Hello Everybody,
I found a very interesting paper about the explicit formulas for the inertia tensor of a tetrahedron, defined with the 3 coordinates of its 4 vertices:
https://thescipub.com/abstract/jmssp.2005.8.11

The symbolic integration process for the obtention of the inertia tensor’s terms was conducted in the “F. Tonon’s” paper by using the “Mathematica” program.
I used the “SMath’ Maxima plugin” for the symbolic integrations.
My results gave identical numerical results as that of the “F. Tonon’s” example.
My formulas are available in an appended SMath file:
### Tetrahedron's Inertia Tensor - Ioan 2026.sm (3,04 МиБ) скачан 2 раз(а).
I included some additional results obtained by using “Maxima” plugin, for “Eigenvalues and Eigenvectors”. Even if the “Maxima” plugin allows the obtention of symbolic results, the complexity of these formulas lets me prefer the numerical application.
I’m interested in having opinions of those familiar with this category of problems by looking in two directions:
a) the connection between the “Eigenvalues and Eigenvectors” results and the rotation classical procedure for the Inertia Moments Tensor.
b) Could it be formulated a procedure to find the Inertia Moments Tensor for the general case of Polyhedral Solid, similar to the classical procedure for 2D polygons, very nicely developed by Davide Carpi in the “Properties of generic Polygons” included in the “SMath Examples”. If the polygon problems are enough available in the literature, I do not know similar procedures for 3D polyhedral objects, defined by their vertex’s coordinates.
Best Regards,
Ioan
Отредактировано 15.02.2026 13:13:56
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