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      <title>SPLINE2</title>
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      <div class="title_refTopic" id="xps10_pagetitle">SPLINE2 </div>
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      <h4 class="refClassification">Linear Spline </h4>
      <p class="para_refTopic">Defines a beam spline for interpolating motion and/or forces for aeroelastic problems on aerodynamic geometries defined by regular arrays of aerodynamic points. </p>
      <div class="title_refCategory">Format: </div>
      <div class="refCategoryContent">
         <table border="1" width="100%" align="center">
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                     <p class="para_th">1 </p>
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                  <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>
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                     <p class="para_th">4 </p>
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                     <p class="para_th">5 </p>
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                     <p class="para_th">6 </p>
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                     <p class="para_th">7 </p>
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                     <p class="para_th">8 </p>
                  </th>
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                     <p class="para_th">9 </p>
                  </th>
                  <th align="center" colspan="1" rowspan="1">
                     <p class="para_th">10 </p>
                  </th>
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            </thead>
            <tbody>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">SPLINE2 </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">CAERO </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">ID1 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">ID2 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">SETG </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">DZ </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">DTOR </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">&nbsp; </p>
                  </td>
               </tr>
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                  <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">DTHX </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">DTHY </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">USAGE </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">
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                     <p class="para_td">SPLINE2 </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">8 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">12 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">24 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">60 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">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">3 </p>
                  </td>
                  <td align="center" colspan="1" rowspan="1">
                     <p class="para_td">&nbsp; </p>
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                  <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. </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>
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                     <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>
                  </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>
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         </table><br></div>
      <div class="title_refCategory">Fields:</div>
      <div class="refCategoryContent">
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                     <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>
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            </thead>
            <tbody>
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                  <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">CAERO </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Aero panel or body (CAEROi entry ID) that is to be interpolated.  (Integer &gt; 0) </p>
                  </td>
               </tr>
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                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">ID1, ID2 </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">First and last box or body element whose motions are interpolated using this spline.  See Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/19topic_74.html#ref52811');return(false);">102-6</a> when using the Mach Box method.  (Integer &gt; 0, ID2 &ge; ID1) 
                     </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">SETG </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Refers to an SETi entry that lists the structural grid points to which the spline is attached.  (Integer &gt; 0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">DZ </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Linear attachment flexibility.  (Real &ge; 0.0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">DTOR </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Torsional flexibility ratio (<em>EI</em>/<em>GJ</em>).  (Real &gt; 0.0; Default=1.0; use 1.0 for bodies.) 
                     </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">Rectangular coordinate system for which the y-axis defines the axis of the spline.  Not used for bodies, CAERO2.  (Integer &ge; 0) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">DTHX, DTHY </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Rotational attachment flexibility.  DTHX is for rotation about the spline&rsquo;s x-axis (in-plane bending rotations); however, it is not used for bodies.  DTHY is for rotation about the spline&rsquo;s y-axis (torsion); however, it is used for slope of bodies.  (Real) </p>
                  </td>
               </tr>
               <tr>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">USAGE </p>
                  </td>
                  <td align="left" colspan="1" rowspan="1" valign="top">
                     <p class="para_td">Spline usage flag to determine whether this spline applies to the force transformation, displacement transformation or both.  FORCE, DISP or BOTH. See Remark <a class="links" href="javascript:void(0)" onclick="top.openFile('QRG/19topic_74.html#ref57266');return(false);">102-9. </a> (Character, Default=BOTH) 
                     </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 interpolated points (k-set) will be defined by aero boxes. </p>
            </li>
            <li>
               <p class="para_item">The spline axis for panels is the projection of the y-axis of coordinate system CID, projected onto the plane of the panel.  For bodies, the spline axis is parallel to the x-axis of the aerodynamic coordinate system. </p>
            </li>
            <li>
               <p class="para_item">The flexibilities DZ, DTHX, and DTHY are used for smoothing.  (Zero attachment flexibility values will imply rigid attachment (i.e., no smoothing, whereas negative values of DTHX or DTHY will imply infinity, therefore, no attachment). See the <em><a class="links" href="javascript:void(0)" onclick="top.popUpPage('QRG/linkInter_target_not_resolved.html#aero:ref86112:-aux,-home','linkInter','menubar=yes,status=yes,resizable=yes,toolbar=yes,scrollbars=yes,location=no,directories=no');return(false);">NX Nastran Aeroelastic Analysis User&rsquo;s Guide</a></em> for a discussion of special cases. 
               </p>
            </li>
            <li>
               <p class="para_item">The continuation entry is required. </p>
            </li>
            <li>
               <p class="para_item">The SPLINE2 EID must be unique with respect to all SPLINEi entries. </p>
            </li>
            <li><a name="ref52811"></a><p class="para_item">When using the Mach Box method, ID1 and ID2 refer to the ID number of the first and last aerodynamic grids (x,y pairs on the AEFACT entry) which will be used for interpolation to the structural grids.  ID1 and ID2 do not refer to Mach Boxes. </p>
            </li>
            <li>
               <p class="para_item">DTOR is the ratio of rotational to linear deflection and, in lieu of a more accurate estimate, a value of 1.0 is recommended.  A different value may be used; e.g., if DTOR is much greater than 1.0, primarily rotational deflection will occur; if DTOR is much less than 1.0, primarily linear deflection will occur. </p>
            </li>
            <li>
               <p class="para_item">If a SPLINE2 element only references one grid point, the job will fail without a message in the GI Module. </p>
            </li>
            <li><a name="ref57266"></a><p class="para_item">The USAGE field allows you to specify that the particular spline interpolant defined in this entry is to be used for just the force transformation (FORCE) or just the displacement transformation (DISP) or for both (BOTH). </p>
               <p class="para_item"><em>Fg</em>=[<em>GPkg</em>]<sup class="superscript"><em>T</em></sup> {<em>Pk</em>}  (FORCE/BOTH splines are in the transform) 
               </p>
               <p class="para_item"><em>Uk</em>=[<em>GDkg</em>] {<em>Ug</em>} (DISP/BOTH splines are in the transform) 
               </p>
               <p class="para_item">In general, the two transforms are done with distinct matrices.  Only when ALL splines are of type BOTH is the familiar transpose relationship [<em>GPgk</em>]<sup class="superscript"><em>T</em></sup>]=[<em>GDkg</em>] satisfied. The default behavior (BOTH for all splines) is compatible with versions of MSC.Nastran prior to Version 70.5. 
               </p>
               <p class="para_item">In general, the USAGE field can be used to apply aerodynamic forces to the structure from aerodynamic panels that are intended NOT to move (USAGE=FORCE) or to apply structural displacements to aerodynamic grids whose forces are not to be applied to the structure (USAGE=DISP). The DISP option is somewhat esoteric in that you are then suggesting that the aeroelastic effect of the surface is important while its forces are not.  (In other words, only the forces arising from tis effects on other surfaces is important.) While there may be circumstances where this is true, it is unlikely.  Take care that you included all the FORCEs from aerodynamic panels that are important by including them in either FORCE or BOTH spline(s).  NX Nastran will NOT issue a warning unless ALL forces are omitted.  All displacements may be omitted without warning (and is a means to perform &ldquo;rigid aerodynamic&rdquo; analyses). </p>
            </li>
         </ol>
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