Converging-diverging shock-driven instabilities along soft hydrogel surfaces.
Daniel Pickard1,2, Dmitro Martynowych2,3, Jet Lem2,3
1Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Physical Review. E
|March 18, 2023
Summary
Laser shock loading causes unique surface eruptions on hydrogel cylinders. These instabilities differ from known types and arise from internal shock reflections, not single shock events.
Area of Science:
- Fluid dynamics
- Materials science
- Mechanical engineering
Background:
- Hydrogel films under shock loading can exhibit complex behaviors.
- Understanding mechanical instabilities is crucial for predicting material response.
Purpose of the Study:
- To investigate the mechanisms behind intense surface eruptions on hydrogel cylinders under laser-induced shock loading.
- To differentiate these instabilities from known phenomena like acoustic parametric instability and Richtmyer-Meshkov instability.
Main Methods:
- Experimental observation of surface eruptions on confined cylindrical hydrogel films.
- Detailed numerical simulations to identify dominant instability mechanisms.
Main Results:
- Identified a new class of surface instability driven by cycles of internal shock reflections.
- Observed eruption formation timescales significantly larger than single shock reflections.
- Surface undulations occurred exclusively along external boundaries of the solid hydrogel cylinders.
Conclusions:
- The study reveals novel shock-driven surface instabilities in hydrogels.
- These instabilities are distinct from previously documented shock-driven phenomena.
- The findings suggest a new mechanism for impulsively excited surface instabilities in soft solids.
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