Theoretical Shear Stress
Frenkel performed a simple calculation of the theoretical shear strength of crystals by considering two adjacent and parallel lines of atoms subjected to a shear stress as shown in Figure 10.2.
“b” is the inter-atomic distance or the distance between atoms in the slip directions
“a” is the separation between adjacent planes or the spacing between adjacent lattice planes.
Under the action of the stress ?, the top line will move in relation to the bottom line; the atoms will pass through successive equilibrium positions A, B, C, for which ? is zero.