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<a name = "hj-top"> </a><table class = "table1" id = "table11"><tr><td><table class = "DocHeader"><tr><td class = "DocHeader1" colspan = "2"><h1>CONSTRAINT</h1></td></tr><tr><td class = "DocHeader4" colspan = "2"/></tr><tr><td class = "DocHeader3"><table class = "DocHeaderIntro" id = "table12"><tr><td class = "Intro1Only"><p class = "header"><p class = "abstract">
<span class = "shortdesc">Definition of an equality or inequality (less or equal/ greater or equal) constraint. The constraint is defined with respect to a design response.</span>

</p>
<p>This page discusses: </p><ul><li><a href = "#tso-r-cmd-constraint__tso-r-cmd-constraint-rmk" id = "toc_rg" title = "">Remarks</a></li><li><a href = "#tso-r-cmd-constraint__tso-r-cmd-constraint-exmp" id = "toc_rg" title = "">Examples</a></li></ul>
</p></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 = "Optimization tasks normally have restrictions that limit the values of the design responses or linear combinations of the design responses. If the constraint is not fulfilled, the optimization result is not feasible." href = "../TsoUserMap/tso-c-usr-terms-constraint.htm#tso-c-usr-terms-constraint">About Constraints</a></td></tr></table></td></tr></table>




<div class = "body refbody">
<table class = "table" id = "tso-r-cmd-constraint__aa1041563"><caption/><colgroup><col/><col/><col/></colgroup><tbody class = "tbody">
<tr class = "row">
<td class = "entry"><p><span class = "ph uicontrol">ID_NAME</span></p></td>
<td class = "entry"><p>= <code class = "ph codeph">&lt;name_of_constraint&gt;</code> </p></td>
<td class = "entry"><p>Name of the <code class = "ph codeph"> CONSTRAINT</code> definition.</p></td>
</tr>
<tr class = "row">
<td class = "entry"><p><span class = "ph uicontrol">DRESP</span></p></td>
<td class = "entry"><p>= <var class = "keyword varname varname">&lt;name_of_dresp&gt;</var></p></td>
<td class = "entry"><p>Name of the design response that should be restricted.</p></td>
</tr>
<tr class = "row">
<td class = "entry"><p><span class = "ph uicontrol">MAGNITUDE</span></p></td>
<td class = "entry">
  <p>= ABS</p>
  <p>= REL</p>
</td>
<td class = "entry"><p>Constraints can be given in absolute or relative values.</p></td>
</tr>
<tr class = "row">
<td class = "entry"><p><span class = "ph uicontrol">EQ_VALUE</span></p></td>
<td class = "entry"><p>= <code class = "ph codeph">&lt;value&gt;</code></p></td>
<td class = "entry"><p>Value of equality constraint.</p></td>
</tr>
<tr class = "row">
<td class = "entry"><p><span class = "ph uicontrol">GE_VALUE</span></p></td>
<td class = "entry"><p>= <code class = "ph codeph">&lt;value&gt;</code></p></td>
<td class = "entry"><p>Value of greater or equal constraint.</p></td>
</tr>
<tr class = "row">
<td class = "entry"><p><span class = "ph uicontrol">LE_VALUE</span></p></td>
<td class = "entry"><p>= <code class = "ph codeph">&lt;value&gt;</code></p></td>
<td class = "entry"><p>Value of less or equal constraint.</p></td>
</tr>
</tbody></table>

<div class = "section" id = "tso-r-cmd-constraint__tso-r-cmd-constraint-rmk"><h2 class = "title sectiontitle">Remarks</h2>

<ol class = "ol">
<li class = "li">Only one item of the following list of items can be used within a constraint definition:
<ul class = "ul">
<li class = "li"><code class = "ph codeph">EQ_VALUE</code></li>
<li class = "li"><code class = "ph codeph">GE_VALUE</code></li>
<li class = "li"><code class = "ph codeph">LE_VALUE</code></li>
</ul>
</li>
<li class = "li"><code class = "ph codeph">MAGNITUDE</code>: relative values always refer to the design response of the start model for the optimization. Example: The relative value 0.8 represents 80%.  <p>
<span class = "ph uicontrol">Please note:</span> In topology optimization, the start model for the optimization is the model used for the first finite element analysis in the optimization procedure (iteration 0).
The element densities might differ from the initial model (for example, when no volume constraint is present they are set to 50% of the original density).
Take this into account when defining, for example, relative displacement or frequency constraints.</p>
This behavior can be controlled by the user with the parameter <code class = "ph codeph">DENSITY_INITIAL</code> in the <code class = "ph codeph">OPT_PARAM</code> command. </li>
<li class = "li">For <code class = "ph codeph">EQ_VALUE</code> only a value greater equal to zero can be set for <code class = "ph codeph">MAGNITUDE=REL</code>.</li>
<li class = "li">For shape optimization, a volume constraint might be defined for an element group which contains the complete mesh_smooth area.</li>
<li class = "li"><span class = "ph uicontrol">Inequality</span> constraints can only be used for the <span class = "ph uicontrol">sensitivity</span>-based bead, sizing, shape and topology optimization.</li>
<li class = "li"><span class = "ph uicontrol">Equality</span> constraints can be used for <span class = "ph uicontrol">controller</span>-based shape, bead, and topology optimization. If accidentally an equality constraint is defined for a sensitivity-based optimization an error message is shown.</li>
<li class = "li">Special care must be taken when using relative magnitude in an inequality constraint with a negative start model design response value: When converting the relative magnitude to absolute, the inequality is multiplied with a negative number and thus the constraint type changes from "lesser equal" to "greater equal" and vice versa. This behavior can be changed with the <code class = "ph codeph">OPT_PARAM</code> parameter <code class = "ph codeph">MOD_NEG_REL_CONSTR</code>.</li>

</ol></div>

<div class = "section" id = "tso-r-cmd-constraint__tso-r-cmd-constraint-exmp"><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 sectiontitle">Examples</h2>

<p>For sensitivity-based topology optimization:</p>
<pre class = "codeblock">
<code class = "ph codeph">
CONSTRAINT
 ID_NAME   = my_constraint
 DRESP     = volume_part_1
 MAGNITUDE = REL
 LE_VALUE  = 0.8
END_
</code>
</pre>
<p>For controller-based bead optimization:
</p><pre class = "codeblock">
<code class = "ph codeph">
CONSTRAINT
 ID_NAME   = bead_height_constraint
 DRESP     = dresp_bead_height
 MAGNITUDE = ABS
 EQ_VALUE  = 20.0
END_
</code></pre>
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