demo01 of writeMesh

Triangular mesh with single phase
Cite as: Ma, J., & Li, Y. (2025). Im2mesh: A MATLAB/Octave package for generating finite element mesh based on 2D multi-phase image (2.1.5). Zenodo. https://doi.org/10.5281/zenodo.14847059
Jiexian Ma, mjx0799@gmail.com. Project website.
Table of Contents
Initialize Load mesh Plot mesh Export as inp file (Abaqus) Export as bdf file (Nastran bulk data) Export as msh file (Gmsh mesh file)

Initialize

clearvars
Set default image size.
x = 250; y = 250; width = 250; height = 250;
set(groot, 'DefaultFigurePosition', [x,y,width,height])
% To reset:
% set(groot, 'DefaultFigurePosition', 'factory')

Load mesh

Let's load the mesh data from "mesh_data_1.mat"
load("mesh_data_1.mat")
We will see 2 variables: vert, ele
vert
vert = 96×2
44.5000 48.5000 52.5000 98.5000 76.5000 158.5000 84.5000 96.5000 100.5000 156.5000 104.5000 17.5000 104.5000 47.5000 105.5000 205.5000 105.5000 222.5000 109.5000 214.5000
ele
ele = 135×3
36 17 86 49 77 58 77 84 88 57 82 92 45 71 22 4 73 40 87 67 66 52 28 46 86 35 36 5 82 64

Plot mesh

Use function plotMeshes to plot mesh.
plotMeshes(vert,ele);

Export as inp file (Abaqus)

We use function printInp2d to write 2d mesh to inp file.
The exported inp file would have a model with one part, which contains one section.
Please refer to demo06 to learn about format setting of inp file.
When using function printInp2d, we can specify element type, precision and file name.
ele_type = 'CPS3';
precision = 8;
file_name = 'test.inp';
printInp2d( vert, ele, [], ele_type, precision, file_name );
printInp2d Done! Check the inp file!

Export as bdf file (Nastran bulk data)

We use function printBdf2d to write 2d mesh to bdf file.
precision = 8;
file_name = 'test.bdf';
printBdf2d( vert, ele, [], [], precision, file_name );
printBdf2d Done! Check the bdf file!

Export as msh file (Gmsh mesh file)

We use function printMsh to write 2d mesh to msh file.
precision = 8;
file_name = 'test.msh';
printMsh( vert, ele, [], [], precision, file_name );
printMsh Done! Check the msh file!
When we open 'test.msh' in Gmsh, we can see 1 physical surface, which corresponds to 1 phase in our mesh.
% reset image size
set(groot, 'DefaultFigurePosition', 'factory')
% end of demo