01:08:06
Valid hardness measurements require actually causing plasticity. Thus, we must know the threshold and locus for the onset of plasticity. In this session, we use the Tresca criterion to understand the onset of plasticity for both Hertzian and conical indentation. These criteria guide our understanding of the minimum depth at which one can measure a meaningful hardness.
52:42
Force and displacement measurements obtained from instrumented indentation experiments are interpreted using elastic contact models, even when the contact causes plastic deformation. Elastic contact models specify the ideal relationship between force, displacement, and elastic properties. Such models are explained in this presentation. Ian Sneddon’s elastic contact model is given special attention due to its generality, and the models of Hertz and Love are shown to be special cases of Sneddon’s model. Many examples are provided which show how to apply Sneddon’s model to specific geometries ...
