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20.5.26 14:30 s.t. - Seminarroom 25.32 O2.51
Smarajit Karmakar: „Response of Amorphous Solids under Oscillatory Shear and Active Dopants”
Tata Institute of Fundamental Research, Hyderabad, India
Understanding the mechanical properties of amorphous solids has been a field of intense research not only for the zoo of interesting phenomena one observes once these solids are subjected to external deformations but also for their importance in industrial applications. Amorphous solids fail catastrophically via shear band formation, and tuning their mechanical yielding is important for designing better materials. I will focus on the annealing mechanisms in these solids as they are of practical importance. I will first highlight the response of these solids under oscillatory shear deformation, and then study the response of these solids in the presence of self-propelled particles (SPPs). I will show that both oscillatory shear and SPPs lead to annealing of glasses and use these tools to fine-tune the failure mode of the system under uniaxial tensile deformation. I will demonstrate a strong correspondence between the yielding behavior of glassy systems under active dynamics and their yielding under oscillatory shear. The yielded region of the phase diagram correlates with tissue fluidization, while the annealing region explains age-related maturation and stiffening. This suggests that some mechanical changes observed in ageing tissues can partially stem from processes analogous to enhanced ageing observed in active glasses. In addition to showing similar yielding diagrams, I will strengthen the correspondence to oscillatory shear by demonstrating diverging time scales to steady states, the possibility of memory encoding and reading, and the importance of stress reversals in the annealing process in both cases. Finally, we study yielding in active solids and demonstrate that given the correct geometry, one can either suppress or promote brittle failure via shear band formation by tuning activity. Finally, I will touch upon the effect of fragility on the yielding transition in these solids under oscillatory shear and demonstrate how the underlying energy landscape, especially the energy barriers, controls the responses of these solids in a unified manner.
References
- Rishabh Sharma, Smarajit Karmakar, Nature Physics 21, 253-261 (2025)
- Roni Chatterjee, Monoj Adhikari, and Smarajit Karmakar, Nature Communications 2026, https://doi.org/10.1038/s41467-026-71157-w
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