Seminar Jorge Alcalá: Multi-scale mechanistic interpretations to indentation experiments across the material length scales: from continuum to atomistics

Prof. Jorge Alcalá (Universitat Politècnica de Catalunya)

We provide a fundamental contact mechanics background to the interpretation of spherical indentation experiments performed in polycrystalline aggregates, single crystalline units, thin films, and minute material scales comprising an atomistic ensemble. A central issue under examination is the extraction of mechanical properties from hardness measurements as well as from instrumented indentation applied load-penetration depth curves performed in all such material lengths. Our analyses shed light into the role of the plasticity mechanisms (dislocation slip vs twining) upon the onset of size effects in metal plasticity. Emphasis is given to the analysis of noticeable differences between nanocontact plasticity in face-centered cubic (FCC) and body-centered cubic (BCC) crystals leading to characteristic surface topographies (material pileup and surface rosettes) upon indenter tip removal. The investigation comprises systematic continuum polycrystalline and crystal plasticity finite element simulations, molecular dynamics simulations and macro/micro/nano-indentation experiments.

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