FEM CalculiX
Introduction
This page collects information on the CalculiX finite element solver, the default solver in the FEM Workbench for structural and thermo-mechanical analysis. Depending on the operating system you are working with, you'll need to install CalculiX before running your first simulation. Please see FEM Install.
The solver is able to do linear and non-linear calculations, for static, dynamic, and thermal problems. The solver operates on an Abaqus-like input file (.inp), which means it can be used with different pre-processors that support this format. The program includes its own graphical preprocessor which, however, is not used by FreeCAD, only the solver itself.
CalculiX is designed to run on Unix platforms like Linux and Irix computers but also on MS-Windows. CalculiX was developed by engineers from MTU Aero Engines, Munich, Germany, to assist them in designing machinery such as jet turbines. The software is currently released to the public on the terms of the GPL version 2.
Integration with FreeCAD
Interaction between the FEM Workbench and CalculiX is done through writing and reading text files. The sequence of operations is as follows:
- A CalculiX input file is created with details required to run the simulation
- The CalculiX solver is started with this input file
- The output from the solver is logged
- The output files from the solver are read, if they are available
The FEM Control Solver tool manages the whole process. User interaction in the process is possible.
Preprocessing interface
The input file that CalculiX uses can be prepared and edited before the solver is started. The units used in the input file are independent of the units set in FreeCAD; they will always be millimeters (mm) and Newton (N).
(ToDo: check this. What happens with the mesh if inch is used in FreeCAD? As density was introduced, with this we have kg and s and no longer N?! how about this?!)
The CalculiX interface supports the following objects:
Элементы МКЭ
- Tet4 and Tet10
- S3 and S6
- B31 and B32
- and those described in FEM Mesh CalculiX
Анализ
- Linear and nonlinear static analysis
- Frequency analysis
- Linear buckling analysis
- Coupled thermal-structural analysis
Материалы
- Linear elastic isotropic materials (uniformity in all directions)
- Plasticity with isotropic hardening
Postprocessing interface
The FEM Workbench loads CalculiX results into a result object which will contain:
- Displacements
- Stresses
- Strains
- Equivalent plastic strain (PEEQ) – if nonlinear material was used
- Temperature – for thermomechanical analysis
FreeCAD reads results from *.frd file which was created by CalculiX. If these results contain multiple time steps, each time step is imported to FreeCAD as a new result object. Same behavior applies for Frequency or Buckling analysis with multiple eigenvalues.
Reaction forces can be found in ccx_dat_file which contains reaction force components (fx, fy, fz) for each fixed boundary condition and for each displacement boundary condition which constrains translation degrees of freedom.
Related
- FEM Mesh CalculiX
- CalculiX page in the FEM Workbench preferences
- Materials: Solid Material, Fluid Material, Non-Linear Mechanical Material, Reinforced Material (Concrete); Material Editor
- Element Geometry: Beam Cross Section, Beam Rotation, Shell Plate Thickness, Fluid Section for 1D Flow
- Electromagnetic Boundary Conditions: Electrostatic Potential Boundary Condition, Current Density Boundary Condition, Magnetization Boundary Condition, Electric Charge Density
- Fluid Boundary Conditions: Initial Flow Velocity Condition, Initial Pressure Condition, Flow Velocity Boundary Condition
- Geometrical Analysis Features: Plane Multi-Point Constraint, Section Print Feature, Local Coordinate System
- Mechanical Boundary Conditions and Loads: Fixed Boundary Condition, Rigid Body Constraint, Displacement Boundary Condition, Contact Constraint, Tie Constraint, Spring Boundary Condition, Force Load, Pressure Load, Centrifugal Load, Gravity Load
- Thermal Boundary Conditions and Loads: Initial Temperature, Heat Flux Load, Temperature Boundary Condition, Body Heat Source
- Overwrite Constants: Constant Vacuum Permittivity
- Mesh: Mesh From Shape by Netgen, Mesh From Shape by Gmsh, Mesh Boundary Layer, Mesh Refinement, Mesh Group, Erase Elements, FEM Mesh to Mesh
- Solve: Solver CalculiX, Solver Elmer, Solver Mystran, Solver Z88; Mechanical Equations: Elasticity Equation, Deformation Equation; Electromagnetic Equations: Electrostatic Equation, Electricforce Equation, Magnetodynamic Equation, Magnetodynamic 2D Equation, Static Current Equation; Flow Equation, Flux Equation, Heat Equation, Solver Job Control, Run Solver
- Results: Purge Results, Show Result, Apply Changes to Pipeline, Post Pipeline From Result, Pipeline Branch, Warp Filter, Scalar Clip Filter, Function Cut Filter, Region Clip Filter, Contours Filter, Glyph Filter, Line Clip Filter, Stress Linearization Plot, Data at Point Clip Filter, Calculator Filter; Filter Functions: Plane, Sphere, Cylinder, Box; Data Visualizations: Create Lineplot, Create Histogram, Create Table
- Utilities: Clipping Plane on Face, Remove All Clipping Planes, FEM Examples; Clear FEM Mesh, Display Mesh Info
- Additional: Preferences; FEM Install, FEM Mesh, FEM Solver, FEM CalculiX, FEM Concrete; FEM Element Types