Rigid Constraints

Rigid constraints are defined using the command `PROPERTY BOUNDARY CONSTRAINT'. The user supplies a degree of freedom indicator (eg. 1234) to indicate which degrees of freedom are to be constrained. The names of the degrees of freedom and the degree of freedom macros that may be used are shown in table below.

Degree of freedom name Meaning

1 or X x-translation

2 or Y y-translation

3 or Z z-translation

4 or RX x-rotation

5 or RY y-rotation

6 or RZ z-rotation

XSYMM x-translation, y,z-rotations

YSYMM y-translation, x,z-rotations

ZSYMM z-translation, x,y-rotations

ALL x,y,z-translations, x,y,z-rotations

XASYMM x-rotation, y,z-translations

YASYMM y-rotation, x,z-translations

ZASYMM z-rotation, x,y-translations

ENCASTRE x,y,z-translations, x,y,z-rotations

PINNED x,y,z-translations

NOROTATE x,y,z-rotations

The interface produces a node set for each constraint definition using '*NSET' cards, and then defines and attaches the constraint to the node set using a '*BOUNDARY' card. For example:

Example FEMGEN Command:

PROPERTY BOUNDARY CONSTRAINT L1 1234

Corresponding ABAQUS Input File:

*NSET, NSET=L1  
    1    2    3
*BOUNDARY
 L1      1    4

Where the point element variant RB-REF has NOT been used to define rigid body reference nodes (for rigid surface definitions), the interface will automatically constrain the new nodes which it creates.