Interpreting strain bursts and size effects in micropillars using gradient plasticity

X. Zhang, K. E. Aifantis

Research output: Contribution to journalArticle

25 Scopus citations

Abstract

Size effects and strain bursts that are observed in compression experiments of single crystalline micropillars are interpreted using a gradient plasticity model that can capture the process of sequential slip and heterogeneous yielding of thin material layers. According to in situ experiments during compression sub-grains and significant strain gradients develop, while deformation occurs through slip layers in the gauge region. In the multilayer strain gradient model, the higher order stress is discontinuous across the interface between a plastic layer and an elastic layer, but it becomes continuous across the interface between two plastic layers. Strain bursts occur when two neighboring layers yield. Based on this hypothesis the experimental stress-strain curves with strain bursts observed in micropillars can be fitted by properly selecting the number of layers that yield and the ratio of the internal length over the specimen size; the modulus and the yield stress are obtained from the experimental curves while the hardening modulus evolves during deformation based on the dislocation mechanisms.

Original languageEnglish (US)
Pages (from-to)5036-5043
Number of pages8
JournalMaterials Science and Engineering A
Volume528
Issue number15
DOIs
StatePublished - Jun 15 2011

Keywords

  • Micropillar compression
  • Size effects
  • Strain bursts
  • Strain gradient

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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