Abstract
Purpose: The purpose of this study is to investigate the effect of anisotropy of cortical bone tissue on measurement of properties such as direction-dependent moduli and hardness. Methods: An advanced three-dimensional finite element model of microindentation was developed. Different modelling schemes were considered to account for anisotropy of elastic or/and plastic regimes. The elastic anisotropic behaviour was modelled employing an elasticity tensor, and Hill’s criteria were used to represent
the direction-dependent post-yield behaviour. The Oliver–Pharr method was used in the data analysis. Results: A decrease in the
value of the transverse elasticity modulus resulted in the increased material’s indentation modulus measured in the longitudinal
direction and a decreased one in the transverse direction, while they were insensitive to the anisotropy in post-elastic regime. On
the other hand, an increase in plastic anisotropy led to a decrease in measured hardness for both directions, but by a larger amount
in the transverse one. The size effect phenomenon was found to be also sensitive to anisotropy. Conclusions: The undertaken
analysis suggests that the Oliver–Pharr method is a useful tool for first-order approximations in the analysis of mechanical properties of anisotropic materials similar to cortical bone, but not necessarily for the materials with low hardening reserves in the
plastic regime.
the direction-dependent post-yield behaviour. The Oliver–Pharr method was used in the data analysis. Results: A decrease in the
value of the transverse elasticity modulus resulted in the increased material’s indentation modulus measured in the longitudinal
direction and a decreased one in the transverse direction, while they were insensitive to the anisotropy in post-elastic regime. On
the other hand, an increase in plastic anisotropy led to a decrease in measured hardness for both directions, but by a larger amount
in the transverse one. The size effect phenomenon was found to be also sensitive to anisotropy. Conclusions: The undertaken
analysis suggests that the Oliver–Pharr method is a useful tool for first-order approximations in the analysis of mechanical properties of anisotropic materials similar to cortical bone, but not necessarily for the materials with low hardening reserves in the
plastic regime.
| Original language | English |
|---|---|
| Pages (from-to) | 3-14 |
| Number of pages | 12 |
| Journal | Acta of Bioengineering and Biomechanics |
| Volume | 17 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 2015 |
Keywords
- finite element analysis
- anisotropy
- Oliver–Pharr method
- cortical bone tissue
- indentation