Structrual Engineer's blog

Does pure shear stress exist?

1. Frictional force applied on a surface:

  A frictional force is often taken to be a horizontal resistance offered by the surface on a interacting surface. let us observe that frictional force arises only when there is unevenness in the contacting surfaces and a horizontal force is along with normal force is applied on the contact surface.  Thus, it is essentially the  sum of all horizontal components of normal contact forces between the uneven boundaries in the horizontal direction of motion of the surfaces in contact.

I have been bugged by this question ever since I studied cauchy's stress theory 10 years ago.

In cauchy's analysis of solids, there two popular geometries.

First one is a unit cube used for deriving equations of equilibrium.

And the second one is a tetraheadon used for deriving Cauchy's stress theorem.

In both the cases limit of force equilibrium as solid geometry shrinks to a point is derived.

My question has been, how come limit of force equilibrium at a point inside a solid depenent on the path taken by limiting process.