<!DOCTYPE html
  PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<!--
Copyright (c) 2006 UGS Corp.

All Rights Reserved.

This software and related documentation are proprietary to UGS Corp.
-->
<html>
   <head>
      <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
      <title>Representing Boundary Conditions</title>
      <script language="javaScript">
        abridged="false";
        displayConditions=new Array();
      </script>
      <link type="text/css" href="../css/main_styles.css" rel="stylesheet">
   </head>
   <body class="bodydocs" onload="top.pageLoader()" bgcolor="#FFFFFF">
      <div class="title_topic2" id="xps10_pagetitle">Representing Boundary Conditions</div>
      <hr noshade="true"><a name="gsprelim_10446"></a><p class="para_topic">The beam is hinged, so we must constrain GRID points 1 and 4 to represent this behavior.  We will use one SPC1 Bulk Data entry for both grid points since the constraints at each end are the same.</p><a name="gsprelim_10526"></a><p class="para_topic">The format of the SPC1 entry is as follows:      </p>
      <table border="1" cellpadding="2" cellspacing="1" width="100%" align="center">
         <colgroup span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
         </colgroup>
         <thead>
            <tr>
               <td align="center" colspan="1" rowspan="1">
                  <p class="para_td">1</p>
               </td>
               <th colspan="1" rowspan="1">
                  <p class="para_th">2</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">3</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">4</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">5</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">6</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">7</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">8</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">9</p>
               </th>
               <th colspan="1" rowspan="1">
                  <p class="para_th">10</p>
               </th>
            </tr>
         </thead>
         <tbody>
            <tr>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10470"></a><p class="para_td">SPC1</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10472"></a><p class="para_td">SID</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10474"></a><p class="para_td">C</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10476"></a><p class="para_td">G1</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10478"></a><p class="para_td">G2</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10480"></a><p class="para_td">G3</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10482"></a><p class="para_td">G4</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10484"></a><p class="para_td">G5</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10486"></a><p class="para_td">G6</p>
               </td>
               <td colspan="1" rowspan="1"></td>
            </tr>
            <tr>
               <td align="center" colspan="1" rowspan="1"></td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10492"></a><p class="para_td">G7</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10494"></a><p class="para_td">G8</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10496"></a><p class="para_td">G9</p>
               </td>
               <td align="center" colspan="1" rowspan="1"><a name="gsprelim_10498"></a><p class="para_td">-etc.-</p>
               </td>
               <td align="center" colspan="1" rowspan="1"></td>
               <td align="center" colspan="1" rowspan="1"></td>
               <td align="center" colspan="1" rowspan="1"></td>
               <td align="center" colspan="1" rowspan="1"></td>
               <td colspan="1" rowspan="1"></td>
            </tr>
         </tbody>
      </table><br><table cellpadding="8" width="100%" align="center">
         <colgroup span="1">
            <col span="1" width="47*">
            <col span="1" width="151*">
         </colgroup>
         <tr>
            <th align="left" colspan="1" rowspan="1">
               <p class="para_th">Field</p>
            </th>
            <th align="left" colspan="1" rowspan="1">
               <p class="para_th">Contents</p>
            </th>
         </tr>
         <tr valign="top">
            <td colspan="1" rowspan="1"><a name="gsprelim_10515"></a><p class="para_td">SID</p>
            </td>
            <td colspan="1" rowspan="1"><a name="gsprelim_10517"></a><p class="para_td">Identification number of single-point constraint set. (Integer &gt; 0)</p>
            </td>
         </tr>
         <tr valign="top">
            <td colspan="1" height="77" rowspan="1"><a name="gsprelim_10519"></a><p class="para_td">C</p>
            </td>
            <td colspan="1" height="77" rowspan="1"><a name="gsprelim_10521"></a><p class="para_td">Component numbers. (Any unique combination of the Integers 1 through 6 with no embedded blanks for grid points. This number must be Integer 0 or blank for scalar points)</p>
            </td>
         </tr>
         <tr valign="top">
            <td colspan="1" rowspan="1"><a name="gsprelim_10523"></a><p class="para_td">Gi</p>
            </td>
            <td colspan="1" rowspan="1"><a name="gsprelim_10525"></a><p class="para_td">Grid or scalar point identification numbers. (Integer &gt; 0 or &ldquo;THRU&rdquo;; for &ldquo;THRU&rdquo; option, G1 &lt; G2. NX Nastran allows missing grid points in the sequence G1 through G2)</p>
            </td>
         </tr>
      </table><br><a name="gsprelim_10527"></a><p class="para_topic">An SPC set identification number (SID) of 100 is arbitrarily chosen and entered in field 2.  To select the SPC, the following Case Control command must be added to the Case Control Section:</p><a name="gsprelim_10528"></a><pre class="indent">
    SPC=100
  </pre><a name="gsprelim_10529"></a><p class="para_topic">Constraints are applied in the GRID point&rsquo;s displacement coordinate system&mdash;in our problem this is the basic coordinate system.  The required components of constraint are shown below:</p><a name="gsprelim_10568"></a><p class="para_topic"><img align="bottom" src="graphics/gsprelim20.gif" border="0"></p><a name="gsprelim_10569"></a><p class="para_topic">Grids 1 and 4 cannot translate in the x, y, or z directions (constrain DOFs 1, 2, and 3). Grids 1 and 4 cannot rotate about the x-axis or y-axis (constrain DOFs 4 and 5). Grids 1 and 4 can rotate about the z-axis (leave DOF 6 unconstrained).</p><a name="gsprelim_10591"></a><p class="para_topic">Therefore, the required SPC1 entry is written as follows:      </p>
      <table border="1" width="100%" align="center">
         <colgroup span="1">
            <col align="center" span="1">
            <col align="center" span="1">
            <col align="center" span="1">
            <col align="center" span="1">
            <col align="center" span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
            <col span="1">
         </colgroup>
         <tr>
            <td colspan="1" rowspan="1"><a name="gsprelim_10572"></a><p class="para_td">SPC1</p>
            </td>
            <td colspan="1" rowspan="1"><a name="gsprelim_10574"></a><p class="para_td">100</p>
            </td>
            <td colspan="1" rowspan="1"><a name="gsprelim_10576"></a><p class="para_td">12345</p>
            </td>
            <td colspan="1" rowspan="1"><a name="gsprelim_10578"></a><p class="para_td">1</p>
            </td>
            <td colspan="1" rowspan="1"><a name="gsprelim_10580"></a><p class="para_td">4</p>
            </td>
            <td colspan="1" rowspan="1"></td>
            <td colspan="1" rowspan="1"></td>
            <td colspan="1" rowspan="1"></td>
            <td colspan="1" rowspan="1"></td>
            <td colspan="1" rowspan="1"></td>
         </tr>
      </table><br><a name="gsprelim_10592"></a><p class="para_topic">Or in free field format we enter:</p><a name="gsprelim_10593"></a><pre class="indent">
    SPC1,100,12345,1,4
  </pre></body>
</html>