Equation entities contain mathematical equations that define more complex loads. They are used to define linear constraints in local and global coordinate systems.
The following panels can be used to create and edit equations:
Equations
Load Types
The data names associated with equation loads can be found in the data names section of the HyperMesh Reference Guide.
Solver Card Support for Equations
Supported Card
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Solver Description
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Supported Load Types
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Notes
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Defines a multipoint constraint equation of the form.
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Equation
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Each load or constraint must belong to a load collector. Loads or constraints in history data (under *STEP) should be organized into load collectors with HISTORY card image. These load collectors need to be added to a load step from the Load Steps panel. Loads or constraints in model data, however, should be organized into load collectors with the INITIAL_CONDITION card image. These load collectors do not need to be added to a load step. All Loads and Boundary conditions are recommended to be defined from the Step Manager in the Abaqus user profile.
| Note: | If a **HMLOAD_SETS_EXPAND comment is found in the input file, all loads and boundary conditions on sets are expanded to individual nodes and elements. |
Supported Card
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Solver Description
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Supported Load Types
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Supported Parameters
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*EQUATION
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Define linear multi-point constraints
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Equations
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Explicit node IDs are supported. Node sets are not supported.
Equations are considered as loads and therefore, they are collected in load collectors. Upon export, they write to the bulk data portion of the Abaqus deck.
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Supported Card
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Solver Description
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Supported Load Types
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Notes
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CE
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Defines a constraint equation relating to degrees of freedom.
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Equation
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Several load types cause three cards to be output for x, y, and z components. During input, these are grouped into one load. Loads cannot be applied to sets, components, or boxes. Load curves are input and output. Use the Card Editor to select load curves.
Load cards cannot be edited.
Supported Card
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Solver Description
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Supported Load Types
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Notes
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*CONSTRAINED_LINEAR
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Define linear constraint equations between displacements and rotations, which can be defined in a local coordinate system.
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Equations
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*CONSTRAINED_LINEAR_
GLOBAL
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Define linear constraint equations between displacements and rotations, which can be defined in global coordinate systems.
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Equations
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Supported Card
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Solver Description
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Supported Load Types
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Notes
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CONSTRAINT.LINEAR
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Linear constraint for FE nodes.
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independent node + dependent nodes = references to nodes representing GROUP_LIST
dof1 = DOF_DX
dof2 = DOF_DY
dof3 = DOF_DZ
dof4 = DOF_RX
dof5 = DOF_RY
dof6 = DOF_RZ
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In the Element Types panel, select CONSTRAINT for element type = rigid.
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EQUATION.MASTER
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Dependent part of linear constraint equation (eliminated degree of freedom).
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node = NODE_ID
Select:
dof1 for DIRECTION = D1
dof2 for DIRECTION = D2
dof3 for DIRECTION= D3
dof4 for DIRECTION = R1
dof5 for DIRECTION = R2
dof6 for DIRECTION = R3 or an arbitrary DOF for DIRECTION = ALL
w = FACTOR
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Select set all DOFs of MASTER NODE equal to the corresponding DOFs of the SLAVE NODE(s) for DIRECTION = ALL.
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EQUATION.SLAVE
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Independent part linear constraint equation (retained degrees of freedom).
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Equations
nodes = NODE_ID
Select:
dof1 for DIRECTION = D1
dof2 for DIRECTION = D2
dof3 for DIRECTION = D3
dof4 for DIRECTION = R1
dof5 for DIRECTION = R2
dof6 for DIRECTION = R3.
w = FACTOR
constant is not used
Each unique combination of a node and a DOF represents one EQUATION.SLAVE.
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Select set all DOFs of MASTER NODE equal to the corresponding DOFs of the SLAVE NODE(s) for DIRECTION = ALL.
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Supported Card
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Solver Description
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Supported Load Types
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Notes
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MPC
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Defines a multipoint constraint equation of the form.
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Equation
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Individual weight factors can be created on the nodes of an MPC equation using the update functionality in the Equations panel.
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| Note: | Other loads such as SPCADD, MPCADD, FREQ, FREQ1, EIGR, EIGRL, EIGC, EIGP, EIGB, GRAV, and RFORCE are supported as load collectors. |
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Supported Card
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Solver Description
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Supported Load Types
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Notes
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$MPC GENERAL
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General linear constraint equation
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Equation
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For more information on MPC cards and using duplicate ID pools, see the Permas Interface Overview topic.
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See Also:
Include Files
Load Collectors
