Abstract
Experimental and numerical studies of the behavior of a slurry in a shear flow over a rough surface with a defined micro-structure are presented. A new ring shear device was built which contains an optically transparent test chamber. Its bottom wall contains arrays of micro-cantilever force sensors simulating a defined surface roughness created by deep-etching of micro-pillars in a silicon wafer. The results of visual observation of the interaction of the suspension with the structured surface during severe deformation are shown. Observations comprise the liquid phase motion, i.e., the interaction between the liquid phase and solid particles, the movement of separate particles and their interactions with the micro-pillars. Abrupt changes in rotational motion and translational velocity of particles are observed that induce mutual collisions and successive formation and break-up of cluster structures of various types. In addition to the experiments the process was simulated with discrete element (DEM) simulations. Many characteristics found in the experiments are reproduced by the simulations. Furthermore the physical quantities of the process like contact forces or velocities can be quantified which helps us to develop more detailed models of the abrasive behavior of slurries.
Highlights
In many technical applications of material processing and process technology, such as grinding, lapping, and wire sawing, suspensions of abrasive particles and a carrier fluid are used to cause the micro-mechanical removal and to ensure the transport of the removed material [1,2,3]
The present study was carried out using a new ring shear device that contains an optically transparent test chamber which allows observing the slurry motion as well as the particle–wall contact forces
ΚGAðu′′ φ Þ 1⁄4 q: When this model is used in discrete element method (DEM), the distributed load q is zero and the deflection and angles at the ends of the beam are equivalent to those of the particles A and B attached to the beam: q1⁄40
Summary
In many technical applications of material processing and process technology, such as grinding, lapping, and wire sawing, suspensions of abrasive particles and a carrier fluid (slurries) are used to cause the micro-mechanical removal and to ensure the transport of the removed material [1,2,3]. The complex mechanical behavior of abrasive particles in interaction with the walls and multiple contacts among each other in the process gap as well as cluster formation and break-up are not yet sufficiently understood [4,5]. Wall interaction as well as the flow behavior at the micro scale. Unique possibilities for comparison and validation of the numerical simulations Such simulations of the process are performed using discrete element method (DEM) [6]. This method allows for a description of the interaction of particles with the micro-pillars. The motion of the particles as well as the interaction forces and the fracture events of pillars can be simulated for larger number of particles that allows us to gain a statistical description of the abrasion process
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