Simple Clamping Force / friction question
Simple Clamping Force / friction question
(OP)
In the picture attached, can somebody please explain if the axial force in each side of the U bolt creates 6000 N on each side of the bar , or is the 6000 N divided between each side?





RE: Simple Clamping Force / friction question
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Simple Clamping Force / friction question
So the force to slide the bar out of the U-bolt is 12,000*friction coeff?
That's what I was thinking but I'm not yet convinced. Only 6000 N is applied to the assembly after all.
RE: Simple Clamping Force / friction question
another day in paradise, or is paradise one day closer ?
RE: Simple Clamping Force / friction question
another day in paradise, or is paradise one day closer ?
RE: Simple Clamping Force / friction question
Coefficient of friction is determined by the materials only.
Friction depends only on the normal forces and the friction coefficient. It is not dependant on the contact area.
RE: Simple Clamping Force / friction question
test it ... bolt two bars together around a block, bolt two plates around a block; which is harder to move ?
another day in paradise, or is paradise one day closer ?
RE: Simple Clamping Force / friction question
http://boltcouncil.org/files/2ndEditionGuide.pdf
RE: Simple Clamping Force / friction question
RE: Simple Clamping Force / friction question
For locations where axial force is the issue, you really need to have a definable flat area to grip the pipe to avoid these issues or simply clamp the bar between two flat bits of metal.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Simple Clamping Force / friction question
However there is a possible further complication. Once slippage begins the bolt assembly might rotate infinitesimally, which would lead to what I believe are known as "binding forces". It might be this sort of effect that underlies rb1957's feeling that the plate's friction will be greater than the bolt's.
RE: Simple Clamping Force / friction question
I you split the system and diagram it, you will see it must be 6000N on each side (assuming "ideal" bolt that does not bend).
RE: Simple Clamping Force / friction question
Sliding force = 2x6000xFrictCoeff.
This is precisely what I presented to a customer who laughed and told me I was wrong.
I showed on a fbd how there must be an equal reaction force on the opposite side of the U-bolt, but he maintained that if the tension in the bolt is 6000 , it must be 3000 each side.
Obviously I realise that in reality that assembly would rotate and bind etc. before coming off. I just wanted to clarify the theory.
RE: Simple Clamping Force / friction question
RE: Simple Clamping Force / friction question
The round U Bolt is made of different material and has a different finish; it will not be the same.
It is [the load * cof] of the flat plates
Plus
the [load * cof] of the flat plate and the round U bolt.
Charlie
www.facsco.com
RE: Simple Clamping Force / friction question
another day in paradise, or is paradise one day closer ?
RE: Simple Clamping Force / friction question
RE: Simple Clamping Force / friction question
RE: Simple Clamping Force / friction question
RE: Simple Clamping Force / friction question
if you had the plate trapped between two U-bolts there'd be some friction, wouldn't there ?
another day in paradise, or is paradise one day closer ?
RE: Simple Clamping Force / friction question
One approach to equalizing the 2 load paths would be to apply the external load to the middle of the cantilever section of the u-bolt. That may, of course, not be practical in your application. Another approach would be to make the block load path more compliant or the cantilever load path more stiff (in bending I'd think but maybe also in shear).
RE: Simple Clamping Force / friction question
Impossible to model mathematically. Probably also impossible to get reliably reproducible results in a physical experiment. Murphy's Law will prevail: if you want to induce "binding", it won't happen; if you want to avoid binding, it will happen.