We perform three-dimensional dislocation dynamics simulations of solid and annular pillars,
having both free-surface boundary conditions, or strong barriers at the outer and/or inner
surfaces. Both pillar geometries are observed to exhibit a size effect where smaller pillars
are stronger. The scaling observed is consistent with the weakest-link activation mechanism
and depends on the solid pillar diameter, or the annular pillar effective diameter, Deff= D−
Di, where D and Di are the external and internal diameters of the pillar, respectively. An …

We perform three-dimensional dislocation dynamics simulations of solid and annular pillars,
having both free surface boundary conditions, or strong barriers at the outer andor inner
surfaces. Both pillar geometries are observed to exhibit a size effect where smaller pillars
are stronger. The scaling observed is consistent with the weakest-link activation mechanism
and depends on the solid pillar diameter, or the annular pillar effective diameter, Deff D-Di.
An external strong interface is observed to dramatically increase the dislocation density by …