Performing Your First Analysis in FEBio Studio
Prepared for FEBio Studio 2.0
In this tutorial we will load an FEBio plot file (i.e. the file where FEBio stores the results of the analysis) and demonstrate several basic methods of analyzing the result of an FEBio simulation in FEBio Studio.
Opening the Simulation Output
Assuming that the model file that you created in the previous tutorial is still open in FEBio Studio, you can open the plot file as follows.
- Select the job that was added to the Jobs item of the Model Tree, which is usually located on the left side of your screen.
- Under the Properties section, click the button to the right of the plot file field.
- Alternatively, you can also double-click on the job’s item in the model tree.
You can also open a plot file via the menu File\Open Model File, and then navigate to the location of the plot file in your file system. In any case, notice the changes to the UI when a plot file is loaded into FEBio Studio: The Model panel is replaced by the Post panel. The Post panel has several tabs:
- View: The View tab displays a post model tree, which contains the items that will be rendered to the graphics view and make up the visualization.
- Material: Display’s the materials in the model and allows the user to customize the appearance of these materials in the graphics view.
- Data: This tab lists the data that is available for this model. Most of it will come directly from the febio plot file, but FEBio Studio may add several others that might be useful for analysis.
- State: This tab shows a list of all the states (i.e. time steps) in the model.
In addition, the timeline panel is shown near the bottom of the window. This panel shows visually all the states of the model. Each state is represented by a colored circle, and clicking on a circle will select and visualize the corresponding state in the graphics view.
Viewing the Model’s Animation
It is always a good idea to watch the simulation’s animation before attempting further analysis. This will give you context for the data that you will extract and in many cases it will help you to identify any mistakes you may have made when preparing the simulation.
- Locate the animation toolbar near the top of the window . If you cannot locate it, ensure that it is enabled by right clicking anywhere on the toolbar and ensuring that the Animation bar is checked. If only part of the toolbar is visible either enlarge your window, or click on the double arrow icon on the left side to expand the toolbar and see all of the options.
- Press the Play button to watch the animation. By default the animation will loop and will continue to play until the play button is pushed again. If you are viewing the simple tensile test that was created in the previous tutorials, you should see the box elongate along the x direction.
- The other blue icons on the toolbar change the currently selected time step to the first, previous, next, or last. Familiarize yourself with the functionality of these buttons.
- The Time Dialog box can be opened by clicking on the time dialog box button . In this box, various animation settings can be changed. Take some time to familiarize yourself with these settings.
- Mode: Select the direction of animation.
- FPS: Select the target frames-per-second. This setting affects how fast FEBio Studio will play the animation. Note that this is just a suggestion, as the actual FPS will depend on many factors, such as model size, complexity of visualization, graphics card, and processor speed.
- Start: The start state of the animation.
- End: The end state of the animation
- Loop: if checked, the animation will repeat until stopped by the user.
- Fixed time step: By default, FEBio Studio will step through the states of the model. If the time steps between states are not constant, then this could result in an apparent acceleration or deceleration of the animation. If this option is checked, FEBio Studio will try to maintain a constant time step size and interpolate between states if necessary.
- Time step size: Set the desired time step size when using the fixed time step option.
Visualizing Data with the Color Map
The Color Map is a useful method of visualizing the spatial distribution of a number of variables.
- The Color Map can be enabled in one of two ways. On the top toolbar locate the dropdown menu that is next to a grayed-out icon showing concentric circles . From this menu, select stress -> Effective stress. Alternatively in the View tab of the Post panel, on the left side of the window, select Color Map. Then in the Properties box that appears below, click on the dropdown menu for the Data field property and select stress -> Effective stress.
- If the model’s animation is not currently playing, press the play button. Watch as the distribution of effective stress is shown on the model for each time step.
- By default, the range of the values in the Color Map dynamically changes for each time step. To set the Color Map’s range to be static locate the property Range type in the Properties box for the Color Map, and select static from the dropdown menu. Allow the model animation to run through one complete cycle during which time the Color Map’s range will update to span the range of values in the simulation. After the first cycle, the range should be static.
- By default, FEBio only records stress for each element in the model, not each node. The default behavior of the Color Map in FEBio Studio is to smooth out the resulting discontinuities by interpolating values for each node. To see the raw element data in the Color Map locate the Nodal Values property in the Color Map’s property box and select No.
Viewing Data Graphically
The colormap option is a great way for getting the big picture. To inspect values on nodes, elements, or faces, you can create graphs. Graphs display information for the current selection.
- The graph window will plot information for the current selection. Nodes, edges, faces, and elements may be selected by clicking on the appropriate icon in the Selection toolbar at the bottom of the graphics view . Select a single element from the model by clicking anywhere on the model.
- To open a new graph click on the New Graph button in the toolbar , select Post\New Graph from the main menu, or press F3.
- In the graph window, from the Type dropdown menu select Line. Select Time from the X dropdown menu, and stress -> Effective stress from the Y dropdown menu. A plot of the effective stress vs time should appear on your graph for your currently selected element.
- The plot will automatically update if your selection is changed. Select a few more elements by holding down the shift key and clicking in various locations on your model. You should now see a plot for each element.
- You may also plot variables against one another. From the Type dropdown menu select Scatter and from the X dropdown menu select Lagrange strain -> effective Lagrange strain. The stress-strain response of the material is now shown on the graph.
- To copy the information currently displayed on your graph, click the Copy button at the top of the graph window. The data can then be pasted directly into a text document, or most spreadsheet applications such as Microsoft Excel.