Description
The SPCD entry defines an enforced displacement value for the transient analysis.
The SPCD entry can be referenced with a LOAD entry. If an SPCD entry is referenced with a LOAD entry, the specified displacement or rotation degrees of freedom will not vary with time. In general, an SPCD entry will be referenced with a TLOAD1 entry, which will use the information on the SPCD entry to create a time-varying kinematic boundary condition.
In general, it is highly recommended that you not introduce an initial non-zero displacement at time zero in the analysis. Instantaneous non-zero boundary conditions applied in an explicit dynamics analysis introduce very strong shocks into the model and, if the magnitude of the displacement is large enough, can turn elements inside-out in the first time increment. Care should be taken to specify an appropriate amplitude via the TABLED1, TABLED2 or TABLEH options.
Format
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| SPCD | SID | G1 | C1 | D1 | G2 | C2 | D2 |
Example
| SPCD | 2 | 523 | 246 | 1.6 |
| Field | Definition | Type | Default |
|---|---|---|---|
| SID | Identification number of single load set. | Integer > 0 | Required |
| Gi | Grid point identification number. | Integer > 0 | Required |
| Ci | Component number of global coordinate. (Up to six unique digits may be placed in the field with no embedded blanks.) | 1 ≤ Integers ≤ 6 | Required |
| D | Enforced displacement for all coordinates designated by G and C. | Real or blank | 0.0 |
Remarks
- Values of D will override the values specified on a conflicting SPC Bulk Data entry, if the SID is selected on the LOAD Case Control command.
- The Bulk Data LOAD combination entry will not combine an SPCD load.
- This is the only method for applying enforced displacements, because the SPC and SPC1 Bulk Data entries only enforce zero displacement boundary conditions.