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Video Credit: Particles and Grains Laboratory, University of Sydney | YouTube
Researchers from the University of Sydney and the San Diego State University have collaborated in a study using puffed rice cereal in order to explain the movement and crushing of porous materials when compressed.
The research team adopted a creative approach in order to explain the patterns of motion which take place in brittle porous materials. The results obtained from their study could significantly improve our understanding of a wide range of motion patterns, from crater patterns created by meteorite showers to the collision of snowballs colliding during avalanches.
The lead author of the study paper, Professor Itai Einav, from the Particles and Grains Laboratory at the University of Sydney, said: “Before we started we knew that brittle porous materials such as rocks, foams or even snow exhibit irreversible compaction patterns. We see such patterns in Sydney’s sandstone all around us, but this geological imprint doesn’t tell us much about the internal motions and the process of pores collapsing within the rock mass. We know rocks move, but it takes millions of years.”
Professor Itai Einav went on to say: “What we didn’t know is in what ways it moves and deforms, and specifically what types of internal patterns develop. We picked puffed rice because they are highly porous and compliant and typify generic brittle porous materials when being compressed.”
We wanted to understand how packs of brittle grains coordinate motion when crushed. Many of us have tried this at home as kids – crushing puffed rice cereal with a spoon. For us this simple experiment revealed surprisingly rich compaction patterns that were due to the competing processes of internal collapse and recovery.
Professor Itai Einav: Particles & Grains Lab - University of Sydney
Dr François Guillard from the University of Sydney, who was the co-lead author of the paper, collaborated with Professor Julio Valdes at San Diego State University to conducting the experiments. Guillard stated that the research model developed provides a new understanding of jerky flows in metallic alloys.
“We used a robust spring-lattice model to capture the process of internal collapse and recovery and are now able explain the dynamics of previously and newly observed patterns. The lattice model we have created can address other brittle porous media such as natural rocks, bones and snow, and manmade ceramics, foams and pharmaceutical powders,” said Dr Guillard.
The results of this study have been published in the journal Nature Physics.