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5.1  FE mesh and the feplot interface

• The main feplot figure
• Toolbar
• Keyboard shortcuts
• Menus and context menu
• Pointers to the figure and the model
• The property figure
• Direct declaration of geometry (truss example)
• Modal test geometry declaration
• Building models with femesh
• Importing models from other codes
• Importing model matrices from other codes
• feplot FAQ

• viewing the model and post-processing the responses,
• setting and displaying the mechanical problem (model properties and cases),
• setting the view properties.

5.1.1  The main feplot figure

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Figure 5.1: Main feplot figure.

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• feplot(model) (display the model in a variable) .
• cf=feplot;cf.model=model; (get a figure pointer cf and redefine the model displayed in this figure), cf=feplot;cf.model={node,elt}; will work for just nodes and elements. Note that cf.model is a method to define the model and is not a pointer.
• feplot('load','File.mat') load a model from a .mat file.

 model=demosdt('demogartfe')
 cf=feplot;       % open FEPLOT and define a pointer CF to the figure
 cf.model=model;

Toolbar

	Model properties used to edit the properties of your model.
	Start/stop animation
	Previous Channel/Deformation
	Next Channel/Deformation
	Zoom

Keyboard shortcuts

Menus and context menu

• Cursor Node tracks mouse movements and displays information about pointed object. This is equivalent to the iimouse('cursor') command line.
• Cursor...[Elt,Sel,Off] selects what information to display when tracking the mouse. The iimouse('cursor[onElt,onSel,Off]') command lines are possible.
• TextNode activates the node labeling. It is equivalent to the fecom('textnode') command line.
• Triax displays the orientation triax. It is equivalent to the fecom('triax') command line.
• Undef shows the undeformed structure. Other options are accessible with the fecom('undef[dot,line]') command line.
• Views... [View n+x,...] selects default plot orientation. The
  iimouse('[vn+x,...]') command lines are available.
• colorbar on shows the colorbar and is equivalent to cingui('ColorBarOn' command line.
• Zoom Reset is the same as the iimouse('resetvie') command line to reset the zoom.
• setlines is the same as the setlines command line

• Feplot:Feplot/Model properties opens the property figure (see section 5.1.3).
• Feplot:Sub commands:Sub IsoViews (same as iicom('subiso')) gets a plot with four views of the same mode. Use iicom('sub2 2 step') to get four views of different modes.
• Feplot:Show menu generates standard plots. For FE analyses one will generally use surface plots color-coded surface plots using patch objects) or wire-frame plots (use Feplot:Show menu to switch).
• Feplot:Misc shows a Triax or opens the channel selector.
• Feplot:Undef is used to show or not the undeformed structure.
• Feplot:Colordata shows structure with standard colors.
• Feplot:Selection shows available selections.
• Feplot:Renderer is used to choose the graphical rendering. Continuous animation in OpenGL rendering is possible for models that are not too large. The fecom SelReduce can be use to coarsen the mesh otherwise.
• Feplot:Anim chooses the animation mode.
• Feplot:View defaults changes the orientation view.

5.1.2  Pointers to the figure and the model

5.1.3  The property figure

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Figure 5.2: Model property interface.

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• Model tab gives general information on the model nodes and elements You can declare those by hand as shown in section 5.1.4, trough structured mesh manipulations with femesh see section 5.1.6, or through import see section 5.1.7. (see section 5.3 and Figure 5.2). You can visualize one or more groups by selecting them in the left group list of this tab.
• Mat tab lists and edits all the material. In the mode, associated elements in selection are shown. See section 5.3.1.
• ElProp tab lists and edits all the properties. See section 5.3.1.
• Stack tab lists and edits general information stored in the model (see section 7.7 for possible entries). You can access the model stack with the cf.Stack method.
• Cases tab lists and edits load and boundary conditions (see section 5.3.3 and Figure 5.9). You can access the case stack with the cf.CStack method.
• Simulate tab allows to launch the static and dynamic simulation (see section 5.5 and Figure 5.10).

	Model properties used to edit the properties of your model.
	Active display of current group, material, element property, stack or case entry. Activate with fecom('ProViewOn');
	Open the iiplot GUI.
	Open/close feplot figure
	Refresh the display, when the model has been modified from script.

5.1.4  Direct declaration of geometry (truss example)

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Figure 5.3: FE model.

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 %     NodeID  unused   x y z
 model.Node=[ 1      0 0 0    0 1 0; ...
              2      0 0 0    0 0 0; ...
              3      0 0 0    1 1 0; ...
              4      0 0 0    1 0 0; ...
              5      0 0 0    2 0 0; ...
              6      0 0 0    2 1 0; ...
              7      0 0 0    1 1 1]; % reference node

 model.Elt=[ ...
  % declaration of element group for longerons
  Inf     abs('beam1') ; ...
  %node1  node2   MatID ProID nodeR, zeros to fill the matrix 
    1       3      1    1     7       0 ; ...
    3       6      1    1     7       0 ; ...
    2       4      1    1     7       0 ; ...
    4       5      1    1     7       0 ; ...
  % declaration of element group for diagonals
  Inf     abs('beam1') ; ...
    2       3      1    2     7       0 ; ...
    4       6      1    2     7       0 ; ...
  % declaration of element group for battens
  Inf     abs('beam1') ; ...
    3       4      1    3     7       0 ; ...
    5       6      1    3     7       0 ];

 cf=feplot; cf.model=model;       % create feplot axes
 fecom(';view2;textnode;triax;'); % manipulate axes 

5.1.5  Modal test geometry declaration

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Figure 5.4: Test analysis : wire-frame model.

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 cf=fecom;cf.model='reset';
 % fecom('AddNode') would open a dialog box
 fecom('AddNode',[0 1 0; 0 0 0]); % add nodes giving coordinates
 fecom('AddNode',[3  1 1 0;4  1 0 0]); % NodId and xyz
 fecom('AddNode',[5      0 0 0    2 0 0;
                  6      0 0 0    2 1 0]);

 fecom('AddLine',[1 3 2 4 3]);  % continous line in first group
 fecom('AddLine',[3 6 0 6 5 0 4 5 0 4 6]); % 0 for discontinuities
 fecom('ProInit');
 %fecom('save')  % will let you save the model to a mat file

• After declaring nodes you can use cf.sel='groupall';fecom(cf,'AddLine') to start a cursor letting you build the wire-frame line graphically. Click on nodes continue the line, while the context menu allows breaks, last point removal, exit, and display of the ldraw building commands in the MATLAB command window. This procedure is particularly useful if you already have a FEM model of your test article.
  
  
• you can also use the femesh ObjectBeamLine command to define the experimental mesh.
  
  
• If you have a FE mesh, you can easily combine the FE and wire frame models using the femesh AddTest command (see gartte). The procedure to solve the common problem of matching coordinate systems when they initially have different scales / orientations  / origins is discussed in section 4.1.1.

5.1.6  Building models with femesh

 FEel0=[]; FEelt=[];
 FEnode=[1 0 0 0  0 0 0;2 0 0 0    0 1 0; ...
         3 0 0 0  1 0 0;4 0 0 0    1 1 0]; ...
 femesh('objectbeamline 1 3 0 2 4 0 3 4 0 1 4');

 femesh(';addsel;transsel 1 0 0;addsel;info');
 model=femesh('model');  % export FEnode and FEelt geometry in model
 cf=feplot; cf.model=model;
 fecom(';view2;textnode;triax;');

 femesh('reset');
 femesh('test2bay');
 femesh('removeelt group2');
 femesh('divide group 1 InNode 1 4');
 femesh('set group1 name bar1');
 femesh(';selgroup2 1;repeatsel 10 1 0 0;addsel');
 femesh(';rotatesel 1 60 1 0 0;addsel;');
 femesh(';selgroup3:4;rotatesel 2 -60 1 0 0;addsel;');
 femesh(';selgroup3:8');
 model=femesh('model0');  % export FEnode and FEel0 in model
 cf=feplot; cf.model=model;
 fecom(';triaxon;view3;view y+180;view s-10');

5.1.7  Importing models from other codes

5.1.8  Importing model matrices from other codes

 upcom('load UpcomFile');
 Up=nasread(Up,'NastranOutput.op2');

 Up=ans2sdt('buildup test1')

• a mass m and stiffness matrix k linked to DOFs mdof which you have imported with your own code (for example, using nasread output2 or output4 and appropriate manipulations to create mdof). Note that the ofact object provides translation from skyline to sparse format.
  
  
• an equivalent mesh defined using standard SDT elements. This mesh will be used to plot the imported model and possibly for repeating the model in a periodic structure.

% Load ubeam model :
model=demosdt('demo ubeam-pro');
cf=feplot; model=cf.mdl; 
% Define superelement from element matrices :
SE=struct('DOF',[180.01 189.01]',...
    'K',{{[.1 0; 0 0.1] 4e10*[1 -1; -1 1]}},...
    'Klab',{{'m','k'}},...
    'Opt',[1 0;2 1]);
% Define visualization mesh :
SE.Node=feutil('GetNode 180 | 189',model);
SE.Elt=feutil('ObjectBeamLine 180 189 -egid -1');
% Add as a superelement to model :
model=fesuper('SEadd -unique 1 1 selt',model,SE);

model.il=[1001 fe_mat('p_super','SI',1) 1 2];

% Define matrices (can be imported from other codes) :
model=femesh('testhexa8');
[m,k,mdof]=fe_mk(model);
% Define the superelement:
SE=struct('DOF',[180.01 189.01]',...
    'K',{{[.1 0; 0 0.1] 4e10*[1 -1; -1 1]}},...
    'Klab',{{'m','k'}},...
    'Opt',[1 0;2 1]);
SE.Node=model.Node; SE.Elt=model.Elt;
% Add as repeated superelement: 
% (need good order of nodes for nodeshift)
model=fesuper('SEAdd -trans 10 0.0 0.0 1.0 4 1000 1000 cube',[],SE);
cf=feplot(model)

5.1.9  feplot FAQ

• How do I keep group colors constant when I select part of a model?
  
  One can define different types of color for selection using fecom ColorData. In particular one can color by groupId, by ProId or by MatId using respectively fecom colordatagroup, colordatapro or colordatamat. Without second argument, colors are attributed automatically. One can define a color map with each row of the form [ID Red Green Blue] as a second argument: fecom('colordata',colormap). All ID do not need to be present in colormap matrix (colors for missing ID are then automatically attributed). Following example defines 3 color views of the same GART model:

  cf=demosdt('demo gartFE plot');
  % ID Red Green Blue
  r1=[(1:10)' [ones(3,1); zeros(7,1)] ...
      [zeros(3,1); ones(7,1)] zeros(10,1)]; % colormap
  fecom('colordatagroup',r1) % all ID associated with color
  % redefine groups 4,5 color
  cf.Stack{'GroupColor'}(4:5,2:4)=[0 0 1;0 0 1]; 
  fecom('colordatagroup');
  % just some ID associated with color
  fecom('colordatapro',[1 1 0 0; 3 1 0 0]) 
  fecom('colordatamat') % no color map defined
  cf.Stack
  

  
  
  
• How do I display part of the model as wire frame? (Advanced object handling)
  
  What is displayed in a feplot figure is defined by a set of objects. Once you have plotted your model with cf=feplot(model), you can access to displayed objects through cf.o(i) (i is the number of the object). Each object is defined by a selection of model elements ('seli') associated to some other properties (see fecom SetObject). Selections are defined as FindElt strings through cf.sel(i). Displayed objects or selections can be removed using cf.o(i)=[] or cf.sel(i)=[].
  Following example loads ubeam model, defines 2 complementary selections, and displays the second as a wire frame (ty2):

  model=demosdt('demoubeam'); cf=feplot
  % define visualisation :
  cf.sel(1)='WithoutNode{z>1 & z<1.5}';
  cf.sel(2)='WithNode{z>1 & z<1.5}';
  cf.o(1)={'sel1 ty1','FaceColor',[1 0 0]}; % red patch
  cf.o(3)={'sel2 ty2','EdgeColor',[0 0 1]}; % blue wire frame
  % reinit visualisation :
  cf.sel(1)='groupall';
  cf.sel(2)=[]; cf.o(3)=[];
  

  
  
  
• Is feplot able to display very large models?
  
  There is no theoretical size limitation for models to be displayed. However, due to the use of Matlab plot figure, and although optimization efforts have been done, feplot can be very slow for large models. To increase fluidity it is possible to reduce the number of displayed patches using fecom command SelReduce rp where rp is the ratio of patches to be kept. Adjusting rp, fluidity can be significantly improved with minor visual quality loss.
  Following example draws a 50x50 patch, and uses fecom('ReduceSel') to keep only a patch out of 10:

  model=feutil('ObjectQuad',[-1 -1 0;-1 1 0;1 1 0;1 -1 0],50,50);
  cf=feplot(model); fecom(cf,'showpatch');
  fecom(cf,'SelReduce .1'); % keep only 10% of patches.
  

  
  
  
• How do I save figures?
  
  comgui imwrite FileName.ext can be used to generate a clean printout of SDT figures. The default extension is .png. If using the MATLAB print, you should use the -noui switch so that the GUI is not printed. Example print -noui -depsc2 FileName.eps
  
  
• MATLAB gives the warning Warning: RGB color data not yet supported in Painter's mode. This is due to the use of true colors for ColorDataMat and other flat colors. You should save your figure as a bitmap or use the fecom ShowLine mode.