Shear banding as a cause of nonmonotonic stress relaxation after flow cessation

Ward, Vanessa K; Fielding, Suzanne M

Abstract

Recent flow cessation experiments on soft materials have shown a counter-intuitive non-monotonic relaxation of the shear stress: following the switch-off of a steady imposed shear flow, the stress initially decays before later increasing again. By simulating the soft glassy rheology model in a form extended to allow steady state shear banding, we show that the presence of shear bands prior to flow cessation can give rise to this phenomenon. We give a mechanistic understanding of the basic physics involved, in terms of (i) the decay of the shear bands after flow cessation, and (ii) the evolution of frustrated local stresses, governed by different time scales for plastic relaxation in each band. In particular, an elastic recoil in the unsheared band gives rise to negative local frustrated stresses, the slow release of which can cause an increase in macroscopic stress. Given that shear banding and frustrated local stresses arise widely across disordered soft solids, we argue that non-monotonic stress relaxation after flow cessation may occur in many different materials.

Citation

Ward, V. K., & Fielding, S. M. (2025). Shear banding as a cause of nonmonotonic stress relaxation after flow cessation. Physical Review Materials, 9(2), Article L022601. https://doi.org/10.1103/PhysRevMaterials.9.L022601

• Journal Article Type: Letter
• Acceptance Date: Jan 15, 2025
• Online Publication Date: Feb 7, 2025
• Publication Date: 2025-02
• Deposit Date: Jan 26, 2025
• Publicly Available Date: Feb 18, 2025
• Electronic ISSN: 2475-9953
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 9
• Issue: 2
• Article Number: L022601
• DOI: https://doi.org/10.1103/PhysRevMaterials.9.L022601
• Keywords: Viscoelasticity; gels; shear flows
• Public URL: https://durham-repository.worktribe.com/output/3343552