FEM Solver/it

Prefazione
Questa pagina raccoglie le informazioni sui risolutori di elementi finiti utilizzati dall'ambiente FEM. L'interfaccia tra un solutore e FreeCAD in pre-elaborazione e post-elaborazione viene eseguita tramite file di testo. Ciò significa che in teoria qualsiasi solutore che può essere configurato e controllato tramite un file di testo è in grado di lavorare con FreeCAD; affinché questa comunicazione funzioni devono essere programmati un parser e uno scrittore appropriati dei file di input e di output.

Risolutori disponibili in varie distribuzioni Linux
Il repository FreeCAD-dependencies tiene traccia delle dipendenze di FreeCAD su molte distribuzioni Linux. La pagina FEM.md esamina i risolutori FEA open source che potrebbero essere utilizzati con FEM. La pagina mostra la versione di un particolare solutore nel repository di una particolare distribuzione Linux. Questa informazione è utile per sapere se un risolutore è aggiornato o non lo è e deve essere aggiornato.

Le informazioni sono anche discusse nel forum: supported and not supported Solver.

Solver con un'interfaccia in FreeCAD
Questi solutori sono ben integrati in FreeCAD, il che significa che è possibile impostare ed eseguire un progetto di simulazione dall'interfaccia grafica e dai pulsanti nell'ambiente FEM.

CalculiX
Questo è il primo solutore che è stato integrato per funzionare con FEM. CalculiX è progettato principalmente per analisi statiche, termomeccaniche e modali. Ulteriori informazioni su questo risolutore sono disponibili in FEM CalculiX.

Elmer
Il solutore multifisico Elmer è stato integrato in FreeCAD come progetto di Google Summer of Code 2017: main website, community portal, code repository, Elmer Integration (GSoC) - Activity Log (discussione nel forum).

Z88
Il solutore Z88 è progettato per simulazioni statiche lineari con particolare attenzione all'insegnamento del metodo degli elementi finiti. È stato il secondo risolutore ad essere integrato in FreeCAD. Successivamente, l'integrazione è stata migliorata come progetto Google Summer of Code 2017.

Vedere le informazioni:
 * Main website, download page, source code repository (and precompiled binaries).
 * Release notes: Z88os V15 released 17.07.2017, Z88os V13 released 20.05.2009 (version in Debian Jessie 8, Stretch 9, Buster 10).
 * Come usare Z88 in FEM? (forum thread).

Ci sono due versioni, Z88OS è l'edizione open source, mentre Z88Aurora è freeware e include un'interfaccia grafica e metodi di soluzione aggiuntivi.

Solver implementati come ambienti esterni
Questi solutori non sono integrati nell'ambiente FEM, il che significa che hanno bisogno di un'interfaccia separata per impostare un progetto di simulazione. Ciò si ottiene attraverso le macro o gli ambienti esterni.

OpenFoam
OpenFoam è un potente framework per la simulazione fluidodinamica computazionale (CFD), distribuito come una serie di librerie C++.

OpenFoam è disponibile in FreeCAD attraverso due ambienti esterni:
 * Cfd, originato da Qingfeng Xia.
 * CfdOF, una biforcazione di Cfd che finalizzata alla facilità d'uso.

Mentre Cfd è concepito come funzionalità completa per utenti avanzati, CfdOF è pensato per gli utenti che stanno iniziando con CFD e OpenFoam.

Per Cfd: update on FreeCAD + OpenFOAM fluid dynamic computation (forum thread), Progress of the general Computational Fluid Dynamics (CFD) workbench: CfdWorkbench (old thread).

Per CfdOF: Computational Fluid Dynamics (CFD) workbench using OpenFOAM (forum thread), training material.

Both workbenches can be installed through the AddonManager, and both have a place for discussion in the CfdOF / CFD subforum.

DualSPHysics
DualSPHysics is a set of C++, CUDA, and Java libraries that use the smoothed particle hydrodynamics (SPH) model named SPHysics to study free-surface flow phenomena such as crashing waves.

DesignSPHysics is an external workbench built into FreeCAD that provides a graphical user interface for DualSPHysics: main website, code repository, Interesting project: DesignSPHysics fluid simulator (forum thread).

DesignSPHysics can be installed through the AddonManager.

FastHenry and FasterCap
FastHenry and FasterCap are inductance-resistance and capacitance field solvers developed by FastFieldSolvers: main website, download page (binary and source code), forum.

The EM Workbench is an external workbench that was created to serve as the front-end for these electromagnetic solvers. FastHenry, for 3D magneto-quasistatic impedance analysis, is fully supported, while FasterCap is accessible through some Python macros.

See: ElectroMagnetic Workbench (main thread), Electromagnetic Workbench - again.., FreeCAD for ElectroMagnetics, code repository for the workbench.

The EM Workbench can be installed through the AddonManager.

fcFEM
fcFEM is a finite element solver for structural and mechanical studies, implemented in Python, and which can be run directly from FreeCAD without calling external binary solvers. Therefore, it can be considered FreeCAD's own internal solver.

fcFEM was designed to overcome certain limitations from other solvers, such as CalculiX, in order to perform various structural engineering studies.

Some of the problems that are intended to be overcome by this solver include
 * Mixed mesh analyses (solid-shell) for dealing with composite columns or prefabricated architectural components: FEM object types.
 * Improved beam and shell elements, as CalculiX's beam elements seem to give wrong results: CalculiX 3-node Beam Element, FEM object types, Example for 1D analysis.
 * Arc-length control for overcoming limit points for elastic-plastic collapse analysis: FEM - Tubular Connection with Shell Elements.
 * Zero-thickness interface elements for various applications, like post-tensioned concrete with friction: pre-stressed pre/post-tensioned concrete bridge.

The author considers FreeCAD a good prototyping platform to quickly set up, test, and visualize different structural problems, so having an integrated yet flexible solver is very helpful. See the main thread, fcFEM - FEA from start to finish.

fcFEM is packaged as a python library and a macro, and can be downloaded from the github repository. It will eventually be available from the AddonManager, or will be distributed as part of FreeCAD itself.

FEniCS
FEniCS is a computing framework for solving partial differential equations (PDEs), with high-level programming interfaces in Python and C++. It can be used to establish scientific problems in finite element formulations that then can be solved numerically.

See: main website, Fenics as Solver (forum thread).

FenicsSolver is a simulation platform to deal with multi-body, multi-physics (coupled), multi-scale problems. It hopes to integrate the FEniCS solver into both the FEM Workbench and the Cfd external workbench, so the resulting system functions like a free alternative to Comsol or Moose. FenicsSolver is being developed by the same author of Cfd.

OOFEM
OOFEM is an object oriented FEM program by the Czech Technical University, for solving mechanical, transport and fluid mechanics problems.

It was mentioned as having some advantages over CalculiX, like interface elements (pre-stressed pre/post-tensioned concrete bridge), and arc-length control for elastic-plastic collapse analysis (FEM - Tubular Connection with Shell Elements).

Preliminary integration into the FEM Workbench has been done. See: OOFem (main thread), test request, multiple solvers.

Until the solver integration is completed and the new code is merged into the main FreeCAD repository, the required files for using the solver in the FEM Workbench can be downloaded from a forked FreeCAD branch.

Solvers not integrated
The following solvers have not been integrated into FreeCAD but they have garnered some interest by the user community. If a developer wishes to create a communication bridge for a particular solver, he or she should refer to the FEM subforum for advice and assistance.

The following articles may be outdated, but the information they contain may still be useful to understand how to integrate solvers into FreeCAD
 * Extend FEM Module
 * Add FEM Equation Tutorial
 * Add FEM Constraint Tutorial

Wikipedia lists many finite element software packages that potentially could be made to work with FreeCAD in the future.

Agros2D and Hermes
Agros2D is a multiplatform graphical program designed for solving different physical problems. Internally it uses the Hermes C++ libraries for the solution of simple and complex time-dependent nonlinear partial differential equation (PDE) systems using a general version of the finite element method (hp-FEM). Main code repository, and tutorials.

Code-Aster and Code-Saturne
Code-Aster is an open source multiphysics solver; together with the Salomé-Meca pre-processor they form a simulation platform developed by EDF-GDF, France's biggest energy company. It was an early package considered for inclusion in FreeCAD: FreeCAD and Code-Aster/Salome-Meca (forum thread).

Code-Saturne is a free, open-source software developed and released by EDF to solve computational fluid dynamics (CFD).

FElt
FElt is a finite element package to solve linear static and dynamic structural analysis problems. The original code is outdated, so it was forked to a new repository to revive the project and make it compile in a modern system.

It was suggested in the forums to perform reinforced concrete frames analysis (beam and column assemblies) using 1D beam elements: Automation in Design, Felt in FEM Workbench.

Frame3DD
Frame3DD is a software package for static and dynamic structural analysis of 2D and 3D frames and trusses, main repository. A preliminary reader for input files was announced in the forums: Test read data from Frame3DD file.

Impact FEM

 * http://www.impact-fem.org/ (broken link)

libMesh
libMesh is a c++ finite element library for the numerical solution of partial differential equations, with a major goal to provide support for adaptive mesh refinement (AMR) computations in parallel: code repository.

It was suggested to integrate this library into FreeCAD as part of a Google Summer of Code project.

Modelica
Modelica is a language to model and optimize complex, and interconnected physical systems, for example, mechanical, electrical, thermal, hydraulic, and others. The language itself and its standard libraries are open source. Some simulation environments based on Modelica, like Catia's Dymola, are proprietary, but there are also free implementations like OpenModelica and JModelica.

With FreeCAD, Modelica was suggested to help perform animations, but more broadly it could be used in mechanical and building engineering to solve equations and optimize a particular design: Modelica (forum thread).

The PyFMI package contains Python bindings to work with FMU models, which are standardized models in binary format produced by compliant Modelica environments, including Dymola, OpenModelica, and JModelica. It was suggested that this library could help FreeCAD connect to a Modelica system (forum post).

Mumps
Mumps is a generic solver for massive systems of equations, which generally deals with factorizing and operating on sparse matrices. It was mentioned in the forum: test request, multiple solvers.

It does not perform finite element analysis directly, but it may be used internally by other packages like Code-Aster.

Nastran
Nastran is a structural analysis program developed by NASA in the 1970s. Modern versions of it are commercial products and closed source; however, older versions of it, Nastran-93 and Nastran-95 were released as open source in 2015. Forum post: Nastran.

There is no technical support for the open source code, and it is probably difficult to compile in a modern system.

OpenSees
OpenSees is a software framework for developing applications to simulate structural and geotechnical systems mainly in the field of earthquake engineering.

SU2
SU2 is a collection of software tools developed in C++ and Python for the solution of partial differential equations (PDE) and PDE-constrained optimization problems on unstructured meshes. It is particularly used in the fields of aerodynamics and computational fluid dynamics (CFD).

Technog
Technog Professional is a closed source program to perform geotechnical simulations such as landslides, driving piles, slope stability, and civil engineering calculations (masonry and earthquake response), website (broken link).

Technog was successfully used in FreeCAD as a substitute of CalculiX, although the trial version is limited in the number of elements it can handle: Integration of tochnog solver in FreeCAD FEM (forum thread).

XC
XC is a FEA program designed to solve structural problems in civil engineering like real beam shell analysis. Internally it uses the OpenSees libraries: main repository, XC, opensource structural engineering FEM code (forum thread).