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Welcome to Granular Dynamics Lab !!

Japanese

Research

Particle damper

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Particle damping is a passive vibration control technique that involves the uses of granular materials operating in the cavity of a primary system. Each collision of the particles with the wall of the cavity results in an attenuation of the response of the primary system.  Particle damping with suitable materials can be performed in a wider temperature range than most other forms of passive damping. The aim of our research is to provide a comprehensive design methodology for particle dampers.

~This vodeo shows an example of the behavior of granular materials in a cavity obtained by the numerical simulation.

Removal of foreign objects in dried foods

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It is very difficult to remove small foreign objects in dried foods such as lettuce or cabbage. The reason is that foreign objects are so small that they disappear behind the foods. Also, foreign objects become attached to the food owing to electrostatic forces. Our novel separator makes it possible to remove foreign objects in dried foods. The separator consists of an inclined rotating drum and a cylinder fixed at the center of the drum. The principle of the separation is based on the difference in the charging characteristics and weights of the food and foreign objects.

~This vodeo shows an example of the separation of foreign objects (white plastics) from dried vegetables. The foreign objects that are in the inner part of the drum are recovered with the suction device. Dried vegetables are so heavy that they fall from the drum.


Granular simulation: Effect of the particle shape on granularity


We are investigating a method for simulating the dynamics of granular materials composed of spherocylinders. Each detection of contact and contact force-overlap relation are defined precisely. From the comparison of experimental and calculated results for a vibratory conveyance, it was found that the calculated results follow the experimental trend with reasonable accuracy.


~This video shows the the experimental (upper) and calculated (lower) results for a vibratory conveyance. To examine the effect of the contact between the cylinders on the flow, the red cylinder was fixed firmly on the vibrating vessel.


Separation of conductors and nonconductors

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A technique for separating copper and polyvinyl chloride (PVC) from chopped waste electric cables has been investigated experimentally. The principle of the separation technique is based on the difference in electric conductivity. Separation tests were performed on a sample containing 50% PVC and 50% copper. The purity of PVC was more than 99% with a recovery rate of 93%, and the purity of copper was more than 99% with a recovery rate of 88.

Separation of plastic mixtures

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In our laboratory, the following plastic separators have been developed.

  • Electrostatic vibratory separator
    This separator consists of a vibratory feeder equipped with two plate electrodes which can be inclined about two axes with respect to the horizontal plane. This separator has the advantage of the use of low voltage.


~ This video shows the triboelectric separation of PVC(red particles) and PET(white particles). The positively charged PET particles are repelled from the lower electrode. The negatively charged PVC particles are conveyed along the lower electrode.


  • Electrostatic separator using cylindrical electrodes
    This separator is of the freefall type and consists of four cylindrical electrodes. This approach makes it possible to avoid the collision of charged particles with the electrodes. 



~ This video shows the triboelectric separation of PP(orange particles) and PE(white particles) . The positively charged particles (PP) are attracted toward the space between the negative electrodes, whereas the negatively charged particles (PE) are attracted toward the space between the positive electrodes.

Motion analysis of foreign objects

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A relay is an electrical device that provides a circuit with electricity by opening and closing the contacts of the relay electrodes using an electromagnet . Foreign objects are occasionally created, as a result of damage of a relay cover. When a foreign object moves between the contact points, electricity is not provided to the circuit. We carried out the experimental and analytical study to investigate the motion of a foreign object between relay electrodes.

Numerical analysis combining the discrete element method and the finite element method

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We have constructed an analytical model for investigating collisions between granular materials and a plate. The model is based on the DEM and FEM. The validity of the analytical model was examined by comparison with experimental results.



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Shibaura Institute of Technology
Fuculty of Engineering, Dept. of Mechanical Engineering

135-8548
3-7-5 Toyosu, Koto-ku, Tokyo, Japan