An atomistically-informed multiplicative hyper-elasto-plasticity-damage model for high-pressure induced densification of silica glass

WT Xu and Y Jiao and J Fish, COMPUTATIONAL MECHANICS, 66, 155-187 (2020).

DOI: 10.1007/s00466-020-01846-w

An atomistically-informed constitutive model based on multiplicative hyper-elasto-plasticity with damage is developed for the study of high- pressure induced densification of silica glass. At the atomistic level, a molecular dynamics (MD) representative volume element of amorphous silica (a-SiO2) is first constructed using the melt-quench approach. Within the MD framework, the deformation response of the RVE at different pressure and strain-rate levels is investigated. Results from the volumetric compression simulations suggest occurrence of irreversible densification at pressure above similar to 8 GPa whereas coupled compression-shear tests show yielding behavior of a-SiO2 upon sufficiently large shear deformation. In addition, rate dependency of densification/yielding behavior has been observed. Based on the data obtained from the MD simulations, a novel continuum-based multiplicative hyper-elasto-plasticity-damage model that accounts for the anomalous densification behavior is developed and then parameterized using both polynomial regression and deep learning techniques. The elasto- plasticity model alone captures densification behavior of "perfect" amorphous silica but does not account for damage evolution attributed to "imperfections". To impart the dynamic damage evolution, a plasticity- damage variable that controls the shrinkage of the yield surface is introduced and integrated into the elasto-plasticity model in a manner similar to the JH-2 model. The resulting coupled elasto-plasticity- damage model is reformulated to a non-ordinary state-based peridynamics model for computational efficiency of impact simulations. We show that the as-developed peridynamics model is capable of reproducing coarse- scale quantities of interest found in MD simulations and yet being able to simulate at a component level. Finally, the proposed atomistically- informed multiplicative hyper-elasto-plasticity-damage model has been validated against limited available experimental results for simulation of hyper-velocity impact simulation of projectiles on silica glass targets.

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