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Author: ddelaiar
Time: 02/07/03 07:37 PST
This is a reply to message no. 10528 by ddelaiar
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Press Fit Pressure
Neil,
I'm also having trouble assuring myself of what to do once I get this pressure.  Maybe just typing this will help me talk my way through it.

Once I have a Pressure acting at the interface of the two pieces (let's call it P for conversation sake) and an area created by the interface (A), then I can create a force (F)

F = P*A

Now, I'm thinking this force should be acting in a LOA through the center of the circle and can be constructed as a point force.  This is where I come into trouble.  Part of me is saying that, since the pressure acts equally (or at least theoretically equally) amongst every place on the area of interference, then a point force won't suffice.  However, another part (and one I tend to agree more with is telling me that, since I incorporated a pressure and area for the entire interface, then it is ok to model it as a point force acting through the center of the circle.  Similar to designing a brake shoe.  Because, we are essentially desingin a brake that encompasses the entire 360-degrees of the item we are trying to constrict.

OK, so I pretty much just talked myself into using a point force, derived from the pressure and total area, that has a LOA through the center of the circle.  This force, in conjunction with the static coefficient of friction, will create a friction force.  I can then figure out what amount of torque (moment) must be applied before slippage occurs.

Does this all sound correct to you?  Sorry to bother you so much, but I'm a young engineer thrown into a position where I'm the only ME (read: I'm in a bit over my head) and just want to make sure I'm not overlooking anything.

Thanks again,
Dan
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