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Articles about engineering

  1. Continuum properties of aluminium honeycomb

    Honeycomb cores are often used in composite structures as an alternative core material to e.g. polymeric foams or end-grain balsa.

    In FEA we want to be able to treat honeycomb as a continuous material instead of having to model individual cells. Otherwise even simple FEA models involving honeycomb would become unmanageably large.

  2. Automating CalculiX with make(1)

    The make program is a staple UNIX development tool. In this article I will show how it can be used to automate and simplify the usage of CalculiX.

    My CalculiX projects are all kept in their own directories. In each of those directories there exists a Makefile. This contains instructions for the make program.

    By default, invoking make in this directory runs the pre-processor and the solver. But there are also specific sub-commands, for example:

    • “make mesh” shows the mesh used in the FEA.
    • “make disp” shows the deformed product in the post-processor.
    • “make stress” shows the stresses in the product in the post-processor.
  3. FEA with Calculix (3)

    This is the third installment of a series of articles about how to analyze sandwich structures with FEA.

    It might be a good idea to read part 1 and part 2 first.

    In this part we will look at a simplified simulation of a three-point bending test of a sandwich panel.

  4. FEA with Calculix (2)

    This is the second part in a series how to analyse sandwich structures with FEA. The first part is here. If you haven’t done so, you should probably read that first.

    In that part we built and analyzed a sandwich where the core and skins shared nodes. We saw how that leads to incorrect stress distribution images because of nodal averaging. In this article, we’re going to fix that by using *TIE constraints.

  5. FEA with Calculix (1)

    This is the first part of a series of articles where I hope to show how to analyze deflection and stress in structures using the free CalculiX software. I’m using version 2.17. The focus will be on sandwich structures because that is the area in which I’m most interested. Compared to parts consisting out of a single material this is a bit more tricky as we will see in this article. The main reason for using finite element analysis (“FEA”) in general is that it allows for complete analysis of problems where no integral solution exists.

    Additionally, some of the assumptions used in Euler–Bernoulli beam theory for analyzing deformation and stresses in beams and plates do not hold for sandwiches.

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