Characterization and modeling of large displacement micro-/nano-lndentation of polymeric solids

Y. C. Lu, D. M. Shinozaki

Research output: Contribution to journalArticlepeer-review

14 Scopus citations


Large displacement micro-indentation tests have been performed on various polymeric solids to measure the plastic properties. Cylindrical flat-ended indenters with diameter in the range of 10-90 μm are mostly used. The mechanism of large-strain indentation has been examined with optical microscopy and finite element simulations. Results show that under a flat-tipped indenter, the material can quickly reach a fully plastic state. The size (diameter) of the plastic zone is constant in large-strain regions and unaffected by the exact tip profile (flat, spherical, and conical). The indentation stress-displacement curve at large strains is linear as a result of the steady-state plastic flow, from which the mean indentation pressure, a measure of yield strength, can be readily extrapolated. The indentation stress-displacement response is independent of the indenter diameters but strongly dependent on the strain-hardening behavior of the material and the friction between a material and an indenter. Compared with other shaped indenters, the flatended indenter requires the least penetration depth in order to probe the plastic properties of a material or structure.

Original languageEnglish
Pages (from-to)410011-410017
Number of pages7
JournalJournal of Engineering Materials and Technology
Issue number4
StatePublished - Oct 2008


  • Finite element
  • Micro-indentation
  • Plasticity
  • Polymer

ASJC Scopus subject areas

  • General Materials Science
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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