11:45 AM - 12:00 PM
[SCG46-11] Peridodic fluctation in a compressed dust-aggregate layer
Keywords:dust aggregate, uniaxial compression, periodic fluctuaion
Granules formed by tiny powder can be found in various situations even in our everyday lives. For example, dust aggregates are considered the candidate for materials forming planetesimals. Granules of flour, sugar, salt can be easily found in a kitchen. Although the fundamental understanding on behaviors of dust aggregates is crucial to properly understand/handle them, systematic physical investigation has not been sufficiently carried out so far. Therefore, we performed a set of simple experiments. In specific, uniaxial compression test of a hierarchical granular matter was performed. The hierarchical granular matter consists of a collection of dust aggregates. Dust aggregates were formed by mixing tiny glass beads (5 micro-meter in diameter) and small amount of water. Diameter of aggregate is approximately 1 mm. Dust aggregates were poured in a cylindrical cell and uniaxially compressed by a universal testing machine (Shimadzu AGX) with a constant speed. The compression speed was varied from 0.17 to 2000 micro-meter per second (over four orders of magnitude). During the compression, the compression force was measured. The compression force gradually increased as the compression proceeds. At the same time, periodic fluctuation of the compression force was observed on the increasing compression force. To characterize the nature of periodic fluctuation, we analyzed the experimental data (fluctuation amplitude, wavelenght, etc.) and obtained an empirical form. In addition, we performed the same experiment with glass beads and compared that result with the dust-aggregate case. In this presentation, details on the analyzed result will be presented.