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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>Loads and Boundary Conditions</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 loads and boundary conditions are discussed.</span>

</p>
<p>This page discusses: </p><ul><li><a href = "#tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-lc" id = "toc_rg" title = "">Load Cases</a></li><li><a href = "#tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-bc" id = "toc_rg" title = "">Supported Boundary Conditions</a></li><li><a href = "#tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-contact" id = "toc_rg" title = "">Contact Boundary Conditions</a></li><li><a href = "#tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-nodeRestr" id = "toc_rg" title = "">Node Restrictions for Shape Optimizations</a></li></ul>
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<div class = "body conbody">

<div class = "section" id = "tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-lc"><h2 class = "title sectiontitle">Load Cases</h2>

<p><code class = "ph codeph">SUBCASE</code> is the default <span class = "ph">load case</span>
statement for <span class = "ph">SIMULIA Tosca Structure</span>.
<code class = "ph codeph">SUBCOM</code> allowed only for controller-based algorithms.</p>
<table class = "Remark" id = "table132"><tr><td class = "Remark"><span class = "run-in.important">Important:
				</span><span class = "notecontent"><p>The iterative solver should be avoided for sensitivity-based algorithms
because of additional pseudo loads usually. </p></span></td></tr></table>

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<div class = "section" id = "tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-bc"><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">Supported Boundary Conditions</h2>

<p><code class = "ph codeph">SPC, SPC1, SPCADD, SPCD</code> </p>
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<div class = "section" id = "tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-contact"><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">Contact Boundary Conditions</h2>

<p>Linear contact conditions (<code class = "ph codeph">SOL 101</code>) are permitted in the analysis model for
        controller-based topology, shape, and bead optimization. Contact definitions with
          <code class = "ph codeph">BCPROP</code> can be used for shape and bead optimization, but are not allowed
        for topology optimization (as element properties are changed). </p>
<p>Defining a contact surface directly on the edge of the design space is allowed in topology
        optimization. The shape optimization algorithm must be inverted (see command
          <code class = "ph codeph">OPT_PARAM</code>, parameter <code class = "ph codeph">SCALE</code>) if the design edge belongs
        to a contact surface in shape optimization. Convergence difficulties in the FE analysis
        might arise in cases of complex contact problems due to large changes in the model during
        optimization. </p>
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<div class = "section" id = "tso-c-usr-solver-mscNastran-bcond__tso-c-usr-solver-mscNastran-bcond-nodeRestr"><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">Node Restrictions for Shape Optimizations</h2>

<p>Node fixations are not loaded when loading the analysis model. The
boundary conditions (<code class = "ph codeph">SPC = NR1</code> and <code class = "ph codeph">SPC = NR2</code>)
are transferred to the optimization model by entering the command</p>
<pre class = "codeblock">
<code class = "ph codeph">
OPTIONS
  READ_BC = ID, NR1, NR2 (or ALL) 
END_
</code>
</pre>
<p>When the optimization boundary conditions have been written into a separate
sub case then the <code class = "ph codeph">Main SPC</code> number can be specified which
has been entered in the <code class = "ph codeph">CASE CONTROL SECTION</code> of the
analysis bulk data file. All <code class = "ph codeph">SPC</code> commands that are linked
in the <span class = "ph">MSC Nastran®</span>
input file with <code class = "ph codeph">SPCADD</code> are also transferred to the optimization
model. Specification of the sub case number itself is not permitted.</p>
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