<!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>GRAV</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">
      <hr noshade="true">
      <div class="title_refTopic" id="xps10_pagetitle">GRAV </div>
      <hr noshade="true">
      <h4 class="refClassification">Acceleration or Gravity Load </h4>
      <p class="para_refTopic">Defines acceleration vectors for gravity or other acceleration loading. </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*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
            </colgroup>
            <thead>
               <tr>
                  <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">
                     <p class="para_td">GRAV </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">SID </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">CID </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">A </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">N1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">N2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">N3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">MB </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="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
               <col span="1" width="10*">
            </colgroup>
            <tbody valign="middle">
               <tr>
                  <td align="left" colspan="1" rowspan="1">
                     <p class="para_td">GRAV </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">3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">32.2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">0.0 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">0.0 </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">&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">
            <colgroup span="1">
               <col span="1" width="16*">
               <col span="1" width="84*">
            </colgroup>
            <thead>
               <tr>
                  <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">SID </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Set identification number.  (Integer &gt; 0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">CID </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Coordinate system identification number.  (Integer &ge; 0; Default = 0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">A </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Acceleration vector scale factor.  (Real) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Ni </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Acceleration vector components measured in coordinate system CID.  (Real; at least one Ni &ne; 0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">MB </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Indicates whether the CID coordinate system is defined in the main Bulk Data Section (MB = -1) or the partitioned superelement Bulk Data Section (MB = 0).  Coordinate systems referenced in the main Bulk Data Section are considered stationary with respect to the assembly basic coordinate system.  See Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/16topic_30.html#ref9eun2d0lori');return(false);">46-10. </a> (Integer; Default = 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">The acceleration vector is defined by </p>
               <p class="para_item"><img align="bottom" src="graphics/bulkfgil-ufig10.gif" border="0">, where 
               </p>
               <p class="para_item"><img align="bottom" src="graphics/bulkfgil-ufig01.gif" border="0"> is the vector defined by (N1, N2, N3).  The magnitude of <img align="bottom" src="graphics/bulkfgil-ufig11.gif" border="0"> is equal to A times the magnitude of <img align="bottom" src="graphics/bulkfgil-ufig01.gif" border="0">.  The static loads generated by this entry are in the direction of <img align="bottom" src="graphics/bulkfgil-ufig11.gif" border="0">. 
               </p>
            </li>
            <li>
               <p class="para_item">A CID of zero references the basic coordinate system. </p>
            </li>
            <li>
               <p class="para_item">Acceleration or gravity loads may be combined with &ldquo;simple loads&rdquo; (e.g., FORCE, MOMENT) only by specification on a LOAD entry.  That is, the SID on a GRAV entry may not be the same as that on a simple load entry. </p>
            </li>
            <li>
               <p class="para_item">In the static solution sequences, the load set ID must be selected by the Case Control command LOAD = SID.  In the dynamic solution sequences, SID must be referenced in the LID field of an LSEQ entry, which in turn must be selected by the Case Control command LOADSET. </p>
            </li>
            <li>
               <p class="para_item">At most nine GRAV entries can be selected in a given run either by Case Control or the LOAD Bulk Data entry.  Multiples or reflections of a given acceleration or gravity load can be economically accomplished by use of the LOAD Bulk Data entry. </p>
            </li>
            <li>
               <p class="para_item">In cyclic symmetry solution sequences, the T3 axis of the coordinate system referenced in field 3 must be parallel to the axis of symmetry.  In dihedral cyclic symmetry (where STYPE = &ldquo;DIH&rdquo; on the CYSYM entry), the T1 axis must, in addition, be parallel to Side 1 of segment 1R of the model. </p>
            </li>
            <li>
               <p class="para_item">For image superelements, the coordinate system must be rotated if the image is rotated relative to its primary superelement. </p>
            </li>
            <li>
               <p class="para_item">Acceleration or gravity loads do not include effects due to mass on scalar points. </p>
            </li>
            <li>
               <p class="para_item">The RFORCE entry may be used to specify rotational accelerations. </p>
            </li>
            <li><a name="ref9eun2d0lori"></a><p class="para_item">The coordinate systems in the main Bulk Data Section are defined relative to the assembly basic coordinate system which is fixed.  This feature is useful when a superelement defined by a partitioned Bulk Data Section is rotated or mirrored and the gravity load is more conveniently defined in terms of coordinates which are fixed. </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">MB is ignored. </p>
            </li>
            <li>
               <p class="para_item">To apply an acceleration or gravity load with constant magnitude, SID is selected by Case Control command LOAD = SID for both static and transient analyses. </p>
            </li>
            <li>
               <p class="para_item">To apply a time-dependent acceleration or gravity load, SID is referenced by the field EXCITEID = SID in the TLOAD1 entry. Time-dependent loads are selected by Case Control command DLOAD. </p>
            </li>
         </ol>
      </div>
   </body>
</html>