FEM ConstraintDisplacement/ru: Difference between revisions

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{{Docnav|[[FEM_ConstraintFixed|Constraint fixed]]|[[FEM_ConstraintPlaneRotation|Constraint plane rotation]]|[[FEM_Module|FEM]]|IconL=FEM_ConstraintFixed.png|IconC=Workbench_FEM.svg|IconR=FEM_ConstraintPlaneRotation.png}}
{{Docnav/ru
|[[FEM_ConstraintFixed/ru|Constraint fixed]]
|[[FEM_ConstraintContact/ru|Constraint contact]]
|[[FEM_Workbench/ru|FEM]]
|IconL=FEM_ConstraintFixed.svg
|IconR=FEM_ConstraintContact.svg
|IconC=Workbench_FEM.svg
}}


<div class="mw-translate-fuzzy">
<div class="mw-translate-fuzzy">
{{GuiCommand/ru
{{GuiCommand/ru|Name=FEM ConstraintDisplacement|Name/ru=FEM ConstraintDisplacement|MenuLocation=FEM → Constraint displacement||Workbenches=[[Fem Workbench/ru|FEM]]|Shortcut=|SeeAlso=[[FEM_tutorial/ru|FEM tutorial]]}}
|Name=FEM ConstraintDisplacement
|Name/ru=FEM ConstraintDisplacement
|MenuLocation=Model → Mechanical Constraints → Constraint displacement
|Workbenches=[[FEM_Workbench/ru|FEM]]
|Shortcut=
|SeeAlso=[[FEM_tutorial/ru|FEM tutorial]]
}}
</div>
</div>


==Description==
<span id="Description"></span>
==Описание==

Creates a FEM boundary condition for a prescribed displacement of a selected object for specified degrees of freedom.

<span id="Usage"></span>
==Применение==

# Press the {{Button|[[Image:FEM_ConstraintDisplacement.svg|16px]] [[FEM_ConstraintDisplacement|Displacement boundary condition]]}} button or select the menu {{MenuCommand|Model → Mechanical boundary conditions and loads → [[Image:FEM_ConstraintDisplacement.svg|16px]] Displacement boundary condition}}.
# In the [[3D_view|3D view]] select the object the boundary condition should be applied to, which can be a vertex (corner), edge, or face.
# Press the {{Button|Add}} button.
# Uncheck ''Unspecified'' to activate the necessary fields for editing.
# Set the values or ({{Version|0.21}}) specify a formula for the displacements.

==Formulas==

{{Version|0.21}}

===General===

For the [[Image:FEM_SolverElmer.svg|32px]] [[FEM_SolverElmer|solver Elmer]] it is possible to define the displacement as a formula. In this case the solver sets the displacement according to the given formula variable.

Take for example the case that we want to perform a [[FEM_SolverElmer_SolverSettings#Timestepping_(transient_analyses)|transient analysis]]. For every time step the displacement <math>d</math> should be increased by 6 mm:

<math>\quad
d(t)=0.006\cdot t
</math>

enter this in the ''Formula'' field:</br>
{{incode| Variable "time"; Real MATC "0.006*tx"}}

This code has the following syntax:
* the prefix ''Variable'' specifies that the displacement is not a constant but a variable
* the variable is the current time
* the displacement values are returned as ''Real'' (floating point) values
* ''MATC'' is a prefix for the Elmer solver indicating that the following code is a formula
* ''tx'' is always the name of the variable in ''MATC'' formulas, no matter that ''tx'' in our case is actually ''t''

===Rotations===

Elmer only uses the '''Displacement *''' fields of the boundary condition. To define rotations, we need a formula.

If for example a face should be rotated according to this condition:


<math>\quad
Creates a FEM constraint for a prescribed displacement of a selected object for a specified degree of freedom.
\begin{align}
d_{x}(t)= & \left(\cos(\phi)-1\right)x-\sin(\phi)y\\
d_{y}(t)= & \left(\cos(\phi)-1\right)y+\sin(\phi)x
\end{align}
</math>


then we need to enter for '''Displacement x'''</br>
==Usage==
{{incode| Variable "time, Coordinate"
Real MATC "(cos(tx(0)*pi)-1.0)*tx(1)-sin(tx(0)*pi)*tx(2)}}


and for '''Displacement y'''</br>
#Click on [[Image:FEM ConstraintDisplacement.png|32px]] or choose {{KEY|Model}} → '''Mechanical Constraints''' → {{KEY|[[Image:FEM ConstraintDisplacement.png|32px]] Constraint displacement}} from the top menu.
{{incode| Variable "time, Coordinate"
#Select in the 3D-view the object the constraint should be applied to, which can be
Real MATC "(cos(tx(0)*pi)-1.0)*tx(2)+sin(tx(0)*pi)*tx(1)}}
## vertices (corners)
## edges
## faces
#Choose a degree of freedom to fix or prescribe a displacement to.


This code has the following syntax:
==Limitations==
* we have 4 variables, the time and all possible coordinates (x, y z)
* ''tx'' is a vector, ''tx(0)'' refers to the first variable, the time, while ''tx(1)'' refers to the first coordinate ''x''
* ''pi'' denotes <math>\pi</math> and was added so that after <math>t=1\rm\, s</math> a rotation of 180° is performed


==Notes==
<span id="Notes"></span>
==Примечания==


For the [[Image:FEM_SolverCalculixCxxtools.svg|32px]] [[FEM_SolverCalculixCxxtools|solver CalculiX]]:
#The constraint uses the *BOUNDARY card in CalculiX. Fixing a degree of freedom is explained at http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node164.html and prescribing a displacement for a degree of freedom is explained at http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node165.html
* This tool uses the *BOUNDARY card.
* Fixing a degree of freedom is explained at http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node164.html
* Prescribing a displacement for a degree of freedom is explained at http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node165.html




{{Docnav/ru
{{Docnav|[[FEM_ConstraintFixed|Constraint fixed]]|[[FEM_ConstraintPlaneRotation|Constraint plane rotation]]|[[FEM_Module|FEM]]|IconL=FEM_ConstraintFixed.png|IconC=Workbench_FEM.svg|IconR=FEM_ConstraintPlaneRotation.png}}
|[[FEM_ConstraintFixed/ru|Constraint fixed]]
|[[FEM_ConstraintContact/ru|Constraint contact]]
|[[FEM_Workbench/ru|FEM]]
|IconL=FEM_ConstraintFixed.svg
|IconR=FEM_ConstraintContact.svg
|IconC=Workbench_FEM.svg
}}


{{FEM Tools navi{{#translation:}}}}
{{FEM Tools navi{{#translation:}}}}
{{Userdocnavi{{#translation:}}}}
{{Userdocnavi{{#translation:}}}}
{{clear}}

Latest revision as of 16:12, 16 November 2023

Other languages:

FEM ConstraintDisplacement

Системное название
FEM ConstraintDisplacement
Расположение в меню
Model → Mechanical Constraints → Constraint displacement
Верстаки
FEM
Быстрые клавиши
Нет
Представлено в версии
-
См. также
FEM tutorial

Описание

Creates a FEM boundary condition for a prescribed displacement of a selected object for specified degrees of freedom.

Применение

  1. Press the Displacement boundary condition button or select the menu Model → Mechanical boundary conditions and loads → Displacement boundary condition.
  2. In the 3D view select the object the boundary condition should be applied to, which can be a vertex (corner), edge, or face.
  3. Press the Add button.
  4. Uncheck Unspecified to activate the necessary fields for editing.
  5. Set the values or (introduced in version 0.21) specify a formula for the displacements.

Formulas

introduced in version 0.21

General

For the solver Elmer it is possible to define the displacement as a formula. In this case the solver sets the displacement according to the given formula variable.

Take for example the case that we want to perform a transient analysis. For every time step the displacement should be increased by 6 mm:

enter this in the Formula field:
Variable "time"; Real MATC "0.006*tx"

This code has the following syntax:

  • the prefix Variable specifies that the displacement is not a constant but a variable
  • the variable is the current time
  • the displacement values are returned as Real (floating point) values
  • MATC is a prefix for the Elmer solver indicating that the following code is a formula
  • tx is always the name of the variable in MATC formulas, no matter that tx in our case is actually t

Rotations

Elmer only uses the Displacement * fields of the boundary condition. To define rotations, we need a formula.

If for example a face should be rotated according to this condition:

then we need to enter for Displacement x
Variable "time, Coordinate" Real MATC "(cos(tx(0)*pi)-1.0)*tx(1)-sin(tx(0)*pi)*tx(2)

and for Displacement y
Variable "time, Coordinate" Real MATC "(cos(tx(0)*pi)-1.0)*tx(2)+sin(tx(0)*pi)*tx(1)

This code has the following syntax:

  • we have 4 variables, the time and all possible coordinates (x, y z)
  • tx is a vector, tx(0) refers to the first variable, the time, while tx(1) refers to the first coordinate x
  • pi denotes and was added so that after a rotation of 180° is performed

Примечания

For the solver CalculiX: