<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE html
  SYSTEM "about:legacy-compat">
<html xmlns:mml = "http://www.w3.org/1998/Math/MathML" lang = "en"><head><meta charset = "UTF-8"/><meta name = "copyright" content = "(C) Copyright 2020"/><meta name = "DC.rights.owner" content = "(C) Copyright 2020"/><meta name = "DC.type" content = "task"/><meta name = "abstract" content = "You can define Design Variables that represent the values to be changed during the optimization. The density of each individual element in the design space is a design variable in topology optimization in Tosca Structure."/><meta name = "description" content = "You can define Design Variables that represent the values to be changed during the optimization. The density of each individual element in the design space is a design variable in topology optimization in Tosca Structure."/><meta name = "DC.relation" scheme = "URI" content = "../TsoCmdMap/tso-r-cmd-dvTopo.htm#tso-r-cmd-dvTopo"/><meta name = "DC.format" content = "HTML5"/><meta name = "DC.identifier" content = "tso-t-user-TopOpt-DesArea-DesVar"/><meta name = "DC.language" content = "en"/><link rel = "stylesheet" type = "text/css" href = "../DSDocUI_XML34.css"/><title>Defining Design Variables for Topology Optimization</title>
<script type = "text/javascript" src = "../DSDocUI_Highlight34.js">
  	/* */
  	</script></head><body onLoad = "highlightSearchTerms();" id = "tso-t-user-TopOpt-DesArea-DesVar">
<a name = "hj-top"> </a><table class = "table1" id = "table11"><tr><td><table class = "DocHeader"><tr><td class = "DocHeader1" colspan = "2"><h1>Defining Design Variables for Topology Optimization</h1></td></tr><tr><td class = "DocHeader4" colspan = "2"/></tr><tr><td class = "DocHeader3"><table class = "DocHeaderIntro" id = "table12"><tr><td class = "Intro1"><p class = "header"><p class = "abstract">
<span class = "shortdesc">
You can define Design Variables that represent
the values to be changed during the optimization. The density of each individual element in the design space is a design
variable in topology optimization in <span class = "ph">Tosca Structure</span>.
</span>

</p>
<p>This task shows you how to:
					</p><ul><li><a href = "#tso-t-user-TopOpt-DesArea-DesVar-gui" id = "toc_rg" title = "">
Define a Design Variable in <span class = "ph">Tosca Structure.gui</span>
</a></li><li><a href = "#tso-t-user-TopOpt-DesArea-DesVar-PrevRun" id = "toc_rg" title = "">Use Results from Previous Runs as Initial Material Distribution</a></li></ul>
</p></td></tr><tr><td class = "Intro2"><hr class = "header"/><span class = "run-in-beforeyoubegin">Before you begin: </span>
Valid design elements are 2D and 3D elements, including shell elements.
Bars can be used as design variables, but not within mixed groups.
The list of valid element types for the topology optimization is given in <a class = "xref" href = "tso-m-usr-solver-sb.htm#tso-m-usr-solver-sb" title = "This chapter describes the formats and functionalities of the different solvers supported by SIMULIA Tosca Structure. The topological and physical properties of the analysis model (finite element input file) are required for the optimization of an FE model. Normally, not all information contained in the analysis model is necessary for an optimization. The optimization module returns the modified model data to the FE solver. The node coordinates are changed during shape and bead optimization. New materials and element properties are generated during topology optimization and the assignments of the elements to the material definitions and material properties are changed. Therefore, there are very few restrictions to the FE modeling (finite element input file).">Solver Specific Features</a> for the different FE solvers.
</td></tr></table></td><td class = "DocHeader2"><table class = "DocTopicsSeeAlso" id = "table13"><tr><td class = "TopicsTitle">See Also</td></tr></table><table class = "DocTopicsInOtherGuides" id = "table14"><tr><td height = "8px"/></tr><tr><td class = "TopicsTitleNormal">In Other Guides</td></tr><tr><td><a title = "Definition of the design elements for topology optimization." href = "../TsoCmdMap/tso-r-cmd-dvTopo.htm#tso-r-cmd-dvTopo">DV_TOPO</a></td></tr></table></td></tr></table>



<div class = "body taskbody">
<div class = "p"><!--xxx--></div>

</div>

<div class = "related-links"/>

<article class = "topic task nested1" aria-labelledby = "ariaid-title2" id = "tso-t-user-TopOpt-DesArea-DesVar-gui">
<h2 class = "title topictitle2">
Define a Design Variable in <span class = "ph">Tosca Structure.gui</span>
</h2>

<div class = "body taskbody">
<section><ol class = "ol steps"><li class = "li step stepexpand">

Choose <span class = "ph uicontrol">Command &gt; DV_TOPO</span>.

</li><li class = "li step stepexpand">

Assign a previously defined element group to be the
design element group for the topology optimization as shown in the following figure:

<p>
The element group
must be a group of elements which are allowed as design elements
for the topology optimization.
<table class = "table" id = "tso-t-user-TopOpt-DesArea-DesVar-gui__ag707978"><caption/><colgroup><col/></colgroup><tbody class = "tbody">
<tr class = "row">
<td class = "entry">
<br/><img class = "image" id = "tso-t-user-TopOpt-DesArea-DesVar-gui__image_0F0D862FB22346F89AC0C63C10DB59F9" src = "../TsoUserImages/topo_DV_TOPO_dialog.png" width = "350"/><br/>
</td>
</tr>
</tbody></table>
</p>
<div class = "itemgroup stepresult">
The resulting command is the <code class = "ph codeph">DV_TOPO</code> command. For more information, see
<a class = "xref" href = "../TsoCmdMap/tso-r-cmd-dvTopo.htm#tso-r-cmd-dvTopo" title = "Definition of the design elements for topology optimization.">DV_TOPO</a>.
<pre class = "codeblock">
<code class = "ph codeph">
DV_TOPO
  ID_NAME  = dv_design_elem
  EL_GROUP = <span class = "ph">design_elem</span>
END_</code>
</pre>
</div>
</li></ol></section>
</div>

</article>

<article class = "topic task nested1" aria-labelledby = "ariaid-title3" id = "tso-t-user-TopOpt-DesArea-DesVar-PrevRun">
<p><map name = "FPMap1"><area href = "#hj-top" title = "Back to Top" shape = "rect" coords = "416, 0, 435, 10"/></map><span class = "itemsprite"/></p><h2 class = "title topictitle2">Use Results from Previous Runs as Initial Material Distribution</h2>

<div class = "body taskbody">
<div class = "p"><!--xxx--><span class = "run-in-beforeyoubegin">Before you begin: </span>
The RESTART file containing the initial material distribution must be
located in the start directory of the optimization job. The format of
the RESTART file must be ONF (Optimization Neutral
File).
</div>

<section><ol class = "ol steps"><li class = "li step stepexpand">

If you want to use the results of already performed
optimizations as the start solution for the current optimization task, use the option <span class = "ph uicontrol">INITIAL_DV_FIELD</span> within
the <span class = "ph uicontrol">DV_TOPO</span> command:

<p>
<pre class = "codeblock">
<code class = "ph codeph">
DV_TOPO
 ID_NAME          = dv_design_elem
 EL_GROUP         = <span class = "ph">design_elem</span>
 INITIAL_DV_FIELD = &lt;my_initial_mat_distribution.ONF&gt;
END_
</code>
</pre>
</p>
<div class = "itemgroup stepresult">
This option leads to the use of the material distribution stated in the result
file instead of a homogeneous material distribution in
the design area.
</div>
</li><li class = "li step stepexpand">

The initial material distribution is extracted from the data block
740 with the title <code class = "ph codeph">MAT_PROP_NORMALIZED</code>.

<p>
<table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent">
<ul class = "ul">
<li class = "li">
When using a material distribution of a previous optimization run (file TP_XXX.onf)
for the new optimization, it is recommended to rename the file (for example,
to INITIAL_MAT.onf). Otherwise name conflicts with the running optimization
(with newly generated material distribution files TP_YYY.onf) might lead
to confusion in the post-processing: the start file TP_XXX.onf might be
considered and shown as the last iteration (if XXX is larger as the last
iteration in the actual optimization).
</li>
<li class = "li">
Depending on the state used as the initial material distribution and depending
on the differences in the optimization definition between the used solution
and the current task, the convergence can be accelerate significantly.
If  the changes are too big, the usage of the initial distribution
may lead to a higher number of iteration.
</li>
<li class = "li">
The restart is not available for the controller-based approach because this approach is already very efficient and the use
of previously defined material distributions does not lead to a speedup
of the optimization process.
</li>
</ul>
</span></td></tr></table>

</p>
</li></ol></section>
</div>

</article>
</td></tr></table><script type = "text/javascript" src = "../DSDocUI_Bottom34.js">/* */</script></body>
</html>
