The stress field of an edge dislocation is more complex than that of a screw disloca­tion. However, in a similar way, a Volterra-type edge dislocation can be created as done for screw dislocation. In Figure 4.13b, such a case is shown. But in this case, the cut has been made perpendicular to the z-axis and a displacement ofb has been made. Thus, the magnitude of the simulated edge dislocation is b that is perpendic­ular to the dislocation line, and hence an edge dislocation. Here also the solution

breaks down when x and y approach zero. So, even in the edge dislocation, the core region does not follow linear elastic solutions. Without getting into the details of derivation, the stress field of an edge dislocation is shown below. It contains both dilatational (oxx, oyy, and ozz) and shear components (txy and tyx).

where C = Gb/(2p(1 — n)).

Here, n is the Poisson’s ratio. At y = 0 where the slip plane lies, all but the shear stress components given in Eq. (4.11c) are zero and the maximum com­pressive stress acts just above the slip plane with maximum tensile stress acting immediately below the slip plane. The stress field of mixed dislocations could also be found out.

4.2.3