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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>Minimizing the Volume of the Crankshaft Model (<span class = "ph">Tosca Structure.gui</span>)</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">This example shows how to add rotational displacement constraints and a center of gravity constraint.
</p></td></tr></table></td><td class = "DocHeader2"><table class = "DocTopicsSeeAlso" id = "table13"><tr><td class = "TopicsTitle">See Also</td></tr><tr><td><a title = "To get an impression of the quality of the optimization, it is necessary to check the values of the constraints and the objective at the end of the optimization." href = "tso-c-example-topo-checkOptResult.htm#tso-c-example-topo-checkOptResult">About Checking the Quality of the Optimization Result</a></td></tr></table></td></tr></table>




<div class = "body taskbody">
<section><ol class = "ol steps"><li class = "li step stepexpand">
Start <span class = "ph">Tosca Structure.pre</span> to define the optimization task.
</li><li class = "li step stepexpand">
Import the analysis model <span class = "ph filepath filepath">crank_shaft.ext</span> (ext=inp, bdf, dat...).
If no groups are defined in the analysis input (for example, for <span class = "ph">MSC Nastran®</span> input), import the groups from the file groups.bdf, which
can be found in the same directory as the analysis input. For more
details please refer to the <span class = "ph">SIMULIA Tosca Structure</span> Getting Started manual.
</li><li class = "li step stepexpand">
Create the design variable area. The group DESIGN_ELEMENTS
contains the design elements.
</li><li class = "li step stepexpand">
Add a design response for the volume as a sum of all design elements
volumes.
</li><li class = "li step stepexpand">
Create a design response for the rotational displacement on node 2 along
the z axis. Select the first <span class = "ph">load case</span> to refer the design response to.
<div class = "itemgroup stepresult">
<p><br/><img class = "image" src = "../TsoExampleImages/sensTopoCrankshaftRotContDef.png"/><br/></p>
</div>
</li><li class = "li step stepexpand">
Create a second design response for rotational displacement on node 2
similar to the previous one. Select the rotation along the x axis and the
assign the second <span class = "ph">load case</span> to the design response.
</li><li class = "li step stepexpand">
Create a design response for the y location of the center of gravity of the
whole model. Make sure to switch the Group Oper toSum.
<div class = "itemgroup stepresult">
<p><br/><img class = "image" src = "../TsoExampleImages/sensTopoCrankshaftCentOfGravDef.png"/><br/></p>
</div>
</li><li class = "li step stepexpand">
Define the objective function to minimize the design volume.
</li><li class = "li step stepexpand">
Define constraints to maintain the torsional and bending stiffness as well as
to set the y location of the gravity center. In the first constraint set the
maximal value of 2.0e-6 for the z rotation of node 2. In the second
constraint set the maximal value of 1.2e-6 for the x rotation of node 2. In
the third constraint set a maximal value of -18 for the y coordinate of the
center of gravity. All constraint types should be less or equal and the
magnitude values should be set to ABS.
</li><li class = "li step stepexpand">
 Compose the optimization task (OPTIMIZE) and select the predefined definitions. Choose
the TOPO_SENSITIVITY optimization strategy. Make sure to reference all defined CONSTRAINT
items in the OPTIMIZE command. 
</li><li class = "li step stepexpand">
Define some additional optimization parameters with the OPT_PARAM
command. Increase the initial density from 0.5 to 0.9.
</li><li class = "li step stepexpand">
Start the complete <span class = "ph">Tosca Structure</span> optimization using the start option type
= all.
</li></ol></section>
<p class = "result">The optimization is finished after approx. 20 design cycles. The
results in form of material distribution
are as follows:
<br/><img class = "image" src = "../TsoExampleImages/sensTopoCrankshaftResult.png"/><br/>
</p>
</div>

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