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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>Optimizing the Threehole Model </h1></td></tr><tr><td class = "DocHeader4" colspan = "2"/></tr><tr><td class = "DocHeader3" colspan = "2"><table class = "DocThemeIntro" id = "table12"><tr><td class = "Intro1Only"><p class = "header"><p class = "abstract">
<span class = "shortdesc">The lowest natural frequency is to be maximized in this example without a
change in volume.</span>

</p>

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<div class = "body taskbody">
<section><ol class = "ol steps"><li class = "li step stepexpand">
Define the first natural eigenfrequency in a Design Response (DRESP):
<div class = "itemgroup stepresult">
<pre class = "codeblock">
DRESP
 ID_NAME  = DRESP_FREQ
 DEF_TYPE = SYSTEM
 TYPE     = DYN_FREQ
 LC_SET   = MODAL,ALL,1
 LC_SEL   = MIN
 UPDATE   = EVER
END_
</pre>
</div>
</li><li class = "li step stepexpand">
Reference the Design Response in the Objective Function (OBJ_FUNC):
<div class = "itemgroup stepresult">
<pre class = "codeblock">
OBJ_FUNC
 ID_NAME = MAXIMIZE_FREQ
 DRESP   = DRESP_FREQ
 TARGET  = MAX
END_
</pre>
<p>Optimization where natural frequencies are to be maximized generally
causes an increase of mass/volume and thus increasing the natural frequencies.</p>
</div>
</li><li class = "li step stepexpand">
To avoid an increase of volume, define a volume constraint as follows:
<ol type = "a" class = "ol substeps">
<li class = "li substep">
Create a Design Response (DRESP) with the sum of all elements:
<div class = "itemgroup stepresult">
<pre class = "codeblock">
DRESP
 ID_NAME    = DRESP_VOL_SHAPE
 DEF_TYPE   = SYSTEM
 TYPE       = VOLUME
 UPDATE     = EVER
 EL_GROUP   = ALL_ELEMENTS
 GROUP_OPER = SUM
END_
</pre>
</div>
</li>
<li class = "li substep">
Reference the Design Response in a constraint (CONSTRAINT):
<div class = "itemgroup stepresult">
<pre class = "codeblock">
CONSTRAINT
 ID_NAME   = volume_constraint
 DRESP     = DRESP_VOL_SHAPE
 MAGNITUDE = REL
 EQ_VALUE  = 1.0
END_
</pre></div>
</li>
</ol>
</li></ol></section>
<p class = "result">
The result looks as follows:
<p><br/><img class = "image" src = "../TsoExampleImages/shapeThreeholeResult.png" width = "600"/><br/></p>
<p>The frequency development looks as follows:<br/><img class = "image" src = "../TsoExampleImages/shapeThreeholeResultFreq.png"/><br/></p>
</p>
</div>

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