FINITE ELEMENT ANALYSIS OF SHELLS - EARLY ACCESS 
14. The full element stiffness matrix
Building the shell element stiffness matrix
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Summary

In this lecture, we'll cover:

  • How to combine the separate membrane, bending, and shear stiffness contributions into one element stiffness function,
  • How to organise the stiffness calculation into a reusable utilities file,
  • How to import and test the function inside a notebook,

In this lecture, we will focus on refactoring the element stiffness matrix calculation into a single function that can be reused for each element in the structure. We build the function so that it accepts the number of sampling points for membrane, bending, and shear calculations, along with the element coordinates and constitutive matrices.

We then streamline the selection of Gauss points and weights with a small dictionary, and assemble the full stiffness matrix by adding the membrane, bending, and shear contributions together. After defining and checking the function in the notebook, we move it into a separate utils.py file so the notebook stays cleaner and the function can be imported later when needed.

Next up

In the next section, we will build the transformation matrix to move from local element coordinates to global 3D coordinates.

Tags

stiffness matrix assemblyGauss integration pointsshell element utilities file

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Finite Element Analysis of Plate and Shell Structures: Part 2 - Shells

Expanding from plate to shell elements - build a workflow that unlocks the behaviour of 3D shell structures

After completing this course...

  • You will understand how we make the leap from Reissner-Mindlin plate elements to shell elements and what extra modelling fidelity that provides.
  • You will be comfortable using a combination of GMSH and the open-source 3D modelling software, Blender, to generate custom finite element meshes.
  • You will be able to use OpenSeesPy to model shell structures, as an alternative to your own custom finite element solver.
  • You will have a much greater understanding of what commercial finite element packages are doing, behind the UI, allowing you to authoritatively interrogate their results.
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15. Section overview - Building the transformation matrix