| Autor: |
Warren, Oden L., Downs, Seth A., Wyrobek, Thomas J. |
| Zdroj: |
International Journal of Materials Research: Zeitschrift fuer Metallkunde; February 2022, Vol. 95 Issue: 5 p287-296, 10p |
| Abstrakt: |
Accurate feedback control of the nanoindentation process is particularly challenging from the perspectives of many orders of magnitude change in contact stiffness and the use of the ramp/hold/ramp protocol. The conventional proportional-integral-derivative feedback control algorithm is not well suited for such an application. Here we provide a description and present performance data for a newly developed digital control algorithm that augments the familiar proportional-integral-derivative routine with an adaptive feedforward control having inputs related to open-loop device physics and encountered contact mechanics. This novel approach results in reproducing even a steep demand ramp with minimal feedback error. Additionally, we discuss interesting observations made with respect to the varied displacement-controlled nanoindentation responses of materials. Metals, in particular, are found to expose especially rich nanomechanical phenomena when the force-displacement curves are measured under displacement control. The findings of this study nicely illustrate the decided scientific advantages of displacement control over load control. |
| Databáze: |
Supplemental Index |
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