Size effect on the compressive strength of hollow micropillars governed by wall thickness

The compressive behavior of hollow micropillars is modeled by three-dimensional discrete dislocation dynamics (3D-DDD). Computational results show that wall thickness is the principal geometrical parameter governing the compressive strength of these micropillars, while inner or outer diameter has a weak influence. This is because the plastic behavior is dominated by the single-arm dislocation sources with statistical lengths determined by the wall thickness. The single-arm source model is further extended to quantitatively describe this thickness effect, showing good agreement with the present 3D-DDD results. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.