Mechanical APDL Basic Analysis Guide - Ansys

2.6. Specifying Load Step Options
As mentioned earlier, load step options is a collective name for options that control how loads are used
during solution and other options such as output controls, damping specifications, and response spectrum
data. Load step options can vary from load step to load step. There are six categories of load step options:
• General Options
• Dynamics Options
• Nonlinear Options
• Output Controls
• Biot-Savart Options
• Spectrum Options
2.6.1. Setting General Options
These include such options as time at the end of a load step in transient and static analyses, number of
substeps or the time step size, stepping or ramping of loads, and reference temperature for thermal strain
calculations. A brief description of each option follows.
2.6.1.1. Solution Controls Dialog Box
If you are performing a static or full transient analysis, you can use the Solution Controls dialog box to set
many of the load step options described on the following pages. Where applicable, the menu path to the
Solution Controls dialog box is included. For details about using the Solution Controls dialog box, see Solution
(p. 97).
2.6.1.2. The Time Option
The TIME command specifies time at the end of a load step in transient and static analyses. In transient and
other rate-dependent analyses, TIME specifies actual, chronological time, and you are required to specify a
time value. In other, rate-independent analyses, time acts as a tracking parameter. You can never set time
to zero in an ANSYS analysis. If you issue TIME,0 or TIME,(blank), or if you do not issue the TIME command
at all, ANSYS uses the default time value: 1.0 for the first load step, and 1.0 + previous time for other load
steps. To start your analysis at "zero" time, such as in a transient analysis, specify a very small value such as
TIME,1E-6.
2.6.1.3. Number of Substeps and Time Step Size
For a nonlinear or transient analysis, you need to specify the number of substeps to be taken within a load
step. This is done as follows:
Command(s): DELTIM
GUI: Main Menu> Preprocessor> Loads> Load Step Opts> Time/Frequenc> Time & Time Step
Main Menu> Solution> Load Step Opts> Sol'n Control ( : Basic Tab)
Main Menu> Solution> Load Step Opts> Time/Frequenc> Time & Time Step
Main Menu> Solution> Load Step Opts> Time/Frequenc> Time & Time Step
Command(s): NSUBST
GUI: Main Menu> Preprocessor> Loads> Load Step Opts> Time/Frequenc> Freq & Substeps (or
Time and Substps)
Main Menu> Solution> Load Step Opts> Sol'n Control ( : Basic Tab)
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2.6.1. Setting General Options
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