Associate Professor Hiromitsu Katsuragi of Nagoya University Graduate School of Environmental Studies collaborated with Braunschweig Institute of Technology in Germany to expand under microgravity regardless of the hardness and brittleness of powder clusters. I found that it can be explained by the same energy distribution law.
It is believed that in the early stages of solar system formation, there were many powder clusters with high porosity formed by repeated aggregation of fine solid particles.Normally, conducting a microgravity experiment that imitates space requires a large-scale fall tower or free-fall flight by an airplane, so it often costs a lot, but the research group is only 1.5 m. For the first time in the world, a collision experiment between a powder cluster and a solid bullet was conducted using a laboratory fall tower.
As a result of experiments using dense hard glass beads and brittle dust aggregates with high porosity at different collision velocities, all experimental results have the same energy regardless of the hardness and brittleness of the powder cluster. I found that it can be explained by the law of distribution.In other words, both hard and brittle powders follow the same expansion mode.According to the experimental results, about 15% of the kinetic energy of the bullet before the collision remains in the bullet, about 5% is distributed to the expansion of the powder cluster, and about 80% is the heat and deformation in the powder cluster. It is said that it will be lost.
This method is expected to help in constructing detailed models such as "how high porosity powder clusters grew" in the process of forming planetesimals in the universe.
Paper information:[Physical Review Letters] Impact-Induced Energy Transfer and Dissipation in Granular Clusters under Microgravity Conditions
