Friction !!!

Hi Every body,
I have following queries:-

kindly tell me whether we can consider friction as a non continuous force ( in the sense that it is not always acting, active only during installation to hot and other thermal cycles).

From what I remember friction coeffecient is area independent.So whether we use a knife edge support or a support with a finite area , in my opinion the friction force should remain same.Am I correct? If we have to consider a guide or directional limit stop ( with zero gap) as a rotational stop also ,then the friction force at these points must equal a force couple which is required to prevent rotation. Can friction generate such a magnitude of force couple which will make the joint rotationally rigid ( as if we model such a support as rotational restraint also, Caesar considers it as a rigid rotational restraint with near infinity stiffness). So is it logical to consider such supports as rigid rotational restraint ?

Regads ,

Raj. Received on Tue Apr 02 03:59:00 2002