huangyhg

relation between torque and tension
folks,
are there any cook book relations between applied torque and tension? i read that the relations are not precise and there a lot of variables in the equation.
i am trying to find out how much bearing pressure is exerted by a nut/washer on a wood member when torque is applied on a expansion anchor that goes through the wood member.

i'm doing this from memory, so hopefully someone will correct me if i'm wrong (and i'm sure they will!!)....
f= torque/(c)(d), where c=national fudge factor for friction, thread pitch, etc., d=nominal diameter of the fastener, f=tensile force in the bolt.
"c" is in the range of 0.02 to 0.04 for high strength bolts
i'm sure this relationship is only good for a small range of bolt diameters, probably from about 3/8" to 1", and i backcalculated the relationship from empirical data based on a typical astm a325 bolt, 3/4" dia. will require between 350 to 400 ft-lbs of torque to achieve 70 percent of its tensile strength (for clamping force in high strength bolted connections)
this will probably get you in the ballpark.
you may getting more info by posting on "welding, bonding & fastener engineering forum".
as above, there have been discussions of this in that forum. do a search first as this quickly becomes a hotly debated topic.

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