FEM ConstraintDisplacement/it: Difference between revisions
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|[[FEM_ConstraintFixed/it|Vincolo fissaggio]] |
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<span id="Description"></span> |
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==Descrizione== |
==Descrizione== |
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Crea un vincolo FEM per un determinato dislocamento di un oggetto selezionato per un dato grado di libertà. |
Crea un vincolo FEM per un determinato dislocamento di un oggetto selezionato per un dato grado di libertà. |
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<span id="Usage"></span> |
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==Utilizzo== |
==Utilizzo== |
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==Formulas== |
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{{Version|0.21}} |
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===General=== |
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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. |
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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: |
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<math>\quad |
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d(t)=0.006\cdot t |
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</math> |
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enter this in the ''Formula'' field:</br> |
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{{incode| Variable "time"; Real MATC "0.006*tx"}} |
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This code has the following syntax: |
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* the prefix ''Variable'' specifies that the displacement is not a constant but a variable |
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* the variable is the current time |
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* the displacement values are returned as ''Real'' (floating point) values |
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* ''MATC'' is a prefix for the Elmer solver indicating that the following code is a formula |
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* ''tx'' is always the name of the variable in ''MATC'' formulas, no matter that ''tx'' in our case is actually ''t'' |
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===Rotations=== |
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Elmer only uses the '''Displacement *''' fields of the boundary condition. To define rotations, we need a formula. |
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If for example a face should be rotated according to this condition: |
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<math>\quad |
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\begin{align} |
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d_{x}(t)= & \left(\cos(\phi)-1\right)x-\sin(\phi)y\\ |
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d_{y}(t)= & \left(\cos(\phi)-1\right)y+\sin(\phi)x |
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\end{align} |
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</math> |
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then we need to enter for '''Displacement x'''</br> |
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{{incode| Variable "time, Coordinate" |
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Real MATC "(cos(tx(0)*pi)-1.0)*tx(1)-sin(tx(0)*pi)*tx(2)}} |
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and for '''Displacement y'''</br> |
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{{incode| Variable "time, Coordinate" |
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Real MATC "(cos(tx(0)*pi)-1.0)*tx(2)+sin(tx(0)*pi)*tx(1)}} |
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This code has the following syntax: |
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* we have 4 variables, the time and all possible coordinates (x, y z) |
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* ''tx'' is a vector, ''tx(0)'' refers to the first variable, the time, while ''tx(1)'' refers to the first coordinate ''x'' |
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* ''pi'' denotes <math>\pi</math> and was added so that after <math>t=1\rm\, s</math> a rotation of 180° is performed |
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<span id="Notes"></span> |
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==Note== |
==Note== |
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#Il vincolo utilizza *BOUNDARY card in CalculiX. Come stabilire un grado di libertà è spiegato in http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node164.html e prescrivere uno dislocamento per un grado di libertà è spiegato in http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node165.html |
#Il vincolo utilizza *BOUNDARY card in CalculiX. Come stabilire un grado di libertà è spiegato in http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node164.html e prescrivere uno dislocamento per un grado di libertà è spiegato in http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node165.html |
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|[[FEM_ConstraintFixed/it|Vincolo fissaggio]] |
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|[[FEM_ConstraintPlaneRotation/it|Vincolo piano di rotazione]] |
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|[[FEM_Workbench/it|FEM]] |
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Latest revision as of 16:12, 16 November 2023
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Posizione nel menu |
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Modello → Vincoli meccanici → Vincolo dislocamento |
Ambiente |
FEM |
Avvio veloce |
Nessuno |
Introdotto nella versione |
- |
Vedere anche |
Tutorial di FEM |
Descrizione
Crea un vincolo FEM per un determinato dislocamento di un oggetto selezionato per un dato grado di libertà.
Utilizzo
Formulas
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
Note
- Il vincolo utilizza *BOUNDARY card in CalculiX. Come stabilire un grado di libertà è spiegato in http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node164.html e prescrivere uno dislocamento per un grado di libertà è spiegato in http://web.mit.edu/calculix_v2.7/CalculiX/ccx_2.7/doc/ccx/node165.html
- Materials: Solid, Fluid, Nonlinear mechanical, Reinforced (concrete); Material editor
- Element geometry: Beam (1D), Beam rotation (1D), Shell (2D), Fluid flow (1D)
Constraints
- Electromagnetic: Electrostatic potential, Current density, Magnetization
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- Overwrite Constants: Constant vacuum permittivity
- Solve: CalculiX Standard, Elmer, Mystran, Z88; Equations: Deformation, Elasticity, Electrostatic, Electricforce, Magnetodynamic, Magnetodynamic 2D, Flow, Flux, Heat; Solver: Solver control, Solver run
- Results: Purge, Show; Postprocessing: Apply changes, Pipeline from result, Warp filter, Scalar clip filter, Function cut filter, Region clip filter, Contours filter, Line clip filter, Stress linearization plot, Data at point clip filter, Filter function plane, Filter function sphere, Filter function cylinder, Filter function box
- Additional: Preferences; FEM Install, FEM Mesh, FEM Solver, FEM CalculiX, FEM Concrete; FEM Element Types
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