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      <title>BCTPARA</title>
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      <div class="title_refTopic" id="xps10_pagetitle">BCTPARA </div>
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      <h4 class="refClassification">Contact Set Parameters (SOLs 601 and 701 only) </h4>
      <p class="para_refTopic">Defines parameters for a contact set. </p>
      <div class="title_refCategory">Format: </div>
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                     <p class="para_td">1 </p>
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                     <p class="para_td">2 </p>
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                     <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>
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                     <p class="para_td">7 </p>
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                     <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">BCTPARA </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>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <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>
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                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
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                  <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">BCTPARA </p>
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                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">EPSN </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">1.0E-10 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">TZPENE </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">0.1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">CSTIFF </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">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
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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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                     <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>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PARAMi </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Name of the BCTPARA parameter. Allowable names are given in the parameter listing below. (Character) </p>
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                     <p class="para_td">VALUEi </p>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Value of the parameter. See <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/12topic_30.html#ref62357');return(false);">Table 11-2</a> for parameter listing. (Real or Integer) 
                     </p>
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         </table><br><a name="ref62357"></a><div class="title_tableWrapper">Table 11-2. BCTPARA Parameters for SOL 601 </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">General Parameters </p>
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                     <p class="para_td">TYPE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Selects the type of contact algorithm. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Constraint function algorithm is used.</p>
                     <p class="para_td">1 &ndash; Segment method algorithm is used.</p>
                     <p class="para_td">2 &ndash; Rigid target algorithm is used.</p>
                  </td>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">NSIDE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Flags single or double-sided contact. (Integer; Default=1)</p>
                     <p class="para_td">1 &ndash; Contact surfaces are single-sided.</p>
                     <p class="para_td">2 &ndash; Contact surfaces are double-sided. </p>
                  </td>
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                     <p class="para_td">TBIRTH </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Birth time for contact set. (Real; Default=0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" height="12" rowspan="1" valign="top">
                     <p class="para_td">TDEATH </p>
                  </td>
                  <td align="left" colspan="1" height="12" rowspan="1" valign="top">
                     <p class="para_td">Death time for contact set. (Real; Default=0.0) If TDEATH &le; TBIRTH, it is ignored. </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">Flags how initial penetrations or gaps are handled. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Initial penetrations are eliminated. </p>
                     <p class="para_td">1 &ndash; Initial penetrations are eliminated and the list of pentrating nodes is printed. </p>
                     <p class="para_td">2 &ndash; Initial penetrations are ignored. In successive steps, each contractor node is allowed to penetrate the target up to its initial penetration.</p>
                     <p class="para_td">3 &ndash; Initial penetrations or gaps are overridden by GAPVAL. This option is not available for rigid target algorithm (TYPE = 2).</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">GAPVAL </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies a constant gap distance between the source region (contactor) and the target region when INIPENE = 3. Negative GAPVAL means initial penetrations which will be eliminated.  (Real, Default = 0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PDEPTH </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Penetration depth for single-sided contact (i.e. NSIDE=1). (Real; Default=0.0)If PDEPTH &gt; 0.0, then penetration is detected. When penetration &le; PDEPTH, and if penetration &gt; PDEPTH, penetration is deemed not to occur. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">SEGNORM </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Indicates whether a continuous (interpolated) contact segment normal is used for the contact surfaces. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; SEGNORM=1 if NSIDE=1, SEGNORM=-1 if NSIDE=2. </p>
                     <p class="para_td">1 &ndash; Continuous segment normal is used. </p>
                     <p class="para_td">-1 &ndash; Continuous segment normal is not used. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OFFTYPE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Type of offset for contact regions. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; User specified offset value only for single-sided contact (i.e., NSIDE=1). Use offset of 0.001 for double-sided contact (i.e., NSIDE=2) </p>
                     <p class="para_td">1 &ndash; Use specified offset value for either single- or double-sided contact. </p>
                     <p class="para_td">2 &ndash; Half the shell thickness is used for contact regions on shell elements and no offset is used otherwise. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OFFSET </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Default offset distance for contact regions. (Real &ge; 0.0; Default=0.0) </p>
                     <p class="para_td">Note: For contact algorithm TYPE=0 or 1, individual offset distances can be specified for each contact region using the BCRPARA entry to override the default offset distance specified here. </p>
                  </td>
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               <tr>
                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">Standard contact algorithm (TYPE=0 or 1) </p>
                  </td>
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                     <p class="para_td">DISP</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Selects the displacement formulation used for this contact set. (Integer; Default = 0)</p>
                     <p class="para_td">0 &ndash; Use the formulation selected by CTDISP in NXSTRAT entry (default)</p>
                     <p class="para_td">1 &ndash; Use small displacement formulation (contact conditions are not updated)</p>
                     <p class="para_td">2 &ndash; Use large displacement formulation (contact conditions are updated)</p>
                  </td>
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               <tr>
                  <td align="left" colspan="1" height="60" rowspan="1" valign="top">
                     <p class="para_td">TZPENE </p>
                  </td>
                  <td align="left" colspan="1" height="60" rowspan="1" valign="top">
                     <p class="para_td">Time to eliminate initial penetrations. (Real &ge;0.0; Default=0.0) If TZPENE=0.0 and INIPENE=0 or 1, then the initial penetrations are eliminated in the first time step. This may cause convergence difficulties for certain problems. By using TZPENE &gt; 0.0, the initial penetrations are eliminated gradually over time TZPENE. </p>
                  </td>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">CSTIFF </p>
                  </td>
                  <td colspan="1" rowspan="1">
                     <p class="para_td">Indicates whether consistent contact stiffness is used. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Consistent contact stiffness is not used </p>
                     <p class="para_td">1 &ndash; Consistent contact stiffness is used </p>
                  </td>
               </tr>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TIED </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Indicates whether contact regions in each contact pair are tied together. Currently, tied contact option assumes small rotations of the contact regions. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Not tied </p>
                     <p class="para_td">1 &ndash; Tied </p>
                  </td>
               </tr>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TIEDTOL </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Tolerance used to determine whether contactor nodes are tied to the target region when TIED=1 is specified. A contactor node is tied to its target region if the distance between them is less than or equal to TIEDTOL. (Real; Default=0.0) </p>
                  </td>
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               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">EXTFAC </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Factor for extending contact surfaces beyond their boundaries. The amount of extension is given by this factor multiplied by the length of the contact segments. (1.0E-6 &le; Real &le; 0.1; Default=0.001) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FRICMOD </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Type of friction model (0 &le; Integer &le; 13; Default=0). See Remark 1. </p>
                     <p class="para_td">0 &ndash; Constant coefficient of friction specified for each contact pair, i.e. FRICi in the BCTSET entry. </p>
                     <p class="para_td">1 &ndash; Constant coefficient of friction specified by FPARA1. </p>
                     <p class="para_td">2 &ndash; Friction model 1; uses FPARA1 and FPARA2. </p>
                     <p class="para_td">3 &ndash; Friction model 2; uses FPARA1, FPARA2, and FPARA3. </p>
                     <p class="para_td">4 &ndash; Use different static and dynamic friction coefficients; uses FPARA1, FPARA2, and FPARA3. </p>
                     <p class="para_td">5 &ndash; Friction coefficient varies with sliding velocity; uses FPARA1, FPARA2 and FPARA3. </p>
                     <p class="para_td">6 &ndash; Anisotropic friction model; uses FPARA1, FPARA2, FPARA3, FPARA4, and FPARA5. </p>
                     <p class="para_td">7 &ndash; Friction coefficient varies with consistent contact force; uses FPARA1 and FPARA2. </p>
                     <p class="para_td">8 &ndash; Friction coefficient varies with time; uses FPARA1, FPARA2 and FPARA3. </p>
                     <p class="para_td">9 &ndash; Friction coefficient varies with coordinate values; uses FPARA1, FPARA2, FPARA3, FPARA4, and FPARA5. </p>
                     <p class="para_td">12 &ndash; Modified friction model 1; uses FPARA1 and FPARA2. </p>
                     <p class="para_td">13 &ndash; Modified friction model 2; uses FPARA1, FPARA2, and FPARA3. </p>
                     <p class="para_td">See Section 4.4 of the Advanced Nonlinear Theory and Modeling Guide for a description of friction models. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FPARA1 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Friction parameter A1 </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FPARA2 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Friction parameter A2 </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FPARA3 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Friction parameter A3 </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FPARA4 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Friction parameter A4 </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FPARA5 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Friction parameter A5 </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">FRICDLY</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Indicates whether the application of friction is delayed, i.e., friction is applied on a node one time step after the node comes into contact. Delay of friction application may improve the convergence of the solution. (Integer; Default = 0) </p>
                     <p class="para_td">0 &ndash; No delay </p>
                     <p class="para_td">1 &ndash; Delay</p>
                  </td>
               </tr>
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                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">Constraint Function Contact Algorithm (Type=0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">EPSN </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Parameter for normal constraint function, w. (Real; Default=1.0E-12) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">EPST </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Parameter for frictional constraint function, v. (Real &gt; 0.0; Default=0.001) </p>
                  </td>
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               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">CFACTOR1 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Compliance factor. (Real; Default=0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">Rigid Target Algorithm (TYPE=2) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">NCMOD </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Normal contact modulus. (Real; Default=1.0E11) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="2" rowspan="1" valign="top"></td>
               </tr>
               <tr>
                  <td align="left" colspan="2" height="29" rowspan="1" valign="top">
                     <p class="para_td">Parameters used with current rigid-target algorithm (RTALG=0 in NXSTRAT)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TFORCE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">The maximum tensile contact force allowed for a converged solution. (Real &ge; 0.0, Default = 0.001)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">SLIDVEL </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">The maximum sliding velocity used in modeling sticking friction. When the velocity is smaller than SLIDVEL, sticking is assumed; when the velocity is larger than SLIDVEL, sliding is assumed. (Real &gt; 0.0, Default = 1.0E-10)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OCHECK </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies whether oscillation checking is performed and when it is done. (Integer &gt;= 0;  Default = 5)  </p>
                     <p class="para_td">If OCHECK=0, no oscillation checking is performed. Otherwise, oscillation checking is performed after equilibrium iteration OCHECK.  Oscillation checking consists of two checks: </p>
                     <p class="para_td">a) If a contactor node oscillates between two neighboring target segments during the equilibrium iterations, oscillation checking puts the contactor node into contact with the boundary edge between the target segments. </p>
                     <p class="para_td">b) In analysis with friction, if the sliding velocity of a contactor node oscillates during the equilibrium iterations, oscillation checking puts the contactor node into sticking contact.</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">GAPBIAS </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Contact is detected when the distance between the target and contactor (accounting for any offsets) is less than GAPBIAS. (Real; Default = 0.0)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OFFDET</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Selects the implementation of offsets. (Integer; Default = 0) 0 &ndash; Program chooses the implementation based upon the shape of the target surfaces; if a target surface is flat or convex, spheres are used, otherwise, normals are used. </p>
                     <p class="para_td">1 &ndash; A sphere of radius equal to the offset is placed around each contactor node, and contact is detected between the sphere and the target surface. </p>
                     <p class="para_td">2 &ndash; Two surfaces are constructed for each contactor surface: an upper surface and a lower surface. These surfaces are constructed using the offsets and the averaged contactor normals.  Contact is then detected between points on the constructed contactor surfaces and target surface. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="2" rowspan="1" valign="top"></td>
               </tr>
               <tr>
                  <td align="left" colspan="2" rowspan="1" valign="top">
                     <p class="para_td">Parameters used with old (NX Nastran Version 4) rigid-target algorithm (RTALG=1 in NXSTRAT) which may be removed in a future release.</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PENETOL </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Penetration tolerance which gives the maximum penetration allowed into a rigid target surface. (Real; Default=1.0E-8) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TCMOD </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Tangential contact modulus. (Real; Default=0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">RFORCE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Minimum tensile contact force required to change the state of a contact node from &quot;node in contact&quot; to &quot;free node&quot;, i.e., if the normal tensile force is greater than RFORCE, a &quot;node in contact&quot; becomes a &quot;free node&quot;. (Real; Default=0.001) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">LFORCE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Limit (maximum) for the sum of all contact forces for nodes changing from the state of &quot;node in contact&quot; to &quot;free node&quot;. If the absolute value of the sum of the forces is bigger than LFORCE, then the automatic time stepping (ATS) method will be activated to subdivide the current time step into smaller time increments. (Real; Default=1.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">RTPCHECK </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies whether penetration is checked (in addition to checking the tensile contact force) against the maximum allowable penetration when the rigid-target algorithm is used. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Penetration is not checked. Note that with this setting there is a possibility that the rigid target surface may penetrate the contactor surface excessively. </p>
                     <p class="para_td">1 &ndash; Penetration is checked and subdivision of the time step occurs if the penetration exceeds (RTPMAX * maximum model length.) </p>
                     <p class="para_td">2 &ndash; Penetration is checked and subdivision of time step occurs if the penetration exceeds RTPMAX. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">RTPMAX </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies the maximum allowable penetration when the rigid target algorithm is used. RTPMAX is either a factor of the model size or an absolute value depending on the RTPCHECK parameter. (Real &gt; 0.0; Default=0.001) </p>
                  </td>
               </tr>
            </tbody>
         </table><br><div class="title_tableWrapper">Table 11-3. BCTPARA Parameters for SOL 701 </div>
         <table cellpadding="10" width="100%" align="center">
            <colgroup span="1">
               <col span="1" width="16.58*">
               <col span="1" width="83.42*">
            </colgroup>
            <thead>
               <tr>
                  <th align="left" colspan="1" rowspan="1">
                     <p class="para_th"><b class="uiTerm">Name </b></p>
                  </th>
                  <th align="left" colspan="1" rowspan="1">
                     <p class="para_th"><b class="uiTerm">Description </b></p>
                  </th>
               </tr>
            </thead>
            <tbody>
               <tr>
                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">General Parameters </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" height="128" rowspan="1" valign="top">
                     <p class="para_td">XTYPE </p>
                  </td>
                  <td align="left" colspan="1" height="128" rowspan="1" valign="top">
                     <p class="para_td">Selects the type of contact algorithm. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Kinematic constraint algorithm is used. </p>
                     <p class="para_td">1 &ndash; Penalty algorithm is used. </p>
                     <p class="para_td">3 &ndash; Rigid target algorithm is used. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">NSIDE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Flags single or double-sided contact. (Integer; Default=1) </p>
                     <p class="para_td">1 &ndash; Contact surfaces are single-sided. </p>
                     <p class="para_td">2 &ndash; Contact surfaces are double-sided. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TBIRTH </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Birth time for contact set. (Real; Default=0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TDEATH </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Death time for contact set. (Real; Default=0.0) If TDEATH &le; TBIRTH, it is ignored. </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">Flags how initial penetrations are handled. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Initial penetrations are eliminated. </p>
                     <p class="para_td">1 &ndash; Initial penetrations are eliminated and the list of penetrating nodes is printed. </p>
                     <p class="para_td">2 &ndash; Initial penetrations are ignored. In successive steps, each contactor node is allowed to penetrate the target up to its initial penetration. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PDEPTH </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Penetration depth for single-sided contact (i.e. NSIDE=1). (Real; Default=0.0)If PDEPTH &gt; 0.0, then penetration is detected. When penetration &le; PDEPTH, and if penetration &gt; PDEPTH, penetration is deemed not to occur. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OFFTYPE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Type of offset for contact regions. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Use specified offset value only for single-sided contact (i.e., NSIDE=1). Use offset of 0.001 for double-sided contact (i.e., NSIDE=2). </p>
                     <p class="para_td">1 &ndash; Use specified offset value for either single- or double-sided contact. </p>
                     <p class="para_td">2 &ndash; Half the shell thickness is used for contact regions on shell elements and no offset is used otherwise. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OFFSET </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Default offset distance for contact regions. (Real; Default=0.0)Note: For contact algorithm XTYPE=0 or 1, individual offset distances can be specified for each contact region using the BCRPARA entry to override the default offset distance specified here. </p>
                  </td>
               </tr>
               <tr>
                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">Contact Algorithm XTYPE=0 or 1 </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TZPENE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Time to eliminate initial penetrations. (Real=0.0; Default=0.0)If TZPENE=0.0 and INIPENE=0 or 1, then the initial penetrations are eliminated in the first time step. This may cause convergence difficulties for certain problems. By using TZPENE &gt; 0.0, the initial penetrations are eliminated gradually over time TZPENE. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">EXTFAC </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Factor for extending contact surfaces beyond their boundaries. The amount of extension is given by this factor multiplied by the length of the contact segments. (1.0E-6 &le; Real &le; 0.1; Default=0.001) </p>
                  </td>
               </tr>
               <tr>
                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">Penalty Contact Algorithm (XTYPE=1) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">XKNCRIT </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Selects the criterion for evaluation of normal penalty stiffness. (Integer; Default=0) </p>
                     <p class="para_td">0 - The program calculates the normal penalty stiffness. </p>
                     <p class="para_td">1 - The user specifies the normal penalty stiffness (XKN). </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">XKN </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies the normal penalty stiffness to be used when XKNCRIT=1. (Real) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">XKTCRIT </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Selects the criterion for evaluation of tangential penalty stiffness. (Integer; Default=0) </p>
                     <p class="para_td">0 - The program calculates the normal penalty stiffness </p>
                     <p class="para_td">1 - The user specifies the normal penalty stiffness (XKT). </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">XKT </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies the tangential penalty stiffness to be used when XKTCRIT=1. (Real) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">XDAMP </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Indicates whether damping is used when the penalty explicit contact algorithm is used. (Integer; Default=0) </p>
                     <p class="para_td">0 &ndash; Damping is not used, i.e., the XNDAMP parameter is ignored. </p>
                     <p class="para_td">1 &ndash; Damping is used and XNDAMP is a factor of the critical damping, i.e., the damping coefficient is given by XNDAMP multiplied by the critical damping. This is the recommended choice if damping is used. </p>
                     <p class="para_td">2 &ndash; Damping is included and the damping coefficient is specified directly by XNDAMP. </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">XNDAMP </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Specifies the relative or absolute damping coefficient (for normal penalty stiffness) when the penalty explicit contact algorithm is used and XDAMP=1 or 2. (Real=0.0; Default=0.1) </p>
                  </td>
               </tr>
               <tr>
                  <td align="center" bgcolor="gray" colspan="2" rowspan="1">
                     <p class="para_td">Rigid Target Algorithm (XTYPE=3) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="2" rowspan="1" valign="top">
                     <p class="para_td">Parameters used with current rigid-target algorithm (RTALG=0 in NXSTRAT)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">SLIDVEL</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">The maximum sliding velocity used in modeling sticking friction. When the velocity is smaller than SLIDVEL, sticking is assumed; when the velocity is larger than SLIDVEL, sliding is assumed. (Real &gt; 0.0, Default = 1.0E-10)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">GAPBIAS</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Contact is detected when the distance between the target and contactor (accounting for any offsets) is less than GAPBIAS. (Real; Default = 0.0)</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">OFFDET</p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Selects the implementation of offsets. (Integer; Default = 0) </p>
                     <p class="para_td">0 &ndash; Program chooses the implementation based upon the shape of the target surfaces; if a target surface is flat or convex, spheres are used, otherwise, normals are used. </p>
                     <p class="para_td">1 &ndash; A sphere of radius equal to the offset is placed around each contactor node, and contact is detected between the sphere and the target surface. </p>
                     <p class="para_td">2 &ndash; Two surfaces are constructed for each contactor surface: an upper surface and a lower surface. These surfaces are constructed using the offsets and the averaged contactor normals.  Contact is then detected between points on the constructed contactor surfaces and target surface.</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="2" rowspan="1" valign="top">
                     <p class="para_td">Parameters used with old (v4) rigid-target algorithm (RTALG=1 in NXSTRAT) which may be removed in a future release.</p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PENETOL </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Penetration tolerance which gives the maximum penetration allowed into a rigid target surface. (Real; Default=1.0E-8) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TCMOD </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Tangential contact modulus. (Real; Default=0.0) </p>
                  </td>
               </tr>
            </tbody>
         </table><br></div>
      <div class="title_refCategory">Remarks: </div>
      <div class="refCategoryContent">
         <ol type="1" start="1">
            <li>
               <p class="para_item">Multiple BCTPARA with the same CSID can be used. The parameters specified in all BCTPARA with the same CSID will be combined and assigned to the contact set. </p>
            </li>
            <li>
               <p class="para_item">If duplicate parameters are specified, the last parameter value will be used. </p>
            </li>
            <li>
               <p class="para_item">Field 9 on line 1 should be blank. Beginning on the continuation lines, fields 2 to 9 can be used for 4 pairs of PARAM/VALUE </p>
            </li>
         </ol>
      </div>
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