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Description
Liping Huang1

1, Rensselaer Polytechnic Institute, Troy, New York, United States

To evaluate the damage resistance of glasses, instrumented indentation using sharp indenters is the method of choice, as it can mimic real-life damage incidents under controlled conditions. Furthermore, indentation provides a useful system to study crack initiation, as unstable crack propagation is prevented by the highly localized stress state. However, unravelling the nature of structural change under indentation is a formidable task in experiment because of the complexity that originates from the atomic-scale disorder of glass, and the experimental difficulties associated with the in-situ investigation at a local scale (tens of microns) under very high stresses. To this send, computer simulations can provide an important complement to experimental approaches. In this work, we carried out large scale molecular dynamics (MD) simulations to investigate the effect of quench pressuring during hot compression and chemical composition variation on the response of glass to nanoindentation. A rigid hollow Vickers indenter made of carbon atoms is used to indent the glass sample with a fixed loading rate, during which atoms in the indenter interact with the glass via a repulsive force field. To minimize the boundary condition effects in simulated nanoindentation tests, large samples of several hundred nm in lateral dimensions are used. The indenter angle is varied to study the effect of the indenter sharpness on the deformation of glasses, as what has been done in experiments. Short- and medium-range order of the plastically deformed glass are compared with those in the undeformed region. These simulated nanoindentation tests reveal how the stress field and glass structure evolve with the deformation underneath the indenter, which in turn shed light on the degree of densification and pile-up in different glasses.

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