Indentation of elastically soft and plastically compressible solids

A. Needleman, Viggo Tvergaard, E. Van der Giessen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The effect of soft elasticity, i.e., a relatively small value of the ratio of Young's modulus to yield strength and plastic compressibility on the indentation of isotropically hardening elastic-viscoplastic solids is investigated. Calculations are carried out for indentation of a perfectly sticking rigid sharp indenter into a cylinder modeling indentation of a half space. The material is characterized by a finite strain elastic-viscoplastic constitutive relation that allows for plastic as well as elastic compressibility. Both soft elasticity and plastic compressibility significantly reduce the ratio of nominal indentation hardness to yield strength. A linear relation is found between the nominal indentation hardness and the logarithm of the ratio of Young's modulus to yield strength, but with a different coefficient than reported in previous studies. The nominal indentation hardness decreases rapidly for small deviations from plastic incompressibility and then decreases rather slowly for values of the plastic Poisson's ratio less than 0.25. For both soft elasticity and plastic compressibility, the main reason for the lower values of indentation hardness is related to the reduction in the hydrostatic stress level in the material below the indenter.
Original languageEnglish
JournalActa Mechanica Sinica
Volume31
Issue number4
Pages (from-to)473-480
ISSN0567-7718
DOIs
Publication statusPublished - 2015

Keywords

  • Plasticity
  • Compressibility
  • Indentation
  • Finite element analysis

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