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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>Files and Formats</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">Within this section supported file formats are discussed.</span>
</p>
<p>This page discusses: </p><ul><li><a href = "#tso-c-usr-solver-mscNastran-files__tso-c-usr-solver-mscNastran-files-input" id = "toc_rg" title = "">Input Files and Formats</a></li><li><a href = "#tso-c-usr-solver-mscNastran-files__tso-c-usr-solver-mscNastran-files-result" id = "toc_rg" title = "">Result Files and Formats</a></li><li><a href = "#tso-c-usr-solver-mscNastran-files__tso-c-usr-solver-mscNastran-files-rem" id = "toc_rg" title = "">Remarks</a></li></ul>
</p></td></tr></table></td></tr></table>




<div class = "body conbody">

<div class = "section" id = "tso-c-usr-solver-mscNastran-files__tso-c-usr-solver-mscNastran-files-input"><h2 class = "title sectiontitle">Input Files and Formats</h2>

<p>The optimization preprocessor reads the ASCII input files <code class = "ph codeph">*.bdf</code>.
The Bulk entries must be in fixed format and in either small or large
field format. Parameter statements (<code class = "ph codeph">PARAM</code>) might be set
as free format.</p>
</div>


<div class = "section" id = "tso-c-usr-solver-mscNastran-files__tso-c-usr-solver-mscNastran-files-result"><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">Result Files and Formats</h2>

<p><span class = "ph">Tosca Structure</span>
uses <span class = "ph">MSC Nastran®</span>
output <code class = "ph codeph">OP2</code>. The following parameters are automatically
generated or changed by <span class = "ph">Tosca Structure</span>:</p>
<pre class = "codeblock">
<code class = "ph codeph">
PARAM,POST,-1
PARAM,POSTEXT,YES
PARAM,TINY,0.0
PARAM,DBALL,SCRATCH
PARAM,OUGCORD,BASIC
</code>
</pre>
<p>For sensitivity-based topology optimization, <code class = "ph codeph">PARAM, POST, -4</code>
is set in the first iteration.</p>
<p>To make FemToOnf skip the <code class = "ph codeph">PARAM, POST, -1</code> check in the <span class = "ph">MSC Nastran®</span> interface, you can add the following <code class = "ph codeph">DRIVER</code> block:</p>
<pre class = "codeblock">
<code class = "ph codeph">
DRIVER
  driver.Modules[ ToscaModules.FEM_2_ONF ].AddCallArgs = [ r'--ignore_ppr 1' ]
END_
</code>
</pre>

<p><span class = "ph">Tosca Structure</span>
<span class = "ph">2023</span>
adds any output (<code class = "ph codeph">DISPLACEMENTS, STRESS,</code> etc.) required by the optimization if no outputs are given.</p>
<table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent">
<p>Let <span class = "ph">Tosca Structure</span>
add the output request for obtaining the lowest possible CPU-time of
the optimization. In many cases output writing is the most CPU-time consuming
task for <span class = "ph">MSC Nastran®</span>
and thus <span class = "ph">Tosca Structure</span>
adds only those output requests that are necessary for the optimization.
Therefore, the user should set as few output requests as possible, if any.</p>
</span></td></tr></table>

</div>


<div class = "section" id = "tso-c-usr-solver-mscNastran-files__tso-c-usr-solver-mscNastran-files-rem"><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">Remarks</h2>

<table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent">
<p>
<ul class = "ul">
<li class = "li">The validation input file is created based on the original
input deck. Thus for an automatic validation all required outputs have
to be added in the beginning to the original input file or the validation
input file must be changed manually after generation before starting
the validation run.</li>
<li class = "li">When <span class = "ph">MSC Nastran®</span>
is configured to run in mode=i4, you must set the following flag in your <span class = "ph">Tosca Structure</span>
configuration or the CONFIG section in your job parameter file:
<p>
<code class = "ph codeph">
driver.Solver.AddCallArgs = ['--mode', 'i4']
</code>
</p>
<p>The default mode used by <span class = "ph">Tosca Structure</span> is i8.</p>
</li>
<li class = "li">In topology optimization, large changes are applied to the elements' density and, thus, Young's
              modulus. This might result in problems with the pivot ratio of the stiffness matrices
              during a <span class = "ph">Nastran</span> run. This could be overcome by changing the <code class = "ph codeph">MAXRATIO</code> parameter in
              the bulk data section like, for example: <code class = "ph codeph">PARAM,MAXRATIO,10.E10</code>
            </li>
<li class = "li">All <code class = "ph codeph">PARAM</code> statements must be located in the Bulk Data section. Having <code class = "ph codeph">PARAM</code> statements in the Case Control section will cause generation of invalid modified input files.</li>
</ul>
</p>
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