Athermal Shear-Transformation-Zone Theory of Amorphous Plastic Deformation I: Basic Principles

TL;DR

This paper introduces an athermal shear-transformation-zone (STZ) theory for amorphous plasticity, applicable when thermal activation is negligible, simplifying previous models and clarifying the yielding process without relying on thermal fluctuations.

Contribution

It develops a simplified, thermodynamics-consistent athermal STZ theory with explicit transition threshold distribution and an effective temperature concept, broadening applicability to non-thermal amorphous materials.

Findings

Broader applicability to athermal systems

Simpler thermodynamic consistency

Clearer interpretation of yielding

Abstract

We develop an athermal version of the shear-transformation-zone (STZ) theory of amorphous plasticity in materials where thermal activation of irreversible molecular rearrangements is negligible or nonexistent. In many respects, this theory has broader applicability and yet is simpler than its thermal predecessors. For example, it needs no special effort to assure consistency with the laws of thermodynamics, and the interpretation of yielding as an exchange of dynamic stability between jammed and flowing states is clearer than before. The athermal theory presented here incorporates an explicit distribution of STZ transition thresholds. Although this theory contains no conventional thermal fluctuations, the concept of an effective temperature is essential for understanding how the STZ density is related to the state of disorder of the system.