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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> Typical Optimization Tasks for Modal Analysis</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">Within modal analysis structural optimization can be used
to manipulate the eigenfrequency spectrum. Possible optimization tasks
are discussed in this chapter. </span>

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</p><hr class = "header"/></td></tr><tr><td class = "Intro2"><span class = "run-in">In this section:</span><br/><ul class = "ulthemes"><li><a title = "Often the design target is to increase the first eigenfrequencies in an eigenfrequency spectrum. It is important to consider more than the first natural eigenfrequency when increasing the natural frequencies using optimization. Otherwise, the first and secondary mode might switch during the optimization as shown in the figure below." href = "tso-c-user-TopOpt-ModAna-ov.htm#tso-c-user-TopOpt-ModAna-ov">About Typical Optimization Tasks for Modal Analysis</a></li><li><a title = "You can increase several lowest eigenfrequencies." href = "tso-t-user-TopOpt-ModAna-Max1Fr.htm">Maximizing the First Eigenfrequencies</a></li><li><a title = "You can increase a specific eigenfrequency in the eigenfrequency spectrum belonging to a certain eigenmode. In this case, a specific eigenfrequency is defined using TYPE = DYN_FREQ." href = "tso-t-user-TopOpt-ModAna-MaxFr.htm">Maximizing the Eigenfrequency of a Certain Eigenmode</a></li><li><a title = "Sometimes it is desirable that the first eigenfrequencies are as far away as possible from a certain value. For example, if an engine mainly works at 150 Hz, there should be an as large as possible interval called a band gap around 150 Hz in the eigenfrequency spectrum containing no eigenfrequencies. You can maximize the band gap to decrease some eigenfrequencies and increase others." href = "tso-t-user-TopOpt-ModAna-MaxBandGap.htm">Maximizing the Band Gap</a></li><li><a title = "You can define constraints for eigenfrequencies in the topology optimization tasks such as stiffness optimization or minimizing the mass." href = "tso-t-user-TopOpt-ConstFR.htm">Constraining an Eigenfrequency</a></li></ul></td></tr></table></td></tr></table>

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