### Abstract

The indentation size effect in spherical indentation experiments is studied via the conventional theory of mechanism-based strain gradient plasticity (CMSG) established from the Taylor dislocation model. Two approaches are adopted in the present study. The first, an extension of Johnson's [Johnson, K.L., 1970. The correlation of indentation experiments. Journal of the Mechanics and Physics of Solids 18, 115-126.] theoretical indentation model based on CMSG, fails to predict the experimental data for iridium. The finite element method for CMSG is used to characterize the indented material in the second approach. The predicted indentation hardness agrees well with the experimental data. A simple, analytic indentation model is established to give the indentation hardness H=H02+141α2μ2bR in terms of the radius R of the spherical indenter, where H
_{0}
is the indentation hardness without accounting for the tip radius effect (i.e., given by classical plasticity theories), μ is the shear modulus, b is the magnitude of the Burgers vector, and α is the empirical coefficient around 1/3 in the Taylor dislocation model.

Original language | English (US) |
---|---|

Pages (from-to) | 1265-1286 |

Number of pages | 22 |

Journal | International journal of plasticity |

Volume | 22 |

Issue number | 7 |

DOIs | |

State | Published - Jul 1 2006 |

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### Keywords

- Indentation size effect

### ASJC Scopus subject areas

- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering

### Cite this

*International journal of plasticity*,

*22*(7), 1265-1286. https://doi.org/10.1016/j.ijplas.2005.07.008

}

*International journal of plasticity*, vol. 22, no. 7, pp. 1265-1286. https://doi.org/10.1016/j.ijplas.2005.07.008

**The indentation size effect in the spherical indentation of iridium : A study via the conventional theory of mechanism-based strain gradient plasticity.** / Qu, S.; Huang, Y.; Pharr, G. M.; Hwang, K. C.

Research output: Contribution to journal › Article

TY - JOUR

T1 - The indentation size effect in the spherical indentation of iridium

T2 - A study via the conventional theory of mechanism-based strain gradient plasticity

AU - Qu, S.

AU - Huang, Y.

AU - Pharr, G. M.

AU - Hwang, K. C.

PY - 2006/7/1

Y1 - 2006/7/1

N2 - The indentation size effect in spherical indentation experiments is studied via the conventional theory of mechanism-based strain gradient plasticity (CMSG) established from the Taylor dislocation model. Two approaches are adopted in the present study. The first, an extension of Johnson's [Johnson, K.L., 1970. The correlation of indentation experiments. Journal of the Mechanics and Physics of Solids 18, 115-126.] theoretical indentation model based on CMSG, fails to predict the experimental data for iridium. The finite element method for CMSG is used to characterize the indented material in the second approach. The predicted indentation hardness agrees well with the experimental data. A simple, analytic indentation model is established to give the indentation hardness H=H02+141α2μ2bR in terms of the radius R of the spherical indenter, where H 0 is the indentation hardness without accounting for the tip radius effect (i.e., given by classical plasticity theories), μ is the shear modulus, b is the magnitude of the Burgers vector, and α is the empirical coefficient around 1/3 in the Taylor dislocation model.

AB - The indentation size effect in spherical indentation experiments is studied via the conventional theory of mechanism-based strain gradient plasticity (CMSG) established from the Taylor dislocation model. Two approaches are adopted in the present study. The first, an extension of Johnson's [Johnson, K.L., 1970. The correlation of indentation experiments. Journal of the Mechanics and Physics of Solids 18, 115-126.] theoretical indentation model based on CMSG, fails to predict the experimental data for iridium. The finite element method for CMSG is used to characterize the indented material in the second approach. The predicted indentation hardness agrees well with the experimental data. A simple, analytic indentation model is established to give the indentation hardness H=H02+141α2μ2bR in terms of the radius R of the spherical indenter, where H 0 is the indentation hardness without accounting for the tip radius effect (i.e., given by classical plasticity theories), μ is the shear modulus, b is the magnitude of the Burgers vector, and α is the empirical coefficient around 1/3 in the Taylor dislocation model.

KW - Indentation size effect

UR - http://www.scopus.com/inward/record.url?scp=33344475846&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33344475846&partnerID=8YFLogxK

U2 - 10.1016/j.ijplas.2005.07.008

DO - 10.1016/j.ijplas.2005.07.008

M3 - Article

VL - 22

SP - 1265

EP - 1286

JO - International Journal of Plasticity

JF - International Journal of Plasticity

SN - 0749-6419

IS - 7

ER -