Shear localization as a mesoscopic stress-relaxation mechanism in fused silica glass at high strain rates
Molecular dynamics (MD) simulations of fused silica glass deforming in pressure-shear, while revealing useful insights into processes unfolding at the atomic level, fail spectacularly in that they grossly overestimate the magnitude of the stresses relative to those observed, e. g., in plate-impact experiments. We interpret this gap as evidence of relaxation mechanisms that operate at mesoscopic lengthscales and which, therefore, are not taken into account in atomic-level calculations. We specifically hypothesize that the dominant mesoscopic relaxation mechanism is shear banding. We evaluate this hypothesis by first generating MD data over the relevant range of temperature and strain rate and then carrying out continuum shear-banding calculations in a plate-impact configuration using a critical-state plasticity model fitted to the MD data. The main outcome of the analysis is a knock-down factor due to shear banding that effectively brings the predicted level of stress into alignment with experimental observation, thus resolving the predictive gap of MD calculations.
© 2020 Elsevier Ltd. Received 22 November 2019, Revised 12 March 2020, Accepted 14 March 2020, Available online 20 March 2020. We gratefully acknowledge support from the US Office of Naval Research, Naval Materials S&T Division, Dr. R. G. Barsoum manager, through grant N000141512453. This work was supported by a NASA Space Technology Research Fellowship. We are also grateful to R. J. Clifton for many illuminating comments and suggestions. Author statement: We would appreciate your consideration of the revision of our manuscript entitled: "Shear localization as a mesoscopic stress-relaxation mechanism in fused silica glass at high strain rates," Ref: JMPS 2019 1006, co-authored with W. Schill, J.P. Mendez and L. Stainier. We have addressed all the substantive queries raised by the referees and made the corresponding changes to the manuscript. We are not aware of any conflicts of interest.