Coefficient of friction of the two surfaces...

[ALEng2]

Hi, I have what should be a simple problem but have already had multiple different answers from qualified engineers.

Looking at the attached image the problem is as follows:

The green wedge is pushed downwards by force F.

Due to the shape of the wedge and the retaining jaws there will be horizontal forces pushing the jaws outwards – R1 and R2. As the geometry is the same each side, R1 will equal R2.

The jaws are retained and cannot move.

In terms of F, what does R1 (and R2) equal?

The basic equation is answered in my post below, but how does the coefficient of friction affect this?

Thanks.

 

[Denial]

Maybe the jaws cannot MOVE, but they can DEFORM, as can the wedge.[ ] As far as the friction force (or lack of it) is concerned there is little essential difference.[ ] I stand by my above conclusion that in the absence of full knowledge of the load history we can only put upper and lower bounds on the R force.

Maybe the OP can give us some help with this.

 

[desertfox]

Hi
Denial but if the jaws deform they are moving and thre is relative movement between the faces but
OP said there is no movement.
If you take a pin joint in a structure like in a roof truss do you consider the friction force in it due to the joint distorting?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[tmschrader]

Hello in this case there is a Force pushing on the Block. As per OP
In the conventional case of a block on a horizontal surface the normal force is totally dependent on the weight. friction is in the horizontal direction that does not affect the weight.

In this case and many others the the force creates the normal force. And by the sum of the forces in the Force direction, the one component of friction opposes some of the Force thereby reducing the normal force. As shown in my previous post. The friction may be irrelevant from a practical standpoint but this is an academic question. Wieght has been ignored or is trivial.

A similar problem might be a heavy block an inclined surface. Where the inclination is pretty close to the friction Factor. If the force is not parallel to the inclined surface it will either add or subtract from the normal force created by the weight of the block

 

[desertfox]

Hi tmschrader

The sketch shown in the original post shows only a cross section and no mention of whether the block is on an incline or not, I assumed it was horizontal and that the mass was negiable compared to the force holding it in position, however again the friction force will be zero unless it is opposing a force tending to create motion, this is also the case even if the parts deform under load.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein