著者

祖山 均 田中 麻友 滝口 尚 山本 松男

出版者

一般社団法人 日本機械学会

雑誌

東北支部総会・講演会 講演論文集 2020.55 (ISSN:24242713)

巻号頁・発行日

pp.111_paper, 2020 (Released:2020-09-25)

著者

國分 朋之 祖山 均

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.18-00161, 2018 (Released:2018-07-25)

参考文献数

23

被引用文献数

1

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Peening is one of the mechanical surface modification techniques, which is used to improve the fatigue strength by the introduction of the compressive residual stress into the surface of specimen. Several peening techniques, such as shot peening, cavitation peening and laser peening have been proposed and demonstrated the improvement of fatigue strength. Mechanical properties on surface modification layer vary with the techniques because of the difference of mechanism of impacts and strain rate. Therefore, it is possible to improve the fatigue strength further by hybrid peening, which is a combination of different peening techniques, due to controlling the mechanical properties on surface modification layer. In this paper, in order to demonstrate the suppression of fatigue crack propagation by hybrid peening combining shot peening and cavitation peening or cavitation peening and laser peening, the fatigue crack propagation in duralumin treated by hybrid peening was investigated, and the crack propagation behavior of the specimen treated by hybrid peening and single peening method was compared. The relationship between the fatigue crack propagation and the mechanical properties was also evaluated. It was revealed that hybrid peening (former process: laser peening, latter process: cavitation peening and former process: cavitation peening, latter process: shot peening) was more effective to suppress the fatigue crack propagation than single peening method and the number of cycle to failure of the specimen treated by hybrid peening was the largest. The new indicator f(σR’, HV’, Rz’, β’) = σR・HV・β/Rz combined with four factors i.e. compressive residual stress σR, Vickers hardness HV, full-width at half maximum β and maximum height roughness Rz showed the effect of suppression of fatigue crack propagation by peening.

著者

星野 柊 祖山 均

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.855, pp.17-00400-17-00400, 2017 (Released:2017-11-25)

参考文献数

30

被引用文献数

1

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For hydrodynamic cavitation produced by a Venturi tube, cavitation bubble is collapsed at downstream of a nozzle and its intensity is influenced by upstream pressure and downstream pressure. In order to investigate the effect of the upstream pressure p1 and the downstream pressure p2 on aggressive intensity of hydrodynamic cavitation, an experiment measuring acoustic power by an AE sensor was conducted. Relationship between pressure conditions and acoustic power PA was studied. The higher the upstream pressure p1, the higher the acoustic power PA. Acoustic power had a maximum value at the upstream pressure p1 = 1.6, 2.1, 2.6, 3.1 and 3.6 MPa. At the upstream pressure p1 = 2.6 MPa and the downstream pressure p2 = 0.5 MPa, the aggressive intensity of hydrodynamic cavitation increased to be 36 times larger of the value corresponding to the atmospheric downstream pressure. While the optimum downstream pressure depended on the upstream pressure, the cavitation number was nearly constant for all upstream pressures. It was concluded that increasing the downstream pressure is an effective means to increase the aggressive intensity of the hydrodynamic cavitation without increasing the input energy.

著者

國分 朋之 祖山 均

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.853, pp.17-00190-17-00190, 2017 (Released:2017-09-25)

参考文献数

24

被引用文献数

1

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Peening techniques are used to introduce the compressive residual stress into the surface of metallic materials in order to improve the fatigue properties. The fatigue crack propagation is affected by many factors in surface modification layer, however, the effect of these factors on the fatigue crack propagation is not clarified in detail. In this study, the fatigue crack propagation behavior in surface modification layer of duralumin treated by various peening techniques including shot peening, cavitation peening and laser peening was investigated. The relationship between the fatigue crack propagation behavior and mechanical properties was also evaluated. The fatigue crack propagation behavior varies depending on peening techniques despite the condition of the same peening intensity, since the mechanical properties in surface modification layer are changed with the peening techniques. The compressive residual stress σR and Vickers hardness HV are the important factors about fatigue crack propagation, however they do not show a correlation with the number of cycle to failure of the specimen Nf. Therefore, the new indicator combined with four factors i.e. σR, HV, full-width at half maximum β and maximum height roughness Rz were proposed. It revealed a significant correlation with Nf, and possibility to evaluate the effect of suppression of fatigue crack propagation by peening.

著者

星野 純輝 祖山 均

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.849, pp.16-00502-16-00502, 2017 (Released:2017-05-25)

参考文献数

10

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In order to establish a new approach to manufacturing of CaCO3 which can be adapted to structural materials, the formation of CaCO3 using continuous-wave laser has been conducted on austenitic stainless steel JIS SUS316L surface. It has been demonstrated that localized heating by laser irradiation could control the formation. CaCO3 was obtained from heating Ca(HCO3)2. The film thickness of CaCO3 formed at various conditions was measured, therefore it was revealed the effect of various factors on the formation of CaCO3. The higher laser power P, the thicker the film thickness of CaCO3, however, high laser power (1.5 W) decreases the film thickness when laser irradiation is continued for many hours. Changing the distance from condenser lens d to specimen, it can control the film thickness and the width of CaCO3 film without increasing energy. When the velocity of specimen v is 1.0 mm/s, the film thickness is the highest among other velocities and the shape of CaCO3 film is clear. The temperature of Ca(HCO3)2 Tw have not much effect on the film thickness, although the temperature have effect on the width of CaCO3 film. Therefore, CaCO3 film can be formed efficiently by controlling the factors such as laser power. The optimum condition of fabrication of CaCO3 which we inferred from these results was P = 1.0 W, d = 30 mm, v = 0.1 mm/s, Tw = 45 °C, laser irradiation time t = 5 h. This manufacturing have probability to be able to fabricate the structure of CaCO3 flexibly.

著者

祖山 均 巨 陽

出版者

東北大学

雑誌

萌芽研究

巻号頁・発行日

2004

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本研究は,半導体にひずみを付与すると電気的特性が変化することを活用し,半導体の一種である亜酸化銅太陽電池を取り上げ,ひずみの付与による太陽エネルギを電気エネルギへ変換する変換効率を向上させて亜酸化銅太陽電池を高性能化することを目的とする。本年度は初年度の研究を発展させ、ひずみを活用した亜酸化銅太陽電池の高性能化を図った。1.光起電力効果におけるひずみの影響の定量的評価 銅板を高温酸化させて亜酸化銅を銅板上に生成させた試験片を作製し,それを片持ちはりとして荷重-変位を測定し,亜酸化銅の縦弾性係数を求めた。また酸化条件を変化させた亜酸化銅のひずみを,2次元検出器を有するX線回折装置を使用して2D法により,求めた縦弾性係数を用いて亜酸化銅の残留ひずみを評価した。その結果,酸化条件により残留ひずみが異なることを明らかにした。また亜酸化銅太陽電池に曲げ応力や垂直応力を与えることにより,光起電力が向上することを明らかにし,求めた縦弾性係数により,亜酸化銅に負荷した応力をひずみに換算して評価した。2.光起電力効果におけるひずみの影響の電気的特性の評価 銅板から生成した亜酸化銅太陽電池について太陽電池シミュレータにより光起電力を計測しながら,ひずみを付与して,ひずみにより光起電力が向上することを明らかにした。また亜酸化銅太陽電池にひずみを付与しながら亜酸化銅太陽電池の抵抗などを計測した結果,ひずみによる光起電力向上には,亜酸化銅太陽電池のショットキー障壁が変化している可能性を明らかにした。3.ひずみを活用した亜酸化銅太陽電池の高性能化 亜酸化銅を酸化する際の酸化時間や酸素分圧により光起電力が異なることを明らかにし,最適酸化条件を得た。また亜酸化銅太陽電池に曲げ応力を負荷するよりも垂直応力を負荷したほうが亜酸化銅太陽電池を高性能化できることを明らかにした。