SPC

Bulk Data Entry This entry can be used to define single-point constraints and enforced displacements for structural Analysis.

Attention: Valid for Implicit and Explicit Analysis
It can also be used for the following:
  • Temperature boundary conditions for Thermal (Steady-State and Transient) Analysis.
  • Electric potential for Electrical Analysis.
  • Electric potential for Structural Analysis with piezoelectric materials.

Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
SPC SID GID/GSETID C D GID/GSETID C D
GSET

Example

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
SPC 2 32 436 0.0
SPC 3 44 53 F

Definitions

Field Contents SI Unit Example
SID Identification number of the single-point constraint.

(Integer > 0)
GID/ GSETID GID:

Grid or scalar point identification number.

(Integer > 0 or <PartName.number>) 9

GSETID:

An identification for a SET of grid points. In this case, the GSET continuation line must be specified.
Integer
Specifies an identification number for the set.
<String>
Specifies a user-defined string label for the set. 10

(Integer > 0 or <String>)
C Component numbers.
V
Flag to indicate that the subsequent field is the value of electric potential for structural analysis with piezoelectric materials.
Important: For Electrical and Thermal Analysis, this field needs to be blank.

(Integer zero or blank for scalar points, or up to six unique digits (0 < digit ≤ 6) may be placed in the field with no embedded blanks for grid points. The components refer to the coordinate system referenced by the grid points.)
D
(Real)
Value of enforced displacement for all coordinates designated by G and C.
When C=V, it is the value of the electric potential.
(F)
This option is used in conjunction with the CNTNLSUB entry to retain the deformed boundary resulting from a preceding nonlinear subcase. This is supported for both analysis and optimization jobs. 5
(M)
This option is used in conjunction with the submodeling feature, in the local model. The enforced displacements are mapped internally by OptiStruct from the global model.
For more details, refer to Two Step Modeling in the User Guide.

Default = 0.0
GSET Indicates that the G/GSETID field is identified as a SET of Grid points at which the SPC constraints are applied.

Comments

  1. The degree-of-freedom declared dependent on this entry may not be:
    • Included in a single point constraint (SPC or SPC1)
    • Declared a dependent degree-of-freedom on any RBAR, RBE1, RBE2, or RROD entry
    • Declared a dependent degree-of-freedom on an MPC set referenced in the same subcase
  2. Single-point forces of constraint are recovered during stress data recovery.
  3. Up to twelve single-point constraints may be defined on a single entry.
  4. Continuations are not allowed.
  5. SPC degrees-of-freedom may be redundantly specified as permanent constraints on the GRID entry.
  6. For Static Analysis, SPCs can be used to define enforced displacements.
  7. For Static and Dynamic Analysis, when the SPSYNTAX setting on the SYSSETTING I/O Option is set to CHECK (default) or STRICT, it is required for grid/component pairs (G#/C#) that the component be 0 or blank when the grid reference is a scalar point (SPOINT), and that the component be ≥ 1 when the grid reference is a structural grid point (GRID). When SPSYNTAX is set to MIXED, it is allowed for grid/component pairs (G#/C#) that the grid reference be either a scalar point (SPOINT) or a structural grid point (GRID) when the component is 0, 1 or blank; interpreting all of these as 0 for scalar points and as 1 for structural grids. When the component is greater than 1, the grid reference must always be a structural grid (GRID).
  8. For Linear Steady-state Heat Transfer Analysis, an SPC may be used to define a temperature boundary condition. For thermal boundary conditions, the component should be 0 or blank when the SPSYNTAX setting on the SYSSETTING I/O Option is set to CHECK (default) or STRICT. When SPSYNTAX is set to MIXED, 1 is also accepted as the component.
  9. Supported local entries in specific parts can be referenced by the use of "fully-qualified references" on SPC entries in the model. A fully-qualified reference (PartName.number) is similar to the format of a numeric reference. PartName is the name of the part that contains the referenced local entry (part names are defined on the BEGIN Bulk Data Entry in the model). number is the identification number of a referenced local entry in the part PartName. Refer to Parts and Instances in the User Guide for information on the use of fully-qualified references.
  10. String based labels allow for easier visual identification of sets, including when being referenced by other cards. For more details, refer to String Label Based Input File in the Bulk Data Input File.
  11. This card is represented as a constraint load in HyperMesh.