Welcome
This is my home in the virtual world, where I write
about things that I want to share. The freely available software that
I've written as well as some of the photographs I've taken over the
years can also be found here. Please use the navigation links on the
right if you are looking for something.
Recent articles
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In this article an FEA workflow based on CAD geometry in the form of STEP
files and gmsh for mesh generation and CalculiX as the solver will be discussed.
This workfloe is primarily suited for isotropic materials.
If one is working with FreeCAD, the FEM workbench enables a similar workflow,
if gmsh and CalculiX are installed.
But the author prefers this method because it makes the details of the process
more transparent and accessible.
All the software used here is freely available.
On UNIX-like systems (e.g. FreeBSD, Linux) it can generally be
installed by the native package manager.
Installing the prerequisites under ms-windows is outside the scope of this article.
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After having used the built-in tracing profiler cProfile for a while now,
I came across the statistical (sampling) profiler pyinstrument.
A statistical profiler does not influence the runtime of the program as much
as a tracing profiler as cProfile
does.
Additionally, pyinstrument
shows the result in a different way from cProfile
.
So in this article, I will be profiling my repotool
program.
This program helps me maintain a mirror of FreeBSD packages that I use.
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The Dutch-language engineering book “Constructieprincipes” by M.P. Koster
contains flexure made out of four folded leaf springs that kind of acts like
a ball joint.
The point where the load is applied should rotate around a virtual center
formed by the point where the fold lines meet.
The goal of this article is to simulate that and see if it works.
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Based on a question from Bill Seymour, this is what I came up with.
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Rectangular tubes are one of the standard shapes of beams.
This article shows how to create them in CalculiX GraphiX.
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In this article a methd of creating a second order hex mesh for circular cross-sections
will be shown.
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Composite sandwich products loaded in bending tend to fail by buckling of the
laminate under compression.
The author’s intuition is that corrugating the surface under compression
should help.
So the question is; does it help, and how much.
That is what will be investigated in this article.
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The line
command in CalculiX Graphics can create lines, arc and splines
but not elliptical arcs.
This article describes how to approximate elliptical arcs using splines.
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In this article the difference in the images of the stresses between
a quadrilateral hexahedron (“hex”) mesh and a tetraeder (“tet”) mesh will be
investigated.
In both cases, second order elements will be used.
Hopefully this will make it clear to the reader why hex meshes are generally preferred.
The plate with a hole that was the subject of a previous article will again
be used.
The analyses will be done using CalculiX.
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The way FEA works can lead to concentrations of high stress in single elements
or even nodes. This article aims to show how such singularities can be
recognized and when they can be safely ignored.