| About this Abstract |
| Meeting |
2020 TMS Annual Meeting & Exhibition
|
| Symposium
|
Mechanical Behavior at the Nanoscale V
|
| Presentation Title |
Extending the Range of Constant Strain Rate
Nanoindentation Testing |
| Author(s) |
Benoit Merle, George M. Pharr |
| On-Site Speaker (Planned) |
Benoit Merle |
| Abstract Scope |
Constant strain rate nanoindentation is a popular method for accessing the local strength of complex materials. However, with currently available testing systems using continuous stiffness measurement (CSM), nanoindentation is so far limited to strain rates of ~0.1 s<sup>-1</sup>, which precludes it from ballistic applications.
Here, we show that the current limitation derives primarily from a plasticity issue related to the continuous stiffness measurements. Using a “sweet spot” frequency one order of magnitude higher than the standard harmonic oscillation, we show that valid hardness measurements are possible up to ~1 s<sup>-1</sup>.
In order to access even higher deformation rates, the Oliver-Pharr evaluation method was modified, so as to avoid the need for a measurement of the contact stiffness. With this improvement, the experimental upper strain rate limit is mostly determined by the time constants of the hardware components and lies around 100 s<sup>-1</sup> with most current commercial systems. |
| Proceedings Inclusion? |
Planned: Supplemental Proceedings volume |