Load Interpolation
Description: Interpolates grid point force, moment, pressure, and heat flux data from a known set of input grid points and loads to a set of output grid points and loads based on geometric position in 2d or 3d space.
Format:
LOADINTERPOLATE, olsid, ogsid, ilsid, igsid, ltype, nnri, ndlsf, cgsize, maxnus
Example:
LOADINTERPOLATE, 100, 10, 1, 1
| Option | Definition | Type | Default |
|---|---|---|---|
| olsid | Output load set identification number. See Remark 1. | Integer > 0 | Required |
| ogsid | Output grid set identification number. Set identification of previously appearing SET command. Only grid points whose identification numbers appear on this SET command will be used. | Integer > 0 or blank | All grid points in model |
| ilsid | Input load set identification number. See Remark 2. | Integer > 0 | Required |
| igsid | Input grid set identification number. Set identification of previously appearing SET command. Only grid points whose identification numbers appear on this SET command will be used. | Integer > 0 or blank | All grid points in load set |
| ltype | Load type. One of the following character variables: FORCE, SFORCE, MOMENT, PRESSURE, PNORMAL, or HEATFLUX. See Remark 3. | Character | Required |
| nnri | Number of interpolation nodes within radius of influence. | Integer > 0 or blank | See Remark 4 |
| ndlsf | Number of data nodes in least squares fit. | Integer > 0 or blank | See Remark 5 |
| cgsize | Number of rows, columns, and planes in the cell grid. A box containing the nodes is partitioned into cells in order to increase search efficiency. | Integer > 0 or blank | See Remark 6 |
| maxnus | Maximum number of unique solution occurrences. | Integer > 0 or blank | See Remark 7 |
Remarks:
- For ltype equal to FORCE or MOMENT, output is FORCE and MOMENT Bulk Data entries at grid points defined by ogsid. For ltype equal to PRESSURE, output is PLOAD4 Bulk Data entries on element faces that have grid points defined by ogsid.
- Input is GRID, FORCE, MOMENT, PLOADG, and QBDYG Bulk Data entries which need not be associated with the analysis model. See Section 4, Bulk Data, for more information on GRID, FORCE, MOMENT, PLOADG, and QBDYG Bulk Data entries.
- FORCE, SFORCE, or MOMENT interpolation is not recommended for non-planar structures. FORCE and MOMENT interpolation may result in an output load total different than the input one. SFORCE provides a scaled output load total that is equal to the input total. It is recommended that the input forces are in a consistent direction. Multiple LOADINTERPOLATE commands may be required to affect this. PNORMAL is similar to PRESSURE, except the pressure vector is forced to be normal to the element surface (pressure magnitude interpolation only). This option is recommended when the input pressure is normal to applied surface.
- The valid range for nnri is 1 ≤ nnri ≤ min(100, n -1), where n is the number of input data points. The default is 100. A lower value may increase performance at the cost of accuracy. A value greater than or equal to 32 is recommended.
- The valid range for ndlsf is 9 ≤ ndlsf ≤ min(100, n -1), where n is the number of input data points. The default is 100. A lower value may increase performance at the cost of accuracy. A value greater than or equal to 17 is recommended.
- The recommended value for
cgsize is:
where n is the number of input data points. The default is determined using the above formula.
- A 3d interpolation algorithm is used initially, but will automatically revert to a 2d algorithm if the number of no unique solution errors exceeds maxnus while processing the input data points. Models that are dominantly flat but still have 3d features that default to the 2d interpolation algorithm may not be interpolated accurately. A larger maxnus value can be used to force a 3d interpolation. It is advisable to always check the interpolated loads.
- Generated FORCE and MOMENT Bulk Data entries can be exported using the TRSLMODLDATA Model Initialization directive. (See Section 2, Initialization, for more information on TRSLMODLDATA.)