Yield Stress of a Polycluster

As a result of stress concentration on the edges of boundary shift sections, the stress may achieve the LRC strength limit 

In this case, the glide layer propagates from the boundary into the cluster body, which leads to the nonuniform plastic deformation of a polycluster. Thus the macroscopic yield stress of a polycluster a, as it follows from (6.25), is determined by the relation 

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