著者

佐藤 理 岩井 裕 吉田 英生

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.80, no.820, pp.TEP0360, 2014 (Released:2014-12-25)

参考文献数

9

被引用文献数

4 2

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The purpose of this study is to clarify the effect of a component for high-pressure water separation, which is included in the air conditioning system of the general commercial aircrafts, on the air-cycle operation (reverse Brayton cycle); the high-pressure water separation consists of water separator and two heat exchangers called reheater and condenser, respectively. This paper briefly describes the typical system configuration of the air-cycle refrigeration progressed with evolutions in turbofan engine. Since nowadays, 4-Wheel air-cycle has been a trend on the aircraft air conditioning system, this paper theoretically shows its advantage on the basis of the thermodynamic cycle study. In the following chapters, an analysis was conducted on the interaction between a reheater and a condenser when each heat transfer performance changes from the baseline operating point. Also, the comparative study was made on the system performances by the 3-wheel and 4-wheel air-cycle. In addition, this paper describes how the heat transfer performance is designed for the reheater and the condenser under the system requirements for the entire air conditioning system.

著者

竹内 和也 松島 紀佐 金崎 雅博 楠瀬 一洋

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.81, no.827, pp.15-00037, 2015 (Released:2015-07-25)

参考文献数

9

被引用文献数

3 3

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To systematically investigate the aerodynamic characteristics of wings with 30, 45 and 60 degree swept-back angles, and different taper ratios, Navier-Stokes (N-S) simulations for flows over a wing have been conducted. The Mach numbers of the flows range from 0.8 to 2.8. The planforms of wings are in various shapes whose half span aspect ratios are identically fixed in 2.0. The simulation and investigation has revealed new knowledge on the relation between swept-back angles and aerodynamic characteristics of a wing in a supersonic flow. As the aerodynamic characteristics, drag coefficient CD variation is primarily observed along flow Mach number increase. Results of N-S simulations show a realistic profile of the variation which is substantially different from that by the thin-wing theory commonly printed in a textbook. Moreover, the simulation results indicate not only the swept-back angle of a leading edge but also that of a trailing edge take important role on aerodynamics of a wing. Finely, the effect of drag coefficients induced by lift is analyzed using simulation results. It is found that the induced drag in realistic supersonic flows can be treated by the thin-wing theory if three-dimensionality is properly evaluated.

著者

藤川 正毅 田中 真人 井元 佑介 三目 直登 浦本 武雄 山中 脩也

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

巻号頁・発行日

vol.86, no.881, pp.19-00256-19-00256, 2020

被引用文献数

1

---

<p>A numerical calculation scheme for stress and its consistent tangent moduli with hyper-dual numbers(HDN) for Ogden-type hyperelastic material model was proposed. The main advantage of this scheme is that once the framework is coded, any Ogden-type hyperelastic material model can be implemented by only re-coding the strain energy density function. In this scheme, the new differentiation method for eigenvalue and eigenvector of the symmetric matrices with HDN were proposed. The proposed method can calculate the eigenvalue and eigenvector in non-real part analytically by using the eigenvalue and eigenvector in real part, in case that all eigenvalues in real part are not multiple root. We implemented the Neo-Hookean model and the Ogden model with the proposed scheme, to confirm the effectiveness and robustness of this method, and applied it to some examples. As the results, it was confirmed that the numerical results of the proposed method showed good agreement with analytical ones.</p>

著者

中川 智皓 森田 悠介 新谷 篤彦 伊藤 智博

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.82, no.838, pp.16-00052, 2016 (Released:2016-06-25)

参考文献数

11

被引用文献数

1

---

In recent years, personal mobility vehicles (PMVs) have attracted huge attentions and widely developed. Compact PMVs can move through narrow spaces and they are expected to be used in pedestrian spaces. In this study, we aim to develop a four-wheel stand-up-type personal mobility vehicle for people who cannot walk far distantly because of the pain of foot or waist although they are able to walk for a short distance. The coupled model of human and vehicle is constructed by using multibody dynamics. In the model, the vehicle is expressed by one rigid body. The wheels, body, and handle are considered as a rigid body together. A human is expressed by 8 rigid bodies (foot, lower leg, femoral, body, head, upper arm, lower arm, and hand). The vehicle of the coupled model is accelerated in the numerical simulations. The behaviors of the center of gravity of a human with and without handle constraint are analyzed. As the result of the parametric study, it is found that the center of gravity movement is smaller when the value of the maximum acceleration and the acceleration time are small. It is also found that as the angle of the upper arm becomes large, the movement of the center of gravity is decreased.

著者

藤川 正毅 田中 真人 井元 佑介 三目 直登 浦本 武雄 山中 脩也

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

巻号頁・発行日

2019

被引用文献数

1

---

<p>A numerical calculation scheme for stress and its consistent tangent moduli with hyper-dual numbers(HDN) for Ogden-type hyperelastic material model was proposed. The main advantage of this scheme is that once the framework is coded, any Ogden-type hyperelastic material model can be implemented by only re-coding the strain energy density function. In this scheme, the new differentiation method for eigenvalue and eigenvector of the symmetric matrices with HDN were proposed. The proposed method can calculate the eigenvalue and eigenvector in non-real part analytically by using the eigenvalue and eigenvector in real part, in case that all eigenvalues in real part are not multiple root. We implemented the Neo-Hookean model and the Ogden model with the proposed scheme, to confirm the effectiveness and robustness of this method, and applied it to some examples. As the results, it was confirmed that the numerical results of the proposed method showed good agreement with analytical ones.</p>

著者

沖野 友洋 永田 恵輔 堀川 敬太郎 小林 秀敏

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.19-00249, (Released:2019-12-26)

参考文献数

13

被引用文献数

2

---

The crash safety structure of the railway vehicles is effective as one of the safety measures against the train crews and the passengers in the event of a collision accident. The standards for crashworthiness of railway vehicles are defined in Europe and the U.S., while there are no standards for crash safety in Japan. Therefore, it is important to establish the evaluation method for crashworthiness of railway vehicles considering the actual situation of collision accidents in Japan. The authors carried out finite element analyses of a level crossing accident under various conditions (collision speed, mass of the obstacle and relative position between the train and the obstacle) based on the statistical analysis of serious level-crossing accidents in the past in Japan, and calculated the deceleration time histories in the passenger area under each condition. We evaluated these deceleration waveforms according to European and the U.S. standards for crashworthiness, and we also performed finite element analyses of dummy’s behavior and injury values using these deceleration waveforms as input. We verified the correlation between the evaluation results in terms of the deceleration according to these standards and dummy’s injury values obtained by finite element analyses. As a result, the evaluation according to the velocity at which a passenger contacts the seat back ahead of him (the U.S. standards) was the most effective. Moreover, the integrated values of the deceleration of the passenger area during an integration time t360 had the highest correlation with the dummy’s injury values.

著者

神田 康行

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

巻号頁・発行日

2019

被引用文献数

1

---

<p>The rigid plastic finite element method (RPFEM) is used in many re-meshing procedures in material processing analysis. Currently, the four-node quadrilateral element, which can avoid volumetric locking, is applied in the RPFEM. However, it is desirable to apply the three-node triangular element instead because of its easy and robust mesh generation procedure. This study applied the three-node triangular element with drilling and strain degrees of freedoms (GNTri3) to the RPFEM, the validity of which was verified by analyzing some numerical examples. First, as verification for the volumetric locking characteristic of the GNTri3, FEM analysis of a nearly incompressible elastic body under plane strain conditions was performed. Volumetric locking was recognized by applying full integration to the element stiffness matrix of the GNTri3. Therefore, it was revealed that the RPFEM using the GNTri3 is necessary for applying selective reduced integration to the element stiffness matrix. Analysis of the RPFEM using the GNTri3 showed that the tool pressure was in good agreement with theoretical solutions and FEM results obtained using a conventional four-node quadrilateral element at a rigid punch indentation. In addition, reasonable material processing deformations were computed in the plane strain compression test.Therefore, validity of the RPFEM using the GNTri3 was verified by numerical results.</p>

著者

原 進 鈴木 健太 山田 陽滋

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.2017transjsmeE01, 2017 (Released:2019-12-25)

著者

佐藤 拓哉 宮武 昌史

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.880, pp.19-00092, 2019 (Released:2019-12-25)

参考文献数

13

被引用文献数

1

---

Battery train is in development as train which can travel in non-electrified section using power supplied from onboard storage system such as lithium-ion battery. However, as characteristics of this type of train, an energy consumption of battery train depends on the state of charge of the storage system. In consideration of these characteristics, we propose a generation method of the timetable which is the most energy-saving when a single battery train travels on a route section containing multiple stations in this research. Although this optimization can be defined as a nonlinear programming problem, we ease to solve this problem using linear approximation to the energy consumption characteristic. In the end, we carried out a simulation in a simple case and achieved 4.7% reduction in energy consumption by the proposed method.

著者

岡田 光貴 末岡 裕一郎 中西 大輔 大須賀 公一

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.19-00151, (Released:2019-12-04)

参考文献数

13

---

This paper is concerned with the demonstration of scallop-like swimming with the aid of robot toy; using jet propulsion by clapping the shells quickly. Previous works from biological approach have indicated what structures contributes to generate the jet propulsion. This paper tries to perform quick underwater locomotion by mimicking the structures of scallop based on constructive approach: development of scallop-like robot with autonomous generation of jet propulsion. After designing the structure and actuation mechanism by mimicking the scallop, we focus on the effect of the mantle property on swimming. Firstly we confirm that developed robot can perform scallop-like swimming. Secondly we also compare the swimming speed by changing the property of designed mantles.

著者

木下 泰宏

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 (ISSN:21879761)

巻号頁・発行日

vol.80, no.810, pp.LH0036, 2014 (Released:2014-02-25)

参考文献数

40

---

The purpose of this paper is to clarify the factors which influenced the development of the technology in the Edo period. Especially, this paper tries to consider the influence on the mechanical technology development by the “Shinki-hatto”. “Shinki-hatto” law was promulgated in 1721. It has been proposed in the field of the history of engineering and intellectual property that invention is strictly prohibited by this law and the law causes Japan's stagnant technology development in the Edo period. This paper makes clear that the principal purpose of the law was to maintain the economic and institutional status quo. In addition, the paper suggests the possibility that the law fell short of expectations in terms of effectiveness.

著者

森上 雄太 中山 裕太 高木 健 石井 抱

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.80, no.819, pp.DR0322, 2014 (Released:2014-11-25)

参考文献数

15

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This paper describes a monocular stereo system that can switch its viewpoint hundreds of times of more in a second using a four-pinhole viewpoint switching iris mechanism. Our system can measure the three-dimensional information of a moving object correctly using two different viewpoint images, which are selected from the four switched viewpoint images in a short interval using a four-pinhole viewpoint switching iris mechanism, corresponding to the moving direction of the object. Using a prototype of monocular stereo system that consists of the four-pinhole viewpoint switching iris mechanism and an offline high-speed video camera, we verified its effectiveness in monocular stereo measurement by performing several experiments of moving objects.

著者

木村 勇次 井上 忠信 中田 隆之 福田 又一

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.860, pp.17-00493, 2018 (Released:2018-04-25)

参考文献数

24

被引用文献数

1 7

---

Delayed fracture susceptibility of 1.8 GPa-class ultra-high strength bolts was evaluated by an outdoor exposure test. Low-alloy steel bars with a chemical composition of Fe-0.4%C-2%Si-1%Cr-1%Mo (mass%) were quenched and tempered at 500 °C for 1 h, caliber-rolled at 500 °C with a rolling reduction of 78%, in order to create fail-safe steels (FS steels) with an ultrafine elongated grain structure. Subsequently, FS steel bars were formed into JIS M12 hexagon head bolts with a nominal length of 60 mm (FS bolts). Bolt heading was performed at 700~730 °C, and screw part was formed by thread-rolling at 500 °C to maintain the ultrafine grain structure with a strong <110>//rolling direction fiber texture. Conventionally quenched and tempered bolts (QT bolts) with a tempered martensitic structure were prepared for comparison. A steel plate was fastened by the bolts on 23 April 2013, and the outdoor exposure test was started on 21 May 2013 in Miyako Island test site of Japan Weathering Test Center. The bolt fastening force was 122 kN (=0.85 σ0.2 at thread part) for FS bolts and 89 kN (=0.70 σ0.2 at thread part) for QT bolts. The outdoor exposure test demonstrated an excellent delayed fracture resistance of FS bolts at the ultra-high tensile strength of 1.8 GPa; FS bolts have not been broken for 53 months, in contrast to QT bolts exhibiting delayed fracture. Intergranular cracking along the prior-austenite grain boundaries was commonly observed in the broken QT bolts. The accelerated laboratory test using tensile tests of pre-hydrogen-charged specimens and immersion test (30 °C, pH2) showed that the FS bolts had high resistance to hydrogen embrittlement, and it was in good agreement with the result of outdoor exposure test of the FS bolts.

著者

佐藤 悠 井上 健司

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 (ISSN:21879761)

巻号頁・発行日

vol.82, no.843, pp.16-00348, 2016 (Released:2016-11-25)

参考文献数

20

被引用文献数

1

---

A method for a six-legged robot of walking on terrain with various undulations by tripod gait is proposed. First the robot detects foot landing using touch sensors, and estimates the inclination angle of the ground from the landing positions; the estimated ground is called “reference ground”. Second the robot measures the inclination angle of its body using acceleration sensor. Then the legs move up and down so that the body may be parallel to and may keep a constant distance from the reference ground. If the robot encounters deep depressions or downward slopes, the robot suspends walking and actively inclines the reference ground. As a result the body inclines, and the swing leg goes further down. When the swing leg reaches the ground, the robot restarts walking. Due to the feedback gain of body orientation control, the robot does not respond to fine change of undulation. Hence the body keeps a constant orientation on short distance undulation or rugged surface, and gradually inclines its body on long distance undulation such as slopes and stairs. The ability of climbing up and down slopes and steps in longitudinal and transverse directions is evaluated by experiments. The maximum angle of climbing up slopes is 30 degree, and that of climbing down slopes is 40 degree. The maximum height of climbing up steps is 150 mm, and that of climbing down steps is 180 mm. The robot can also go through a bump of 125 mm width and 60 mm height.

著者

横山 真男 瀬田 陽平 矢川 元基

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.17-00287, (Released:2017-12-06)

参考文献数

15

---

Based on experimental observation of liquid dripping, a method to prevent liquid adhesion at the wall of cup was proposed in this paper. When water or sauce etc. is poured from edge of a cup or a pot, the liquid adheres to the wall of cup, which often makes a table or clothes dirty. To clarify the above annoying problem, the flow dripping from the cup, whose edge was shaped to have various thin channels, was observed by using high speed camera. We found the water adhesion on cup's wall reduced when the channels were located at the outside of edge of the cup.

著者

齊藤 亜由子 宮脇 和人 小松 瞭 巖見 武裕

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 (ISSN:21879761)

巻号頁・発行日

vol.84, no.865, pp.18-00263, 2018 (Released:2018-09-25)

参考文献数

20

被引用文献数

1

---

This paper describes the use of nine-axis motion sensors to evaluate the motion sensor position on the thigh and lower leg during walking. The motion sensors are mounted on a subject's body using adhesive tape. The muscles constantly relax or contract because of human movement. Therefore, joint angle estimation using motion sensors produces different accuracy depending on the position where the motion sensor is mounted. Evaluating the motion sensor position is important for improving the joint angle estimation accuracy. For this study, the authors used six nine-axis motion sensors and a 3D motion analysis system to assess walking exercise. Three motion sensors were mounted to the thigh; three were mounted to the lower leg. The knee joint angle was estimated using a sensor fusion algorithm that corrected the centrifugal acceleration and the tangential acceleration in the acceleration sensor output. We evaluated the accuracy of knee joint angle estimation by comparing the nine-axis motion sensor results and the 3D motion analysis system results. Results demonstrated the possibility of high-accuracy estimation when the motion sensor is attached to a position 50% or 75% from the upper end of the thigh and another sensor is attached to a position 25% or 50% from the upper end of the lower leg.

著者

松永 拓也 越塚 誠一 保坂 知幸 石井 英二

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.19-00186, 2019 (Released:2019-09-25)

参考文献数

37

被引用文献数

1

---

In this paper, we proposed a new particle method for numerical simulation of droplet dynamics. In the proposed method, the moving surface mesh is used to define interface between gas and liquid. The volume enclosed by the mesh represents the liquid droplet, and the outer domain is inactive gas with constant pressure. The incompressible liquid flow is calculated using a particle method, in which spatial derivatives are evaluated using an arbitrary high order accurate scheme. On the free surface, the surface stress balance equations, including surface tension and viscous stress, are adopted for the boundary conditions. Deformation of the gas-liquid interface is explicitly calculated by surface nodes that move in a Lagrangian fashion. Surface tension force is directly evaluated with high accuracy on each node utilizing the mesh shape. As numerical verification, simulations of three benchmark problems, namely circular patch test, Laplace pressure test and 2D droplet (liquid column) oscillation problems with different oscillation modes, have been carried out. The computation results were compared with the theoretical solutions, and excellent agreements were obtained. As a result, high accuracy and validity of the proposed computational method were confirmed.

著者

炭竈 美穂 梅原 徳次 野老山 貴行 上坂 裕之

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.80, no.811, pp.SMM0038, 2014 (Released:2014-03-25)

参考文献数

13

---

Disc brake is one of the most important auto mobile components and the toughest frictional components. Nowadays, the lightweight disc brake is needed for better fuel-efficient. To reduce the weight, high frictional and low aggressive brake pad is required. However, generally high friction cannot provide low wear of counter-part, therefore to make such brake pad is difficult. In addition, including many kinds of materials such as abrasive, binder, filler and so on, we cannot design it theoretically. In order to overcome these issues we focused on abrasive shape in brake pad, especially focused on open angle of abrasive φ and the important index “degree of wear fab”. If degree of wear fab decreases with open angle φ of abrasive and reduction of wear is more than reduction of friction, we can propose the high frictional and low aggressive brake pad which includes small open angle abrasive. In order to validate our proposals, we conducted the scratch test using Vickers indenter and Knoop indenter. As a result of the scratch test, we clarified that the ratio of wear coefficient to friction coefficient K / μ is correlated with degree of wear fab, and in the region of ploughing and wedge, degree of wear fab decreased with decreasing open angle φ. Due to these phenomena, the ratio of wear coefficient to friction coefficient K / μ decreased with decreasing open angle φ in the region of ploughing and wedge. Thus it was valid that small open angle abrasive provides high friction and low aggressiveness.

著者

天寅 喬文 渕端 学

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.875, pp.18-00399, 2019 (Released:2019-07-25)

参考文献数

8

---

In recent years, NOx and soot contained in the exhaust gas of diesel engines become problems. Currently they are elutriated by exhaust gas aftertreatment devices, which make the engine system more complicated. Therefore, we focused on emulsion fuel, which is known as one of the simultaneous reduction technology of NOx and soot. Although emulsion fuels are generally characterized by its water content, some literatures report that the effect on the diesel engine performance could not be controlled by the water content properly. Therefore, we focused on dispersed water droplet diameter as the other factor. In this study, we prepared emulsion fuels of different water droplet diameters and investigated the exhaust gas and power performance of a diesel engine with these fuels. The emulsion fuels consist of light oil, water and surfactant. We added 2.0 vol% of surfactant whose HLB value was adjusted to 6.0 to light oil. The water content was 10 and 15 vol%. We prepared emulsion fuels of three different mean dispersed water droplet diameters. The test fuel was 6 types of emulsion fuel (3 kinds of dispersed water droplet diameter, water content 10 and 15 vol%) and light oil. The diesel engine used in our experiment was of air-cooled, single-cylinder, jerk pump driven direct injection type. The displacement is 320 cc. We measured in-cylinder pressure, ignition delay, exhaust gas emission (NOx, Soot and CO) and power performance (Output power and Thermal efficiency). We found a relationship between the Sauter Mean Diameter of dispersed water droplets (DS.M.D.) and each parameter. The smaller DS.M.D. is, the more the NOx and soot are reduced. On the other hand, the bigger DS.M.D. is, the higher the output and thermal efficiency are.

著者

野口 聖史 小國 健二

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.874, pp.19-00099, 2019 (Released:2019-06-25)

参考文献数

16

---

Differential form is an alternative mathematical form to describe the field variables and the operators in electromagnetism. From the viewpoint of differential forms, discretization of electromagnetic field is divided into two steps, i) discretization of the exterior derivative operator (Maxwell’s equations), and ii) discretization of the Hodge star operator (constitutive equations). The first step, the discrete form of the Maxwell’s equations based on differential forms has been obtained by other researchers. In contrast, the discrete Hodge star operators (discrete constitutive equations) have not been obtained so far. In the previous studies, unsigned diagonal discrete Hodge star operators are defined using the unsigned area and length for circumcenter dual meshes, however, it does not lead to correct solution of partial differential equations in the general Delaunay meshes. In this paper, we propose a definition of the signed diagonal discrete Hodge star using the signed area and length operator for circumcenter dual meshes. Also, based on this definition, we propose a simple practical calculation method for the signed discrete Hodge star operators. The result of convergence experiment indicates that the signed diagonal Hodge star operators produce the correct numerical solution for the general Delaunay meshes. Therefore, this definition and calculation method for the signed discrete Hodge star operator provides us with the explicit dynamics formulation for finite element analysis of electromagnetic field.