Grinding characteristics of CVD diamond grits in single grit grinding of SiC ceramics
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Rubbing
Brittleness
The paper offers a simulation model of the grinding force with account for the current condition of the grinding wheel's working surface—the value of the abrasive grain blunting area. The model of blunting area takes into account various wear mechanisms for abrasive grains: the mechanical wear is realized on the provisions of the kinetic theory of the strength of a solid subjected to cyclic loads, and the physicochemical wear is based on the intensity of interaction between the abrasive and the treated material at grinding temperatures. The offered model of the grinding force takes into account the unsteady stochastic nature of the interaction between abrasive grains of the grinding wheel and the working surface and the intensity of workpiece material deformation resistance. The model is multifactorial and complex and can be realized by supercomputer modeling. The numerical implementation of the model was performed with application of supercomputer devices engaging parallel calculations. The performed experiments on measurement of the grinding force during circular grinding have shown a 10% convergence with the calculated values. The developed grinding force model can be used as a forecast model to determine the operational functionality of grinding wheel when used in varying technological conditions.
Intensity
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Rubbing
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Transitions in wear rate and mechanism are a common feature of the erosive and abrasive wear of ceramics and other brittle materials. In such cases, a relatively small change in applied conditions, such as impact velocity or angle in the case of erosion, or of applied load in abrasion, results in a significant change in the mechanism of wear. Such a transition often represents a change in the extent or nature of fracture, leading to a concomitant change in the rate of material removal. Transitions in wear mechanism can also be associated with a change in the shape, hardness or size of the abrasive particles. In this paper, theoretical models for the onset of fracture and plastic flow in a material being eroded or abraded, and also in the abrasive or erosive particles, are used to define regimes over which a single wear mechanism will be dominant. A method is outlined by which these regimes can be illustrated graphically on plots of particle size against impact velocity or applied load, and it is suggested that in this way `maps' showing wear rates and mechanisms might be developed for the abrasive and erosive wear of brittle materials.
Abrasion (mechanical)
Brittleness
Brittle fracture
Particle (ecology)
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Alignment failure sometimes occurs during the rubbing process because the rubbing cloth comes in direct contacts with the surface of the alignment film. A number of researches observed and evaluated the surface of the alignment film after the rubbing process had been reported. The real-time rubbing process has not been observed directly yet, though. In this study, the movement of the piles of the rubbing cloth during the rubbing process was observed with a high-speed camera. Furthermore, the relationship between the rubbing scratch on the alignment films and the movement of the pile was investigated. It was found that the movement of the pile affected the rubbing scratches.
Rubbing
Scratch
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Coefficleats of static friction were determined for mild steel rubbing on mild steel, Ti RC 130B on mild steel, Ti RC 130-B rubbing on U, U rubbing on U, Be rubbing on U and Le rubbing on Ti for both statically and dynamically applied loads. Normal rubbing pressures range between 1500 and 12,000 psi for statically applied loads and between 12,000 psi and 21,000 psi for dynamically applied loads. Coefficients of kinetic friction have been determined between varlous metals for rubbing speeds between 30 and 50 fps and rubbing pressures of 1600 to 3,000 psi. (auth)
Rubbing
Static friction
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The mechanism and characteristics of abrasive belt grinding are summaried.The present research status of this technology at home and abroad is reviewed. Some problems existing in abrasive belt grinding technique,grinding theory and grinding materials are discussed.The development trends on abrasive belt grinding technique are analysed.
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Abstract In order to improve the stability of the rubbing process, the authors have employed a new parameter — the amount of frictional work W — as a rubbing controlling parameter instead of rubbing strength L which has been used in the past. The applicability of this new parameter to control the surface alignment properties of liquid crystal is experimentally confirmed. The relationship between surface alignment properties, including anchoring energy (azimuthal direction) and pretilt angle, and rubbing condition parameters is investigated, and it is proven that by using the amount of frictional work, anchoring energy and pretilt angle under various rubbing conditions can be summarized uniformly. It is also shown that differences in anchoring energy as a result of using different kinds of rubbing cloth can be cancelled by using the amount of frictional work as a reference parameter.
Rubbing
Anchoring
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Experimental Study on Rubbing Acoustic Emission for Rotor-Bearing System Based on Parameter Analysis
Rubbing between the rotor and the stator is the frequent fault and will cause very serious accident, even catastrophe, to rotating machinery. Therefore, timely detection of such rubbing is very important avoid severe consequences. Vibration based methods are very mature and traditional methods but not effective to detect incipient rubbing in rotating machinery. Rubbing between the rotor and the stator will cause elastic strain in the rubbing location and thus can produce acoustic emission (AE). Apparently, such AE contains direct and abundant information about the rubbing and can be used to detect and diagnose such fault effectively. In this paper, the AE based method is proposed for detecting and identifying the rubbing of the rotor-bearing system. An experimental study is presented to investigate the characteristics and features of rubbing AE using parameter analysis method. The results show that AE is very sensitive to the rubbing and AE parameters can reveal the characteristics and features of rubbing AE. Parameter analysis demonstrates that rubbing AE contains multiple modals, which will attenuate with propagation by negative exponent manner.
Rubbing
Acoustic Emission
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We have investigated the alignment properties of liquid crystals induced by multiple rubbing of the surfaces in different directions. Experiments were carried out using homeotropic and hybrid-aligned samples. It is experimentally found that the alignment of the liquid crystals is along neither of the rubbing directions, but instead lies along an axis intermediate between these two directions, and that the direction depended on the relative strength of rubbing along the two axes. A model that assumed the grooves along two rubbing directions is proposed, and the relation between the orientation of the liquid crystal and the relative rubbing strength is analyzed. We found that this model can explain the observed experimental results.
Rubbing
Homeotropic alignment
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In this study, an experimental apparatus designed to test abrasive wear by mean of an abrasive belt was used to rub between virgin surfaces. The effects of contact load, the rubbing direction and amplitude of vibration on wear characteristics were examined in a series of the experiments. Results obtained are as follows. (1) The wear volume of CFRP becomes larger in the order, L, T, N. (2) The wear volume in both the X- and Y-directions decreases corresponding to the amount of over lapping. (3) In the Y-direction, wear volume is influenced by the rubbing direction.
Rubbing
Lapping
Adhesive wear
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