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How to obtain the mass moment of inertia

Posted May 6, 2014, 9:51 p.m. EDT Heat Transfer & Phase Change, Geometry, Structural Mechanics Version 4.4 3 Replies

Ezequiel Hernández
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Hi!
I need to find the moment of inertia of a complex structure. Anyone knows a way to calculate it? I took a look at the forums but the info I saw was very confusing.

Thanks a lot!
3 Replies Last Post May 7, 2014, 12:20 p.m. EDT
Nagi Elabbasi Facebook Reality Labs
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Posted: 1 decade ago May 7, 2014, 12:13 a.m. EDT
Hi Ezequiel,

If you integrate the density over a domain you get its mass. Similarly, if you integrate “density * (x^2 + y^2)” over a domain you get its mass moment of inertial about the z-axis, I_zz. Similar integrals get you the other terms in the mass moment of inertia tensor if needed.

Nagi Elabbasi
Veryst Engineering
Hi Ezequiel, If you integrate the density over a domain you get its mass. Similarly, if you integrate “density * (x^2 + y^2)” over a domain you get its mass moment of inertial about the z-axis, I_zz. Similar integrals get you the other terms in the mass moment of inertia tensor if needed. Nagi Elabbasi Veryst Engineering
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago May 7, 2014, 1:40 a.m. EDT
Hi

in the latest 4.4 you can add a sub-node in the "Definitions" section (as for old v3.5) and get a set of variables defining mass, Cog, moment of inertia etc very handy
But do not forget to define the appropriate density (solid.rho, or materials.rho or whatever applies)

--
Good luck
Ivar
Hi in the latest 4.4 you can add a sub-node in the "Definitions" section (as for old v3.5) and get a set of variables defining mass, Cog, moment of inertia etc very handy But do not forget to define the appropriate density (solid.rho, or materials.rho or whatever applies) -- Good luck Ivar
Ezequiel Hernández
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Posted: 1 decade ago May 7, 2014, 12:20 p.m. EDT
Thanks Nagi and Ivar! :D
Thanks Nagi and Ivar! :D

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