Experimental investigations of density-induced segregation in binary granular mixtures under vertical vibrations

The objective of this work is aimed to investigate experimentally the influences of density ratio on segregation of cylindrical granular mixtures under vertical vibrations. Polytetrafluoroethylene, Polyamide, Polyethylene terephthalate, Balsa woods and Hinoki woods were used as the cylindrical particles, with 10 mm in diameter and 60 mm in length. The granular sample is composed of 1000 particles with two different materials with each type of 500 particles. All particles are periodically filled into the rectangular container with size 300 x 300 x 60 mm, as the initial condition. Density ratios are 2.73, 3.36, 5.27, and 13.63. The experimental operated by vertical shaker for 10 minute to achieve a steady state condition with same amplitude at 5 mm. The dimensionless vibration accelerations changed by frequency for 5 experimental, experiment the dimensionless vibration accelerations = 1, 2, 3, 4, and 5. The beginning state and the end state collected data by shooting the image. The segregation is considered by average height or the segregation coefficient. The result showed that for the density ratios of 2.73 and 3.36 for all dimensionless acceleration values, the segregation does not occur. On the other hand, for density ratio more than 5.27, the segregation occur by the way that the higher density particles move downward to the bottom of the sample, while the lower density particles move up to the top of the container. The segregation occurs when the dimensionless acceleration is more than 2 and the segregation is clearer when the dimensionless acceleration increases. (paper)