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rdiederich1-Visitor
1-Visitor
July 14, 2015
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Finding Moment of Inertia of Parts

  • July 14, 2015
  • 1 reply
  • 6556 views

I'm using Creo Elements 5.0.

I'm trying to find the moment of inertia for a part. I know it's somewhere under "Mass Properties," but I don't have a clue how to interpret the information. For example, the report gives me the following:

INERTIA with respect to _PULLEY coordinate frame:  (KILOGRAM * M^2)

INERTIA TENSOR:

Ixx Ixy Ixz  1.8052873e-04  0.0000000e+00  0.0000000e+00
Iyx Iyy Iyz  0.0000000e+00  1.8052885e-04  0.0000000e+00
Izx Izy Izz  0.0000000e+00  0.0000000e+00  2.3059436e-04

INERTIA at CENTER OF GRAVITY with respect to _PULLEY coordinate frame:  (KILOGRAM * M^2)

INERTIA TENSOR:

Ixx Ixy Ixz  1.3803196e-04  0.0000000e+00  0.0000000e+00
Iyx Iyy Iyz  0.0000000e+00  1.3803208e-04  0.0000000e+00
Izx Izy Izz  0.0000000e+00  0.0000000e+00  2.3059436e-04

PRINCIPAL MOMENTS OF INERTIA:  (KILOGRAM * M^2)

I1  I2  I3   1.3803182e-04  1.3803222e-04  2.3059436e-04

I have no idea what any of this means. And to make things worse, I'm supposed to get is 0.00023030136 kg*m^2, (or 2.30E-04 kg*m^2), which doesn't match any of the numbers. Material of the part is correct, the dimensions are correct; as far as I can tell, the part is constructed correctly, but for the life of me I can't figure out what I'm doing wrong.

Thank you for any help you can provide.


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Best answer by Chris3

Are you sure? See below bolded

PRINCIPAL MOMENTS OF INERTIA:  (KILOGRAM * M^2)

I1  I2  I3   1.3803182e-04  1.3803222e-04  2.3059436e-04

I have no idea what any of this means. And to make things worse, I'm supposed to get is 0.00023030136 kg*m^2, (or 2.30E-04 kg*m^2), which doesn't match any of the numbers.

1 reply

C
Chris321-Topaz IAnswer
21-Topaz I
July 20, 2015

Are you sure? See below bolded

PRINCIPAL MOMENTS OF INERTIA:  (KILOGRAM * M^2)

I1  I2  I3   1.3803182e-04  1.3803222e-04  2.3059436e-04

I have no idea what any of this means. And to make things worse, I'm supposed to get is 0.00023030136 kg*m^2, (or 2.30E-04 kg*m^2), which doesn't match any of the numbers.

    R
    rdiederich1-VisitorAuthor
    1-Visitor
    July 22, 2015

    I inherited this project, but no one remembers who did it, or how they did it. If the number (if the other person did it corrently, which I'm not entirely sure they did) that was given was accurate, it should have rounded to 2.30E-04 kg*m^2. But the number Creo gives me should round to 2.31E-04 kg*m^2. Granted, the difference between the two numbers without scientific notation is only 0.000000293 (or 2.93E-07), but this is my first internship, and I would rather not mess it up. I'll speak with my supervisor, and see if the numbers are "close enough for jazz," as my father likes to say.

    Thank you very much for your help.

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