CALCULATING APPLIED PRESSURE FROM TORQUE 1

[radebenno]

Hi Folks

I'm intending to laminate some wooden beams and want to use bolts acting through a series of theaded arms along the lenght of the beam to consistently apply the necessary pressure, about 200psi along the length of the beam every 6 inches or so. Is there a way of calculating the pressure generated by a specific torque applied to a bolt of given diameter and thread pitch?

radebenno

 

[quark]

You can use design principles of a screw jack, IMHO.

 

[MintJulep]

The relationship between torque and tension of a threaded fastener is well documented, although tenuous.

The simplest formula is F = T/KD

where F is the tension produced, T is the torque applied in pound-inches, D is the diameter of the fastener in inches and K is the "nut factor", commonly assumed to be about 0.2.

Applied to your case, add up the tension of all of the individual fasteners and divide by the total contact area between the laminations. This will produce a very crude approximation of the average contact pressure.

Wood is far from rigid, so the pressure will not be uniform at all.

 

[CoryPad]

The long-form of the equation MintJulep shows is provided here:

faq725-536

Regards,

Cory

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