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      <title>CQUAD4</title>
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      <div class="title_refTopic" id="xps10_pagetitle">CQUAD4 </div>
      <hr noshade="true">
      <h4 class="refClassification">Quadrilateral Plate Element Connection </h4>
      <p class="para_refTopic">Defines an isoparametric membrane-bending or plane strain quadrilateral plate element. </p>
      <div class="title_refCategory">Format: </div>
      <div class="refCategoryContent">
         <table border="1" width="100%" align="center">
            <colgroup span="1">
               <col span="1" width="10.93*">
               <col span="1" width="9.98*">
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            <thead>
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                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">1 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">2 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">3 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">4 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">5 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">6 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">7 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">8 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">9 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">10 </p>
                  </th>
               </tr>
            </thead>
            <tbody>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">CQUAD4 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">EID </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">PID </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">G1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">G2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">G3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">G4 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">THETA or MCID </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">ZOFFS </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" bgcolor="gray" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">TFLAG </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">T1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">T2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">T3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">T4 </p>
                  </td>
                  <td align="center" bgcolor="gray" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" bgcolor="gray" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
                  <td align="center" bgcolor="gray" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
               </tr>
            </tbody>
         </table><br></div>
      <div class="title_refCategory">Example: </div>
      <div class="refCategoryContent">
         <table border="1" width="100%" align="center">
            <colgroup span="1">
               <col span="1" width="11.24*">
               <col span="1" width="9.93*">
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               <col span="1" width="9.93*">
               <col span="1" width="9.34*">
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            <tbody>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">CQUAD4 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">111 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">203 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">31 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">74 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">75 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">32 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">2.6 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">0.3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <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">1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">1.77 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">2.04 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">2.09 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">1.80 </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>
               </tr>
            </tbody>
         </table><br></div>
      <div class="title_refCategory">Fields:</div>
      <div class="refCategoryContent">
         <table cellpadding="9" width="100%" align="center">
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               <col span="1" width="84*">
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                  <th align="left" colspan="1" rowspan="1">
                     <p class="para_th"><b class="uiTerm">Field </b></p>
                  </th>
                  <th align="left" colspan="1" rowspan="1">
                     <p class="para_th"><b class="uiTerm">Contents </b></p>
                  </th>
               </tr>
            </thead>
            <tbody>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">EID </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Element identification number.  (Integer &gt; 0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">PID </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Property identification number of a PSHELL, PCOMP, or PLPLANE entry.  (Integer &gt; 0; Default = EID) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Gi </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Grid point identification numbers of connection points.  (Integers &gt; 0, all unique.) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">THETA </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Material property orientation angle in degrees.  THETA is ignored for hyperelastic elements.  See <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/14topic_16.html#ref97873');return(false);">Figure 13-</a>.  (Real; Default = 0.0) 
                     </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">MCID </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Material coordinate system identification number.  The x-axis of the material coordinate system is determined by projecting the x-axis of the MCID coordinate system (defined by the CORDij entry or zero for the basic coordinate system) onto the surface of the element.  MCID is ignored for hyperelastic elements.  (Integer &ge; 0;  If blank, then THETA = 0.0 is assumed.) </p>
                  </td>
               </tr>
            </tbody>
         </table><br><a name="ref32916"></a><div class="figure">
            <p align="center"><img align="bottom" src="graphics/bulkc2-fig11.gif"></p>
         </div>
         <div class="title_figure">Figure. MCID Coordinate System Definition </div>
         <table width="100%" align="center">
            <colgroup span="1">
               <col span="1" width="16*">
               <col span="1" width="84*">
            </colgroup>
            <tbody>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">ZOFFS </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Offset from the surface of grid points to the element reference plane.  ZOFFS is ignored for hyperelastic elements.  See Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/14topic_16.html#ref27418');return(false);">23-6. </a> (Real) 
                     </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">TFLAG </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Integer Flag which specifies how Ti is used to define membrane thickness of element. (0, 1, or blank) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Ti </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Membrane thickness of element at grid points G1 through G4 if TFLAG=0 or blank. If TFLAG=1, membrane thickness becomes a product of Ti and the thickness on the PSHELL card. Ti is ignored for hyperelastic elements.  (Real &ge; 0.0 or blank, not all zero.  See Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/14topic_16.html#ref82374');return(false);">23-4. </a> for the default.) 
                     </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">Element identification numbers should be unique with respect to all other element identification numbers. </p>
            </li>
            <li>
               <p class="para_item">Grid points G1 through G4 must be ordered consecutively around the perimeter of the element. </p>
            </li>
            <li>
               <p class="para_item">All interior angles must be less than 180&deg;. </p>
            </li>
            <li><a name="ref82374"></a><p class="para_item">The continuation is optional.  If it is not supplied, then T1 through T4 will be set equal to the value of T on the PSHELL entry. </p><a name="ref97873"></a><div class="figure">
                  <p align="center"><img align="bottom" src="graphics/bulkc2-fig12.gif"></p>
               </div>
               <div class="title_figure">Figure. CQUAD4 Element Geometry and Coordinate Systems </div>
            </li>
            <li>
               <p class="para_item">The reference coordinate system for the output of stress, strain and element force depends on the element type. </p>
               <ul>
                  <li>
                     <p class="para_item">For CQUAD4 elements which are not p-elements and not hyperelastic, the reference coordinate system for output is the element coordinate system. </p>
                  </li>
                  <li>
                     <p class="para_item">For CQUAD4 elements referenced by a PSET or PVAL entry, the stresses, strains and element forces are output in the local tangent plane of the element.  The local tangents are oriented in a user defined direction which is uniform across a set of elements.  By default, the local tangent x-direction is oriented in the positive x-direction of the basic coordinate system.  See the Bulk Data entry, <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/18topic_6.html');return(false);">&ldquo;OUTRCV&rdquo; </a> for user defined output coordinate systems. 
                     </p>
                  </li>
                  <li>
                     <p class="para_item">For hyperelastic elements, the stress and strain are output according to CID on the PLPLANE entry. </p>
                  </li>
               </ul>
            </li>
            <li><a name="ref27418"></a><p class="para_item">Elements may be offset from the connection points by means of ZOFFS.  Other data, such as material matrices and stress fiber locations, are given relative to the reference plane.  A positive value of ZOFFS implies that the element reference plane is offset a distance of ZOFFS along the positive z-axis of the element coordinate system.  If the ZOFFS field is used, then both the MID1 and the MID2 fields must be specified on the PSHELL entry referenced by PID on the CQUAD4 entry. </p>
               <p class="para_item">The specification of offset vectors gives erroneous results in solution sequences that compute differential stiffness:  linear buckling analysis provided in SOLs 5, 16, 105 and 200, and geometric nonlinear analysis provided in SOLs 106, 129, 153, and 159 with PARAM,LGDISP,1. </p>
            </li>
            <li>
               <p class="para_item">For finite deformation hyperelastic analysis, the plot codes are given by the CQUADFD element name in <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/09ref75809_1.html');return(false);">&ldquo;Item Codes&rdquo;</a>. 
               </p>
            </li>
            <li>
               <p class="para_item">If a CQUAD4 element is referenced by a PSET or PVAL entry, then a p-version formulation is used and the element can have curved edges. </p>
               <ul>
                  <li>
                     <p class="para_item">If a curved edge of a p-element is shared by an h-element CQUAD4, the geometry of the edge is ignored and set straight. </p>
                  </li>
               </ul>
            </li>
            <li>
               <p class="para_item">By default, all four edges of the element are considered straight unless the element is a p-element and the edge is associated to curved geometry with a FEEDGE or FEFACE entry. </p>
            </li>
         </ol>
      </div>
      <div class="title_refCategory">Remarks related to SOLs 601 and 701: </div>
      <div class="refCategoryContent">
         <ol type="1" start="1">
            <li>
               <p class="para_item">ZOFFS is ignored. </p>
            </li>
            <li>
               <p class="para_item">Incompatible modes are used for this element if it is used as a shell element. Incompatible modes may be turned off by specifying ICMODE=0 in the NXSTRAT entry. For modeling shell elements, CQUAD4 is most effective. </p>
            </li>
            <li>
               <p class="para_item">Incompatible modes are not used for this element if it used as a plane strain element (SOL 601 only). The use of CQUAD or CQUAD8 to model 9-node or 8-node plane strain elements is recommended. </p>
            </li>
         </ol>
      </div>
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