quad4_quad8

Below is a demonstration of the features of the quad4_quad8 function

Syntax
Description
Examples
CONVERSION FROM QUAD4 TO QUAD8
CONVERSION FROM QUAD4 TO QUAD8, EXAMPLE FOR A CONVERSION OF NODAL PARAMETERS

Syntax

[QUAD8,V8,VX8C]=quad4_quad8(QUAD4,V4,VXC);

Description

The quad4_quad8 converts 4-node quads to 8-node quads. These correspond to linear and quadratic quadrilateral elements for finite element analysis. The 8-node triangular element follows the FEBio format such that the first 4 points are the 4-node quad points, the following 4 nodes are the mid-edge points. To plot it with a command such as patch or gpatch one therefore needs to use element2patch or use: QUAD8(:,[1 5 2 6 3 7 4 8]);

Examples

clear; close all; clc;

% Plot settings
fontSize=25;
faceColor='b';
faceAlpha=0.3;
edgeColor='k';
edgeWidth1=2;
edgeWidth2=1;
markerSize1=75;
markerSize2=10;

CONVERSION FROM QUAD4 TO QUAD8

Creating an example triangulated mesh

[QUAD4,V4]=quadSphere(2,1);

Converting to a single 10-node tetrahedron

[QUAD8,V8,~]=quad4_quad8(QUAD4,V4);
[F8]=element2patch(QUAD8,[],'quad8');

Plotting elements

cFigure; % Open figure for plotting
subplot(1,2,1); hold on;
title('4-node linear quads','FontSize',fontSize);

gpatch(QUAD4,V4,'rw'); %Plotting surface
patchNormPlot(QUAD4,V4); %Plotting face normals
plotV(V4,'k.','MarkerSize',25);
axisGeom;
camlight('headlight');

subplot(1,2,2); hold on;
title('8-node quadratic quads','FontSize',fontSize);

% gpatch(TRI6(:,[1 4 2 5 3 6]),V6,'gw'); %Plotting surface
gpatch(F8,V8,'gw'); %Plotting surface
patchNormPlot(F8,V8); %Plotting face normals
plotV(V8,'k.','MarkerSize',25);
axisGeom;
camlight('headlight');

drawnow;

CONVERSION FROM QUAD4 TO QUAD8, EXAMPLE FOR A CONVERSION OF NODAL PARAMETERS

nodalData_quad4=V4(:,3)*2;

Converting to a single 10-node tetrahedron

dataCell_quad4={nodalData_quad4};
[QUAD8,V8,dataCell_quad8]=quad4_quad8(QUAD4,V4,dataCell_quad4);
[F8]=element2patch(QUAD8,[],'quad8');
nodalData_quad8=dataCell_quad8{1};

Plotting elements

hf=cFigure; % Open figure for plotting

subplot(2,2,1); hold on;
title('4-node linear quads','FontSize',fontSize);

gpatch(QUAD4,V4,'rw'); %Plotting surface
plotV(V4,'k.','MarkerSize',25);
axisGeom;
camlight('headlight');

subplot(2,2,3); hold on;
title('Data on quad4 mesh','FontSize',fontSize);
gpatch(QUAD4,V4,nodalData_quad4); %Plotting surface
plotV(V4,'k.','MarkerSize',25);
axisGeom;
camlight('headlight');

subplot(2,2,2); hold on;
title('8-node quadratic quads','FontSize',fontSize);

gpatch(F8,V8,'gw'); %Plotting surface
plotV(V8,'k.','MarkerSize',25);
axisGeom;
camlight('headlight');
colormap(gjet(250));
subplot(2,2,4); hold on;
title('Mapped data on quad8 mesh','FontSize',fontSize);
gpatch(F8,V8,nodalData_quad8); %Plotting surface
plotV(V8,'k.','MarkerSize',25);
axisGeom;
camlight('headlight');
colormap(gjet(250));

drawnow;

GIBBON www.gibboncode.org

Kevin Mattheus Moerman, [email protected]

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License: https://github.com/gibbonCode/GIBBON/blob/master/LICENSE

GIBBON: The Geometry and Image-based Bioengineering add-On. A toolbox for image segmentation, image-based modeling, meshing, and finite element analysis.

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.

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