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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>Restricting the Direction of Displacement</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">This section shows you how to influence and restrict the displacement
direction of design nodes.</span>

</p>
<p>This page discusses: </p><ul><li><a href = "#tso-c-usr-bead-restrictions-DispDirection__tso-c-usr-restrictionsBeadDispDirection-readBc" id = "toc_rg" title = "">Loading Node Fixations through the Interface from the FE Program</a></li><li><a href = "#tso-c-usr-bead-restrictions-DispDirection__tso-c-usr-restrictionsBeadDispDirection-checkDof" id = "toc_rg" title = "">Definition of the Displacement Direction by Command</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 = "Defines restrictions of the design variables in bead optimization." href = "../TsoCmdMap/tso-r-cmd-dvconBead.htm#tso-r-cmd-dvconBead">DVCON_BEAD</a></td></tr></table></td></tr></table>




<div class = "body conbody">
<p>In <span class = "ph">Tosca Structure.bead</span>,
the displacement direction of the design nodes (optimization displacement
vector) is normally determined as the surface normal (see <a class = "xref" href = "tso-c-usr-beadParamCtrl-vector.htm#tso-c-usr-beadParamCtrl-vector" title = "It is described how to influence the update of the optimization directions.">Update of Optimization Displacement Vectors (VECTOR)</a>). A
restriction of the displacement direction in bead optimization might be
necessary due to two reasons:</p>
<ol class = "ol" id = "tso-c-usr-bead-restrictions-DispDirection__ol_BA3A73898FCF4A6DB744B6BC1A78C76D">
<li class = "li"> Standardly, the displacement direction in bead optimization is determined
in the initial model and is not modified during optimization (OPT_PARAM,
VECTOR = FIRST). In order to define own displacement directions, the original
displacement directions might be restricted.</li>
<li class = "li"> Some areas in the design domain should not be modified during optimization,
for example, the boundary of the design domain. These areas might be restricted
using the <code class = "ph codeph">CHECK_DOF</code> or <code class = "ph codeph">CHECK_BC</code> parameters.</li>
</ol>
<table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent"><p>The displacement boundary condition must be unique. In contrast to FE
boundary conditions of several <span class = "ph">load cases</span>,
the total of all supports for all <span class = "ph">load cases</span>
are considered as supports in the optimization. A prescribed node displacement
as an optimization boundary condition is also not permitted.</p></span></td></tr></table>


<div class = "section" id = "tso-c-usr-bead-restrictions-DispDirection__tso-c-usr-restrictionsBeadDispDirection-readBc"><h2 class = "title sectiontitle">Loading Node Fixations through the Interface from the FE Program</h2>

<p>The full or partial fixation of nodes is the most common and most
important type of restriction, it is practically used in every optimization
model. The most efficient method is to define the displacement restrictions
in the FE preprocessing as an extra <span class = "ph">load case</span>
in the transition model and then to load it through the FE interface in the
optimization preprocessor. </p>
<p>In order to do this, the interface must
first be activated with OPTIONS, <code class = "ph codeph">READ_BC=...</code>. In this way, all node fixations for
the optimization model can be defined in advance in the FE preprocessor.
The fixation is always based on the FE displacement coordinate system
of the node.</p>
<p>The parameter</p>
<pre class = "codeblock">
<code class = "ph codeph">CHECK_BC = ALL
</code></pre>
<p>activates the node fixations of the node group (<code class = "ph codeph">ND_GROUP</code>
parameter) which are loaded through the FE interface. Fixations that
reference nodes not contained in the node groups are not activated.</p>
<p>To prevent loaded fixations from being activated, enter: </p>
<pre class = "codeblock">
<code class = "ph codeph">
CHECK_BC = NO
</code>
</pre>
</div>


<div class = "section" id = "tso-c-usr-bead-restrictions-DispDirection__tso-c-usr-restrictionsBeadDispDirection-checkDof"><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">Definition of the Displacement Direction by Command</h2>

<p>The <code class = "ph codeph">CHECK_DOF</code> parameter can be used to restrict other
displacement directions if necessary as an addition or at a later stage.
When entering node fixations by command and in contrast to load the
node fixations through the FE interface, it is necessary to first compile
all nodes that should be assigned a certain attribute to a node group.
The coordinate system must also be defined or loaded.</p>
<p>With the parameter</p>
<pre class = "codeblock">
<code class = "ph codeph">
CHECK_DOF = cs_name,[FIX|FREE],[FIX|FREE],[FIX|FREE]
</code>
</pre>
<p>all the displacements of all nodes in the node group selected with <code class = "ph codeph">ND_GROUP</code>
are fixed (<code class = "ph codeph">FIX</code>) or free (<code class = "ph codeph">FREE</code>) relative to the specified
coordinate directions of the coordinate system, cs_name. Either <code class = "ph codeph">FREE</code>
or <code class = "ph codeph">FIX</code> is allowed for each coordinate direction. </p>
<p><div class = "note"><span class = "run-in.note">Note:
			</span><span class = "notecontent">
<p>The main difference between <code class = "ph codeph">CHECK_BC</code> and <code class = "ph codeph">CHECK_DOF</code>
is: <code class = "ph codeph">CHECK_BC</code> is read in through the FE interface whereas
<code class = "ph codeph">CHECK_DOF</code> is defined in the optimization preprocessor.
Generally, with <code class = "ph codeph">CHECK_BC</code> each node has its own fixation
in its own displacement coordinate system, whereas all nodes of the node
group are all fixed in the same coordinate system with <code class = "ph codeph">CHECK_DOF</code>.</p>
</span></div>
</p>

</div>

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