著者

窪田 格太郎

出版者

一般社団法人 日本機械学会

雑誌

機械学會論文集 (ISSN:21851123)

巻号頁・発行日

vol.2, no.7, pp.291-303, 1936-05-01 (Released:2008-03-28)

被引用文献数

1 1

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羽根車の刻み円外側の輪廓線が円弧の場合と円漸開線の場合とに於て畫法で輪廓線を決定する代りに算式を用ふる方法を研究して、羽根車の回轉角の函数で表す輪廓線の方程式を求めた。羽根車の各部の適當な比例を定めて、輪廓線の向径及び直交軸座標の刻み円半径に対する比を算出して数式による設計を容易にした。

著者

吉野 信太郎

出版者

一般社団法人 日本機械学会

雑誌

機械學會誌 (ISSN:24331546)

巻号頁・発行日

vol.40, no.237, pp.11-12, 1937-01-01 (Released:2017-08-01)

著者

田平 航幹 林 隆三

出版者

一般社団法人 日本機械学会

雑誌

交通・物流部門大会講演論文集 2021.30 (ISSN:24243175)

巻号頁・発行日

pp.TL4-2, 2021 (Released:2022-06-25)

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When driving on a narrow L-shaped road, there are situations where a K-turn combining forward turning and backward turning is necessary. And in some cases, repetitive K-turn are required. The purpose of this research is to propose an automatic driving method for narrow L-shaped roads that includes K-turn, which is often difficult for drivers. The vehicle trajectory is generated geometrically based on the road and vehicle characteristics. When repetitive K-turn are required, the trajectory is divided into three phases: first forward turning (1st phase), repetitive K-turn (2nd phase), final forward turning (3rd phase). Trajectory are generated in the reverse order of the order in which vehicle run. By conducting driving simulations, we confirmed that the proposed method can be used for automatic driving on narrow L-shaped roads.

著者

森山 幸平 岡永 博夫

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.89, no.924, pp.23-00083, 2023 (Released:2023-08-25)

参考文献数

16

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The surface of a golf ball is provided with innumerable dents called dimples to improve the flight distance. In this study, we manufactured 15 model balls in which the dimple occupancy and the dimple volume ratio was changed by the dimple diameter and the number of dimples, and the dimple shapes. Using these balls, we carried out lift and drag measurements of the rotating balls in wind tunnel experiments. Then, a flight trajectory simulation was performed based on the obtained experimental results. As a result, the influence of the base shape showed different results for both drag and lift coefficients for each occupancy. However, the drag coefficient decreased and the lift coefficient increased as the dimple volume ratio increased regardless of the dimple shape. In addition, the relationship between the lift-drag ratio and the dimple volume ratio showed that the lift-drag ratio decreased as the dimple volume ratio increased. The flight trajectory simulation results showed that the flying distance was greater for O=52.6% and O=63.1% with a conical base when the dimple volume ratio was small and the dimple depth is DD/d=4.55×10-3. Two spheres with a spherical base and a conical base at O=83.1%, also exhibited similar flying distances. However, the flight distance tends to increase as the dimple volume ratio decreases. The ball's trajectory was lower when the volume ratio was small, and higher trajectory was obtained when the occupancy ratio was high.

著者

荻野 琢己 飯田 明由 大田 浩嗣 杉田 光弘

出版者

一般社団法人 日本機械学会

雑誌

流体工学部門講演会講演論文集 2019 (ISSN:24242896)

巻号頁・発行日

pp.IS-29, 2019 (Released:2020-07-25)

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The aim of this investigation is to estimate drag force acting on a bicycle helmet and power required for wind speed of bicycle race. It is known that a helmet of bicycle race has not only role to protect the head but also reduce aerodynamic drag force. Since the required power of caused by aerodynamic force acting on the helmet and head is about 18% of the total power of cycling, development of the low drag force helmet is required. To evaluate and understand the unsteady aerodynamic force and its generation mechanism, LES analysis was performed. As a result, the streamlined shape helmet placed in straight against the flow has low drag, but the drag force rapidly increases in the posture during goal sprinting. Therefore, the power required for top speed of bicycle race is more than three times that in steady state. Since, the flow around the helmet is unsteady, the maximum fluid force reaches 3.5 times that of the average. For this reason, it is required to develop robust shape helmet against changes in posture with small fluctuating drag force.

著者

座光寺 伸治 杉本 公一 深田 茂生

出版者

一般社団法人 日本機械学会

雑誌

北陸信越支部総会・講演会 講演論文集 2010.47 (ISSN:24242772)

巻号頁・発行日

pp.323-324, 2010-03-05 (Released:2017-06-19)

著者

藤本 由紀夫 新宅 英司 田中 義和 藤吉 潤

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.78, no.791, pp.2438-2449, 2012 (Released:2012-07-25)

参考文献数

8

被引用文献数

4 5

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Pad type compressive force sensor suitable for high speed impact force measurement is developed. A piezoelectric film is sandwiched by a pair of the thin metal sheets. The electric wire is connected to the metal sheets which are the electrode of piezoelectric film. The whole of the sensor is covered by thin resin sheet, and layer components inside the sensor are fixed together in one body. A sensor is about 1mm in thickness and it can be made in the various shape according to the purpose of use. Several pad sensors are made for trial purpose, and the performance are examined through experiments by applying fluctuating loads and impact loads. Finally, the pad sensor is applied to the impact force measurement of golf ball shot by setting up the sensor to No5 and No9 golf irons.

著者

谷村 眞治 王 虎 森田 浩章 海津 浩一 山崎 勝広 三村 耕司

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 A編 (ISSN:03875008)

巻号頁・発行日

vol.61, no.586, pp.1344-1348, 1995-06-25 (Released:2008-02-21)

参考文献数

6

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The existence of critical impact velocity has been confirmed in experiments in which a sheet was perforated by a flying projectile. The experiments were performed to measure the values of parameters relevant to the normal impact of the cylinder against the sheets. By examining the relationship between the diameter of blanks and impact velocity, the phenomenon of the critical impact velocity was confirmed. The theoretical approach was also presented, for the same conditions as in the case of simple wave propagation, as in the Karman-Duwez solution. The comparison between theoretical examination and experimental results was also discussed.

著者

竹田 憲生 亀山 達也

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.22-00095, (Released:2022-06-07)

参考文献数

14

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A practical structural health monitoring has been proposed for evaluating the structural health of a whole mechanical asset by using digital twin with data collected during the operation of the asset. Digital twin can be utilized to predict the remaining useful life by estimating the variation of the physical quantity that dominates the life, even though any records of failure do no exist. However, a mechanical asset includes huge number of local hot spots where structural health should be evaluated, and accordingly, huge man-hours are required to integrate a monitoring system that evaluates the health at all the hot spots by using digital twin. A hierarchical structural health monitoring has been therefore developed to overcome this drawback. In the first stage of the health monitoring, the overview of the mechanical damage of the components included in a asset is evaluated according to a metric, D factor, that defines the cumulative damage of the components, and the assets having relatively large damage are extracted. The extracted assets are then evaluated in detail in the second stage; that is, structural health is checked at the local hot spots. The monitoring system that employs digital twin and the hierarchical health monitoring was applied to the health management of wind turbines. As the result of evaluating the structural health of the main components of wind turbines, about a hundred wind turbines can be prioritized according to the D factor. In this first stage, a surrogate model based on a machine learning was utilized for evaluating the overview of the damage with low computational cost; the approximation error of the D factor was less than 3 % by using the surrogate model. It can be therefore concluded that this practical structural health monitoring is useful for the decision making of fleet health management of mechanical assets.

著者

谷田 涼 内野 敬太 松村 雄一

出版者

一般社団法人 日本機械学会

雑誌

Dynamics & Design Conference 2010 (ISSN:24242993)

巻号頁・発行日

pp._740-1_-_740-6_, 2010-09-14 (Released:2017-06-19)

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This paper clarified the excitation mechanism of picking the strings of a guitar. The picking excites forced vibration and free vibration of the strings by giving the strings impact force, friction force and initial condition. At first, separate influence of these force and initial condition was experimentally examined. Then, generation mechanism of transient responses of the strings was examined for ordinary picking technique, by the viewpoint of the influence of impact force, friction force and initial condition.

著者

劉 浩

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.109, no.1049, pp.265-268, 2006-04-05 (Released:2017-06-21)

参考文献数

6

著者

史 金星 山田 陸人

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.89, no.922, pp.23-00054, 2023 (Released:2023-06-25)

参考文献数

20

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Lure fishing is a well-known type of fishing that uses artificial lures instead of traditional live baits. Vibratory lure is a kind of lures performs greater vibration behavior than other kinds of lures. In common, more excellent vibration behavior of vibrating lure can attract carnivorous fish more efficiently. Up to now, lure design is generally based on the intuition of the designer, and there is little academic research on vibrating lure. In this study, we build the finite element model of a commercial vibration lure using a 3D scanner at first. Then, fluid–structure interaction (FSI) analysis is carried out to reproduce underwater motion of the vibration lure, where we can calculate the frequency of the flow induced vibration (FIV). Finally, in order to obtain the best FIV behavior of the vibration lure, based on the simulation results of FSI analysis, we perform structural design optimization of the vibration lure using the Box-Behnken design method, which belongs to the response surface methodology. In the structural design optimization, we set three design variables, which are the positions (x and z) of the weight placed in the lower part of the lure, and the eye position (i.e., the knot position between fishing line and lure) along the lure body. According to optimal results, the highest frequency of the FIV can reach 7.07 Hz. However, the present work is still in the early stage of the academic research on lure design, we aim to develop more optimization method for lure design that make lure fishing more interesting for both beginners and anglers.

著者

横溝 将晴 宮元 克弥 青木 岳史

出版者

一般社団法人 日本機械学会

雑誌

ロボティクス・メカトロニクス講演会講演概要集 2019 (ISSN:24243124)

巻号頁・発行日

pp.1A1-S08, 2019 (Released:2019-12-25)

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In agriculture work, weeding work in paddy field has been physical burden and taken a lot of working time. As a solution of this problem, stopping the growth of weed by stirring the soil is affective. An example is "Duck farming" that ducks stir the mad by swimming in paddy fields. In this paper, we propose new robot that imitate snakes to stir the soil. A body segment of this robot is composed of three bending modules and two wire driving mechanisms, we approximate the serpenoid curve by curves without using straight lines.

著者

山田 敏郎 可児 弘毅 生田 耕治

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 B編 (ISSN:03875016)

巻号頁・発行日

vol.47, no.415, pp.450-460, 1981-03-25 (Released:2008-03-28)

参考文献数

19

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衝撃超高圧力研究用に超高速飛しょう体発射装置(二段式軽ガス銃)が試作され, その性能の数値解析が試みられた. 試作装置により16.4gの飛しょう体が3.57km/sまで加速・発射された. 発射実験結果と性能解析の予想値との良い一致により, 解析法の妥当性が確かめられた. 性能解析により, 試作装置は9.5gの飛しょう体が5km/sまで加速できることおよび発射速度支配因子のうち, 特に装薬量と飛しょう体質量の影響が大であることなどが明らかにされた.

著者

近藤 恭三

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.69, no.567, pp.412-417, 1966-04-05 (Released:2017-06-21)

著者

石田 勝裕 渡邉 鉄也 田中 基八郎

出版者

一般社団法人 日本機械学会

雑誌

ジョイント・シンポジウム講演論文集:スポーツ工学シンポジウム:シンポジウム:ヒューマン・ダイナミックス 2007 (ISSN:24331309)

巻号頁・発行日

pp.172-177, 2007-11-13 (Released:2017-08-01)

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Lure fishing and fly-fishing have been positioned as sports deliberately different from the traditional Japanese fishing-style. In the case of fly-fishing, casting is the element which anglers must master in order to cast a fly, done so by using the weight of a line. This study uses experimental and computational analysis to investigate the dynamic behavior of a fly line. Fly-fishing constitutes various elements, but the importance that casting holds is extremely large. Fling speed, the casting process and the loop shape of the line while in flight are important for the proper presentation of flies. Moreover, the shape of a fly line is also important for a long cast or controlled cast. However, it is difficult to grasp the phenomenon or to make a numerical model because a fly line is an object of flexible string. Therefore, the most suitable casting method will be clarified from the viewpoint of sports engineering and human dynamics. In addition, measuring an angler performing movements with a flexible object such as a rod or a line is difficult. So establishing a method to measure the dynamic behavior precisely is also one of the purposes of this study. For the past study, casting that uses only one hand have been analyzed. However, casting that uses both hands is often done in the actual fishing field. In this paper, line's behavior is examined in double haul casting.

著者

小林 宜弘

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.116, no.1132, pp.152-153, 2013-03-05 (Released:2017-06-21)

参考文献数

3

著者

横山 博史 北宮 克哉 飯田 明由

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:18848346)

巻号頁・発行日

vol.79, no.804, pp.1419-1433, 2013 (Released:2013-08-25)

参考文献数

16

被引用文献数

1 1

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To clarify the mechanism of acoustic radiation in flows around a cascade of flat plates, fluid structures and acoustic fields were elucidated by direct simulations. The simulations were mainly performed for flows around 5 parallel plates and the separation-to-thickness ratio s/d was 6.0. The freestream velocity was changed from 30 m/sec to 60 m/sec, and the acoustic resonance occurs between plates at the freestream velocity of 44 m/sec. At that velocity, the Reynolds number based on the chord length and the freestream velocity was 8.7×104 and that based on the plate thickness was 5.8×103. Computational results were validated by the experimental results performed in the present research. The computational results showed that large-scale vortices composed of fine-scale vortices are shed in the wakes of the plates independently of the acoustic resonance. When the large-scale vortex is shed from the upper or lower face, an expansion wave is radiated around the downstream edge of the upper or lower face, respectively. The compression wave is radiated around the downstream edge of the opposite face. The simulation for the flow around a single plate was also performed, and the results confirmed the above-mentioned acoustic radiation mechanism. For the flows around a cascade of flat plates, the sheddings of the vortices from neighboring plates are synchronized when the acoustic resonance occurs. It was also clarified that the mode of the synchronization is an anti-phase mode and the standing waves generated between plates are reinforced.

著者

仲田 翔太 石川 亮太 佐藤 靖徳 高橋 勉

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.88, no.906, pp.21-00369, 2022 (Released:2022-02-25)

参考文献数

17

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A prediction model of the fluid force on a cylindrical blade driven by the Necklace vortex is developed and verified by experiments when the yaw angle is given. Based on the measurement results of the velocity ratio of blade and wind velocity and the fluid force coefficient at zero yaw angle, a prediction model for the relationship between the rotation angle of the cylindrical blade and the fluid force coefficient considering the yaw angle was derived from the analysis of the two-dimensional velocity components acting on the cylindrical blade. The validity of the predictive model was demonstrated by experimental verification. From the comparison, it was found that there was a time delay in the formation and disappearance of the Necklace vortex. Based on the experimental results, the characteristics of the fluid force acting on the cylindrical blade were classified into five angular regions and based on the characteristics of the effective velocity ratio considering the yaw angle, the classification was made into 12 angular regions. Depending on the yaw angle, wind speed, and rotational speed of the blade, all of these regions may appear or only some of them may appear. Therefore, the yaw angle characteristics of the cylindrical blade wind turbine driven by the Necklace vortex are very complicated.

著者

仲田 翔太 佐藤 靖徳 高橋 勉

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.88, no.907, pp.21-00349, 2022 (Released:2022-03-25)

参考文献数

21

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In a circular cylinder blade wind turbine driven by a longitudinal vortex, the torque characteristics of the turbine are greatly affected by the flow field at the blade tip. In general, wind turbines reduce drag by making the blade tips thinner. However, because this wind turbine uses a cylinder as a blade, it is important to control the flow field at the blade tip. From the experiments, it was found that the torque coefficient can be increased by attaching the endplate to the blade tips, and the rotational force can be obtained stably up to very low rotation speeds. The installation of fairing or endplates in circular cylinder blade wind turbines enables stable rotation at low speeds even under high loads, and also reduces drag at high speeds and increases the maximum speed. In the case of a disk-shaped endplate, the torque coefficient can be increased by up to 20 % by attaching an endplate with a diameter 2.5 to 3 times the diameter of the cylinder to the outer blade tip only. The L-type endplate has the effect of shifting the characteristics to the higher rotation side than the disk-type, and increases the torque coefficient at the same tip speed ratio. However, the lower limit of stable rotation becomes higher, and as a result, the value of the maximum torque coefficient obtained at high load decreases. If the endplate attached inside has a negative effect on the stable formation of the necklace vortex, it will inhibit the rotation at a low speed due to high load, making it difficult to obtain high torque.