Relation between Torque and Tension

[slickdeals]

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.

 

[Ron]

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.

 

[kslee1000]

You may getting more info by posting on "Welding, Bonding & Fastener engineering Forum".

 

[Bribyk]

As above, there have been discussions of this in that forum. Do a search first as this quickly becomes a hotly debated topic.