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Re: Torsional constant
Re: Torsional constant -- ollagnij	Post Reply	Top of thread	Forum

Posted by: cakub ® 11/08/2006, 17:40:49 Author Profile eMail author Edit

You don't need to use any integral. Just tables of polar moments of inertia of your I beam. The angle of twist Fi of a beam that has constant polar moment of inertia Jp [m^4], length L[m]and the torque T[N.m] applied at both ends of the beam is Fi=T.L/(G.Jp). The torsional spring constant of such a beam is found from the condition T=Kfi*Fi. Comparing these two expressions you get Kfi=G.Jp/L[N.m/rad]. If your beam has several (say n parts) of uniform Jpi and lengths Li, then you have to calculate torsional constant for each part first. You will get Kfi1, Kfi2,....,Kfin. These parts are in fact torsional springs in series. Therefore resulting torsional spring constant K of whole beam will be found from 1/K=1/Kfi1+1/Kfi2+.....+1/Kfin

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Re: Re: Torsional constant
Re: Re: Torsional constant -- cakub	Post Reply	Top of thread	Forum

Posted by: phatso86 ® 07/05/2007, 11:52:32 Author Profile eMail author Edit

i had to register to correct the last statement the polar moment of inertia is NOT the torsional constant you will be really screwed up if u assume it is for anything besides a circular cross section

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