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# Re: CG in cylindrical CSYS

Gears Phenom
Me too. Looks like they fixed it..
Graham Inchley Snr R&D Engineer (Systems Development), Sandvik Coromant
Dell 7530 Precision, Win10, 32GB. Developing in: Java | C | KF
Production: [NX12.0.2 MP1]

# Re: CG in cylindrical CSYS

Gears Esteemed Contributor

Use an associative measure body to create a point at the CG of the body then use measure point to get expressions for the X,Y,Z coordinates of the CG. In the expression system, you can create expressions to get the r and theta values (you already have the z value).

r = sqrt(x^2 + y^2)

theta = atangent2(x,y)

Use the measure point expression names for the X and Y coordinates in place of x and y above.

The above will work in NX 9, but I'm not sure if lower versions have the "measure point" function.

# Re: CG in cylindrical CSYS

Experimenter

Thank you @mike_fdo i can see it now.

But it seems your files are in NX11 and here i am using NX9.

# Re: CG in cylindrical CSYS

Siemens Phenom

@cowski1 wrote:

Use an associative measure body to create a point at the CG of the body then use measure point to get expressions for the X,Y,Z coordinates of the CG. In the expression system, you can create expressions to get the r and theta values (you already have the z value).

r = sqrt(x^2 + y^2)

theta = atangent2(x,y)

Use the measure point expression names for the X and Y coordinates in place of x and y above.

The above will work in NX 9, but I'm not sure if lower versions have the "measure point" function.

Just to mention that, 'Measure Point' command was introduced in NX 9.

# Re: CG in cylindrical CSYS

Experimenter

Expression and formulae you mentioned will give me cylinderical coordinates of Point created at CG and not the radial CG value.

For Example :

If we consider and cylinder with radius 10 and z-axis as cylinder axis, CG values in X-and Y direction from cartesian CSYS will be equal to zero and hence r and theta value calculated from these X and Y values will also be zero.

But on the other hand if i calculate CG in cyclinderical CSYS from basics formulae R = integration (m.dr)/total mass and setiing limits of integration from 0 to 10 , i will get a positive value.

Hope you got what i am looking for.

# Re: CG in cylindrical CSYS

Gears Esteemed Contributor

Are you saying that if you calculate the center of gravity  of a cylinder with the cylinder's axis = Z axis using cylindrical coordinates, the CG does NOT lie on the axis? If so, either you are calculating something other than the CG of the body or you need to check your math.

# Re: CG in cylindrical CSYS

Siemens Phenom
I'm with Cowski, here. The CG is where it is.Changing the variables you use in integration isn't going to change the location of the CG.