Acta Mechanica Solida Sinica

, Volume 21, Issue 4, pp 283–288 | Cite as

Analysis on Pseudo-Steady Indentation Creep

  • Hidenari Takagi
  • Ming Dao
  • Masami Fujiwara
Article

Abstract

Theoretical analysis and finite element (FE) simulation have been carried out for a constant specific load rate (CSLR) indentation creep test. Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover, the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate underneath the indenter evolve with geometrical self-similarity. This suggests that pseudo-steady indentation creep occurs in the region beneath the indenter. The representative points in the region are defined as the ones with the equivalent stress equal to the representative stress. In addition, it is revealed that the proportionality between indentation strain rate and equivalent plastic strain rate holds at the representative points during the pseudo-steady indentation creep of a power law material. A control volume (CV) beneath the indenter, which governs the indenter velocity, is identified. The size of the CV at the indented surface is approximately 2.5 times the size of the impression. The stress exponent for creep can be obtained from the pseudo-steady indentation creep data. These results demonstrate that the CSLR testing technique can be used to evaluate creep parameters with the same accuracy as conventional uniaxial creep tests.

Key Words

indentation creep finite element method conical indenter geometrical self-similarity pseudo-steady state control volume stress exponent 

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Copyright information

© The Chinese Society of Theoretical and Applied Mechanics and Technology 2008

Authors and Affiliations

  • Hidenari Takagi
    • 1
  • Ming Dao
    • 2
  • Masami Fujiwara
    • 1
  1. 1.Division of Applied Physics, College of EngineeringNihon UniversityFukushimaJapan
  2. 2.Department of Materials Science and Engineering, School of EngineeringMassachusetts Institute of TechnologyCambridgeUSA

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