Questions tagged [finite-element-analysis]

Anything related to finite element analysis or finite element methods (FEMs), i.e. a number of advanced numerical analysis techniques for finding approximate solutions of differential equations. FEMs are heavily used in many branches of engineering, for example to simplify the design phase of a project.

The methods transform the differential equation into a weak form over the problem domain, which is then discretized by a set of elements (e.g. a triangle-shaped plate or quadrilateral shells). This allows for a per-element approximation of the solution and an assembly of global quantities by local quadrature rules, resulting in a possibly nonlinear system of equations. For large problem statements, finding a solution might require parallel computing strategies.

Many areas of engineering profit from these techniques, e.g. solid and structural mechanics on various time- and size-scales, electrical field theory or diffusion problems, and there are plenty of (free) software solutions available. In scientific computing, users regularly need to extend the method by custom element formulations or new solution procedures, which is often done in fortran, c++ or python.

See also the Wikipedia page on FEMs.

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Save gmsh-generated nodes and elements to std::vector or other container

I am using the gmsh C++ API as a part of a larger optimization project. All I need gmsh for is to mesh some polygons at every iteration in order to conduct a finite element analysis. According to the tutorials, once a mesh instance is generated, it…
giacomo-b
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How to resolve gmsh Mesh generation errors

I am trying to 3D mesh 10 ellipses with various aspect ratio's for an OpenFOAM simulation. I've noticed that I'm getting the same 3 meshing errors when I try to generate a 3D mesh. The 3 error messages are: Error: Unable to recover the edge 405…
RobotBarry
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Python: Read vtk file, add data set then write vtk

I have an exisiting vtk file (of a FE mesh, regular hexahedron mesh) and I would like to add a data set to this that I have in Python. Specifically, I would like to add this numpy data set to each node and then visualize it in ParaView. Any tips…
edub
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easy to use adaptive mesh refinement for characteristic function - Python

I have a (discontinous) function f from R^n to {0, 1}, provided by the user. E.g. something like this "circle inquality": def charfunc(x): # assume x is a numpy array return x[0]**2 + x[1]**2 < 1 I want to find the border of the region(s)…
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Need help solving a pde with finite elements in matlab

I have an initial value problem u''''=f with u(0)=u'(0)=u(1)=u'(1)=0 It comes then by multiplying with test function v and integrating to following formulation: integral( 0 to 1) u''v'' dx= integral (o to 1) fv So the basis…
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Reference Abaqus C++ API static libraries to read ODB files

I have Abaqus CAE, Visual Studio 2017, Visual C++ compiler installed in my computer. I'm trying to reference Abaqus CAE's static libraries in my Visual Studio C++ project to read my ODB file. This is the code file that I'm trying to compile &…
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How to increase a number-representation precision for a FEM comptuting in NumPy?

For my master's dissertation, I am making a FEM program that requires a lot of precision — more than 30 decimal places, I think — but I can't do that as NumPy's float64 data-type only allows 16 places. I've tried NumPy longdouble, but it gives me…
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(PETSc with FEM) How can we set the boundary conditions (Dirichlet and neumann)?

I need help for understanding the PETSc examples of finite element method with SNES nonlinear solver. Is there any good materials or sources to understand the examples? (I already read PETSc user manual, but there is no information which I need.) I…
서승진
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How to model 4 points bending reinforced concrete beam with ABAQUS?

I have some questions about how to define boundary conditions for 4 points bending reinforced concrete with Abaqus. So I model this beam but I don't know how to define boundary conditions and step. Can You please help me? The model is 1/4 beam…
Mona
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How to use tabular amplitude data in Abaqus BC using Python scripts?

I have a long set of tabular data which I need to use as amplitude in Abaqus, using the script. Using scripts, normally I can enter a tabular amplitude as…
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How to define two reference points in two edges of a Rectangular plate in the same instance using Python Scripts in Abaqus?

I want to define two Reference points in two edges of the same instance in the assembly so that I can use them for defining constraints later on in the model. My code looks like this…
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Looking for a better algorithm or data structure to improve conversion of connectivity from ID's to indices

I'm working with Python 3.6.2 and numpy. I'm writing code to visualize a finite element model and results. The visualization code requires the finite element mesh nodes and elements to be identified by indices (starting a zero, no gaps) but the…
max375
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How to extract stress within a certain bounding geometry in an Abaqus ODB using scripting?

I wish to be able to extract stress (S11) and its corresponding element's z-coordinates only in a certain bounding cylinder. My ODB files are relatively big and it would be quite helpful if I could limit the number of elements I have to compute. I…
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Deleting a self intersecting face by its number

I have a mesh that I import to the Meshlab and simplify, clean, and reconstruct the mesh. I export the final mesh from meshlab and import into finite element software (COMSOL). While importing, I received the error message of "Self intersecting…
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Use finite element method to solve 2D diffusion equation (heat equation) but explode

I try to use finite element to solve 2D diffusion equation: numx = 101; % number of grid points in x numy = 101; numt = 1001; % number of time steps to be iterated over dx = 1/(numx - 1); dy = 1/(numy - 1); dt = 1/(10*(numt - 1)); x =…