Inertia Calculations

Off topic:
This brings to my mind my discussion with some ... engineer.


The topic was vacuum pumps. Their name plates were stating something like -0.2 bar and second one 0.6 bar. According to that guy, the first one was "creating" better vacuum. Or maybe more vacuum in vacuum?


And why did I mention it? Well, mathematical description of things requires models. They are build one on top of the other from very simple (like F=m*g) to more complicated (which is in fact usually the order the humanity discovered them). The trick is to know why they are so simplified and can still work while the reality is much more abstruse.

Regards,
Jacek Dobrowolski
 
Hi Friends,

Can we calculate thickness of tube if following parameter is provided-

Outer Diameter of Tube- 159 mm
Tube Length - 4231 mm
Continuous Torque @2.0 SF- 621 N-m
Peak Overload Torque - 1864 N-m
Tube Assembly - Composite Material

Thanks & Regards,
Prashant
 
Hi Phil, I hope you read this

I read a lot on the subject and I still have not reached a conclusion, maybe you can help me:

I use software for motor starting calculations in which I am asked to enter the following data:

"Enter the rated speed in revolutions per minute (RPM) and WR2 in either lb-ft2 for English unit system or in Kg-m2 for Metric unit system or H in MW-sec/MVA for the Motor, Coupling Gear, and Load. ETAP calculates WR2 or H when one of them is known and RPM has been entered based on the following equation:<pre>

H = 5.48 * 10-9 * WR2 * RPM2 / MVA (for WR2 = Moment of inertia in kg-m2)</pre>

So... my doubt is whether I should insert GD^2 or GD^2/4 as WR^2

I am using metric units, and I only have a "box" to enter a value for WR^2

What do you think?

Best regards,
Juan
 
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