<!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>RFORCE</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">RFORCE </div>
      <hr noshade="true">
      <h4 class="refClassification">Rotational Force </h4>
      <p class="para_refTopic">Defines a static loading condition due to an angular velocity and/or acceleration. </p>
      <div class="title_refCategory">Format: </div>
      <div class="refCategoryContent">
         <table border="1" width="100%" align="center">
            <colgroup span="1">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="9.90*">
               <col span="1" width="11.77*">
               <col span="1" width="8.99*">
            </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" valign="top">
                     <p class="para_td">RFORCE </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">G </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">R1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">R2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">R3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">METHOD </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">RACC </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>
                  <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>
                  <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>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">RFORCE </p>
                  </td>
                  <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">5 </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">-6.4 </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">2 </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">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>
                  <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>
                  <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">Load set identification number.  (Integer &gt; 0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">G </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Grid point identification number through which the rotation vector acts.  (Integer &ge; 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 defining the components of the rotation vector.  See Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/19topic_26.html#ref32681');return(false);">38-16. </a> (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">Scale factor of the angular velocity in revolutions per unit time.  (Real) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">R1, R2, R3 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Rectangular components of rotation vector </p>
                     <p class="para_td"><img align="bottom" src="graphics/bulkqrs-ufig04.gif" border="0">.  The vector defined will pass through point G.  (Real; <em>R</em>1<sup class="superscript">2</sup> + <em>R</em>2<sup class="superscript">2</sup> + <em>R</em>3<sup class="superscript">2</sup> &gt; 0.0) 
                     </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">METHOD </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Method used to compute centrifugal forces due to angular velocity.  For angular acceleration, see Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/19topic_26.html#ref50881');return(false);">38-13. </a> (Integer=1 or 2; Default=1) 
                     </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">RACC </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Scale factor of the angular acceleration in revolutions per unit time squared.  (Real; Default=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/19topic_26.html#refWaiun265lori');return(false);">38-15. </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">In <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/19topic_26.html#ref20646');return(false);">Figure 18-</a>, the force vector at grid point Gi is given by 
               </p>
               <p align="center"><img align="bottom" src="graphics/bulkqrs-equ08.gif"></p>
               <p class="para_item">where </p>
               <table cellpadding="9" width="100%" align="center">
                  <colgroup align="left" span="1">
                     <col align="center" span="1" width="2696*">
                     <col span="1" width="540*">
                     <col span="1" width="6762*">
                  </colgroup>
                  <tbody valign="top">
                     <tr>
                        <td colspan="1" rowspan="1" valign="middle">
                           <p class="para_td">angular velocity </p>
                        </td>
                        <td align="center" colspan="1" rowspan="1" valign="middle">
                           <p class="para_td">= </p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td"><img align="bottom" src="graphics/bulkqrs-ufig05.gif" border="0"></p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1" valign="middle">
                           <p class="para_td">angular acceleration </p>
                        </td>
                        <td align="center" colspan="1" rowspan="1" valign="middle">
                           <p class="para_td">= </p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td"><img align="bottom" src="graphics/bulkqrs-ufig06.gif" border="0"></p>
                        </td>
                     </tr>
                     <tr>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">[<em>m</em>]<em><sub class="subscript">i</sub></em></p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">= </p>
                        </td>
                        <td colspan="1" rowspan="1">
                           <p class="para_td">3 × 3 translational mass matrix at grid point Gi </p>
                        </td>
                     </tr>
                  </tbody>
               </table><br><p class="para_item">Note: The equation for <img align="bottom" src="graphics/bulkqrs-ufig07.gif" border="0"> will have additional terms if the mass is offset and METHOD=1 is selected. 
               </p><a name="ref20646"></a><div class="figure">
                  <p align="center"><img align="bottom" src="graphics/bulkqrs-fig01.gif"></p>
               </div>
               <div class="title_figure">Figure. RFORCE Vector at Grid Point Gi </div>
            </li>
            <li>
               <p class="para_item">In the static solution sequences, the load set ID (SID) is selected by the Case Control command LOAD.  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">G=0 signifies that the rotation vector acts through the origin of the basic coordinate system. </p>
            </li>
            <li>
               <p class="para_item">CID=0 (Default) signifies that the rotation vector is defined in the basic coordinate system. </p>
            </li>
            <li>
               <p class="para_item">The load vector generated by this entry can be printed with an OLOAD command in the Case Control Section. </p>
            </li>
            <li>
               <p class="para_item">METHOD=1 yields correct results only when there is no coupling in the mass matrix.  This occurs when the lumped mass option is used with or without the ZOFFS option (see the CQUAD4 entry for a description of ZOFFS).  METHOD=2 yields correct results for lumped or consistent mass matrix only if the ZOFFS option is not used.  The acceleration terms due to the mass offset (X1, X2, X3) on the CONM2 entry are not computed with METHOD=2.  All the possible combinations of mass matrices and offset and the correct method to be used are shown below. </p>
               <table border="1" width="100%" align="center">
                  <colgroup span="1">
                     <col span="1" width="29.30*">
                     <col span="1" width="35.35*">
                     <col span="1" width="35.35*">
                  </colgroup>
                  <thead>
                     <tr>
                        <th align="left" colspan="1" rowspan="1">
                           <p class="para_th">&nbsp; </p>
                        </th>
                        <th align="center" colspan="1" rowspan="1">
                           <p class="para_th"><b class="uiTerm">No Offset </b></p>
                        </th>
                        <th align="center" colspan="1" rowspan="1">
                           <p class="para_th"><b class="uiTerm">Offset </b></p>
                        </th>
                     </tr>
                  </thead>
                  <tbody>
                     <tr>
                        <td align="center" colspan="1" rowspan="1">
                           <p class="para_td">Lumped </p>
                        </td>
                        <td align="center" colspan="1" rowspan="1">
                           <p class="para_td">METHOD=1 or METHOD=2 </p>
                        </td>
                        <td align="center" colspan="1" rowspan="1">
                           <p class="para_td">METHOD=1 </p>
                        </td>
                     </tr>
                     <tr>
                        <td align="center" colspan="1" rowspan="1">
                           <p class="para_td">Coupled </p>
                        </td>
                        <td align="center" colspan="1" rowspan="1">
                           <p class="para_td">METHOD=2 </p>
                        </td>
                        <td align="center" colspan="1" rowspan="1">
                           <p class="para_td">Neither </p>
                        </td>
                     </tr>
                  </tbody>
               </table><br></li>
            <li>
               <p class="para_item">In cyclic symmetry analyses, the T3 axis of the basic coordinate system must be coincident with the axis of symmetry.  In the DIH type of cyclic symmetry, the T1 axis also must be parallel to side 1 of segment 1R of the model. </p>
            </li>
            <li>
               <p class="para_item">For superelement analysis, G should reference a residual structure point that is exterior to all superelements.  If it is not exterior to a superelement, then centrifugal loads will not be generated for that superelement.  However, in cyclic analysis, User Fatal Message 4347 will be issued. </p>
            </li>
            <li>
               <p class="para_item">In a geometric nonlinear static analysis (SOL 4 or SOL 106 when PARAM LDGISP is set to +1), this type of loading is a follower force type of loading.  However, the orientation of coordinate system CID is not updated. </p>
            </li>
            <li>
               <p class="para_item">In nonlinear static solutions when there is more than one increment (INC) specified on the NLPARM entry for a given subcase, the load vector resulting from the RFORCE input (and not the angular velocity vector) is scaled linearly.  This means that loading by increments in the angular velocity can only be achieved by having subcases where the RFORCE loading is applied in a single increment. </p>
            </li>
            <li>
               <p class="para_item">The continuation entry is optional. </p>
            </li>
            <li>
               <p class="para_item">Forces due to angular acceleration (RACC) are computed with METHOD=2 even if METHOD=1 is specified. </p>
            </li>
            <li><a name="ref50881"></a><p class="para_item">Loads derived from this entry do not include effects due to mass specified for scalar points. </p>
            </li>
            <li>
               <p class="para_item">The follower force effects due to loads from this entry are included in the stiffness in all linear solution sequences that calculate a differential stiffness. The solution sequences are SOLs 103, 105, 107 to 112, 115 and 116 (see also the parameter <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/08ref24356_2.html#ref32029');return(false);">&ldquo;FOLLOWK&rdquo;</a>). In addition, follower force effects are included in the force balance in the nonlinear static and nonlinear transient dynamic solution sequences, SOLs 106, 129, 153, and 159, if geometric nonlinear effects are turned on with PARAM,LGDISP,1. The follower force stiffness is included in the nonlinear static solution sequences (SOLs 106 and 153) but not in the nonlinear transient dynamic solution sequences (SOLs 129 and 159). 
               </p>
            </li>
            <li><a name="refWaiun265lori"></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>
            <li><a name="ref32681"></a><p class="para_item">If CID is not a rectangular coordinate system, RFORCE will treat it as if it were and unexpected answers may result. </p>
            </li>
            <li>
               <p class="para_item">Follower force stiffness (param,followk,yes) is supported for method 2 only. </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">METHOD, RACC and MB are ignored. </p>
            </li>
            <li>
               <p class="para_item">To apply rotational force with constant magnitude (not considering magnitude change due to large deformation, see Remark 4), 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 rotational 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>
            <li>
               <p class="para_item">By default, in large deformation analysis, the magnitude of the rotational force changes due to the deformation. The use of LOADOPT=0 in NXSTRAT entry causes the rotational load to be independent of deformation. </p>
            </li>
            <li>
               <p class="para_item">Only one RFORCE can be applied in an analysis. </p>
            </li>
            <li>
               <p class="para_item">CID must be a rectangular coordinate system. </p>
            </li>
         </ol>
      </div>
   </body>
</html>