equations that together define an advanced boundary condition.
• Primary Variable -- An independent variable evaluated and used by the program during solution.
• Regime -- A portion of an operating range or design space characterized by a single regime variable.
Regimes are partitioned according to lower and upper bounds of the regime variable. The regime variable
must be continuous across the entire regime. Each regime contains a unique equation to evaluate the
function.
• Regime Variable -- The defining variable that governs which of the set of equations is used to evaluate
the function.
• Equation Variable -- A dependent (user-specified) variable, defined when the function is loaded.
3.2. Using the Function Editor
The Function Editor defines an equation or a function (a series of equations). You use a set of primary variables,
equation variables, and mathematical functions to build the equations. Each equation applies to a particular
regime. The equations defined for each regime, taken together, define a function, and the function as a
whole is applied (for example, as a boundary condition, or to define the nonlinear material behavior for a
joint).
The following topics related to the Function Editor component of the Function Tool are available:
3.2.1. How the Function Editor Works
3.2.2. Creating a Function with the Function Editor
3.2.3. Using Your Function
3.2.1. How the Function Editor Works
Using the Function Editor is similar to using a scientific calculator. For example, when building an equation,
you can:
• Click buttons on the on-screen keypad.
The keypad includes the numbers 0-9, parentheses, and a set of mathematical operators. In addition to
the default set of operators, you can also click the INV key to access an alternate set of operators.
• Use any variable name.
The editor interprets any variable name you type as an equation variable. You can use up to 10 userdefined
equation variables in a function (up to six regimes). You can use any name you wish, but ANSYS
recommends against using the same name as one of the primary variables. You define the values for
these variables when you load the function (described in Using the Function Loader (p. 79)).
• Select a primary variable from a drop-down list.
As you build an equation, it appears in standard mathematical syntax in the equation box above the keypad.
The various components (primary variables, equation variables, mathematical operators, and numbers) appear
in different colors so that you can more easily verify the equation you are entering. You can also graph or
list the equation using the GRAPH/LIST button in the Function Editor dialog box; see Graphing a Function
(p. 85) for more information about this feature.
Ensuring the Validity of Your Equation
The Function Editor does not validate the equation construction. (ANSYS generates an error message if you
enter an inappropriate equation construction.) You must also ensure the mathematical validity of any
equation.
76
Release 13.0 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information
of ANSYS, Inc. and its subsidiaries and affiliates.