Elastic-Viscoplastic transition in a modified Soft Glassy Rheology model

The elastic-viscoplastic transition of glassy materials is studied with a modified Soft Glassy Rheology (SGR) model that is newly suggested for more accurate description of rheological behavior of glassy materials. The modified SGR model incorporates sophisticated features of glassy materials, such as collective dynamics. The modified SGR model demonstrates different elastic-viscoplastic transitions depending on conditions such as methods of glassy dynamics description, flow conditions, and shear history. The rheological transition of SGR model under startup shear is interpreted in terms of local strain distribution change that represents physical state change. Based on the findings, we interrogate how various features of glassy dynamics affect the elastic-viscoplastic transition in glassy materials and discuss effective ways to describe glassy materials. Our results provide some clue to understand the physical origin of the elastic-viscoplastic transition in glassy materials.