Papers by Author: Yu Guo Wang

Abstract: An improved model with polygonal aggregates is proposed to analyze the thermal stability of the resin concrete in this paper. A 2D polygonal aggregates model is established to make the calculating results closer to the reality and the 2D model is the slice directly captured from the 3D model based on the predecessors theory. A comparison is made between the conventional model with spherical aggregates and the polygonal aggregates model in this paper. The results of the analysis on the improved model are closer to the previous research results and more accurate than the spherical aggregates model. It confirms that the polygonal aggregates model is accurate enough to analyze the properties of the resin concrete.

Abstract: In this paper, an experiment has been made to take vibration and surface waviness of two kinds of engineering ceramics ( zirconia ceramics and alumina ceramics) as research targets. The experimental research results show that two kinds of surface waviness are on the workpiece, one is sparse and the other one is dense. It is known that the sparse one is caused by the forced vibration. In order to find out the generation mechanism of the dense one, a further exploration has been made. It shows that the dense surface waviness is caused by the self-excited vibration. Finally, some methods are put forward to reduce the surface waviness.

Abstract: With the aesthetics’ enhancement, there is a growing demand for the use of restorative ceramics in dental surgery. However, ceramic materials are hard and brittle, and problems such as surface damage, crack, and fatigue were easily produced in dental abrasive finishing. Consequently, these flaws could cause the strength decrease of the ceramic, which manifest the shortage of the lifespan in dental. Contraposing these problems, a high-speed handpiece with diamond burs was used when finishing the leucite glass ceramic in the dental surgery. In this paper, finishing force, specific energy and surface integrity including the roughness and morphology were observed. the results revealed that both normal and tangential forces increased with the increasing of feed rate and depth of cut, while there is an apparent decrease of the specific energy. These two parameters were bigger in the up finishing than that of down finishing. Finishing parameters have little effect on surface roughness, according to the observation of a scanning electron microscope. It is easily found that the finished surface was consisting of brittle fracture and plastic deformation. For comprehensive, good surface quality could be obtained in the down cutting other than up cutting.

Abstract: Fiber-reinforced ceramic matrix composites are considered to be difficult-to-machine materials, its machining especially forming machining is very difficult. The silica fiber reinforced silica composite is studied by grinding experiment in this paper. The surface morphology of the specimens are analyzed by scanning electron microscopy, and the grinding mechanism of the composite is also analyzed. Grinding depth and feed speed is separately changed to study the grinding force. The influence of the blunt wheel on surface morphology and geometric accuracy of the specimen after grinding is explored. This research may be helpful to improve the machining quality of silica fiber reinforced silica composite.

Abstract: Through the odd factor grinding experiment of microwave ferrite, the tangential and normal force were measured in different grinding parameters (wheel speed, feed rate, cutting depth, wheel size). According to the variation of the tangential force and normal force in different grinding parameters after grinding, the reasonable grinding parameters of microwave ferrite were explored. The results demonstrated that the grinding force had different variations in different grinding parameters. These could be the reference and guidance for the future processing of microwave ferrite materials.

Abstract: The grinding experiments of Quartz Fiber-Reinforced Quartz Composites（QFRQC） were conducted on MK9025 NC optical curve grinding machine. Grinding forces were measured by KISTLER dynamometer and the morphologies of the grinding surface were observed with Hatchi S-4800 SEM. In this paper, the effect of grinding orientation on the ground surface damage of QFRQC was discussed. Grinding orientation has a big influence on the ground surface damage. When grinding orientation is perpendicular to fiber orientation, the surface of the workpiece is poor; By contrast, when grinding orientation is parallel to fiber orientation, the surface of the workpiece is good; when grinding is on the fiber end-faces, the surface of the workpiece is best.

Abstract: Through the odd factor grinding experiment of microwave ferrite, the residual flexural strength and surface roughness after grinding were measured in different grinding parameters(wheel speed, feed rate, cutting depth, wheel size). The surface of microwave ferrites was observed in high magnification through an optical microscope after grinding, in order to show the variation of surface roughness in different grinding parameters. The results showed that with the increase of the surface roughness, the residual flexural strength increased.

Abstract: The single factor experience of Fiber Reinforced Ceramic Matrix Composites (briefly named FCC) grinding was done on a NC optical curve grinding machine, and then the morphologie of the grinding surface was observed with an optical microscope. The effect of the grinding parameters, which include mainly grinding depth, abrasive grain size of diamond grinding wheel and grinding direction, on the grinding-induced surface damage of FCC was discussed, finally, the paper drew the conclusions that both increasing of grinding depth and increasing of abrasive grain sizes of diamond wheel can make the grinding-induced surface damage worse, and that different grinding directions also produce different effects on the grinding-induced surface damage.