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.
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.
Based on a question from Bill Seymour, this is what I came up with.
Rectangular tubes are one of the standard shapes of beams.
This article shows how to create them in CalculiX GraphiX.
In this article a methd of creating a second order hex mesh for circular cross-sections
will be shown.
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
So the question is; does it help, and how much.
That is what will be investigated in this article.
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.
In this article the difference in the images of the stresses between
a quadrilateral hexahedron (“hex”) mesh and a tetraeder (“tet”) mesh will be
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
The analyses will be done using CalculiX.
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.
TL;DR, this was a triumph of stupidity and greed over good engineering.
Engineering design standards are often written in blood, in the sense that
these standards often came into being after accidents involving serious loss
The CEO of Oceangate ignored them, apparently because they got in his way of
As it turns out, reality is not susceptible to CEO bullshit.
Unsurprisingly, “move fast and break things” is not a good strategy when
lives are at stake.
To monitor the power usage of my electric motorcycle and appliances, I bought
a Basetech EM2000.
Before using it for real monitoring, I wanted to test it to get a feel for the accuracy