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      <title>BCTPARM</title>
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      <div class="title_refTopic" id="xps10_pagetitle">BCTPARM </div>
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      <h4 class="refClassification">Contact Parameters (SOLs 101, 103, 111 and 112). </h4>
      <p class="para_refTopic">Control parameters for the SOL 101 contact algorithm. </p>
      <div class="title_refCategory">Format:</div>
      <div class="refCategoryContent">
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                     <p class="para_td">1 </p>
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                     <p class="para_td">2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">3 </p>
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                     <p class="para_td">4 </p>
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                     <p class="para_td">5 </p>
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                     <p class="para_td">6 </p>
                  </td>
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                     <p class="para_td">7 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">8 </p>
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                     <p class="para_td">9 </p>
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                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">10 </p>
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            <tbody>
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                  <td align="left" colspan="1" rowspan="1">
                     <p class="para_td">BCTPARM </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">CSID </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Param1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Value1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Param2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Value2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Param3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Value3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
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                     <p class="para_td">&nbsp; </p>
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                     <p class="para_td">Param4 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Value4 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Param5 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">Value5 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">-etc- </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
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      <div class="title_refCategory">Example:</div>
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                     <p class="para_td">BCTPARM </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">PENN </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">1.0 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">CTOL </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">0.001 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
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      <div class="title_refCategory">Fields:</div>
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                     <p class="para_th"><b class="uiTerm">Field </b></p>
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                  <th align="left" colspan="1" rowspan="1">
                     <p class="para_th"><b class="uiTerm">Contents </b></p>
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                     <p class="para_td">CSID </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Contact set ID. Parameters defined in this command apply to contact set CSID defined by a BCTSET entry. (Integer &gt; 0) </p>
                  </td>
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                     <p class="para_td">PARAMi </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Name of the BCTPARM parameter. Allowable names are given in the parameter listing below. (Character) </p>
                  </td>
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                     <p class="para_td">VALUEi </p>
                  </td>
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                     <p class="para_td">Value of the parameter. See <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/12topic_31.html#ref71895');return(false);">Table 11-4</a> for the parameter listing. (Real or Integer) 
                     </p>
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         </table><br><a name="ref71895"></a><div class="title_tableWrapper">Table 11-4. BCTPARM Parameters </div>
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                     <p class="para_th"><b class="uiTerm">Name </b></p>
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                     <p class="para_th"><b class="uiTerm">Description </b></p>
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                     <p class="para_td">PENN </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Penalty factor for normal direction. (Default=10.0) See <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/12topic_31.html#bctparm2');return(false);">Remark 2</a>.
                     </p>
                  </td>
               </tr>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PENT </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Penalty factor for tangential direction. (Default=1.0) See <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/12topic_31.html#bctparm2');return(false);">Remark 2</a>.
                     </p>
                  </td>
               </tr>
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                     <p class="para_td">CTOL </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Contact force convergence tolerance. (Default=0.01)</p>
                  </td>
               </tr>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">MAXF </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Maximum number of iterations for force a loop. (Default=10)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">MAXS </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Maximum number of iterations for a status loop. (Default=20)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">NCHG </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Allowable number of contact changes for convergence. (Default=0)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">MPER </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Minimum contact set percentage. (Default=100)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">SHLTHK </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Shell thickness offset flag. </p>
                     <p class="para_td">0 - Includes half shell thickness as surface offset. (Default) </p>
                     <p class="para_td">1 - Does not include thickness offset. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">RESET </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Flag to indicate if the contact status for a specific subcase is to start from the final status of the previous subcase </p>
                     <p class="para_td">0 - Starts from previous subcase. (Default) </p>
                     <p class="para_td">1 - Starts from initial state.</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">AVGSTS </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Determines the averaging method for contact pressure/traction results. </p>
                     <p class="para_td">0 - The averaging of Pressure/Traction values for a contact grid will include the results from ALL contact elements attached to the grid regardless of whether they are active or inactive in the contact problem (Default). </p>
                     <p class="para_td">1 - The averaging of the Pressure/Traction values for a contact grid will exclude those contact elements which are not active in the contact solution and thus have a zero Pressure/Traction value.</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">INIPENE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Use when the goal is for a pair of contact regions to be initially touching without interference, but due to the faceted nature of finite elements around curved geometry, some of the element faces may have a slight gap or penetration.</p>
                     <p class="para_td">0 or 1 - Contact is evaluated exactly as geometry is modeled. No corrections will occur for gaps or penetrations (Default).</p>
                     <p class="para_td">2 - Penetrations will be reset to a new initial condition in which there is no interference. </p>
                     <p class="para_td">3 - Gaps and penetrations are both reset to a new initial condition in which there is no interference. </p>
                     <p class="para_td">Remarks: </p>
                     <p class="para_td">See <a class="links" href="javascript:void(0)" onclick="top.popUpPage('QRG/linkInter_target_not_resolved.html#User:refh1:-aux,-home','linkInter','menubar=yes,status=yes,resizable=yes,toolbar=yes,scrollbars=yes,location=no,directories=no');return(false);">&ldquo;Understanding the Contact Control Parameters Used in SOL 101 - BCTPARM&rdquo; </a>in the <em>NX Nastran User&rsquo;s Guide</em> for more information on the BCTPARM options. 
                     </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">REFINE</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Determines if the mesh on the source region is refined during the contact solution.</p>
                     <p class="para_td">0 - Do not refine the contact source region based on target surface definition.</p>
                     <p class="para_td">1 - Refine the contact source region based on target surface definition (default).</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">INTORD</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Determines the number of contact evaluation points for a single element face on the source region. The number of contact evaluation points is dependent on the value of INTORD, and on the type of element face. See the table in <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/12topic_31.html#intord_notes');return(false);">Remark 29-1</a> for specific values.
                     </p>
                     <p class="para_td">1 &ndash; The reduced number of contact evaluation points is used.</p>
                     <p class="para_td">2 - Use an increased number of contact evaluation points (default).</p>
                     <p class="para_td">3 &ndash; Use a high number of contact evaluation points.</p>
                  </td>
               </tr>
            </tbody>
         </table><br></div>
      <div class="title_refCategory">Remarks: </div>
      <div class="refCategoryContent">
         <ol type="1" start="1">
            <li><a name="intord_notes"></a><p class="para_item">A higher number of contact evaluation points can be used to increase the accuracy of a contact solution. Inaccuracies sometimes appear in the form of nonuniform contact pressure and stress results. There may be a penalty associated with using more evaluation points since the time for a contact problem to converge may be longer. The table below shows how the number of contact evaluation points is dependent on the element type, and how it can be adjusted using the INTORD option. The &ldquo;Face Type&rdquo; column applies to shell elements, and to the solid element with the associated face type.</p>
               <table border="1" cellpadding="2" cellspacing="1" align="center">
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                        <td colspan="1" height="17" rowspan="1"></td>
                        <td align="center" colspan="3" height="17" rowspan="1">
                           <p class="para_td"><b class="uiTerm">Number of Contact Evaluation Points</b></p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1">
                           <p class="para_td"><b class="uiTerm">Face Type</b></p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">INTORD=1</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">INTORD=2</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">INTORD=3</p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">Linear Triangle</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">1</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">3</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">7</p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">Parabolic Triangle</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">3</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">7</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">12</p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">Linear Quad</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">1</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">4</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">9</p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">Parabolic Quad</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">4</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">9</p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">16</p>
                        </td>
                     </tr>
                  </tbody>
               </table><br></li>
            <li><a name="bctparm2"></a><p class="para_item">Penalty factors have units of 1/(length).  A physical interpretation is that it is equivalent to the axial stiffness of a rod (K=e*E*dA) with area dA, modulus E, and length 1/e.  The defaults for the penalty factors generally work well, but in the event that meshes have very large or very small edge lengths, adjustments may be necessary. See the chapter Surface Contact for SOL 101 in the <em>NX Nastran User's Guide</em> for tips on adjusting penalty factors.
               </p>
            </li>
         </ol>
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