1.3 Mechanical APDL Environment
There are two basic levels in ANSYS - Begin level and Processor level. The Begin level acts as a doorway into and out of the program. It is also used for performing operations such as changing the jobname, clearing the database, and copying binary files. When the analyst first enters the program, s/he is at the Begin level. At the Processor level, many processors are available. Each processor is a set of functions that performs a specific analysis task. The model is built in the general preprocessor (PREP7). Loads are applied and the solution is obtained in the solution processor (SOLUTION). The results of a solution are assessed in the general postprocessor (POST1). An additional postprocessor, POST26, permits to evaluate solution results at specific points in the model as a function of time.
1.3.1 Entering a Processor
Select a processor to enter it from the Main Menu of the GUI. Choose Main Menu> Preprocessor to enter into PREP7.
1.3.2 Exiting from a Processor or from the Program
Pick Main Menu> Finish to return to the Begin level from a processor. Without returning to the Begin level, the user can move from one processor to another. Simply pick the processor necessary to do so. Pick Utility Menu> File> Exit to leave ANSYS. By default, ANSYS saves the model and loads automatically and writes them to the database file, Jobname.DB. If a backup of the current database file already exists, ANSYS writes it to Jobname.DBB. Other portions of the database can be saved using options in the dialog box. The user can as well quit without saving.
 In order to input a new file, select Utility Menu> File> Clear & Start New to clear the current file from memory, then select a file to input. In order to return to processing the original file, select Utility Menu> File> Read Input from..., select the name of the file to resume from and select the OKbutton. The processing of an input file can be stopped as it is being input. Most files will display the Process Status window at the top of the screen. Use the STOP button on the Process Status window to terminate the input of a file. Stopping file input is useful when a binary file is input unintentionally.
 1.3.3 The Database
ANSYS stores all input data and results data in one large database in an structured manner. The main advantage of the database is any specific data item can quickly and easily be listed, displayed, modified, or deleted. No matter which processor the analyst is in, s/he works with the same database. This gives basic access to the model and loads portions of the database from anywhere in the program. "Basic access" refers the ability to select, list, or display an item.
1.3.3.1 Defining or Deleting Database Items
The analyst must be in the right processor to define or delete items from the database. Nodes, elements, and other geometry can be defined only in PREP7, the general preprocessor. Loads can be specified and applied in either the PREP7 or the SOLUTION processor. However, geometry items can be selected, listed, or displayed from anywhere in ANSYS.
1.3.3.2 Saving the Database
The analyst should frequently save copies of database to a file as it contains all the input data. Pick Utility Menu> File> Save as Jobname.DB to do this. This choice writes the database to the file Jobname.DB. SAVE command has the following options: Pick Utility Menu> File> Save as to specify a different file name. Any save operation first writes a backup of the present database file to Jobname.DBB. If a Jobname.DBB file already exists, the new backup file overwrites it.
1.3.3.3 Restoring Database Contents
Pick Utility Menu> File> Resume Jobname.DB to restore data from the database file. This reads the file Jobname.DB. Pick Utility Menu> File> Resume from to specify a different file name. The database can be saved or resumed from anywhere in ANSYS, including the Begin level. A resume operation replaces the data currently in memory with the data in the named database file. Using the save and resume operations together is helpful when "testing" a function or command.
1.3.3.4 Session Editor
During an analysis, it may be necessary to modify or delete commands entered since the last SAVE or RESUME. The session editor is used for displaying and editing the sequence of operations performed since the last SAVE or RESUME command. The analyst can modify command parameters, delete whole sections of text or save a portion of the command string to a separate file. The session editor (Fig. 1.4) can be accessed by choosing Main Menu> Session Editor.
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Fig. 1.4 The Session Editor
The following file operations are available in the session editor: The Session Editor is available in GUI mode only. It is a powerful ANSYS Undo. ANSYS keeps a running copy of the log file from the last save command. By modifying the values in the Session Editor window and clicking OK, the modified commands are read back into ANSYS. If no SAVE or RESUME command has been issued during the analysis, all commands from the current session will be executed, including the start160.ans file, if present.
1.3.3.5 Clearing the Database
In building a model, sometimes it may be necessary to clear out the database contents and start afresh. Choose Utility Menu> File> Clear & Start New to do so. This method clears the database stored in memory. Clearing the database has the same effect as leaving and re-entering the program, but does not require to exit.
1.3.4 Program Files
The program writes and reads many files for data storage and retrieval. File names follow this pattern: Name.Ext. Name defaults to the jobname, which the analyst specifies while entering the program or by choosing Utility Menu> File> Change Jobname. The default jobname is FILE (or file). Ext is a unique, two- to four-character identifier that identifies the contents of the file. For example, Jobname.DB is the database file, Jobname.EMAT is the element matrix file, and Jobname.GRPH is the neutral graphics file.
1.3.4.1 File Types
The filename can contain up to 248 characters, including the directory name, and the extension can contain up to eight characters. ANSYS can process blanks in file or directory names, so blank spaces are permitted in object names. When an object has a blank space in its name, always enclose the name in a pair of single quotes. Use back slashes (\) instead of (/) slashes in directory names. For example, a typical directory path looks like this: C:\Program Files\ANSYS Inc\ANSYS Student\v201\ANSYS\apdl\start.ans
1.3.4.2 The Jobname.LOG File
The Jobname.LOG file (the session log) is mainly important, as it provides a complete log of the session. This file opens immediately when the analyst enters ANSYS, and it records all commands executed. S/he can read the Jobname.LOG file, view it while in ANSYS, edit it, and input it later.
The program always appends log data to the log file instead of overwriting it. If the analyst changes the jobname while in a session, the log file name does not change to the new jobname.
1.3.5 Communicating with ANSYS
The easiest way to communicate with the ANSYS is by using the intuitive menu system, called the GUI.
1.3.5.1 Communicating via the GUI
The GUI consists of windows, menus, dialog boxes and other components that permits to feed input data and execute functions simply by picking buttons with a mouse or typing in responses to prompts. All users, both beginner and advanced, find it convenient to use the GUI for interactive work.
1.3.5.2 Communicating Via Commands
Commands are the instructions that instruct the program. The program offers numerous commands, each meant for a specific function. Most commands are allied with specific processors, and work in respective processor(s). The analyst can either type in the appropriate command or access that function from the GUI to use it. Program commands have a specific format. A typical command consists of a command name in the first field, usually followed by a comma and several more fields (containing arguments). A comma separates each field. For example, the F command, which applies a force at a node, looks like this: F commmand F,NODE,Lab,VALUE To apply an X-direction force of 2000 at node number 376, the F command would read as follows: F,376,FX,2000 Command arguments may take a number or an alphanumeric labels, depending on their function. In the F command example described previously, NODE and VALUE are numeric arguments, but Lab is an alphanumeric argument. In this book, numeric arguments appear in all uppercase italic letters (as in NODE and VALUE), and alphanumeric arguments appear in initial uppercase italic format (as in Lab).
1.3.5.3 Abbreviations
If a GUI function is used frequently, it can be renamed or abbreviated to a string of up to eight alphanumeric characters using: Utility Menu> Macro> Edit Abbreviations or Utility Menu> MenuCtrls> Edit Toolbar. In the GUI, abbreviations appear as push buttons on the Toolbar. They can be executed with a quick click of the mouse.
1.3.5.4 Command Macro Files
A frequently used sequence of commands can be recorded in a macro file, thus creating a custom command. If an unrecognized command is entered, the program searches for a macro file by that name (with an extension of .MAC or .mac).