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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>Defining a Displacement Constraint</h1></td></tr><tr><td class = "DocHeader4" colspan = "2"/></tr><tr><td class = "DocHeader3" colspan = "2"><table class = "DocThemeIntro" id = "table12"><tr><td class = "Intro1"><p class = "header"><p class = "abstract">
<span class = "shortdesc">
You can define a Displacement Constraint to obtain the structure with
maximal stiffness subject to the constraint on the difference of the
displacements of two nodes.
</span>

</p>
<p>This task shows you how to:
					</p><ul><li><a href = "#tso-t-user-TopOpt-StaAna-DispConst-gui" id = "toc_rg" title = "">
Define a Displacement Constraint in <span class = "ph">Tosca Structure.gui</span>
</a></li><li><a href = "#tso-t-user-TopOpt-StaAna-DiffDisp-gui" id = "toc_rg" title = "">
Common Steps for <span class = "ph">Tosca Structure.gui</span>
</a></li></ul>
</p></td></tr><tr><td class = "Intro2"><hr class = "header"/><span class = "run-in-beforeyoubegin">Before you begin: </span>Five design responses are needed in this example: The displacements at two different nodes, their difference, the volume and the strain energy.</td></tr></table></td></tr></table>



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

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

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

Define a design response (<span class = "ph uicontrol">DRESP</span>) for the displacement of the first node.

<p>
<p>
For a list of existing types, see <a class = "xref" href = "tso-c-usr-terms-displRotOvw.htm#tso-c-usr-terms-displRotOvw" title = "This section describes the theory of displacements and rotation.">Overview of Displacement and Rotation</a>.
</p>
<div class = "note"><span class = "run-in.note">Note:
			</span><span class = "notecontent">The total absolute value cannot be used as design response.
</span></div>

</p>
</li><li class = "li step stepexpand">
Define a design response for the displacement of the second node,
similar to the first one.
</li><li class = "li step stepexpand">

To define a design response with the difference of the nodal displacement
from the two nodes, choose <span class = "ph menucascade"><span class = "ph uicontrol">Command</span><abbr title = "and then"> &gt; </abbr><span class = "ph uicontrol">DRESP</span></span>.

</li><li class = "li step stepexpand">
In the DRESP dialog, select
<span class = "ph uicontrol">DefType = Operator</span> and <span class = "ph uicontrol">Operator = SUB_ABS</span>.
</li></ol></section>
</div>

</article>

<article class = "topic task nested1" aria-labelledby = "ariaid-title3" id = "tso-t-user-TopOpt-StaAna-DiffDisp-gui">
<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">
Common Steps for <span class = "ph">Tosca Structure.gui</span>
</h2>

<div class = "body taskbody">
<section><ol class = "ol steps"><li class = "li step stepexpand">
Define a second constraint for the relative material volume.
<p>
Only a few elements will be removed in the short arm in order to obtain
equal displacements of the two arms. In most cases, the intention is to
have a structure with a given weight and the maximum stiffness.
</p>
</li><li class = "li step stepexpand">

Define the objective function as minimization of the compliance
of the whole model. This is defined as the sum of the strain energy of
all elements (<code class = "ph codeph">ALL_ELEMENTS</code> element group).

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

<article class = "topic task nested2" aria-labelledby = "ariaid-title4" id = "tso-t-user-TopOpt-StaAna-DispConst-parFile">
<h3 class = "title topictitle3">
<span class = "ph">SIMULIA Tosca Structure</span> Parameter File
</h3>

<div class = "body taskbody">
<section><div class = "li step p">
The commands in the parameter file for this problem look like follows:
<p>
<pre class = "codeblock">
<code class = "ph codeph">
DRESP
 ID_NAME        = DISP_TIP_RIGHT
 TYPE           = DISP_Z
 DEF_TYPE       = SYSTEM
 LC_SET         = STATIC,1,
 GROUP_OPER     = Max
 ND_GROUP       = TIP_RIGHT
END_

DRESP
 ID_NAME        = DISP_TIP_LEFT
 TYPE           = DISP_Z
 DEF_TYPE       = SYSTEM
 LC_SET         = STATIC,1,
 GROUP_OPER     = Max
 ND_GROUP       = TIP_LEFT
END_

DRESP
 ID_NAME        = DISP_DIFFERENCE
 DEF_TYPE       = OPER
 VAR_OPER       = SUB_ABS
 VAR_A          = DISP_TIP_RIGHT
 VAR_B          = DISP_TIP_LEFT
END_

DRESP
 ID_NAME        = DRESP_SUM_ENERGY_LC1
 TYPE           = STRAIN_ENERGY
 DEF_TYPE       = SYSTEM
 LC_SET         = STATIC,1
 GROUP_OPER     = SUM
 EL_GROUP       = ALL_ELEMENTS
END_

OBJ_FUNC
 ID_NAME        = MY_OBJ_FUNC
 TARGET         = MIN
 DRESP          = DRESP_SUM_ENERGY_LC1
END_

CONSTRAINT
 ID_NAME        = DISP_DIFF_CONSTRAINT
 MAGNITUDE      = ABS
 DRESP          = DISP_DIFFERENCE
 LE_VALUE       = 0.1
END_

DRESP
 ID_NAME        = DRESP_VOL_TOPO
 TYPE           = VOLUME
 DEF_TYPE       = SYSTEM
 GROUP_OPER     = SUM
 EL_GROUP       = ALL_ELEMENTS
END_

CONSTRAINT
 ID_NAME        = VOL_CONSTRAINT
 MAGNITUDE      = REL
 DRESP          = DRESP_VOL_TOPO
 LE_VALUE       = 0.3
END_
</code>
</pre>
</p>
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