Journal article
Influence of modulus-to-hardness ratio and harmonic parameters on continuous stiffness measurement during nanoindentation
Publication Details
Authors: | Merle, B.; Maier-Kiener, V.; Pharr, G. |
Publisher: | PERGAMON-ELSEVIER SCIENCE LTD |
Publication year: | 2017 |
Journal: | Acta Materialia |
Pages range : | 167-176 |
Volume number: | 134 |
Start page: | 167 |
End page: | 176 |
Number of pages: | 10 |
ISSN: | 1359-6454 |
DOI-Link der Erstveröffentlichung: |
Abstract
Dynamic nanoindentation is a popular method for continuously probing the mechanical properties of a sample as a function of depth. It is shown here that special caution should be exercised when testing materials with high modulus-to-hardness ratios (E/H) at fast loading rates, as the choice of harmonic parameters can result in a significant underestimation of the contact stiffness and hence the elastic modulus. The origin of this behavior is traced back to a bias occurring during signal processing by the lock-in amplifier. The possible consequences of flawed measurements are highlighted and a practical method for detecting possible occurrence from the phase angle signal is presented. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Dynamic nanoindentation is a popular method for continuously probing the mechanical properties of a sample as a function of depth. It is shown here that special caution should be exercised when testing materials with high modulus-to-hardness ratios (E/H) at fast loading rates, as the choice of harmonic parameters can result in a significant underestimation of the contact stiffness and hence the elastic modulus. The origin of this behavior is traced back to a bias occurring during signal processing by the lock-in amplifier. The possible consequences of flawed measurements are highlighted and a practical method for detecting possible occurrence from the phase angle signal is presented. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
Keywords
Continuous stiffness measurement, Harmonic parameters, Lock-in amplifier, Nanoindentation, Stiffness bias
