Structural aging of a cohesive and amorphous granular solid under cyclic loading
William Hobson-Rhoades1, Douglas J Durian2, Yue Fan1
1Department of Mechanical Engineering, University of Michigan, Ann Arbor, MI 48109, USA. hongyix@umich.edu.
Soft Matter
|April 29, 2026
Summary
Cyclic loading ages granular rafts at air-oil interfaces, increasing packing fraction and structural heterogeneity. Aged rafts exhibit enhanced strength and stiffness but reduced ductility compared to non-aged rafts.
Area of Science:
- Physics of granular materials
- Soft matter physics
- Interface phenomena
Background:
- Granular rafts at fluid interfaces exhibit cohesive behavior due to capillary forces.
- Particle packing and structural evolution are key to understanding material properties.
Purpose of the Study:
- To investigate the effects of cyclic loading on the structure and deformation of cohesive granular rafts.
- To characterize the aging process and its impact on mechanical properties.
Main Methods:
- Uniaxial cyclic loading with small strain amplitude was applied to granular rafts.
- Quasi-static tension and compression tests were performed to assess mechanical behavior until failure.
- Analysis of packing fraction and structural heterogeneity changes over time.
Main Results:
- Cyclic loading induced an aging process, marked by logarithmically increasing packing fraction and decreasing structural heterogeneity.
- Particle dynamics were observed to organize around evolving voids within the raft structure.
- Aged rafts demonstrated increased strength and stiffness, with reduced ductility and a stress overshoot phenomenon.
Conclusions:
- Cyclic loading significantly alters the microstructure and mechanical response of granular rafts.
- The observed aging mechanism enhances raft strength and stiffness, offering insights into the design of interfacial granular materials.
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