How to construct an inertia tensor?

Richard Smith
Richard Smith Altair Community Member
edited April 2022 in Community Q&A

I wish to apply the correct inertial properties to a rigid body, in my case a model of an engine.

From the the supplier of the engine they have provided me the moments of inertia of the engine around the 3 principle axes of the body centred at its centre of mass as such:

Ixx = 19.2 kg.m^2

Iyy = 49.6 kg.m^2

Izz =  42.9 kg.m^2

I need to fill out the inertia tensor matrix for this part for my solver (in my case LS-Dyna) within HM in the form.

Ixx  Ixy  Ixz

Iyx  Iyy  Iyz

Izx  Izy  Izz

Now obviously to develop the inertia matrix the diagnol terms are just those supplied to me by the engine supplier as above.

How do i develop the the off diagnol terms in this matrix given only the info from the supplier?

Can I calculate off diagnol terms from the info supplied or must these terms be also given from the supplier?

 

Thanks.

 

 

 

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Answers

  • PaulAltair
    PaulAltair
    Altair Employee
    edited April 2022

    Assume you are creating a *PART_INERTIA, for a rigid representation of the engine? In that case IXX,IYY,IZZ are sufficient, you can leave the other terms as 0.

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