FEM EquationElasticity

Solver Z88

Electricforce equation

FEM

FEM EquationElasticity
Menu location
Solve → Elasticity equation
Workbenches
FEM
Default shortcut
None
Introduced in version
0.19
See also
FEM tutorial

Description

This equation describes the mechanical properties of rigid bodies.

Usage

1. After adding an Elmer solver as described here, select it in the tree view.
2. Now either use the toolbar button or the menu Solve → Elasticity equation.
3. Change the equation's solver settings or the general solver settings if necessary.

Solver Settings

For the general solver settings, see the Elmer solver settings.

The elasticity equation provides these special settings:

• DataCalculate Pangle: If the principal angles should be calculated.
• DataCalculate Principal: If all stresses should be calculated.
• DataCalculate Strains: If strains will be calculated. This will also calculate the stresses, even if DataCalculate Principal or DataCalculate Stresses is false.
• DataCalculate Stresses: If stresses should be calculated. Compared to DataCalculate Principal the Tresca and the pincipal stress will not be calculated.
• DataDo Frequency Analysis: If a frequency analysis should be performed (calculation of eigenmodes and eigenfrequencies).
• DataEigenmodes Count: The number of the highest eigenmode that should be calculated.

Constraint Information

The elasticity equation takes the following constraints into account if they are set:

• Constraint fixed
• Constraint displacement
• Constraint force
• Constraint pressure
• Constraint self weight
• Constraint initial temperature

Notes

For all above constraints it is important that they act on a face. Constraints set to lines or vertices are not recognized by the Elmer solver.

Eigenmode Analysis

To perform an eigenmode analysis (calculation if the eigenmodes and eigenfrequencies), you need to

1. Set DataDo Frequency Analysis: to true
2. Set DataEigenmodes Cout: to the highest number of eigenmodes you are interested in. The smaller this number the shorter the solver runtime since higher modes can be omitted to be determined.
3. Add a constraint fixed and set at least one face of the body as fixed.
4. Accordingto the Elmer manual the best results for eigenmode analysis are obtained with direct solving. Therefore
   1. Set DataLinear Sover Type to Direct.
   2. Set DataLinear Direct Method to Umfpack.
5. Eventually run the solver.

Note: If you use more than one CPU core for the solver (introduced in version 1.0), you cannot use Umfpack, the only direct method for parallel solving is MUMPS.
Also note that iterative solving is not recommended for eigenmode analysis.

Results

The available results depend on the solver settings. If none of them was set to true, only the displacement is calculated. Otherwise also the corresponding results will be available. If DataDo Frequency Analysis was set to true all results will be available for every calculated eigenmode.

If DataDo Frequency Analysis was set to true, the eigenvalues are output at the end of the document SolverElmerOutput that will be created in the tree view after the solver has finished. A typical output would for example be

EigenSolve: Computed 5 Eigen Values
EigenSolve: 1:    9.584853E+04   0.000000E+00
EigenSolve: 2:    3.080755E+06   0.000000E+00
EigenSolve: 3:    3.725429E+06   0.000000E+00
EigenSolve: 4:    2.909430E+07   0.000000E+00
EigenSolve: 5:    3.525298E+07   0.000000E+00

The second column is hereby the real part of the eigenvalue $\omega ^{2}$, the third column the imaginary part.

To calculate the eigenfrequency $f_{e}$ out of it, this has to be done (because of the root the imaginary part cannot just be omitted):

$\quad f_{e}={\cfrac {\sqrt {\omega ^{2}}}{2\pi }}$

Solver Z88

Electricforce equation

FEM

FEM

• FEM Analysis

• Materials: Solid, Fluid, Nonlinear mechanical, Reinforced (concrete); Material editor

• Element geometry: Beam (1D), Beam rotation (1D), Shell (2D), Fluid flow (1D)

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Constraints

• Electromagnetic: Electrostatic potential, Current density, Magnetization

• Fluid: Initial flow velocity, Initial pressure, Flow velocity

• Geometrical: Plane rotation, Section print, Transform

• Mechanical: Fixed, Displacement, Contact, Tie, Spring, Force, Pressure, Centrif, Self weight

• Thermal: Initial temperature, Heat flux, Temperature, Body heat source

• Overwrite Constants: Constant vacuum permittivity

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• Mesh: Mesh Netgen, Mesh GMSH, Mesh boundary layer, Mesh region, Mesh group, Nodes set, Mesh to mesh

• 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

• Utilities: Clipping plane, Remove clipping planes, Open FEM examples; Mesh clear, Mesh display info

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• Additional: Preferences; FEM Install, FEM Mesh, FEM Solver, FEM CalculiX, FEM Concrete; FEM Element Types

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