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Discrete element modelling of particulate flow in die filling and powder transfer

By Mohd Radzi Mohamed Yunus


In this thesis, numerical investigation of die filling and powder transfer within discrete element method framework is presented. The main focus of the work is to explore the contribution of die filling and powder transfer processes towards the density variation of the powder mass before compaction. The numerical investigations are carried out to provide alternative solutions in understanding die filling and powder transfer mechanisms because of the lack of theoretical and experimental solutions in the two fields. Validation of the code used was successfully carried out by comparing simulation results with the existing results of powder flow experiments conducted in controlled environment which imitate realistic industrial settings. The effects of shoe kinematics, punch kinematics, contact parameters, modelling parameters, die geometry, die orientation, and shoe volume on die filling and powder transfer have been identified. It has been confirmed that multiple passes, multiple shoe columns and powder shifting can improve powder packing. The die fill is found to decrease with the increase in friction and cohesion. On the contrary, it increases with the increase of damping. The combination of slow shoe speed during filling and slow punch speed during transfer is found to result in homogeneous powder packing inside the die. The research has also successfully integrated die filling and powder transfer in one continuous sequence in a three dimensional setting. Simulation works have also been performed on the Variable Aperture Flowmeter to evaluate the effects of particle composition on critical aperture and angle of repose, and to determine powder flow rate. Investigations were also conducted on the bridging phenomena which conclude that bridging for monodispersed circular particles stops when the orifice is set at 5.5 particle width. The result however may change with different values of contact parameters and particle properties. Numerical study performed has shown that the discrete element method is capable of reproducing several key phenomena observed in die filling and powder transfer processes and to some extent capable of characterising powder flow in a simulated variable aperture flowmeter

Topics: TA401-492 Materials of engineering and construction. Mechanics of materials, TN Mining engineering. Metallurgy
Year: 2009
OAI identifier: oai:eprints.uthm.edu.my:1649
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