Finite Element Analysis Toolbox
This section describes how to use the FEATool GUI (available with Matlab or Octave version 4.0 or later). Please note that the GUI may look different depending on your system configuration and the Octave or Matlab version running FEATool.
After launching FEATool in Octave or Matlab (by typing featool at the command prompt) the GUI will load. The main GUI window which will open is composed of the main GUI axes, top menu and toolbar, left vertical mode and tool button bars, and also input, output, and terminal command windows. The function of these is explained below.
The main GUI axes is where the geometry, computational grid, and postprocessing results are displayed. The view can be controlled by the Zoom In , Zoom Out , Pan , and Rotate buttons in the top toolbar.
On the top of the GUI toolbar there are menus for file, options, mode, and help operations. The function of these menus are described in detail below
The File menu features the following options:
The Options menu firstly allows the axes and grid settings to be modified (these settings are described in the axes/grid settings section below). Additionally, the FEATool GUI options can be inspected and edited by opening the Options... dialog box (this will effectively edit the guiparam.txt parameter file located in the featool/gui folder).
The Geometry menu allows for switching to Geometry Mode, adding specific points Add Point..., and also accessing the Combine Objects... option which allows specification of a complex formula for geometry object composition.
The Grid menu allows for switching to Grid Mode as well as accessing and specifying the Grid Generation Call.... Generate Quadrilateral Grid calls the structured quadrilateral grid generation routine (gridgen_quad). Convert Grid Cells converts between triangular and quadrilateral cells in 2D, and between tetrahedral and hexahedral cells in 3D. The Grid Smoothing menu option performs relaxed smoothing steps with either Laplacian or umbrella smoothing.
Grid Mode also supports import and export of grids through external ASCII format files, these option can also be accessed from the Grid menu
In grid mode the overall global maximum grid cell size variable hmax can be changed from the Grid Size edit field in the grid tools toolbar.
The Equation and Boundary menus allows for switching to Equation/Boundary Modes and also opening the Equation/Boundary Settings... dialog boxes (see the equation and boundary mode sections). Moreover, the Model Constant and Expressions... option allows for input of modeling variables and expressions that can be used in equations and boundary settings, and postprocessing. Point sources and constraints can also be added here with the corresponding Add Point Sources... and Add Point Constraints... menu options.
The Solve menu similarly allows for switching to Solve Mode and also opening the Solver Settings... dialog box (these settings are described in the solver settings section). This menu also features an option to Get Initial Solution which computes the expressions defined in the equation settings Initial Condition fields and returns this as the solution. Moreover, the solver call command can be changed with the Solver Call Command... option.
The Post menu allows for switching to Postprocessing Mode, and opening the Postprocessing Settings... dialog box (see the postprocessing settings section below). In addition there are options for evaluating the minima and maxima for general expressions with Min/Max Evaluation..., points and line evaluation Point/Line Evaluation..., and integration of postprocessing expressions over subdomains Subdomain Integration... (calling intsubd) and boundaries Boundary Integration... (calling intbdr). The postprocessing call command can be inspected and changed with the Postprocessing Call... option. Moreover, the solution and postprocessing data can also be exported to be used with the General Mesh Viewer (GMV) through the Export Results... > GMV Format... menu option.
The Help menu opens the About... information dialog box and shows FEATool version information, and selecting Register FEATool... allows entering a FEATool license key. Moreover, there is also a link to open the FEATool Documentation and visit the online FEATool Articles and Blog archive.
The top GUI toolbar contains the following shortcut buttons (note that the GUI might show different options and icons depending on the Octave or Matlab version used)
To the left of the main view axes is the mode toolbar which consists of six mode buttons which switches between the different modes
Below these buttons are the mode tool buttons which can change depending on which mode is selected.
Below the main GUI axes is the output terminal window which displays messages, and output from the local FEATool workspace including output from the command input window below.
On the bottom is the command input window which allows Matlab commands to be operated in the FEATool workspace (note that although the FEATool fea problem struct can be inspected and edited it might break and cause errors in the GUI operation).
Pressing the New Problem button or selecting New... from the File menu starts a new problem definition and opens the New Problem dialog box.
The New Problem dialog box firstly allows for selecting the number of space dimensions to work in. The Select Space Dimensions frame allows one to choose from 1D, 2D, Axi 2D (for axisymmetric/cylindrical pseudo three-dimensional coordinate system), and 3D. Depending on which selection is made the default Space Dimension Names (x, y, and z, or alternatively r and z in cylindrical coordinates) will be shown in the corresponding edit field. The space dimension or independent variable names can be changed if desired, and are used in FEATool defining equation, boundary, postprocessing, and other expressions.
The Select Physics drop down box shows a list of pre-defined physics application modes available for the selected space dimension. By choosing one of the physics modes the corresponding physics equation and default Dependent Variable Names will be updated. This will be the first physics mode defining a new model. The dependent variable names can also be changed as long as they do not conflict with each other or other physics modes. Additional physics modes can be added later by using the + tab in the Equation Settings dialog box in Subdomain Mode, as described the Multiphysics section.
To finish the initial selection process and start a new model press OK, or press Cancel to return to the previous model.
Equation, Boundary, Solve, and Postprocessing mode usage and corresponding dialog boxes are described in the following sections.
In the Axis/Grid Settings dialog box the Grid on option turns on and off the grid. By having Axis equal checked the x and-axes will have equal proportional lengths. Bounding box indicates how much extra relative space should be shown apart from the geometry. Alternatively, one can manually set the Axis limits.
The following keyboard shortcuts are available in FEATool:
Moreover, in 2D Geometry mode one can hold down a Shift key while using the Create circle/ellipse tool to restrict to a circular geometry instead of allowing elliptical ones. In the FEATool Command Window prompt it is also possible to use the up and down arrow keys to scroll backwards and forwards through the command log history, and Ctrl + c to clear the command input edit field.