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Rotational Velocity Units

Gears Phenom Gears Phenom
Gears Phenom

What is the units for Rotational Velocity applied as a body load?

 

Using the NX User guide this is clearly rad/s:

 

UNITS1.JPG

 

However, whenever I use rad/s I'm experiencing some strange results. Using a NAFEMS benchmark (attached), see the below results. Essentially the analysed disk should see approx. 32MPa at the the centre of the disk.

 

Using rad/s:

 

rads.JPG

 

Using rev/m:

 

rpm.JPG

 

Using rev/s:

 

revs.JPG

 

 

3 REPLIES 3
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Re: Rotational Velocity Units

Gears Phenom Gears Phenom
Gears Phenom

Look like rotational speed units are rev/time instead of rad/time. Nastran internally multiply angular speed by 2*pi.

Here is part of RFORCE card description.

1.JPG

Re: Rotational Velocity Units

Gears Phenom Gears Phenom
Gears Phenom
Hi Karachun

Which makes sense as that is the unit that Nastran is using for the calculation.

Seems strange to me to mix up the units in Femap - the user guide calls out rad/s - nastran uses rad/s - I would assume Femap would be in rad/s.

But then again the RFORCE cards calls it out.

Re: Rotational Velocity Units

Gears Phenom Gears Phenom
Gears Phenom

I think that NX gui take rad/s and convert it to rev/s when write Nastran input file. Femap directly write value from preprocessor to .dat file.