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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>Analysis Types</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">In <span class = "ph">Abaqus</span>,
a general static <code class = "ph codeph">STEP</code> definition without the explicit
<code class = "ph codeph">PERTURBATION</code> option is nonlinear. That means to optimize
these models with <span class = "ph">Tosca Structure</span>
an advanced license for <span class = "ph">Tosca Structure.nonlinear</span>.
is needed. Otherwise use only <code class = "ph codeph">*STEP</code><span class = "ph">, </span><code class = "ph codeph">PERTURBATION</code>
in <span class = "ph">Abaqus</span>
input file.</span>

</p>
<p>This page discusses: </p><ul><li><a href = "#tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-geomnonlin" id = "toc_rg" title = "">Geometric Nonlinear Analysis</a></li><li><a href = "#tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-explicit" id = "toc_rg" title = "">Optimizing Using <span class = "ph">Abaqus</span>/Explicit</a></li><li><a href = "#tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-sensbasedopt" id = "toc_rg" title = "">Allowed Analysis Types for Sensitivity-Based Optimizations</a></li><li><a href = "#tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-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-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-geomnonlin"><h2 class = "title sectiontitle">Geometric Nonlinear Analysis</h2>

<p>Geometric nonlinear analysis (parameter <code class = "ph codeph">NLGEOM</code>) can
be used in topology optimization (both, controller and sensitivity-based), shape and bead (both, controller and sensitivity-based) optimization as well as in sizing optimization.
An excessive deformation of soft elements can occur during topology optimization. This does not
occur for a linear analysis. However, in the case of a geometric nonlinear
analysis this leads to an adverse effect on the convergence, which eventually
leads to the termination of the analysis. This must be considered when
applying topology optimization using hyperelastic material.</p>
</div>

<div class = "section" id = "tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-explicit"><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">Optimizing Using <span class = "ph">Abaqus</span>/Explicit</h2>

<p>The use of <span class = "ph">Abaqus</span>/Explicit
is permitted for shape controller optimization of quasi-static problems. The <code class = "ph codeph">ODB</code>
result interface must be activated which is also default, see <a class = "xref" href = "tso-c-usr-solver-abaqus-files.htm#tso-c-usr-solver-abaqus-files" title = "File formats are explained in this section.">Files and Formats</a>. The result
of one explicit analysis step is divided into 20 increments, which are
interpreted as 20 single substeps in <span class = "ph">Tosca Structure</span>.
A step in the finite element input file must be divided into several
steps if the results of more than 20 substeps should be included in the
optimization.</p>
<p>Topology, bead, and shape sensitivity optimization in combination with <span class = "ph">Abaqus</span>/Explicit
is not supported.</p>
</div>

  
<div class = "section" id = "tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-sensbasedopt"><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">Allowed Analysis Types for Sensitivity-Based Optimizations</h2>

<p>In <span class = "ph">Abaqus</span>
responses from the two following analysis types are allowed:</p>
<pre class = "codeblock">
<code class = "ph codeph">
*STEP
*STATIC
...
*END STEP
</code>
</pre>
<p>and</p>
<pre class = "codeblock">
<code class = "ph codeph">
*STEP, PERTURBATION
*STATIC
...
*END STEP
</code></pre>
<p>and</p>
<pre class = "codeblock">
<code class = "ph codeph">
*STEP
*FREQUENCY
...
*END STEP
</code></pre>
<p>and</p>
<pre class = "codeblock">
<code class = "ph codeph">
*STEP
*Heat Transfer, steady state
...
*END STEP
</code></pre>  
</div>

<div class = "section" id = "tso-c-usr-solver-abaqus-analysis__tso-c-usr-solver-abaqus-analysis-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>

<ul class = "ul">
<li class = "li">If <code class = "ph codeph">PERTURBATION</code> is added, the step command<code class = "ph codeph"> *STEP</code>
will be recognized as a linear static solution in <span class = "ph">Tosca Structure</span>.
If <code class = "ph codeph">PERTURBATION</code> is not added, the analysis is nonlinear.
The sensitivity-based algorithm supports geometrical nonlinearities
(<code class = "ph codeph">NLGEOM</code>) and contact for <span class = "ph">Abaqus</span>.</li>
<li class = "li"><span class = "ph">Abaqus</span>
has no predefined numbers for the <span class = "ph">load cases</span>.
Therefore, the first defined <span class = "ph">load case</span>
in the <code class = "ph codeph">INP</code> file is recognized as <span class = "ph">load case</span>
one, the second defined <span class = "ph">load case</span>
in the <code class = "ph codeph">INP</code> file is recognized as <span class = "ph">load case</span>
two and etc. </li>
<li class = "li">Computationally, it is recommended that the user defines the static
<span class = "ph">load case</span>
in <span class = "ph">Abaqus</span>
using the <span class = "ph">load case</span>
command <code class = "ph codeph">*LOAD CASE</code> in one <code class = "ph codeph">*STEP</code> and
not be defining more steps using <code class = "ph codeph">*STEP</code> several times.
Hence, using the <span class = "ph">load case</span>
command <code class = "ph codeph">*LOAD CASE</code> will keep the CPU-time significant
lower, for example,
<pre class = "codeblock">
<code class = "ph codeph">
*STEP, PERTURBATION
 *STATIC
 *LOAD CASE
 ...
 *END LOAD CASE
 *LOAD CASE
 ...
 *END LOAD CASE
 ...
*END STEP
</code>
</pre>
</li>
<li class = "li">The results of the finite element analysis can only be read from the ODB
file when the command <code class = "ph codeph">*LOAD CASE</code> is activated (default)
and not the <code class = "ph codeph">FIL</code> file. </li>
</ul>
</div>

</div>

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