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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>Maximizing the Lowest Natural Frequency (Controller-Based Optimization)</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 = "shortdesc">The natural frequency might be optimized by
using the maximization the first natural frequency. 
</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 = "The design response command DRESP defines the system response for the current analysis model." href = "../TsoCmdMap/tso-m-cmd-dresp-sb.htm#tso-m-cmd-dresp-sb">DRESP</a></td></tr></table></td></tr></table>



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

The following shows an example of maximization of the first natural eigenfrequency:
        
<p>
<pre class = "codeblock">
<code class = "ph codeph">
DRESP
  ID_NAME  = dresp_max_eigenfrequency
  DEF_TYPE = SYSTEM
  TYPE     = DYN_FREQ
  LC_SET   = Modal,All,1
END_

OBJ_FUNC
  ID_NAME = maximize_eigenfrequency
  DRESP  = dresp_max_eigenfrequency
  TARGET = MAX
END_
</code>
</pre>
</p>
</li><li class = "li step stepexpand">The type of the design response is <code class = "ph codeph">DYN_FREQ</code> (eigenfrequency).
To choose the first eigenfrequency, set the third argument in the item <code class = "ph codeph">LC_SET</code>
to 1. </li><li class = "li step stepexpand">Reference this design responses <code class = "ph codeph">ID_NAME</code> in the <code class = "ph codeph">OBJ_FUNC</code> where it is set to be maximized.</li><li class = "li step stepexpand">To consider for example the second eigenfrequency, the <code class = "ph codeph">LC_SET</code>
parameter must be set as follows: <span class = "ph"><code class = "ph codeph">LC_SET = Modal, All, 2</code></span>.

<p><table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent">Do NOT define the third argument in the <code class = "ph codeph">LC_SET</code> command
as <code class = "ph codeph">All</code> (for example, <span class = "ph"><code class = "ph codeph">LC_SET = Modal,1,all</code></span>). The algorithm will then try
to combine All modes from the modal analysis, which normally will NOT
lead to good results for the controller-based algorithm.<p>Consider that the sensitivity-based algorithm (BEAD_SENSITIVITY)
is usually superior for this task.</p></span></td></tr></table>
</p></li></ol></section>
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