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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
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Demonstrating an In Situ Topological Band Transition in Cylindrical Granular Chains.
R Chaunsali1, E Kim1,2, A Thakkar3
1Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195-2400, USA.
Physical Review Letters
|July 29, 2017
Summary
Researchers demonstrated a tunable mechanical system using granular particles to achieve topological band transitions. This system exhibits protected boundary modes at interfaces between different topological states, observed experimentally.
Area of Science:
- Physics
- Mechanical Engineering
- Materials Science
Background:
- Topological transitions are crucial in condensed matter physics, but realizing them in tunable mechanical systems is challenging.
- Granular materials offer unique mechanical properties and tunability through interparticle interactions.
Purpose of the Study:
- To numerically and experimentally investigate in situ topological band transitions in a tunable mechanical system.
- To demonstrate the emergence of boundary modes and topologically protected interface modes.
Main Methods:
- Utilizing a mechanical system composed of cylindrical granular particles.
- Controlling interparticle stiffness by adjusting contact angles between cylinders.
- Employing numerical simulations, analytical predictions, and experimental validation using laser Doppler vibrometry.
Main Results:
- Achieved in situ topological band transition by spatially varying particle stiffness.
- Observed the emergence of a boundary mode in a finite system.
- Demonstrated a finite-frequency topologically protected mode at the interface of two topologically distinct systems.
Conclusions:
- The granular mechanical system provides a highly tunable platform for exploring topological phenomena.
- The study confirms the existence of topologically protected modes in mechanical systems, with potential applications in wave manipulation and sensing.
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