Non-Circular Torque Calc

[darrenredford]

I need to calaculate the torque required to rotate two components about the x axis. The components consist of a fuel tank and a pallet which have been are fixed together. I have the material properties, dimensions and weights of each component. I have the components assembled within a 3D cad model and from this i have been able of extract the inertial and polar properties of the combined entities. However, from reviewing several texts I have been lead to beleieve that the J - polar moment value is not sufficient for the torsion calculation.

Can somebody help me?

 

[TheTick]

In a frictionless system, torque is directly proportional to radial acceleration.

 

[corus]

They may be referring to the rotary inertia of the system, usually dependent on the mass and radius^2.

corus

http://www.corusresearch.com

 

[mirekp]

Please see the thread 404-75915, it is a similar problem.

Mirekp

http://www.mitcalc.com

Mechanical calculations

 

[CoryPad]

Mirekp,

For future reference, if you remove the space between thread and 404-75915 (e.g. thread404-75915), that will create a link that can be used to go directly to that thread.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[jdkuhndog]

darren,

your statement..."However, from reviewing several texts I have been lead to beleieve that the J - polar moment value is not sufficient for the torsion calculation"

I think (I could be wrong) the texts were referring to the polar moment of inertia not being sufficient for determining the stresses incurred and the angle of twists in a member from a torsional load...i.e. with the equations shearstress = Tc/J and theta = TL/EJ. Some texts (i.e. Blodgett) have developed Torsional Resistance values which better approximate stresses and twists for open beams.

In your case, you are talking about rotating objects of known properties about an axis, therefore this does not apply.