著者

釜谷 昌幸 北條 智博 望月 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.80, no.817, pp.SMM0252-SMM0252, 2014 (Released:2014-09-25)

参考文献数

44

被引用文献数

2 2

---

Load carrying capacity of austenitic stainless steel component is increased due to hardening caused by neutron irradiation if no crack is included in the component. On the other hand, if a crack is initiated in the reactor components, the hardening may decrease the load carrying capacity due to reduction in fracture toughness. In this paper, in order to develop a failure assessment procedure of irradiated cracked components, characteristics of change in failure strength of stainless steels due to cold working were investigated. It was experimentally shown that the proof and tensile strengths were increased by the cold working, whereas the fracture toughness was decreased. The fracture strengths of a cylinder with a circumferential surface crack were analyzed using the obtained material properties. Although the cold working altered the failure mode from plastic collapse to the unsteady ductile crack growth, it did not reduce failure strengths even if 50% cold working was applied. The increase in failure strength was caused not only by increase in flow stress but also by reduction in J-integral value, which was brought by the change in stress-strain curve. It was shown that the failure strength of the hardened stainless steel components could be derived by the two-parameter method, in which the change in material properties could be reasonably considered.

著者

岩田 郷志 宅間 正則 齋藤 賢一 松井 淳基 高橋 可昌 都築 勇人

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.80, no.818, pp.SMM0292-SMM0292, 2014 (Released:2014-10-25)

参考文献数

18

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A6061-T6 alloy has been used in the liner material of high-pressure hydrogen gas storage container that is mounted on a fuel cell vehicle. The degradation of the properties such as strength, toughness and hydrogen embrittlement resistance, etc., has been pointed out, because the grain structure of the mouthpiece part of the liner becomes coarse in the manufacturing process. The tensile and fatigue test for the specimens with different grain size were done, and the detected AE signals during the testing were analyzed. In the tensile test, the characteristics of the signals on dislocation motion, transgranular and intergranular fracture were extracted. In the fatigue test, it was shown that the possibility of which the damage is evaluated by the spectral analysis that utilizes the slope of an approximation straight line in the both logarithmic scale display of FFT analysis result. Then we proposed the amplitude ratio Rv that is the parameter which divided the maximum amplitude of signal for intergranular fracture by that of detected signal, and the correlation between the grain size and the Rv was recognized. These proposed information are able to be utilized in order to evaluate the damage of the container.

著者

末岡 裕一郎 北 卓人 石川 将人 杉本 靖博 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C編 (ISSN:18848354)

巻号頁・発行日

vol.79, no.801, pp.1718-1727, 2013 (Released:2013-05-25)

参考文献数

15

被引用文献数

2 2

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In this paper, we discuss some phenomena of obstacle clustering by distributed autonomous robots, in the light of space-discretization (or cellular automata) approach. This work was motivated by Swiss Robots which collect scattered obstacles into some clusters without any global information nor intelligent concentrated controller. Then we define fundamental event rules in this cellular world, and introduce two types of local rules for robot action: one is the Push & Turn rule, which can collect obstacles, the other is Pull & Turn rule, which can scatter obstacles. By defining several indices (ratio of immobile obstacles, ratio of moved obstacles), we investigate the dynamic equilibrium of obstacle clustering by heterogeneous agents. And, this paper also presents a control method of ratio of immobile obstacles from the estimation of each robot's local information even if all the states of obstacles cannot be measured.

著者

滝田 好宏 伊達 央 大川 真弥

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.812, pp.TRANS0069-TRANS0069, 2014 (Released:2014-04-25)

参考文献数

19

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This paper proposes SSM (Sensor Steering Mechanism) for a lateral guided vehicle with an articulated body. Authors demonstrated the simple lateral guiding method SSM for the front wheel steer type, the reverse phase four-wheel steer type and the rear wheel steer type vehicle. SSM presents the stable lateral guiding performance for automated vehicle which follows a straight and curved path created by guideway. This paper proposes a simplified SSM to remove the following servo system for the camera rotation. The simplified SSM is applied to 1/25 scaled articulated dump truck which is developed by the previous paper. The stability of the simplified SSM is discussed. Experimental and simulation results show the stable moving and the performance of proposed method.

著者

前田 慎市 菅野 祥一郎 古藤 亮平 小原 哲郎

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.14-00332, (Released:2015-01-16)

参考文献数

26

被引用文献数

1

---

The gaseous detonation driven gas gun was developed for accelerating the projectile to a supersonic speed. The gas gun was simply consisted of two straight stainless-steel tubes. The one was the detonation tube and the other was the launch tube. The detonation tube was 50 mm inside diameter with 2180 or 4280 mm long, and the launch tube was 5 mm inside diameter with 1040 mm long. Chapman-Jouguet detonation wave was initiated in the detonation tube, and the projectile was accelerated in the launch tube via combustion products behind the detonation wave. The spherical projectile of 4.76 mm diameter was made of high-density polyethylene with 52 mg mass. The driver mixture was stoichiometric hydrogen-oxygen premixed gas with initial pressure ranging from 120 to 450 kPa. The gas gun was successfully operated, and the maximum projectile velocity of 1400 m/s was obtained for the conditions that the detonation tube was 4280 mm long and the initial pressure of the driver gas was 450 kPa. The results of the longer detonation tube demonstrated that the projectile velocity was 1.15 - 1.25 times higher than the case of shorter detonation tube. This velocity change of the projectile could be explained by the pressure increase at the inlet of the launch tube by using longer detonation tube. The reason of the pressure increase has a possibility that the length of Taylor wave behind the detonation wave becomes longer for the case of longer detonation tube.

著者

武田 好央 中込 恵一 新村 恵一

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 B編 (ISSN:03875016)

巻号頁・発行日

vol.62, no.599, pp.2887-2894, 1996-07-25 (Released:2008-03-28)

参考文献数

6

被引用文献数

5 8 8

---

There is a gradient of fuel concentration in the spray of conventional direct-injection diesel engines. Therefore, a region of stoichiometric mixture ratio exists in the injected spray and a high concentration of NOχ is produced. In this study, fuel injection timing was widely advanced to promote the mixing of fuel and air. Using this injection method, the engine could be driven with premixed lean diesel combustion (PREDIC), and NOχ emissions were greatly reduced. To avoid the fuel spray contacting the cylinder liner, the fuel was injected by two side injectors simultaneously. The two sprays from the side injectors collided with each other and remained in the center region of the cylinder. Thus mixing of fuel and air was promoted by a long ignition delay period. In the case of conventional injection methods, NOχ could not be reduced to under 400ppm (λ=2.7). In contrast, in the case of PREDIC, NOχ emissions were reduced to as low as 20ppm (λ=2.7).

著者

小粥 雅貴 若松 栄史 森永 英二 荒井 栄司 島田 茂樹 眞鍋 賢

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.814, pp.TRANS0141-TRANS0141, 2014 (Released:2014-06-25)

参考文献数

12

被引用文献数

1

---

In this paper, a prediction method of the maximum principal strain of a core/shielding wire contained in a coaxial cable, which is related to the life-cycle of the wire, is proposed. If the central axis of a wire is assumed to be twisted around a virtual cylindrical surface when a coaxial cable is straight and a virtual toroidal surface when the cable is bent, the shape of the wire can be described by the first and the second fundamental form of their surfaces in the differential geometry. The potential energy of the wire, which is bent, twisted, expanded, and/or contracted, is also formulated based on the differential geometry. Friction of the wire against the virtual surface is modeled as a virtual spring in the circumferential direction of the surface and its elastic energy is included in the total potential energy of the wire. Then, the stable shape of the wire can be computed by minimizing its total potential energy under geometric constraints. After that, the maximum principal strain is estimated from the shape of the wire. As a result of simulation, it was founded that a core wire is broken by bending fatigue before the shielding wire is if they have the same radius and rigidity.

著者

瀧下 謙一 米田 篤彦 清水 康夫

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.81, no.827, pp.15-00101-15-00101, 2015 (Released:2015-07-25)

参考文献数

4

---

In this paper, we focused on the fact that the ease of driving changed according to torsional rigidity of the electric power steering system for the purpose of the improvement in control performance of vehicle. First, the influence on transfer characteristics from a steering angle(steering wheel) to front wheel angle(front tires) by torsional rigidity was considered theoretically. As a result, it turned out that a front wheel angle was determined by not only a steering angle but also the influence of the dynamic state of vehicle, and it was shown that the influence of the dynamic state of vehicle can be shut by making steering torsional rigidity into high torsional rigidity. Next, the validity of a theoretical verification was confirmed through numerical simulation of steering correction at the time of a disturbance input. Finally, the lower limit value of torsional rigidity for practical use of a high torsional rigidity steering was determined.

著者

能美 亜衣 高橋 正樹

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.826, pp.14-00297-14-00297, 2015 (Released:2015-06-25)

参考文献数

12

被引用文献数

1

---

This paper proposes a design method of the fault-tolerant attitude control system for spacecraft. In recent years, there has been requirement for accurate and agile attitude control of spacecraft. To meet this demand there has been an increasing use of Control Moment Gyros (CMGs), which can generate much higher torque than reaction wheels that are used as conventional spacecraft actuators. Furthermore, it is important for attitude control systems to be fault-tolerant. In a conventional 4 CMGs system, the CMGs are placed in a pyramid mounting arrangement with a skew angle set to 54.74 degree. The maximum angular momentum of the CMG system is changed according to the skew angle. A suitable skew angle should be designed to consider normal and failure situations. Moreover, the suitable parameters of spacecraft attitude and CMG control systems are changed according to the skew angle. In the proposed method, the skew angle and the parameters of the control system are tuned simultaneously using a genetic algorithm. To verify the fault-tolerance of the proposed method, numerical simulations for the case when one CMG has failed are carried out.

著者

西野 耕一 笠木 伸英 平田 賢 佐田 豊

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.55, no.510, pp.404-412, 1989-02-25 (Released:2008-03-28)

参考文献数

13

被引用文献数

6 8

---

A technique for measuring instantaneous, three-dimensional velocity components in liquid flows was developed using digital image processing system. This system consists of three TV cameras, a digital image processor, a stroboscope, a laser disk recorder and a 16-bit microcomputer. The three-dimensional displacements of fine particles suspended in the liquid are tracked by the TV cameras and recorded on the laser disk recorder. The recorded image data is later replayed and sent to the image processor, and the three-dimensional velocity field is automatically calculated on the microcomputer. Uncertainty intervals associated with the present technique are systematically evaluated. An unsteady laminar Couette flow between two concentric cylinders, of which the outer cylinder starts to rotate impulsively, is measured by the present technique. The instantaneous velocity profiles measured show good agreement with the analytical solutions within the experimental uncertainty, and thus, the present technique is proven to be applicable to the measurement of unsteady flow. The decay of turbulence generated in a stirred water tank is also measured in good agreement with the theoretical prediction.

著者

山川 出雲 武田 定彦 小島 宏行

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 (ISSN:00290270)

巻号頁・発行日

vol.42, no.364, pp.3815-3824, 1976-12-25 (Released:2008-03-28)

参考文献数

5

著者

長谷川 貴大 中島 求

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.795, pp.3665-3676, 2012 (Released:2012-11-25)

参考文献数

9

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The objective of this study was to clarify the effects of men's swimsuits on swimming position and muscle activity of body trunk in gliding motion. For this objective, a swimming experiment to measure electromyogram and gliding position in sagittal plane simultaneously was conducted for 3 types of men's swimsuit (A, B and C). Next, we compared experimental results one-on-one between the swimsuits by ANOVA. The results of the experiment and ANOVA showed that in wearing Swimsuit C, compared to Swimsuits A and B, hip became lower to shoulder (p<0.05), the hip joint became more extended (p<0.05), and the muscle activity of ES (Erector Spinae) and drag coefficient had tendency to decrease. In addition, we established a new index for the effect of body trunk support, which corresponds to the muscle activity of ES considering the change in the hip joint angle. We confirmed statistically that Swimsuit C had effects of extending hip joint and/or reducing the muscle activity of ES (p<0.05). The reason for this was considered to be that the Swimsuit C helped the hip extensor muscles.

著者

鈴木 悟史 吉井 正広 中西 洋喜 山隅 允裕 小田 光茂 上田 敦史 渡邊 恵佑 加藤 裕基 星 亜友美 西田 信一郎

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.824, pp.14-00298-14-00298, 2015 (Released:2015-04-25)

参考文献数

15

被引用文献数

2

---

Image processing is one of the methods used to measure position/attitude for robot control and there are hopes that it can be applied to space robot missions, including REX-J (Robot EXperiment on ISS/JEM). The REX-J mission involves space robot locomotive function experiments using tethers by JAXA. Measuring the robot's motion accurately is crucial to establishing the new locomotive technology using tethers. With conventional methods, a suitable illumination environment is configured for high-precision image processing and a characteristic marker is attached to the measurement object. However, the two challenges posed for image processing during the REX-J mission are: (1) the illumination of space changes significantly with orbital motion and (2) the robot lacks a characteristic marker. Accordingly, our purpose is to develop a marker less image processing method for the illumination environment of space and measure the robot's position/attitude of the REX-J mission by image processing. The proposed new image processing method involves creating virtual points are created at the intersection of the robot's edge in the image, which are then used as markers for image processing. This method is robust for changes in the illumination environment because it allows the creation of a virtual point, even if the edge is incomplete. The method is applied to the REX-J mission and the measurement accuracy of the robot's position/attitude in the illumination environment of space was confirmed as on the sub-pixel level. Subsequently, the position/attitude of the robot during movement by tethers was measured by image processing. In addition, the error in the robot's position/attitude, as estimated from the length of the tethers, was clarified by the image processing result. Based on these results, the robot's locomotive function by the REX-J mission was verified.

著者

髙井 直樹 元木 信弥 山崎 友裕

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A編 (ISSN:18848338)

巻号頁・発行日

vol.79, no.807, pp.1632-1647, 2013 (Released:2013-11-25)

参考文献数

9

被引用文献数

1

---

The effects of applied stresses on dynamic characteristics of piezoelectric ceramics are analyzed based on the nonlinear electroelastic theory. Piezoelectric ceramics are used in many electric devices as functional elements, where mechanical constraint is usually applied. Estimation of piezoelectric properties under applied stresses is important in designing the devices. However, applied stresses cannot be considered in the basic equations in the linear piezoelectric theory, and the effects of the applied stresses cannot be predicted. In this study, we introduce additional terms related to the dissipation effects, specifically, electric conduction and internal viscosity resistance, and nonlinearity of elastic properties into electroelastic theory. As well, considered nonlinear effects are elastic, piezoelectric and dielectric constants up to 3rd order. Frequency dependence of admittance of PZT disks is measured under applied compressions, showing that applied stresses have certain influences on either of thickness and radial vibrations of PZT. Assuming proper material constants, experimental results can be well explained by the nonlinear electroelastic theory.

著者

三輪 洋靖 渡辺 健太郎 福原 知宏 中島 正人 西村 拓一

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.81, no.822, pp.14-00207-14-00207, 2015 (Released:2015-02-25)

参考文献数

29

被引用文献数

1

---

Employees at nursing-care facilities co-operate with each other and provide nursing-care service according to care plans designed to meet residents’ physical condition and needs. Traditionally, improvement of service productivity in nursing-care service has been based on experience and inspiration of managers and employees. Engineering methods to achieve improvement is a relatively new and necessary approach. In this paper, the authors collaborated with eight nursing-care facilities, and developed engineering methods to achieve improvement of their service process and service productivity. At first, we classified employees’ behaviors into a three-layer structure consisting of “service type”, “purpose / situation” and “operation”, and developed task classification for nursing-care service which could express 455 employees’ states. We then described nursing-care service process as transition of employees’ state with eight properties; “id”, “start time”, “end time”, “task”, “place”, “target resident”, “cost” and “detailed information”. Finally, we measured behaviors of 20 employees at four nursing-care facilities to evaluate the task classification for nursing-care service proposed in this paper, and confirmed that it covered 96.9 % of their behaviors. The cover rate was enough high for visualization of nursing-care service process. In addition, we visualized the nursing-care service process of 15 employees at a nursing-care facility with “time-line mode” and “statistical mode”. We also confirmed that our proposed methods were effective to visualize the nursing-care service process and to improve service productivity in the service field.

著者

藤井 文武 西野 誠 和田 憲造

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.74, no.742, pp.1493-1500, 2008-06-25 (Released:2011-03-04)

参考文献数

12

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A new control algorithm to achieve trajectory following motion of a motorcycle is proposed in this paper. Presented algorithm is comprised of a feedforward term and a feedback term, the former of which intends to balance forces acting on a motorcycle that have adverse effects for roll motion stabilization, and the latter controls the steering and human lean angle to achieve trajectory following. What is to be emphasized is that the proposed control law is comparably simpler than the ones presented in the foregoing works on motorcycle motion control. Results of both numerical and actual experiments have been described to illustrate the effectiveness of the proposed algorithm.

著者

小林 正和 川上 拓也 東 正毅

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.76, no.764, pp.1000-1008, 2010

参考文献数

17

---

To maximize designers' creativity during collaborative design processes, this paper focuses on designers' individual differences, especially differences in their idea evaluations, and proposes an analytical method for revealing their differences. During creative group activity, when a designer represents an idea using some words or a short sentence, the others imagine the concrete image of the idea form the presented words and evaluate the concretized idea in their mind. However, the results of their concretizations and evaluations vary among designers in most cases. Such differences or diversities seem to be undesirable, but they have a huge potential for leading new ideas during divergent processes of exploring ideas. Therefore, the method proposed here reveals designers' individual differences by analyzing the results of their idea evaluations and encourages their further idea explanations. In addition, to confirm the effectiveness of the proposed method, the case study is carried out and its results and detailed processes are analyzed.

著者

三村 宣治

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C編 (ISSN:18848354)

巻号頁・発行日

vol.79, no.806, pp.3652-3661, 2013 (Released:2013-10-25)

参考文献数

11

---

This paper investigates an efficient calibration method for 6 DOF parallel mechanisms by simulation. Since a calibration matrix has ill condition, many random measured poses are needed in calibration. In this paper, at first, we investigate about the number of measured poses, the condition number of calibration matrix and the calibration errors. The results show there exist the lower limits in the number of measured poses and the inverted condition number, and the decrease in the number of measured poses increases calibration errors. Next, we investigate reduction of the measured poses and the output data. The results show the calibration may be enabled, even if some measured poses and the output data are reduced. Based on the results, we find a minimal pose set required for a calibration, and show that even if the set of the simplified pose is used, the calibration errors do not increase so much.

著者

Masahiro KANAZAKI Fumio KANAMORI Yosuke KITAGAWA Masaki NAKAMIYA Koki KITAGAWA Toru SHIMADA

出版者

一般社団法人 日本機械学会

雑誌

Journal of Fluid Science and Technology (ISSN:18805558)

巻号頁・発行日

vol.9, no.5, pp.JFST0071-JFST0071, 2014 (Released:2014-11-28)

参考文献数

6

被引用文献数

2

---

The subject of this paper is to improve on parameterization for conceptual design method of three stage hybrid rocket. Multi-Objective Genetic Algorithm (MOGA) is employed to solve multi-disciplinary design exploration of a three-stage launch vehicle concept using a hybrid rocket engine. MOGA which is used as the optimization methods for multi-objective problems utilizes real-number cording and the Pareto ranking method. According to our previous study, the propulsive performance of MOGA's solution was as low as the lower limit of design space. The design space of a conceptual three-stage launch vehicle hybrid rocket engine was reconsidered based on the results of multi-disciplinary design optimization. The design variables of the nozzles were reconsidered by exploring the design space. Specifically, the nozzle expansion ratio was considered as the ratio of the nozzle exit radius to the body radius. In this way, there are no solutions which violate the design constraints about the geometric condition of the nozzle exit. Consequently, the new conceptual design method can effectively explore solutions which have higher propulsive performance than previous method. As the result, the combustion chamber pressure is increased in the first stage. In the second stage, the solutions which are explored, modified parameterization are shown larger thrust level than previously.

著者

斉藤 一哉 野島 武敏

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A編 (ISSN:18848338)

巻号頁・発行日

vol.78, no.787, pp.324-335, 2012 (Released:2012-03-25)

参考文献数

7

被引用文献数

2 3

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This study illustrates a new strategy to fabricate arbitrary cross-section honeycombs. These types of honeycombs are usually manufactured from normal flat honeycombs by curving or carving, but the proposed method enables us to construct objective shaped honeycombs directly. We first introduce the concept of the kirigami honeycomb, which is made from single flat sheets and has periodical slits resembling kirigami (Japanese art of study folding and cutting). In previous studies, honeycombs having various shapes, including tapered and aerofoil honeycombs, were made using this method, and were realized by only changing folding line diagrams (FLDs). In this study, these 3D kirigami honeycombs are generalized by numerical parameters and fabricated using a newly proposed FLD design method, which enables us to draw the FLD of arbitrary cross-section honeycombs