Papers by Keyword: Curved Surfaces

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Authors: Kohichi Miura, Takazo Yamada, Masayuki Takahashi, Hwa Soo Lee
Abstract: It is well known that the superfinishing is a high efficient surface finishing method to cylindrical workpieces. In this method, grinding stones are pressed to the outside of cylindrical surfaces. Rotating cylindrical workpieces and making relative vibrations between grinding stones and ground surfaces in the directions of the center lines of workpiece rotations, the cylindrical surfaces are ground and mirror surfaces are realized relatively in short time. Therefore, this finishing method is widely applied to the finishing of precise machine elements. However, this method cannot be applied in case of that the workpiece which is not simple cylindrical geometries so far. In this study, a new application method of superfinishing to the cylindrical workpieces having curved parts is proposed and its performance is discussed experimentally.
Authors: Tarek Qasim, Chris Ford, Mark Bush, Xiao Zhi Hu
Abstract: The effects of indenter/coating modulus mismatch on contact damage in bilayer systems composed of brittle coating layers on compliant polymeric underlayers is investigated. Convex specimens having curvature of 12 mm inner coating diameter are produced, and loaded using flat indenters of four different moduli. Glass plates of d = 1 mm thick are used as representative of the brittle coating, and soft epoxy filler is used as an underlayer. Specimens are loaded along the convex axis of symmetry. In this fashion the influence of indenter modulus on radial crack initiation and damage evolution is examined. Previous studies utilised hard spherical indenters of various sizes, and did not consider the effect of a compliant indenter on radial crack evolution and subsequent damage patterns. It is demonstrated that critical loads for initiation of radial cracks and subsequent damage patterns especially at specimen margins are sensitive to indenter modulus (indenter/coating modulus mismatch).
Authors: Tarek Qasim, Xiao Zhi Hu, Mark Bush
Abstract: This paper summarizes some of the recent advances that have been made as a result of contact damage tests on bi-layer structures containing one brittle layer on a polymeric support base. The effects of indenter modulus (hard/soft indenters) and of the sate of loading (load location reference to the specimen axis of symmetry) on contact damage in bi-layer systems were investigated. Convex specimens having curvature of 12 mm inner coating diameter and 1mm thick were produced, and loaded along the axis of symmetry and off axis at 45o using flat indenters of six different moduli. The influence of indenter modulus on radial crack initiation and damage evolution was examined in respect to the load location, with particular attention paid to the relevance of such damage to lifetime-limiting failures of biomechanical layered systems. The results of this study illustrates that the fracture behaviour of brittle layered structures is not dominated by certain parameters. Critical loads for initiation of radial cracks are sensitive to indenter modulus (hardness) but not sensitive to load location. Load location plays an important role in crack propagation and subsequent damage patterns, especially at specimen margins.
Authors: Yan Hong Ding, Xin Gai Yao, Xing Xiang Wang, Shi Chun Yang
Abstract: Magnetic abrasive finishing (MAF) is a kind of method for polishing the surfaces and the edges. The investigation for the technique of MAF and the development of the ferromagnetic poles lay a theoretical foundation for developing a new method for finishing the curved surfaces automatically under the numerical control. In the paper, the performance parameters of the developed magneto poles, which are used for finishing the plane surfaces and the curved ones, have been tested. The curvature of the finished surface, the sloping angle of the machined surface and the rotation speed of the poles, which affect the surface roughness, are studied theoretically. What mentioned above supply references to the practical uses of the MAF, especially in the mould manufacturing.
Authors: Bernd Eigenmann
Abstract: In recent years, the demand for high spatial resolution in X-ray residual stress analysis has drastically increased. The locations of interest are frequently small foot radii of teeth of gears. Also the inner surface of holes or hollow cylinders in general with small diameter must be investigated after opening the cylindrical cavities. In resolving such measuring problems, significant progress has been made in reproducibly manufacturing and applying glass capillary X-ray optics. With focusing elliptical polycapillaries and conventional laboratory X-ray sources, spot sizes of few 10 μm can be realized at sufficiently intensities for residual stress analyses. However, glass capillary optics require refined alignment strategies which are completely different from those for conventional beam shaping optics. Moreover, the small spot sizes cannot be aligned and positioned on the sample surface by eye. Microscopy fixtures are required. Finally, measurements in small radii result in high precision requirements for the diffractometers as well as for the sample positioning in axes and directions which are significantly less relevant when measuring on plane surfaces. The specific requirements resulting from residual stress analyses with high spatial resolution using glass capillaries and small spot sizes at curved surfaces are described and discussed.
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