著者

金沢 謙一

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:00214728)

巻号頁・発行日

vol.97, no.902, pp.29-33, 1994

参考文献数

4

著者

石井 幸孝

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:00214728)

巻号頁・発行日

vol.69, no.568, pp.550-559, 1966

著者

水野 湧太 熊谷 正芳 田邉 晃弘 新部 純三

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

pp.23-00242, (Released:2024-01-11)

参考文献数

11

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Since it is known that tensile strength and hardness are roughly proportional, a hardness test is often used as a simple and substitute test. However, it has been reported that the proportional relationship between tensile strength and hardness is broken above 595 HV (≈55 HRC). Besides, there are few examples of mechanical properties determined by compression tests despite the fact that high-hardness and high-strength materials subjected to significant compressive stress are used in machine element parts, e.g. bearings. Tensile strength is used instead of compressive strength for the design. Thus, the relationship between hardness and compressive strength in hard materials, quenched medium carbon steel, was revealed. The compressive strength at 8% plastic strain (compressive strength) was almost the same as the maximum compressive strength. The compressive strength and hardness were at their maximum in the as-quenched specimen and decreased with the increase in tempering temperature. The compressive strength and hardness had a linear relationship up to 2000 MPa similar to the relationship of tensile tests. However, the compressive strength increased slightly in relation to the hardness above 2000 MPa in contrast to tensile tests. Thus, the work-hardening index was introduced as a variation parameter to the function that expresses the relationship between compressive strength and hardness to obtain better estimation. The estimated compressive strengths using the work-hardening index are agreed well to the experimental results.

著者

堤 香津雄 藍 譲二郎

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.123, no.1216, pp.10-12, 2020-03-05 (Released:2020-04-01)

著者

酒井 忍 保富 大輔 史 金星 浦上 晃 溝口 正人

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.85, no.877, pp.19-00118, 2019 (Released:2019-09-25)

参考文献数

19

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In rubber baseball games, when the rubber ball is hit by a baseball bat, the rubber ball is deformed greatly comparing to an official baseball ball, and the batted ball speed decreases due to the energy loss during the deformation. Since the new rubber ball has been applied in games from 2018, the material properties and the restitution characteristics of the new rubber ball attract plenty of attention among scholars. In this study, the difference of the material properties and the restitution characteristics between the new and old rubber balls is investigated deeply by the static compression and collision tests. According to the static compression test, we find that the new rubber ball is harder and more difficult to generate deformation than the old one. In the collision test, the rebound ball speeds of both of the new and the old balls become faster when using a smaller diameter of steel cylinder instead of baseball bat, and the rebound ball speed of the new ball is slower than that of the old one under the same experimental conditions. Furthermore, to develop high performance baseball bats adapting to the new rubber baseball, the diameter of the baseball bat is studied by the impact simulation based on the finite element analysis. In the simulation, the batted ball speed under the analytical conditions of different offset heights and different barrel diameters of the bat are evaluated considering the initial spin. As a result, the batted ball speed generated by the bat with diameter φ55 mm is faster than generated by the bat with diameter φ70 mm when the offset height range is smaller than 14.6 mm, so that the bat diameter φ55 mm is recommended according to the present work.

著者

山藤 勝彦 山本 建 澤田 賢治

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.16-00553-16-00553, 2017 (Released:2017-08-25)

参考文献数

11

被引用文献数

1

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This paper describes self-excited oscillation caused by coulomb friction of electromagnetic proportional valve. Especially, this research focuses on a hydraulic system in which electromagnetic proportional and pressure proportional valves are located tandem. In the system, the coulomb frictional force effects on the displacement direction of the spool of the former valve and the piston is established in the downstream region of the latter valve. Each valve is stable, but, the connection of them causes instability. This paper analyzes the mechanism of this unstable vibration and then investigates an anti-vibration design method. In analysis, this paper clarifies that the vibration is caused by an elastic deformation delay of the oil in the piston. This delay increases the phase delay of the spool due to the coulomb frictional force. After replacing the coulomb frictional force with hysteresis, the proposed method uses the describing function method to express phase delay phenomenon due to the coulomb frictional force. The describing function is the complex function which expresses an amplitude ratio and phase difference with the input and output of nonlinear element. The delay of a vibration factor is linearized by converting coulomb friction into hysteresis. The effectiveness of the proposed method is demonstrated via practical experiment and non-linear simulation results.

著者

近藤 孝晴

出版者

一般社団法人 日本機械学会

雑誌

マイクロ・ナノ工学シンポジウム 2015.7 (ISSN:24329495)

巻号頁・発行日

pp._30am2-C-4, 2015-10-21 (Released:2017-06-19)

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The first breath test in clinical medicine is measurements of hydrogen in breath, applied for the diagnosis of milk intolerance. Since then many gases have been studied in many situations. In this symposium, The usefulness of several gases such as CO, NO, hydrogen, acetone and ammonia have been discussed. Some, but not all, of these gases have been used in clinical practice.

著者

北角 俊実

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.106, no.1021, pp.950-951, 2003-12-05 (Released:2017-06-21)

著者

東 昭 安田 邦男

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.92, no.851, pp.890-897, 1989-10-05 (Released:2017-06-21)

著者

野間口 徹 天谷 賢治

出版者

一般社団法人 日本機械学会

雑誌

計算力学講演会講演論文集 2002.15 (ISSN:24242799)

巻号頁・発行日

pp.405-406, 2002-10-30 (Released:2017-06-19)

著者

中田 金市

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌

巻号頁・発行日

vol.55, no.398, pp.202-203, 1952

著者

小浦方 格 原 利昭

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 C編 (ISSN:03875024)

巻号頁・発行日

vol.69, no.681, pp.1366-1373, 2003-05-25 (Released:2008-02-26)

参考文献数

18

被引用文献数

1 2

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Orbicularis oris superior (OOS), orbicularis oris inferior (OOI), levator anguli oris (LAO), depressor anguli oris (DAO), and mentalis (Ment) are considered as typical perioral muscles that contribute to the force and pressure occurence in and around lip aperture. This study presents the experimental and analytical results that show correlationships between eledrical muscle activities and mechanical parameters on bilabial closing force, puckering force, POM (perioral muscle) value and so forth. Besides, zero-lag correlation coefficients between rectified and smoothed SEMG signals of LAO and DAO was constantly higher than other muscle combinations including OOS-OOI combination considered to be most closely related with lip movement. Among lip tasks, prominently high correlation between LAO and DAO was shown when subjects tried to close their lip bilabially at principally distal part. Consequently authors succeeded to prove the great importance of the coordination between LAO and DAO for producing bilabial consonants, drinking and eating, pooling saliva in oral cavity, and others, while the applicability of POM meter to myofunctional therapy is obscured.

著者

多田 海斗 平塚 将起 伊藤 慎一郎 瀬尾 和哉

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.89, no.924, pp.23-00045, 2023 (Released:2023-08-25)

参考文献数

15

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The paper describes the critical Reynolds number of soccer balls as a function of the total groove volume on the ball surface. In this study, the aerodynamic drag and separation point of 6 soccer balls with different panel orientations were measured in a wind tunnel. Moreover, the total volume of grooves on the ball’s surface was measured by One shot 3D measuring machine. It was found that the drag coefficient in the supercritical region and the critical Reynolds number depend on the design of the ball surface (shape, number of panels, surface roughness). A negative correlation exists between the total groove volume on the surface and the critical Reynolds number. When the total groove volume is large, the drag in the supercritical region increases. The position of the separation point does not change in the subcritical and supercritical regions even if the orientation of the panel is changed. However, when the groove width is wider, the panel orientation dependence becomes significant in the supercritical region. In the transition region, the position of the separation point differs depending on the panel's orientation.

著者

梶島 岳夫 太田 貴士 岡崎 和彦 三宅 裕

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 B編 (ISSN:03875016)

巻号頁・発行日

vol.63, no.614, pp.3247-3254, 1997-10-25 (Released:2008-03-28)

参考文献数

25

被引用文献数

13 13

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To apply the direct numerical simulation (DNS) and the large-eddy simulation (LES) of turbulence to flow fields of complicated geometry, a higher-order finite-difference method (FDM) has been developed for the body-fitted coordinate system. The consistency and the conservation property of FDMs are discussed for the collocated grid. As numerical examples, DNS results of decaying isotropic turbulence and DNS/LES results for plane channel flow are shown and the influence of variable arrangement is examined. The results by the consistent 'interpolation' method for gradient form on the collocated grid agree well with those by other proper FDMs and the spectral method.

著者

大倉 典子

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.114, no.1117, pp.850-851, 2011-12-05 (Released:2017-06-21)

参考文献数

6

被引用文献数

1 1

著者

野間口 徹 天谷 賢治 青木 繁

出版者

一般社団法人 日本機械学会

雑誌

計算力学講演会講演論文集 2001.14 (ISSN:24242799)

巻号頁・発行日

pp.233-234, 2001-11-27 (Released:2017-06-19)

著者

大倉 典子

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.122, no.1208, pp.24-27, 2019-07-05 (Released:2020-02-04)

著者

中井 幹雄 川口 和也

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2006 (ISSN:24242993)

巻号頁・発行日

pp._109-1_-_109-6_, 2006-08-06 (Released:2017-06-19)

被引用文献数

1 1

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ピアノ弦のような曲げ剛性をもつ弦の振動における倍音周波数より高い周波数の系列であるInharmonicityの第1系列と異なる第2の系列について述べる. Inharmonicityの第1系列における第n次の周波数計算では, f_n=nf_0√<1+Bn^2>が一般的に用いられている.ここで, f_0は弦の曲げ剛性を考慮しない場合の固有振動数である.また, Bは非調和度と呼ばれる無次元量である.第1系列と異なる第2の系列では,その非調和度は第1系列の1/4の値となることが経験的にわかっている.打弦および撥弦時のInharmonicityの第2系列の発生機構について実験を行った.周波数スペクトルから各次数のピーク周波数を読み取り,その次数の倍音周波数との差を固有振動数で除し,無次元化した値を各次数について計算する.それらの結果とともに第1系列の周波数値を用いて,和および差の周波数を表す格子線を図A1に示す.実線,点線は第1,2系列を示す.図において,微小なピークはほぼ格子点に一致し,第1系列周波数の和および差の周波数をもつことが明らかとなった.また,この格子線は包絡線をもっており,包絡線周辺は格子点の間隔が狭くなり,数多くのピークが集中することが明らかとなった.この包絡線が,理論的に正確に第1系列の非調和度の1/4の値をもつ曲線となっていることがわかり,第2系列を含むすべての微小なピークの周波数特性が明らかとなった.これらの微小なピークは,弦が大変形するという幾何学的非線形性が原因となって発生すると考えられるので,弦の横振動および縦振動を考慮した次式のような非線形方程式を用いて第2系列について検討した. ρA(∂^2u)/(∂t^2)=EA(∂^2u)/(∂x^2)-(T_0-EA)(∂^2w)/(∂x^2)(∂w)/(∂x) (A1) ρA(∂^2w)/(∂t^2)=T_0(∂^2w)/(∂x^2)-EI(∂^42)/(∂x^4)-C_D(∂w)/(∂t)-(T_0-EA){(∂^2w)/(∂x^2) (∂u)/(∂x)+(∂w)/(∂x) (∂^2u)/(∂x^2)+3/2((∂w)/(∂x))^2(∂^2w)/(∂x^2)} (A2) 図A2(a), (b)は数値計算した横振動と縦振動の変位の周波数分析結果を示す.この図で黒丸が第1系列,白丸が第2系列を示している.この図から,8次モードから第2系列が生じ始めることおよび縦振動のピークと第2系列がほぼ一致していることがわかる.このことは式(A1)におけるwの2次の非線形項が横振動の2つの周波数の和あるいは差をもつ外力として縦振動に作用するとみなすことができることからわかる.さらに,横振動の周波数分析結果に和および差の周波数をもつピークが主に現れることがわかった.しかし,横振動には主に任意の2つの第1系列周波数の和・差の組み合わせ周波数からなる第2系列を含む微小なピークのほかのピークも含まれている.したがって,さらに,横振動については,方程式を検討する必要がある.

著者

富塚 清

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会誌 (ISSN:24242675)

巻号頁・発行日

vol.70, no.576, pp.23-25, 1967-01-05 (Released:2017-06-21)

著者

佐藤 千恵 横矢 重治 渡邊 博美 梅原 英之 中村 裕紀 小林 宏

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C編 (ISSN:18848354)

巻号頁・発行日

vol.79, no.806, pp.3525-3538, 2013 (Released:2013-10-25)

参考文献数

25

被引用文献数

4 4

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Back support muscle suit is applied to the work of lifting heavy material in the material handling field, in order to reduce the workload. The work model is defined based on the idea of value steam map, and the possibility of introduction is shown using productivity, which was calculated from the number of handled products during the test and normalized by the one of the subject in the month, and the result of subjective evaluation of 13 workers, which showed that 9 workers could feel better or neutral during the work with muscle suit than without it. And, it was shown that the productivity of the workers with muscle suit was almost the same as the one without muscle suit. The workers who felt neutral are the ones who felt better when they lifted the loads in the lower part of the palette. It was also shown that, based on the characteristics of the subjects, such as age mainly, the result of the subjective evaluation was considered to be reasonable from the viewpoint of power of standard worker.