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BB_104510931-Visitor
1-Visitor
October 11, 2022
Solved

Inertia measurment

  • October 11, 2022
  • 2 replies
  • 3886 views

I am using Creo Parametric Release 7.0 and Datecode7.0.9.0

When I use Analysis / Mass properties / preview
The coordinate system displayed at center of gravity with respect to principal moment of inertia axis (1, 2, 3) seems not correct. For example, if I extrude a cylinder whose axis is not colinear to origin cordinate frame, the principal moment of inertia displayed is not colinear to the cylinder (when it should be)

Best answer by MartinHanak

Hi,

in Creo 7.0.5.0 I can see this "picture".

MartinHanak_0-1665563317756.png

 

1.] maybe your Creo 7.0.2.0 contains a bug (try installing 7.0.5.0 to verify it)

2.] maybe your config.pro contains some specific option causing the problem (please upload config.pro)

 

2 replies

KenFarley
KenFarley21-Topaz II
21-Topaz II
October 11, 2022

I'm using Creo 9.

Built a cylinder, 1.50 diameter, extruded from Z=0.00 to Z=3.00, centered on X=-2.00, Y=0.00.

Mass Analysis preview shows:

VOLUME = 5.3014376e+00 INCH^3
SURFACE AREA = 1.7671459e+01 INCH^2
DENSITY = 9.9000000e-02 POUND / INCH^3
MASS = 5.2484232e-01 POUND 
CENTER OF GRAVITY with respect to CS0 coordinate frame:
X Y Z -2.0000000e+00 0.0000000e+00 1.5000000e+00 INCH

INERTIA with respect to CS0 coordinate frame: (POUND * INCH^2)

INERTIA TENSOR:
Ixx Ixy Ixz 1.6483330e+00 0.0000000e+00 1.5745270e+00
Iyx Iyy Iyz 0.0000000e+00 3.7477021e+00 0.0000000e+00
Izx Izy Izz 1.5745270e+00 0.0000000e+00 2.2469812e+00

INERTIA at CENTER OF GRAVITY with respect to CS0 coordinate frame: (POUND * INCH^2)

INERTIA TENSOR:
Ixx Ixy Ixz 4.6743777e-01 0.0000000e+00 0.0000000e+00
Iyx Iyy Iyz 0.0000000e+00 4.6743762e-01 0.0000000e+00
Izx Izy Izz 0.0000000e+00 0.0000000e+00 1.4761190e-01

PRINCIPAL MOMENTS OF INERTIA: (POUND * INCH^2)
I1 I2 I3 1.4761190e-01 4.6743744e-01 4.6743795e-01

ROTATION MATRIX from CS0 orientation to PRINCIPAL AXES:
 0.00000 1.00000 0.00000
 0.00000 0.00000 1.00000
 1.00000 0.00000 0.00000

ROTATION ANGLES from CS0 orientation to PRINCIPAL AXES (degrees):
angles about x y z -90.000 0.000 -90.000 

RADII OF GYRATION with respect to PRINCIPAL AXES:
R1 R2 R3 5.3033009e-01 9.4372905e-01 9.4372956e-01 INCH

1-2-3 temp coordinate system at center of gravity is exactly where I'd expect it.

 

 

B
BB_104510931-VisitorAuthor
1-Visitor
October 12, 2022

Hi,

Thank's for your answer,

I made the same cylinder as you did. I have exactly the same mass analysis (different units 😉).
But the axis displayed seems to correspond to nothing, see attached picture. In my opinion, the axis I1 should be colinear to the axis of the cylinder (parallele to z axis).

What do I miss ?!

 

Capture.PNG

 

VOLUME = 5.3014376e+00 MM^3
SURFACE AREA = 1.7671459e+01 MM^2
DENSITY = 1.0000000e-06 KILOGRAM / MM^3
MASS = 5.3014376e-06 KILOGRAM
CENTER OF GRAVITY with respect to _PRT0001 coordinate frame:
X Y Z -2.0000000e+00 0.0000000e+00 1.5000000e+00 MM

INERTIA with respect to _PRT0001 coordinate frame: (KILOGRAM * MM^2)

INERTIA TENSOR:
Ixx Ixy Ixz 1.6649828e-05 0.0000000e+00 1.5904313e-05
Iyx Iyy Iyz 0.0000000e+00 3.7855577e-05 0.0000000e+00
Izx Izy Izz 1.5904313e-05 0.0000000e+00 2.2696780e-05

INERTIA at CENTER OF GRAVITY with respect to _PRT0001 coordinate frame: (KILOGRAM * MM^2)

INERTIA TENSOR:
Ixx Ixy Ixz 4.7215937e-06 0.0000000e+00 0.0000000e+00
Iyx Iyy Iyz 0.0000000e+00 4.7215921e-06 0.0000000e+00
Izx Izy Izz 0.0000000e+00 0.0000000e+00 1.4910293e-06

PRINCIPAL MOMENTS OF INERTIA: (KILOGRAM * MM^2)
I1 I2 I3 1.4910293e-06 4.7215903e-06 4.7215954e-06

ROTATION MATRIX from _PRT0001 orientation to PRINCIPAL AXES:
0.00000 1.00000 0.00000
0.00000 0.00000 1.00000
1.00000 0.00000 0.00000

ROTATION ANGLES from _PRT0001 orientation to PRINCIPAL AXES (degrees):
angles about x y z -90.000 0.000 -90.000

RADII OF GYRATION with respect to PRINCIPAL AXES:
R1 R2 R3 5.3033009e-01 9.4372905e-01 9.4372956e-01 MM

 

M
MartinHanak24-Ruby III
24-Ruby III
October 12, 2022

Hi,

please pack your part into zip file and upload zip file.

Mahesh_Sharma
Mahesh_Sharma22-Sapphire I
22-Sapphire I
October 17, 2022

Hi @BB_10451093,

 

I tested the part in Creo 7.0.2.0 and 7.0.9.0, already tested by Martin in Creo 7.0.5.0, seems it was a bug in Creo 7.0.2.0 as it is reproducible for me  in Creo 7.0.2.0 but not in other datecodes. 

 

Check the image from two of the datecodes 

 

 

I hope this will help. 

 

Thanks. 

P
PF_96936556-Contributor
6-Contributor
April 10, 2024

Hi all,

 

it seems that the bug continues in Creo 10.0.1.0 - . I see the roatation on the COG CS for the assigned parameter calculation.
Can someone confirm? Thanks

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