Séminaire LTDS (comodal : en ligne & présentiel - ECL) : Progress in the Development of High Strain Rate Nanoindentation Experiments

Warren C. Oliver
KLA Corporation, 105 Meco Ln, Oak Ridge, TN, 37830, USA

En présentiel : ECL, Amphi 203

Lien Zoom : https://ec-lyon-fr.zoom.us/j/94841944416?pwd=NzAzZGx5eDBBaGdVUTNmZElQcElmZz09

Résumé au format pdf

High strain rate testing using instrumented indentation has recently received considerable attention. High strain rates are achievable at reasonable indenter velocities because the sample size is small. An instrument capable of 1.25 Mhz displacement measurements, sub nanometer resolution and a time constant of 10 microseconds has been constructed. While the system directly measures the
displacement signal needed accurately, measuring the loads exerted on the sample in sub millisecond experiments can be challenging. In some cases, the time constant of the loading system must be considered. In addition, the load can be dominated by inertial effects. A number of approaches for calculating or measuring the loads exerted on the sample will be discussed. In addition, preliminary experiments will be compared with modeling for two specific experiments. They are the step load experiment in which the load is stepped on from the point of contact and the impact experiment in which the load is stepped on when the indenter is some distance above the sample. The results indicate that the strain rate effect in fused silica is small. In the case of aluminum care must be taken to separate size indentation effects from strain rate effects.