Difference between revisions of "FEA Mesh Generation Commands"

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The best way to generate an FEA mesh is to use [[Keypoint Command|Keypoint]], [[Path Command|Path]], and [[Area Command|Area]] commands. Advanced mesh generation can be done with [[Create a Mesh with Images and Shapes|image files and shape]] commands.
The best way to generate an FEA mesh is to use [[Keypoint Command|Keypoint]], [[Path Command|Path]], and [[Area Command|Area]] commands.
 
__TOC__
== Scripted Input Files ==
== Scripted Input Files ==


In scripted input files, you build the mesh by using multiple [[#Basic Commands|mesh generation commands]]. These commands are usually grouped together, but may be at various locations in the input file. For example, a simple 2D, rectangular mesh of width <tt>#length</tt>, height <tt>#height</tt>, and thickness <tt>#thick</tt> with <tt>#horiz</tt> elements in the horizontal direction and <tt>#vert</tt> elements in the vertical direction (where terms beginning in number signs are [[Variable Names|script variables]]) can be created with:
In scripted input files, you build the mesh by using multiple [[#mesh_cmds|mesh generation commands]]. These commands are usually grouped together, but may be at various locations in the input file. For example, a simple 2D, rectangular mesh of width <tt>#length</tt>, height <tt>#height</tt>, and thickness <tt>#thick</tt> with <tt>#horiz</tt> elements in the horizontal direction and <tt>#vert</tt> elements in the vertical direction (where terms beginning in number signs are [[Variable Names|script variables]]) can be created with:


  Area #matname$,#thick
  Area #matname$,#thick
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   EndPath
   EndPath
   Path "Left",#vert
   Path "Left",#vert
     Keypoints "TopLeft","BotRIght"
     Keypoints "TopLeft","BotRight"
   EndPath
   EndPath
  EndArea
  EndArea
  Resequence "BotRight"
  Resequence "BotRight"


==== Basic Commands ====
<span id="mesh_cmds"></span>The following commands are used for generating the mesh in scripted files.
 
The fundamental commands for generating a mesh are


* [[Area Command|Area]]: Define an area for mesh generation.
* [[Area Command|Area]]: Define an area for mesh generation.
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* [[Keypoint Command|Keypoint]]: Define a keypoint used in defining [[Path Command|paths]]
* [[Keypoint Command|Keypoint]]: Define a keypoint used in defining [[Path Command|paths]]
* [[Keypoint Command|Keypoints]]: Add multiple defined keypoints to a [[Path Command|path]].
* [[Keypoint Command|Keypoints]]: Add multiple defined keypoints to a [[Path Command|path]].
 
* [[Resequence Command]]: To turn on the option to resequence the nodes, which will minimize the bandwidth of the problem and speed the calculations.
==== Mesh Attribute Commands ====
 
* <a href="Origin.html">Origin</a>: Define coordinate system origin for entry of <a href="keypoint.html">Keypoints</a> using polar coordinates.
* <a href="element.html">Element</a>: Define type of element to use in the mesh.
* <a href="fliptriangles.html">FlipTriangles</a>: Select the direction of triangular elements in meshes that use those elements.
* <a href="resequence.html">Resequence</a>: To turn on the option to resequence the nodes, which will minimize the bandwidth of the problem and speed the calculations.


== XML Input Files ==
== XML Input Files ==


In <tt>XML</tt> input files, you build the mesh with [[#Mesh Generation Commands|mesh generation commands]] that must be within a single <tt><Mesh></tt> block. Here is a <tt><Mesh></tt> block that creates at 50X10 mm rectangular mesh with 6 elements in the horizontal direction and 3 in the vertical direction:
In <tt>XML</tt> input files, you build the mesh with [[#mesh_cmds_xml|mesh generation commands]] that must be within a single <tt><Mesh></tt> block. Here is a <tt><Mesh></tt> block that creates at 50X10 rectangular mesh with 6 elements in the horizontal direction and 3 in the vertical direction:


<pre>
<pre>
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</pre>
</pre>


==== Mesh Generation Commands ====
<span id="mesh_cmds_xml"></span>The fundamental <tt>XML</tt> commands for generating a mesh are:
 
The fundamental <tt>XML</tt> commands for generating a mesh are:


* [[Area Command#XML Area Block|Area]]: Define an area for mesh generation.
* [[Keypoint Command#XML Keypoints Block|<tt><Keypoints></tt>]]: Define all key point to be used in defining [[Path Command|paths]]
* [[Path Command|Path]]: Define a path used in defining [[Area Command#XML Area Block|areas]].
* [[Path Command#XML Path Command|<tt><Path></tt>]]: Define a path to be used in defining [[Area Command#XML Area Block|areas]].
* [[Keypoint Command|Keypoints]]: Define a keypoint used in defining [[Path Command|paths]]
* [[Area Command#XML Area Block|<tt><Area></tt>]]: Define an area for mesh generation.
* [[Resequence Command]]: To turn on the option to resequence the nodes, which will minimize the bandwidth of the problem and speed the calculations.


== Notes ==
== Using Images and Shapes ==


# Once the mesh is created, and optional method to create complicated meshes is to define the materials, angles, and final geometry using [[Create a Mesh with Images and Shapes|images and shapes]]. This meshing method is described [[Create a Mesh with Images and Shapes|elsewhere]].
If some elements in the generated mesh are set the material id _NONE_ (see [[Area Command]]) or mat = 0 (see [[Area Command#XML Area Block|<tt><Area></tt> Command]]), you can follow mesh creation with [[Create a Mesh with Images and Shapes|image and shape commands]] to fill in material types, angles, and define the final mesh geometry. This option is described [[Create a Mesh with Images and Shapes|here]].

Latest revision as of 13:17, 2 June 2015

The best way to generate an FEA mesh is to use Keypoint, Path, and Area commands.

Scripted Input Files

In scripted input files, you build the mesh by using multiple mesh generation commands. These commands are usually grouped together, but may be at various locations in the input file. For example, a simple 2D, rectangular mesh of width #length, height #height, and thickness #thick with #horiz elements in the horizontal direction and #vert elements in the vertical direction (where terms beginning in number signs are script variables) can be created with: 

Area #matname$,#thick
  Path "Bottom",#horiz
    Keypoint "BotLeft",0,0
    Keypoint "BotRight",#length,0
  EndPath
  Path "Right",#vert
    Keypoints "BotRight"
    Keypoint "TopRight",#length,#height
  EndPath
  Path "Top",#horiz
    Keypoints "TopRight"
    Keypoint "TopLeft",0,#height
  EndPath
  Path "Left",#vert
    Keypoints "TopLeft","BotRight"
  EndPath
EndArea
Resequence "BotRight"

The following commands are used for generating the mesh in scripted files.

  • Area: Define an area for mesh generation.
  • Path: Define a path used in defining areas.
  • Paths: Add multiple defined paths to an area.
  • Keypoint: Define a keypoint used in defining paths
  • Keypoints: Add multiple defined keypoints to a path.
  • Resequence Command: To turn on the option to resequence the nodes, which will minimize the bandwidth of the problem and speed the calculations.

XML Input Files

In XML input files, you build the mesh with mesh generation commands that must be within a single <Mesh> block. Here is a <Mesh> block that creates at 50X10 rectangular mesh with 6 elements in the horizontal direction and 3 in the vertical direction: 

<Mesh>
  <Keypoints>
    <pt x='0' y='0' id='lowerleft'/>
    <pt x='0' y='10' id='upperleft'/>
    <pt x='50' y='0' id='lowerright'/>
    <pt x='50' y='10' id='upperright'/>
  </Keypoints>

  <Path id="bottom" intervals='6' ratio='1'>
    <keypt id='lowerleft'/>
    <keypt id='lowerright'/>
  </Path>
  <Path id="right" intervals='3'>
    <keypt id='lowerright'/>
    <keypt id='upperright'/>
  </Path>
  <Path id="top" intervals='6'>
    <keypt id='upperright'/>
    <keypt id='upperleft'/>
  </Path>
  <Path id="left" intervals='3'>
    <keypt id='upperleft'/>
    <keypt id='lowerleft'/>
  </Path>

  <Area mat="1" thick="10" type="4" flip="0" angle="0">
    <path id="bottom"/>
    <path id="right"/>
    <path id="top"/>
    <path id="left"/>
  </Area>
</Mesh>

The fundamental XML commands for generating a mesh are:

  • <Keypoints>: Define all key point to be used in defining paths
  • <Path>: Define a path to be used in defining areas.
  • <Area>: Define an area for mesh generation.
  • Resequence Command: To turn on the option to resequence the nodes, which will minimize the bandwidth of the problem and speed the calculations.

Using Images and Shapes

If some elements in the generated mesh are set the material id _NONE_ (see Area Command) or mat = 0 (see <Area> Command), you can follow mesh creation with image and shape commands to fill in material types, angles, and define the final mesh geometry. This option is described here.

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