著者

荒井 正行 佐久間 俊雄 岩田 宇一 山田 隆之 中村 一義 岸本 喜久雄

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.66, no.641, pp.144-150, 2000-01-25

被引用文献数

1 3

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The surfaces of many industrial products, such as a holl drill, gas turbine engine and so on, are coated with diamond and ceramic material for improving the material properties.On the other hand, the surface may accumulate an oxidation layer by reaction of oxygen with inceasing time.These Common damage, in service, is "delamination".It is known that the delamiation will be caused by compressive stress in these coating layer which is generated by vibration and fatigue loading for industrial coating, and volume expansion for oxidation.The actual coating delamination process as follow had been clarified by many studies.The coating layer is buckled locally by compressive loadingand is then delaminated along the substrate.The aim of this study is to clarify the coating delamination mechanism under compressive stress by observing continuously buckling and delaminating process in the coating layer, which is modelled by engineering plastic in this study. The delamination evaluation method is proposed based on an interface mechanics, and an accuracy of the evaluation is examined using finite element analysis.Finally, the proposed evaluation are applied to the experimental results obtained by this study.

著者

金子 堅司 荒井 正行

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.863, pp.18-00147, 2018 (Released:2018-07-25)

参考文献数

16

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We have established the torsion pin test method with tension to evaluate shearing delamination strength of thermal sprayed coating under tension-torsion combined stresses, recently. Apparent delamination strength depends on the diameter of the pin, so the stress distributions around the interface edge between the top-coat and the bond-coat have to be analyzed by using the finite element analysis based on the experimental results to see the real delamination strength. Before analyzing, the deformation properties of the thermal sprayed coating have to be known. In this report, macroscopic elastic deformation properties of the four kinds of porous thermal barrier coating (TBC) is investigated experimentally and analytically. First, the indentation tests are performed to obtain the loading and unloading-depth curves in various load levels, and secondarily Young's moduli are explored by using the unloading-depth curves, Hertz-contact theory and FEM analysis at several loading levels. It becomes clear that the obtained Young's moduli increase with increasing indentation load, which means that the obtained Young's modulus is an apparent modulus of the coating having some structural failure caused by indentation test. As the results, the real Young's moduli are determined at the very small load level with no structural failure for the four kinds of porous thermal barrier coatings.

著者

荒井 正行 水津 竜夫

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.84, no.863, pp.18-00016, 2018 (Released:2018-07-25)

参考文献数

9

被引用文献数

2

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Tensile and fatigue tests were conducted on type 304 stainless steel plate-shaped specimens repaired by High Velocity Oxy Fuel (HVOF) spraying. Specimen surfaces were machined for repair into trapezoid with the same depth, the same length, and various slope angles (called here cutting angles). During tensile tests, damage evolution in the repaired part was continuously monitored under increasing load. Quantitative evaluation of the relationship between the strain gauge attached to the repaired part surface and the cross-head displacement was performed. In fatigue tests, influence of the repaired shape on damage evolution was studied, and obtained fatigue lives were compared between the cutting angles. According to tensile testing results, crack initiation strain values increase with cutting angles. At the same time, residual stresses were mostly compressive and almost independent from cutting angles, thus positively affecting the magnitude of fatigue strength. Fatigue test results indicated that specimens repaired with a cutting angle of 50°possess a superior fatigue life. The results showed that the HVOF spraying can potentially replace welding repair.

著者

安田 優佑 荒井 正行

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.852, pp.17-00150-17-00150, 2017 (Released:2017-08-25)

参考文献数

20

被引用文献数

1

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Icing is one of important problems that have to be prevented in jet engine of airplane. If thin ice layer deposited on the surface of blade is detached in fight, the debris is scattered and then impacts to a rear stage blade. Such impact of the debris could lead to catastrophic fracture of the blades. Numerical simulation is a powerful tool to understand how the icing is grown and detached. Thus, the icing phenomenon has been focused on the point of view from fluid mechanics. However, fundamental knowledge for mechanical property of ice itself and the adhesion of the ice layer is still very poor. The aim of this study is to examine about the mechanical property including Young's modulus, fracture toughness and adhesive strength at a low temperature. First of all, as a result of bending test on ice, it was found that the Young's modulus and fracture toughness of ice was increased as ambient temperature being low and loading speed being increased. Then, a shear force test was performed using ice/aluminum alloy to evaluate the interfacial fracture toughness as adhesive strength. As a result, the interfacial fracture toughness was decreased as ambient temperature being low and loading speed being increased. Based on those results, it is concluded that the mechanical property and adhesive strength are strongly affected by ambient temperature and loading speed.