Authors
Keng-Lin Lee, Ting-Yin Yeh
Published in
Proceedings of the National Academy of Sciences of the United States of America. Volume 122. Issue 40. Pages e2516426122. Oct 07, 2025. Epub Sep 29, 2025.
Abstract
Granular materials under loading exhibit intermittent avalanches of varying sizes prior to full yielding, a hallmark of natural failure phenomena such as landslides and earthquakes. While continuum models for postyield plastic flow are well established, a unified framework connecting preyield avalanche dynamics to bulk rheology remains lacking. Here, we introduce a birefringent double-shear experiment that enables sustained probing of avalanche statistics and quasistatic flow behavior near the yielding transition. We find that the avalanche regime exhibits rate-weakening behavior, while the plastic regime is rate-independent, resulting in dual rheology under identical local shear rates and indicating hysteresis and mechanical instability. Within a stress-activated framework, we identify the mean normalized stress drop, a measure for mesoscale avalanche size, as a key field variable that bridges the two regimes. Incorporating this variable, we formulate a unified constitutive model that captures the entire yielding transition. These findings establish mesoscale avalanche evolution as a central mechanism underlying granular yielding rheology.
PMID:
41021805
Bibliographic data and abstract were imported from PubMed on 30 Sep 2025.
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