著者

安井 学 中野 一史 黒内 正仁 川野 伸一 金子 智

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.862, pp.18-00091, 2018 (Released:2018-06-25)

参考文献数

23

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SU8 is a negative photoresist shows superior characteristics of heat resistance and chemical resistance. And, it is used to make high-aspect ratio micro structures such as master of electroforming. However, it is extremely difficult to remove SU8 from substrate. Researchers have investigated a means of SU8 removal. Therefore we proposed a new SU8 removal method “DI water (H2O) and lithium chloride (LiCl) doped NMP” which promises swelling furtherance of SU8, and we demonstrated that the new method could remove fine SU8 patters from substrate at proper level. The mechanism of SU8 fine patterns removal is presented as follows. A doped NMP broadens the width of SU8 patterns by swelling effect and reduces buckling stress of SU8 patterns. SU8 patterns reducing buckling stress increases the potential of buckling.

著者

古森 健吾 戸井 武司

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.84, no.862, pp.18-00103, 2018 (Released:2018-06-25)

参考文献数

8

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Numerical simulations, such as the finite element method have been widely used to predict noise and vibration behavior. This allows reducing the development time and production cost of products. However, these results have been calculated based on the governing equations at each physical areas as the idealized conditions. Then, these simulations are not taken into account the fluctuation of response characteristic by the uncertainties of noise factors. Therefore, it is important to restrain the fluctuation of products properties by the uncertainties. In this paper, focusing on the transient analysis, we propose a robust design for minimizing the time history amplitude fluctuation by structure uncertainties. The robust design is implemented based on the combined use of the stochastic finite element method and the structural optimization. Since this method is performed by minimizing the 1st sensitivity, we will formulate the 1st and 2nd sensitivity in the time domain. Then, the proposed method is validated by applying it to the simple mass-damper-spring system whether the fluctuation of the time history response amplitude is restrained.

著者

平光 立拓 難波江 裕之 鈴森 康一 遠藤 玄

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.862, pp.18-00083, 2018 (Released:2018-06-25)

参考文献数

10

被引用文献数

1

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Pneumatic artificial muscles have many advantages. They have high force mass ratio, high compliance and simple structures. Especially, the flexibility contributes to compose novel mechanisms. The flexibility of pneumatic artificial muscles releases us from the spatially strict design required for rigid mechanical elements: it could actualize compact mechanisms made of a fewer parts. Our research group developed a thin McKibben actuator. The thin McKibben actuators is more flexible than conventional McKibben actuators. Authors succeeded in manufacturing novel soft mechanisms that are made of only braided artificial muscles. We aim to establish a design method for these novel mechanisms. We already have fabricated a cylindrical mechanism made of helical muscles. In this paper, we report a geometric model for the cylindrical mechanism. We focus on only deformation of a side surface in the coordinate system of muscles to simulate the movements of the cylindrical mechanism. The movement was verified by an experiment, and besides, it was simulated successfully in the geometric model that was created. The deformation of height and radius directions changed according to muscles alignment.

著者

河内 毅 栗山 幸久 鈴木 克幸

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.862, pp.18-00063, 2018 (Released:2018-06-25)

参考文献数

11

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In order to clarify the mechanism of the vehicle body hysteresis affecting “rigidity feeling”, one of the driver's sensory evaluation in the driving test, the influence of friction acting on spot welding flanges on hysteresis, which is drawn by the displacement-load diagram of double-hat-shaped parts assembled by spot welding under static or relatively slow deformation, is experimentally and numerically evaluated. The hysteresis of two specimens, one has the contact around R-tangent of flanges and the other has it around edge, are compared and it is confirmed that the former type has larger hysteresis than the latter. The hysteresis is evaluated by the friction loss which is energy dissipation generated only by friction on the surfaces of the spot welding flanges. The loss calculated by the finite-element-method (FEM) with the contact and friction between two flange surfaces opposing each other has good agreement with that measured by the experiment. Additionally, by studying the detail of the relative slip and friction force distribution on the surface of two flanges obtained by the FEM analyses, the difference in hysteresis of two specimens and the cause of the friction loss are discussed.

著者

根本 健也 山本 浩 成川 輝真

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.862, pp.18-00062, 2018 (Released:2018-06-25)

参考文献数

16

被引用文献数

1

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One of effective ways to suppress vibration of a mechanical system is using a dynamic vibration absorber. The dynamic vibration absorber consists of a mass, a spring and a damper. The optimal tuning of natural frequency and damping ratio of the dynamic vibration absorber is required to suppress vibration, so adding an adjustable mechanism of stiffness and damping of the dynamic vibration absorber makes tuning easy. This paper proposes a new design concept of an adjustable dynamic vibration absorber consisted of an adjustable mechanism of stiffness and damping. The adjustable mechanism of stiffness consists of an arm, a couple of coil springs and a rotatable spring holder. Stiffness is varied by rotating the spring holder. The adjustable mechanism of stiffness can expand the range of stiffness by increasing spring constant of a couple of coil springs. The adjustable mechanism of damping consisted of a copper plate, a couple of magnets and a linkage mechanism. Damping is varied by driving the linkage. Driving the linkage to tune damping is necessary large torque because of attractive force of magnets. A compensation spring attached to the linkage can reduce the driving torque for tuning the damping. We made the proposed adjustable dynamic vibration absorber and verified whether the proposed adjustable mechanism is valid by experiments.

著者

青木 ゆうい 涌井 伸二

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.84, no.862, pp.18-00052, 2018 (Released:2018-06-25)

参考文献数

11

被引用文献数

1

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In this paper, it is confirmed that natural frequency of isolated table is operated and that degeneration, which means that some natural frequencies have the same value, has a bad influence. Pneumatic anti vibration apparatuses (AVAs) support that loaded devices, i.e., XY stages, operate accurately. However, many strict design conditions are imposed on AVAs with six degrees-of-freedom (DOF) which are used on manufacturing floor. There is a risk that the natural frequency of each motion mode approaches, in other words, that isolated table falls into degeneration. This disturbs accurate operations of XY stages. In this paper, AVA with two DOF is used to simplify motion instead of six DOF. First, it is stated that mode control is used to pressure control. Next, position differential feedback (PFB) is proposed. PFB, which is used to the natural frequency control, is applied for each mode. This means that air spring stiffness is considered as each motion mode, and these are deleted or given. It is shown that the natural frequency of each mode can be controlled individually, by calculation, simulation, and experiment. Finally, the degeneration is reproduced to AVA with two DOF by PFB. At this moment, acceleration control which effects to nearby the natural frequency interferes with each other mode. From these results, conclusions are the following: degeneration should be avoided, and mode PFB is effective to control natural frequency of each motion mode. In addition, mode PFB accomplishes not only avoiding degeneration, but also lowering the natural frequency.

著者

髙木 山河 涌井 伸二

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.84, no.862, pp.18-00043, 2018 (Released:2018-06-25)

参考文献数

10

被引用文献数

1

---

In the field of precision positioning such as semiconductor exposure apparatus, weak disturbance vibration from the floor influences processing accuracy. In recent years, as the precision of the device increases, the vibration allowance value becomes more severe, and performance improvement of the vibration isolator is required. In order to improve the performance, there are researchs reducing natural frequency by the frequency characteristics of the vibration transmissibility from the floor to the vibration isolator. Reducing natural frequency and decreasing stiffness are equivalent, and main target was stiffness generated by compressed air of air spring. In addition, rubber bellows of air spring is also targeted for further performance improvement. We already proposed a method combining the two stiffness separately decreasing method. However, decreasing stiffness simultaneously destabilized the device, then it could not be completely decreased. In this paper, as a new stabilization method, stiffness is completely decreased only in the operation frequency band. Since the low frequency has positive rigidity, the localization is maintained. We demonstrated the reducing natural frequency by the experimental result. When stiffness was completely decreased, the servo stiffness which had not been focused in the past became dominant in determining the natural frequency. Therefore, an appropriate design of the servo stiffness is required for further reducing natural frequency. To satisfy this requirement, we calculated the relationship between natural frequency and servo stiffness and gave an index for appropriate design.

著者

平岡 延章 十河 宏行 由良 諭 逸見 知弘 正箱 信一郎 石井 耕平 津守 伸宏 鹿間 共一 漆原 史朗 太良尾 浩生

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.84, no.862, pp.18-00031, 2018 (Released:2018-06-25)

参考文献数

6

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A motor shaft direct drive is known as a simple and low cost scheme for small toy vehicles, however the mechanism how it produces propelling force has not yet been explained nor discussed in detail. A trivial idea that a small dent is formed on the road surface just under the shaft end due to static weight takes us to the unexpected result. Brief calculus reveals that the propelling force vector of the system directs somewhat forward with respect to sagittal plane which includes motor shaft slant axis. It suggests that the motor alternative cw and/or ccw rotation generates gradual forward movement, i.e. the vehicle moves perpendicular direction with respect to that of right-left swinging motion. The forward motion is confirmed experimentally with single motor shaft direct drive vehicle, and also discussed in details.

著者

大平 峻 島田 明

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.862, pp.18-00019, 2018 (Released:2018-06-25)

参考文献数

19

被引用文献数

1

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This study aims to realize fast disturbance estimation with a Kalman filter (KF). This paper presents a methodology of fast estimation and rejection for some types disturbances. This methodology attempts to estimate the state of mechatronics systems that rejected the influences of disturbance and noise by using KF. Most of known disturbance estimation method is the disturbance observer (DOB). However, the conventional DOB can not estimate the disturbance that is contaminated of noises. Generally, KF is known as state estimation algorithm that can consider influences of various noise. In addition, we had done some previous studies to design a linear KF with disturbance estimation. We obtained a fact that the disturbance estimation speed by the KF is slow from these studies results. Therefore, this paper proposes a new design method of KF with disturbance estimation which includes a design parameter to speed up disturbance estimation, where we have never concerned in this paper with KF design method except linear systems. Finally, we show the design method on the proposed method and usefulness via the simulation results relative to the position control for an simple cart system.

著者

中原 健志 藤本 孝

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.862, pp.18-00017, 2018 (Released:2018-06-25)

参考文献数

15

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A semi-active vibration control technique using piezoelectric actuators with switched inductance shunts has been studied. This technique can be used for not only vibration suppression but also energy harvesting. In order to design semi-active vibration control systems and energy harvesters using this technique efficiently, it is necessary to analyze and understand the effects of design parameters on the performance of these systems. Responses of these systems to harmonic disturbance forces can be used for performance evaluation and previous studies analyze periodic responses of semi-active vibration control systems by assuming sinusoidal displacement responses and using method of harmonic balance. However, this control technique induces rectangular control forces and the displacement responses are distorted. Enhancing the control forces leads to stronger distortion of the responses and the validity of the assumption of the previous studies becomes lost. In order to overcome this problem, the authors have proposed to use shooting method which is a numerical method to calculate periodic solutions of non-linear systems without assuming certain forms of responses. This paper presents periodic responses obtained by shooting method with an improved non-dimensional model and the periodic responses are compared with ones obtained by method of harmonic balance. Furthermore, this paper considers not only the periodic responses but also non-periodic chaotic responses obtained by long term simulations with the non-dimensional model.

著者

稲垣 耕 盆子原 康博 近藤 孝広 池 美慧 濵畑 貴之

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.84, no.862, pp.18-00004, 2018 (Released:2018-06-25)

参考文献数

4

被引用文献数

1

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In household refrigerators, the rotational speed of a reciprocating compressor can be appropriately adjusted according to the temperature inside of the refrigerator. The lower rotational speed reduces the power consumption of the compressor. However, several natural frequencies of the compressor exist in the low rotation region, and besides, the unbalance force arising from the piston motion acts on the internal drive unit. Thereby the vibrations of the compressor are likely to be larger due to the resonance in the low rotation region. In this study, a method for supporting the drive unit inside the shell, which is called “the self-standing support” is newly proposed in order to reduce the vibration of the compressor drastically. In the proposed method, a spherical support element is utilized instead of coil springs to support the drive unit. And the drive unit can maintain a stable self-standing state by acting restoring moment due to the gravity while it is directly placed on the shell. The natural frequencies of the compressor can be greatly reduced by decreasing the support stiffness for the drive unit in comparison with the support method using coil springs. Furthermore, in designing the drive unit, the application point of the exciting force is matched with the center of percussion to the contact point on the spherical support. As a consequence, the periodic restraining force acting on the contact point can be minimized. By these two features, it is possible to considerably reduce the vibration transmission from the drive unit to the shell. In the present study, a simplified model for a reciprocating compressor is treated, and the effectiveness of the self-standing support is investigated analytically and experimentally.

著者

木村 秀行 土田 崇弘 木村 康治

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.84, no.862, pp.17-00586, 2018 (Released:2018-06-25)

参考文献数

14

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In this study, vibration characteristics of a single-degree-of-freedom linear oscillator with the fractional order derivative are examined in terms of the critical damping over a wide range of the order of the fractional derivative by using numerical analysis. Two types of the definitions of the critical damping used in the previous studies are considered. It is shown that (i) the critical viscoelastic damping ratio changes according to the order of the fractional derivative and its minimum value for both types of the critical damping is less than 1; (ii) no critical viscoelastic damping ratio is observed in a certain range of the order; (iii) the difference in the existence of the critical damping between the oscillators with the derivative of order 1/3 and 2/3 is caused by the change of the behavior of a component of the response corresponding to one of the roots of the characteristic polynomial for the oscillator. Finally, the impulse response characteristics are classified into three classes depending on the order of the fractional derivative and viscoelastic damping ratio of the oscillator.

著者

中澤 輝彦 服部 治博 樽谷 一郎 安原 伸二 井上 剛志

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.862, pp.17-00543, 2018 (Released:2018-06-25)

参考文献数

20

被引用文献数

3

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CVT chains have become widely used in vehicles because the slip between parts is very small, which enables efficient power transmission. However, the motion caused by the pins of the CVT chain entering and leaving the pulleys one after another during the power transmission process results in periodic motion of the whole chain. This behavior is known to affect noise and other basic performance aspects of CVTs. Therefore, it is important to study the geometrical specifications of the chain that affect periodic motion, such as the shape and dimensions of the parts. This study aimed to (1) identify the periodic motion that affects noise, and (2) formulate a motional theory to derive the ideal specifications of a CVT chain. First, after measuring the acceleration of the pulleys under conditions that generate large CVT noise, it was found that noise was greatly affected by periodic motion caused by the chordal action of the chain. Based on this result, a mathematical model was proposed to describe this chordal action. The pin profile curve was particularly considered in the model since it determines the motion of the chain at both ends of the chord part and has an important effect on the chordal action. Next, the chordal action of the chain was measured using an accelerometer, and the measured results were compared with the results calculated by the model. The results were consistent, which confirmed the validity of the model.

著者

澤田 純平 吉野 正人 鈴木 康祐

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.861, pp.18-00023-18-00023, 2018 (Released:2018-05-25)

参考文献数

22

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Dynamic behavior of binary water droplets approaching each other in cloud is simulated by the improved two-phase lattice Boltzmann method with the Continuum Surface Force (CSF) model. This method does not need to solve the pressure Poisson equation and enables us to calculate two-phase flows with high density ratio accurately and efficiently. In this study, we investigate the effects of the Reynolds number Re, the Weber number We, the impact parameter B (the relative distance between the centers of two droplets), and the droplet size ratio on the behavior of the binary droplets for liquid-gas density ratio of 800. We first simulate a stationary liquid droplet in a gas to confirm the validity of the present method. We next simulate off-center approach of two equal-size droplets and investigate the effects of the Reynolds number and the Weber number. It is seen that at low Weber numbers of We ~ O(10-2), there are two types of behavior during approach of two equal-size droplets, namely coalescence and deviation. In this Weber number region, it is found that they can deviate from each other at low Reynolds numbers of Re ≲ O(1) in spite of B ≤ 1.0, whereas collision and subsequent coalescence occur at higher Reynolds numbers of Re ≳ O(10). We finally simulate approach of two unequalsize droplets with various size ratios. It is found that the behavior of the droplets is different from that in the case of the equal-size droplets owing to asymmetric velocity field and droplet deformation. In addition, the smaller droplet tends to deviate from its original path more significantly than the larger droplet.

著者

潮見 俊輔 押味 良和 沼田 紘司

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.84, no.861, pp.17-00568-17-00568, 2018 (Released:2018-05-25)

参考文献数

8

被引用文献数

2

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Object detection function of turnout and switch mechanism is one of an important function for safety of railway system. An object between a tongue rail and a stock rail on a turnout is detected by a lock mechanism of a switching machine and circuit controllers, which are applied on high-speed railway. Designer of switch mechanism has checks his detecting function design by experiments, which were sole way to check it, using real turnout and switch mechanism. In this paper, we described an equation of motion of the switch mechanism and the turnout using multi-body dynamics and flexible multi-body. Moreover, we described a method, which calculate shape of tongue rails inserted an object between rails. By results of calculations, we confirmed that the proposed method could simulates the shape of rails, which is affected by object. Computing time is 40% shorter than an experiment, however, the result includes an error which causes that the model was assumed deformation of tongue rails as 2-d deformation.

著者

谷口 文彦 中川 智皓 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.84, no.861, pp.17-00534-17-00534, 2018 (Released:2018-05-25)

参考文献数

11

被引用文献数

1

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Inverted pendulum vehicles controlled by movement of driver's center of gravity (COG), such as Winglet or Segway are the examples of Personal Mobility Vehicles (PMV). PMV is sometimes expected to be used in pedestrian spaces. When a driver brakes an inverted pendulum vehicle suddenly, the driver has to move his/her COG backward largely and has the risk to lose his/her balance due to the characteristics of vehicle control. Therefore, we aim to achieve a vehicle control system that is friendly to drivers in emergency. In the previous study, the coupling model of a vehicle and a human had been built on Multibody Dynamics and the technique to brake an inverted pendulum vehicle automatically had been proposed using that model. In this study, we carried out two experiments to decide the timing of the automatic braking system defined as Time To Collision (TTC). We carried out two experiments about stopping distance when a driver brakes an inverted pendulum vehicle suddenly and when the automatic braking system is operated, and we compared those results. Then, it was shown that stopping distance operated by the automatic braking system is shorter than by human driver's sudden braking operations. In addition, we derived TTC1 ( 0.7 s ) of inverted pendulum vehicles from these experiments about stopping distance by human drivers' sudden braking. Then, we derived reaction time ( 0.4 s ). Finally, we proposed a safety system using TTC1 and the reaction time. When TTC reaches 1.1[s], the alarm makes a human brake an inverted pendulum vehicle suddenly. Then if a human doesn't brake an inverted pendulum vehicle suddenly and TTC reaches 0.7[s], the automatic braking is operated.

著者

瀧上 唯夫 秋山 裕喜 朝比奈 峰之 山本 克也

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

vol.84, no.861, pp.17-00531-17-00531, 2018 (Released:2018-05-25)

参考文献数

13

被引用文献数

1

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It is one of the important issues to investigate the vibration behavior of railway bogies, since the vibration of the bogies may result in loosening bolts which fix the parts to the bogie frames or/and fatigue fracture of the parts themselves. A technique for predicting the vibration of bogie parts is proposed by which the acceleration power spectral densities (PSDs) at evaluated points are predicted with the use of frequency response functions (FRFs) between the axle boxes and the evaluated points, together with the use of measured accelerations of axle boxes. Stationary excitation tests are conducted to identify the FRFs, and the axle boxes or rails were hit with impulse hammers to excite the bogies. Alternatively, the new approach without the stationary tests is also proposed in this study. In this case, the FRFs are identified with the accelerations acquired in the preliminary running tests in car depots. The proposed technique is applied to the vibration prediction of the bogies for several types of railway vehicles including electric cars and a diesel car, and the differences or ratio between the predicted and actually measured PSDs are evaluated. It is confirmed that the preliminary running tests are preferable to stationary excitation tests for improving the prediction accuracy. It is also verified that the prediction error can be reduced in the case where not only the vertical but the lateral and longitudinal accelerations of axle boxes are considered as the excitation inputs under the conditions that the principal component regression is applied to identify the FRFs.

著者

成澤 慶宜 水野 毅 高崎 正也 石野 裕二 原 正之 山口 大介

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.861, pp.17-00523-17-00523, 2018 (Released:2018-05-25)

参考文献数

17

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A basic single-degree-of-freedom magnetic suspension system consists of one floator, one electromagnet and one amplifier. For multi-degrees-of-freedom control, multiple electromagnets and multiple amplifiers are necessary, which increases the cost of total system. As a means of overcoming this problem, parallel magnetic suspension has been proposed which controls multiple floators or multi-degree-of-freedom motions with a single power amplifier. In this system, all of the suspended points move simultaneously even when a disturbance acts on one of the suspended points solely because all electromagnet's coils are connected. This paper studies the moving direction of each suspended point with respect to a step disturbance in double parallel magnetic suspension system. The analytical study shows that the response direction is determined by the system parameter that relates the response speed of each subsystem. In the slower subsystem, the suspended point moves in the same direction as the applied force while in the faster subsystem, the suspended point moves in the opposite direction. In other words, the slower subsystem has positive stiffness while the faster system has negative stiffness. To confirm this prediction, step responses are measured in the experimental apparatus.

著者

高田 宗一朗 井上 裕文 篠田 茂樹

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.84, no.861, pp.17-00522-17-00522, 2018 (Released:2018-05-25)

参考文献数

20

被引用文献数

2

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In this paper, deterioration diagnosis for distribution main pipe was studied using the uniform cylindrical shell approximation and in-plane bending mode. The in-plane bending mode is expected to have high accuracy in detection of deterioration, because the eigen frecuency of the mode is proportional to pipe thickness. First, using the finite element method, the characteristics of in-plane bending mode are investigated. It is confirmed that in-plane bending mode has little small dependence on the pipe length and the boundary conditions at the pipe ends, it appears in the audio frequency bands, and it has linear dependence on the pipe thickness. In addition, formula with two dimensional ring approximation is derived. Moreover, the average thickness and the uniform-cylindrical shell approximation are introduced for deal with the deteriorated pipe. Using the thinning pipe thickness of previous study, validity of the average thickness and the uniform-cylindrical shell approximation were confirmed. On the other hand, actual pipeline has the sub-structure, for example, valve, hydrant, and so on. In order to deal with the coupled vibration between the cylindrical shell and the sub-structure, eigenvalue analysis are conducted using the Semi-Analytical Receptance Method (SARM). The experimental consideration were conducted in case of that the sub-structure non-attached case. The in-plane bending mode is observed experimentally on the actual pipe system and its resonant frequency shows good match with the theoretical values.

著者

上道 茜 金築 一平 金子 成彦

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.861, pp.17-00514-17-00514, 2018 (Released:2018-05-25)

参考文献数

15

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Hydrogen combustion is attracting attentions because of zero CO2 emission. Recently, a gas turbine which uses hydrogen-rich fuel is being developed. In our previous study, we examined the influence of hydrogen-containing ratio on combustion oscillation for fuel mixtures of hydrogen and town gas (13A) experimentally. In the experiment, pressure oscillations were measured by a sensor which is installed at the bottom of the combustor. It is found that two oscillation frequencies near 200 Hz and 400 Hz were simultaneously detected in the case of hydrogen-containing fuels, whereas single oscillation frequency around 350 Hz was observed in the case of only 13A fuel. To understand this difference of oscillating frequencies, we conducted acoustic analysis using one-dimensional different diameter acoustic model. However, this simplest model could not reproduce three types of oscillating frequencies obtained by the experiment. Besides, we used an acoustic impedance of the bottom of the combustion chamber as an acoustic boundary condition. The acoustic impedance is measured experimentally under the noncombustion (cold) condition and corrected by combustion temperature obtained by equilibrium calculation. As a result of applying the corrected acoustic impedance, the three types of oscillating frequencies could be reproduced by acoustic analysis. Furthermore, to express the difference among fuel mixtures, delay times, flame positions, and the mean temperature in the chamber were calculated by the CFD simulation. Consequently, it is found that the acoustic analysis result could reproduced the difference among fuel mixtures; hydrogen makes the oscillating frequencies a little higher, because temperature becomes higher and delay time becomes shorter.