Table of Contents

3.5.12. CREATE-CONSTRAINT function

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Description

This function is used to create a constraint case on your model. Currently it allows single point constraint (SPC) definition, and thus it enables the definition of prescribed displacements at the nodes degrees of freedom.

By default, SesamX will understand the degrees of freedom provided in the global basis. However, you can also inform SesamX to use a previously defined basis to prescribe the degrees of freedom values (as showcased in the examples).

Keywords

Name Data Type Data number Optional Default value Physical quantity
MODEL STRING 1 NO
Name of the model on which to create the constraint case.
NAME STRING 1 NO
Name of the constraint case.

DISPLACEMENT-SPC branch

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This branch is used to create a single point constrain (SPC) on the displacements at the nodes (translation and rotation degrees of freedom).

Keywords

Name Data Type Data number Optional Default value Physical quantity
BASIS STRING 1 YES
Name of the basis to use. By default the global basis is used.
TX FLOAT 1 YES TRANSLATION
Translation value to prescribe on the TX degree of freedom.
TY FLOAT 1 YES TRANSLATION
Translation value to prescribe on the TY degree of freedom.
TZ FLOAT 1 YES TRANSLATION
Translation value to prescribe on the TZ degree of freedom.
RX FLOAT 1 YES ROTATION
Translation value to prescribe on the RX degree of freedom.
RY FLOAT 1 YES ROTATION
Translation value to prescribe on the RY degree of freedom.
RZ FLOAT 1 YES ROTATION
Translation value to prescribe on the RZ degree of freedom.
ON-NODES-FROM STRING 1 NO
Name of the nodes selection on which the constraint is applied.

Examples

Displacement SPC in global basis

In the following example, a single point constraint is created in the global basis. 

CREATE-CONSTRAINT  
  MODEL: MY_MODEL
  NAME: CONST_CASE
  DISPLACEMENT-SPC
    TX: 0.  
    RZ: 0.
    ON-NODES-FROM: HOLE_1

For each node of the HOLE_1 selection, this constraint object enforces $T_X = 0$ and $R_Z = 0$, where $T_X$ and $R_Z$ are the degrees of freedom at the nodes in the global basis.

Displacement SPC in user basis

In the following example, a single point constraint is created relative to a previously defined user basis (BASIS_A). 

CREATE-CONSTRAINT  
  MODEL: MY_MODEL
  NAME: CONST_CASE
  DISPLACEMENT-SPC
    BASIS: BASIS_A
    TX: 3.  
    RY: 5. 
    ON-NODES-FROM: HOLE_1

For each node of the HOLE_1 selection, this constraint object enforces $T_X = 0$ and $R_Y = 0$, where $T_X$ and $R_Y$ are the degrees of freedom at the nodes in the user basis.

If $(\underline{u_1}, \underline{u_2}, \underline{u_3})$ are the vectors of BASIS_A, these 2 constraints translate to:

Where $u_1^i$ and $u_2^i$ are the components of the user basis vectors $\underline{u_1}$ and $\underline{u_2}$ in the global basis. And $T_X, T_Y, T_Z, R_X, R_Y, R_Z$ are the degrees of freedom at the node in the global basis.

See also

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References

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