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Mass Moment of Inertia Axis Mismatch with Global Coordinate System

Question asked by Ben Adamcik on Nov 27, 2019
Latest reply on Nov 27, 2019 by Josh Brady

I have a cylinder that I want to get the mass moments of inertia about its central axis. However, when I go to Mass evaluate, the Ix/y/z axes are pointing in different values compared to the global system (lower left corner) as seen below: (specifically, Ix points in +Z, Iy points in +X, Iz points in +Y):

Image displaying how Ix points in +Z axis, Iy points in +X, Iz points in +Y

Zoomed in image of MOI axes:

For the actual MOI that's reported, I get the following values:

Ixx = .000754 kgm^2

Iyy = .000927 kgm^2

Izz = .000754 kgm^2

 

I have the following questions:

1) Why are the inertia axes (pink ones) pointing differently from the global axes?

2) Given how the cylinder is more or less equivalent in the YZ and XY planes, along with Ixx/Izz being the same, is it safe to assume that the Iyy value corresponds to rotation about the global Y axis?

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