日本機械学会論文集
Online ISSN : 2187-9761
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82 巻 , 838 号
選択された号の論文の31件中1~31を表示しています
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材料力学,機械材料,材料加工
  • 五味 健二, 新津 靖
    82 巻 (2016) 838 号 p. 15-00498
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/06
    ジャーナル フリー
    Understanding stress or strain distribution or birefringence properties is important for proper industrial application of polymer films. For example, it is very important to control the stress and birefringence distribution in polymer films that are used for liquid crystal displays of PCs or smart phones, etc. for their performance improvement. As another example, it is very important to understand the stress distribution in packaging polymer films for reliability management of the package because the forming accuracy depends on the stress distribution in the films. Photoelastic analysis is suitable to understand stress, strain distribution and birefringence properties on polymer films; however, understanding of the stress-optical or strain-optical coefficients of the polymer is indispensable when using the analyzing method. In this study, the influence of displacement rate, stress orientation and stress history on birefringence properties is measured for polyvinylidene chloride (PVDC) at room temperature as an example of semi-crystalline polymer films. The stress-optical coefficient of PVDC depends on the displacement rate, stress orientation and stress history. On the other hand, the strain-optical coefficient of PVDC is approximately independent of them. These phenomena are explained by the result from the viscosity, polymer chain orientation and strain-induced crystallization in PVDC. There is potential given that strain-optical coefficients for semi-crystalline rubbery polymers are approximately independent of the displacement rate, stress orientation and stress history on some conditions because of the mechanism of the phenomenon.
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  • 山下 剛志, 植田 大輝, 黒島 義人
    82 巻 (2016) 838 号 p. 15-00647
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/06
    ジャーナル フリー
    Metal thin films don’t necessarily appear general fatigue behavior like a bulk materials. Comparing thin films and bulk materials, since the number of grains of the film thickness direction is different, restricted condition is different. Some studies of axial direction and bending direction loading have been reported, but few studies of in-plane pure shear loading have been reported. In this study, using acryl bar pasted carbon steel film, fatigue test was performed under cyclic in-plane pure shear loading. And about deference of slip band formation factor and crack initiation factor, examination was performed by varying to change carbon content, film thickness and average grain size. As a result, two relations about fatigue behavior were found. Slip ratio was influenced by film thickness / grain size ratio. But crack ratio was influenced by pearlite volume ratio. Therefore, for the carbon steel thin film behavior of slip band and crack initiation are considered to be result of different factors.
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  • 筧 幸次
    82 巻 (2016) 838 号 p. 15-00673
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/27
    ジャーナル フリー
    The effect of plastic anisotropy, which is caused by the arrangement of slip systems, on the creep strength of notched specimens of Ni-based superalloy single crystal, CMSX4, is described. It was revealed that the creep strength of the notched specimens was affected by the crystallographic orientation, not only in the tensile direction, but also in the thickness direction. The creep strength was superior in the notched specimen with the [011] tensile and [011] plate-normal orientations, whereas the notched specimen with [011] tensile and [100] plate-normal orientations exhibited extremely poor creep strength. In the case of specimens whose tensile orientation was [011], results of the creep-rupture tests at 750 °C were in agreement with the assumption of the operation of {111}<112> slip systems. The creep strength in the notched specimen with [001] tensile and [100] plate-normal orientations was superior to that in the notched specimen with [001] tensile and [011] plate-normal orientations. When the tensile orientation was [001], the results of the creep-rupture tests were in agreement with the assumption of the operation of {111}<112> slip systems during primary creep region and {111}<101> slip systems during secondary creep region.
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  • 中佐 啓治郎, 山本 旭宏, 王 栄光, 李木 経孝
    82 巻 (2016) 838 号 p. 16-00059
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/06
    ジャーナル フリー
    Argon ion sputter-etching of SUS420J2 martensitic stainless steel and SUS316 austenitic stainless steel were carried out to form fine protrusions on the specimen surface by using a radio-frequency magnetron sputter-apparatus. Plasma-nitriding was applied to the protrusions by using nitrogen gas of 0.53 Pa mixed with argon gas of 0.67 Pa at a power of 50 W for 1.8 ks. Micro-Vickers hardness tests on cone-shaped protrusions with diameter of about 20 μm formed on the SUS420J2 steel showed that the compressive strength of protrusion tip of the plasma-nitrided specimen is almost four times larger than that of the as-sputter-etched specimen. Nanoindentation tests on quasi-columnar protrusions with sizes smaller than 500 nm formed on the SUS316 steel showed not only much scatter of indentation force vs depth curves but also irregular changes of gradient of the curves. This means that an inhomogeneous contact of the indenter on the protrusions with different heights, sizes and spaces as well as a discontinuous deformation of protrusions occur with progress of indentation. Although the true compressive strength of one protrusion is not obtained directly by usual hardness tests, a measure of the deformation resistance of a group of protrusions can be obtained from the hardness that is extrapolated to zero indentation area on the indentation area vs hardness curve. The compressive resistance of the plasma-nitrided protrusions is almost six times as large as that of the as-sputter-etched ones.
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  • 今泉 俊介, 植田 章裕, 藤本 圭一郎, 波田野 明日可, 泉 聡志, 酒井 信介
    82 巻 (2016) 838 号 p. 16-00085
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/27
    ジャーナル フリー
    Human space flight vehicle requests a high safety level to protect life of astronauts. Launch Abort System (LAS) is a safety system used to quickly separate the space capsule from its launch vehicle rocket in case of catastrophic failure such as explosion of the vehicle. During the launch abort, the blast wave from explosion or off-nominal water landing causes severe transient load on the space capsule, so that the crew might be injured by huge acceleration. In order to evaluate LAS safety, simulation based injury assessment is essential in the basic design phase. This paper purposes to develop a numerical model based on the multi-body simulation approach, which is widely used for analyzing car occupant safety. In this paper, simulation of impact sled tests is conducted to measure human dummy responses and loads. The results are compared with the Hybrid III dummy sled test data to investigate accuracy of this multi-body simulation. It shows that the computed results agree well with the test data. Finally, an injury analysis of crew members subjected to an expected acceleration load during the launch abort is investigated by using the validated model. The results show that a head or neck injury is more likely to happen during the launch abort. The mechanism of the human response is also discussed and the study provides guidelines for seat designs in space vehicle.
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流体工学,流体機械
  • 真田 俊之, 野崎 紘史, 渡部 正夫
    82 巻 (2016) 838 号 p. 16-00048
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/06
    ジャーナル フリー
    Liquid infiltration into small scale structure is important process in the various manufacturing process. However, there are lack of experimental study, especially, the effect of pressure, even in the real process utilized the external pressure like droplet impact. In this study, we examined the liquid infiltration properties from the millimeter to micrometer scale into closed end tubes by applying pressure under two conditions, i.e. gradual and stepwise change, and discussed the gas dissolution effects. As a result, it is found that the amount of dissolved air by applying pressure is small, and it has little effect on the liquid infiltration in millimeter and sub-millimeter size of tubes. The main contribution to the liquid infiltration is gas compression. On the contrary, the micrometer scale of tubes with low aspect ratio, the liquid perfectly infiltrated into small tube by applying three times pressure owing to the gas dissolution. This results indicate that the gas dissolution is the main factor for liquid infiltration into nano-scale structure. Furthermore, we confirmed that the gas compression process well reproduced by the isothermal process.
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  • 萩原 浩貴, 小方 聡, 草野 浩俊, 瀬川 武彦
    82 巻 (2016) 838 号 p. 16-00068
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/13
    ジャーナル フリー
    Dielectric barrier discharge plasma actuators (DBD-PAs) have been developed for active flow control devices that do not contain mechanical moving parts. In this study, flow properties induced by DBD-PAs with fine structure exposed electrodes were investigated in experiment to accelerate the induced flow. We prepared the following four types of test actuators: (1) normal-type, with the conventional type of exposed electrode, (2) span-type, with fine exposed electrode of a width of 0.1 mm, (3) stream-type, with slot-type exposed electrode, into which many 0.15 by 1 mm slots were cut, and (4) porous-type, with porous-type exposed electrode, into which many holes of diameter 0.15 mm were cut. Analyzing the velocity distribution of the induced jet using particle image velocimetry, we found that at Vp-p = 5-7 kV, the velocity of the induced jet was increased for span-type and stream-type actuators, when compared with normal-type actuator. The largest increase of velocity was about 20% at 20 mm downstream from the electrode. In relation to the mechanism of the acceleration, we found that a dielectric barrier discharge (DBD) is generated not only at the downstream edge, but also at the upstream edge. By the Schlieren flow visualization, it could be seen that the DBD generated in the downstream direction produced an induced jet in the downstream direction as normal. However, the DBD generated in the upstream direction was found to have the effect of producing an induced jet in both the downstream and the upstream directions. In other words, it was qualitatively shown that the jet that was induced by the DBD generated on the upstream side of the fine exposed electrodes adds to the induced jet in the downstream direction, and as a result, the velocity of the downstream direction induced jet increases.
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  • 長田 光広, 永岡 真
    82 巻 (2016) 838 号 p. 16-00073
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/06
    ジャーナル フリー
    A direct numerical simulation of compressible turbulent channel flow at low Mach number(Ma = 0.3) subject to strong temperature gradient is conducted. The wall temperature ratios which are defined by a temperature on the upper wall divided by that on the lower one, are set to 2 and 3. It is shown that the flow of high temperature wall side is laminarized as increasing the wall temperature ratio. Moreover, compressible and dilatational motions are induced on the low and high temperature wall sides, respectively. The identity of friction coefficient originally derived by Fukagata et al.(2002) (so-called ‘FIK identity’) is extended to those of friction coefficient and Nusselt number on the compressible channel flow. It is revealed that the viscous variation component attains to 16 % of the friction coefficient on the case of high temperature ratio. Furthermore, the pressure work component occupies about 20 % of the overall Nusselt number for the all cases. The pressure work has a redistributive effect between mean kinetic energy and internal energy. The energy transfer from mean kinetic energy to internal energy appears on the low temperature side whereas that toward the opposite direction on the high temperature side at the present low Mach number flow.
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  • 三浦 健介, 伊藤 靖仁, 酒井 康彦, 岩野 耕治, 長田 孝二
    82 巻 (2016) 838 号 p. 16-00087
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/20
    ジャーナル フリー
    Effects of half delta-wing shaped vortex generators (VGs) on thermal diffusion of an axisymmetric jet are experimentally investigated. The basic experimental setup is same as that of our past study (Miura et al., 2015). Six VGs are equally arrayed around the jet exit. The jet Reynolds number is set to 20,000. The initial temperature of the jet is set to 7.5 K higher than the ambient temperature. Instantaneous velocities and temperature are simultaneously measured by a composite probe which consists of an X-type hot-wire probe and an I-type cold-wire probe. The results show that ambient fluid is rapidly entrained and transported toward the jet center and thermal diffusion is promoted in the case with the VGs. The peak value of the temperature fluctuation in the case with the VGs is smaller than that in the case without the VGs because of the enhanced mixing near the jet exit. The turbulent Prandtl number at the location of half width of the mean velocity is around 0.65 ~ 0.8 in most of the cases but it is around 0.9 between the VGs at x/d = 2. In the downstream region, the effect of the VGs is small.
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  • 河本 仙之介, 早坂 啓祐, 野口 悠斗, 田川 義之
    82 巻 (2016) 838 号 p. 16-00094
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/20
    ジャーナル フリー
    A highly-focused laser-induced microjet by the rapid vaporization of a small mass of liquid in an open liquid-filled tube is expected to solve problems of conventional needle-free injection devices. For practical use of this microjet, in this study, we investigate experimentally the volume of the microjet V ejected from the tube in order to clarify how the volume V is determined. We conduct two experiments. Firstly, we investigate the relationship between the volume V and the maximum volume of a laser-induced bubble Ω. In our method, the laser-induced bubble grows toward one open side of the tube and pushes the liquid because the tube is closed in the other side of the tube. We anticipate that the volume of the laser-induced bubble is strongly related to the volume of the micorjet V. It is found that the volume of the microjet V is nearly equal to the maximum bubble volume Ω although V is slightly smaller than Ω in all data. Secondly, we investigate the position where the liquid pushed by the bubble breaks up. When the laser-induced bubble shrinks, the bubble partly pulls back the liquid into the tube. The liquid then breaks up at the open end of the tube. Based on aforementioned results, we elucidate the mechanism for determining the volume of the microjet V by considering the pressure evolution inside the laser-induced bubble. Furthermore we construct a model for the volume V with taking into account the volume Vbefore that describes the air volume inside the narrow tube between the open end of a narrow tube and an air-water interface. The model shows a good agreement with the experimental data. These results indicate a possible ability of the volume control in the novel needle-free injection system.
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熱工学,内燃機関,動力エネルギーシステム
  • 白神 洋輔, 堀 司, 林 潤, 毛笠 明志, 赤松 史光
    82 巻 (2016) 838 号 p. 15-00585
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/17
    ジャーナル フリー
    Oxygen-enriched combustion is frequently applied to industrial furnaces for requiring high temperature heating. The burned gas temperature in the oxygen-enriched combustion becomes high because of a decrease of inert gas (nitrogen). However, it is difficult to avoid the increase of NOx formation. This research tries to reduce the NOx emission from the oxygen-enriched combustion by the two-stage combustion using the tubular flame in the first combustion zone. The oxygen-enriched combustion experiments were implemented using enriched air (the oxygen concentration; up to 27%) with a prototype tubular flame burner of 1 kW output. The NOx emission from the first combustion zone became approximately zero even when using oxygen-enriched air by applying the rich premixed combustion at the nearly upper flammability limit. The NOx emission of the two-stage combustion using tubular flame was lower than the single-stage combustion. The reduction rate was 58% at 21% O2 air, 73% at 24% O2 and 79% at 27% O2. As the oxygen concentration rose, the NOx reduction rate became higher. Since the heat release rate in the second combustion zone can be mild when introducing the tubular combustion as a flame of the first stage, the NOx emission became decreased. This effect may become clear under the higher temperature condition of higher oxygen concentration.
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  • 小島 匠, 酒井 淳, 清水 信, 井口 史匡, 湯上 浩雄, 井口 浩詠, 久行 輝美, 中川 成人, 山村 武民
    82 巻 (2016) 838 号 p. 15-00588
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/07
    ジャーナル フリー
    We have studied the energy recovery effect in high-temperature furnace using a high-emittance fiber (HEF) unit. Previous studies have shown that energy recovery effect occurs as placing the HEF unit perpendicular to the gas flow. However, there are some problems such as clogging and pressure loss. In this study, we examined the energy recovery effect and mechanisms of the effect when HEF unit placed in parallel to the gas stream. In the numerical simulation based on thermo-fluid dynamics, energy recovery effect was also appeared even though the HEF unit placed parallel to the gas flow. The simulation, confirm that most of thermal radiation through the exhausted pipe from the inside of furnace is absorbed by HEF unit and is emitted back to the furnace. This simulation indicated more than 10% input power reduction is expected. We also reveal that amount of energy conservation is depend on the HEF unit’s length, position, and number of plates in a unit. In the experiment using similar furnace to simulation model, we can also obtain the input power reduction by 3.5% at 1073 K.
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  • 村上 泰城, 石橋 晃, 細川 茂雄, 冨山 明男
    82 巻 (2016) 838 号 p. 15-00685
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/07
    ジャーナル フリー
    A flat tube heat exchanger has attracted attention as one of the solutions to improve energy efficiency and reduce the amount of refrigerant in the development of the air conditioning unit for global warming prevention. An experimental study is carried out to examine the heat exchanger header patterns capable of appropriately distributing gas-liquid two-phase refrigerant into several narrow channels in an inclined flat-tube heat exchanger return junction for the purpose of improving both condensation and evaporation heat transfer performance. First, distribution of the gas-liquid two-phase refrigerant are examined using a return junction model with lower four inlet tubes and upper four outlet tubes to obtain the slit pattern achieving a uniform distribution. Next, an improved slit pattern is examined to obtain a desired distribution rather than a uniform one. Furthermore, an S-shaped path which has two slits is proposed to improve both condensation and evaporation heat transfer performance, and its heat transfer performances is evaluated using the heat exchanger with the S-shaped path. As a result, the overall heat transmission coefficient of the flat-tube heat exchanger with the S-shaped path is improved by about 5% in evaporation and 10% in condensation compared to that of a heat exchanger without the slit.
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機械力学,計測,自動制御,ロボティクス,メカトロニクス
  • 福田 謙吾, 吉田 浩治, 衣笠 哲也
    82 巻 (2016) 838 号 p. 15-00234
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/03
    ジャーナル フリー
    A checkweigher is an automatic machine to measure the weight of in-motion products. We propose the mass estimation method for checkweighers only employs an adaptive FIR filter and a notch FIR filter. To minimize calculation load, the adaptive filter is composed of two coefficients to be updated every sampling period. It estimates the mass of object to be weighed and the natural frequency of the vibration of the mechanical structure for weighing in order to check the validity of the estimated mass. However the actual vibration of the mechanical structure for weighing often includes parasitic vibratory components such as the components generated by the collision of the object and weigh belt and caused by the micro-tremors of the floor where a checkweigher is installed. The notch filter is composed of notch zeros which cancel some of components of the tiny vibrations previously known and zeros for shaping which suppress the gain of the high frequency band. The filter significantly attenuates the vibration components of the weight signal filtered by the adaptive filter from the observation of its output signals. If the filtered weight signal is sufficiently smooth and its part available for estimating the mass of a product is fitted to a straight line, the slope of the line is almost equivalent to zero. By setting upper and lower thresholds for this slope and the natural frequency estimated using the adaptive filter mentioned above, the timing and duration for estimating the mass can be determined without any hardware device. In the present paper, with the detail observation of results obtained by applying the mentioned above methods, which are combined into one algorithm for weighing, to an actual weight signal, we demonstrate the availability and know-how for the implementation of the algorithm.
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  • 辻 善夫, 眞田 明, 岩田 和大, 金島 秀幸
    82 巻 (2016) 838 号 p. 15-00464
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/03
    ジャーナル フリー
    This paper deals with a levelling machine for a seedling bed of a rice plant, which is a labor saving device in agricultural work. In order to make the seedling bed flat, the levelling machine vibrates by rotary motion of an eccentric rotor and presses the ground by the base plate of the machine. It is found that at a specific rotating speed, the machine can propel by itself, although the operators usually pull the machine using leads to move. The purpose of this study is to investigate the operational propelling mechanism of the levelling machine experimentally. The experimental result shows that propelling speed increases significantly under the condition that the rotational frequency of the eccentric weight is slightly higher than the natural frequency of an in-phase torsional mode of the plate. In this condition, a phase difference between the rear and front edges of the plate occurs, synthesizing the rigid mode and the torsional mode with a certain phase difference. In addition, the rear edge of the plate moves over an oval orbit which major axis is inclined to the propelling direction, and strongly kicks the ground surface after the front edge lifts up, then the plate is pushed to the slant upper part. Because the front edge is stuck on the surface at which phase the front edge lands and the rear edge hangs in the air, the plate turns around the front edge. As a result, the rear edge lands forward from the prior position. Because this motion of the plate occurs in turns, the machine can propel by itself effectively.
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  • 藤田 聡, 皆川 佳祐, 長田 修一, 田中 剛
    82 巻 (2016) 838 号 p. 15-00493
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/18
    ジャーナル フリー
    This study proposes a viscous-friction series damper. The series damper consists of an oil damper and a friction damper connected in series. Long period and long time seismic waves were recognized as new problems by the Great East Japan Earthquake. In the case of those seismic waves, there are risks that performance of damper decreases. For example, temperature of inner fluid of viscous dampers may increase, and fatigue failure may occur in steel dampers by such earthquakes. On the other hand, friction dampers have high durability, but they don't operate with small input. Proposed series damper compensates for these weak points. In the case of small input, only the viscous damper operates. In the case of large input, both dampers operate, so energy absorption is divided and the durability is increased. In this paper, an analysis model of the series damper is introduced, and numerical analysis is carried out in order to investigate behavior of the series damper. The target of vibration control is a boiler structure. As a result of analysis, response of the structure with the series damper was smaller than response without the damper. In addition, response of the structure with the series damper approached response with an ordinary viscous damper by increasing friction coefficient. Then test model of the series damper is fabricated, and load experiments by sinusoidal waves are conducted. As a result of the experiments, stabile performance of the series damper against various input condition was confirmed. In addition, experimental results agreed well with analysis results, so proposed analysis model is efficient.
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  • 山下 透, 平野 良樹, 中嶋 敦哉, 杉山 勉, 吉積 敏昭
    82 巻 (2016) 838 号 p. 15-00539
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/31
    ジャーナル フリー
    Two driving systems in which a circuit breaker is driven synchronously and sequentially by two devices which are connected with relatively long hydraulic pipes were investigated. Numerical analysis method of pipe flow, which is modeled by lumped parameter system, was compared with theoretical solutions modeled by using distributed parameter system. It was confirmed that proper results could be obtained by the numerical method. Hydraulic transmission and operating time of two driving system were investigated by using the numerical method and measurement. Dimensions of the connecting pipe and other hydraulic constants influence the motion time of two devices. Particularly, the different length of connecting pipe at asymmetrical arrangement has much influence. The synchronous driving system suppresses the time difference of two operating devices by symmetrical arrangement and appropriate dimensions of connection pipe. The sequential driving system which uses dashpot pressure gives us stable delay time under the change of conditions and makes it possible to adjust the range of delay time by using hydraulic volume and restrictor.
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  • 秋山 陵, 塩幡 宏規, 中島 智美, 山下 穣
    82 巻 (2016) 838 号 p. 15-00603
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/09
    ジャーナル フリー
    In order to analyze the blade vibration caused by flutter, it is necessary to understand both the aerodynamic damping and structural damping of the high vibration stress. Flutter Vibration mode occurring in the rated speed is non-synchronous mode. To measure non-synchronous mode damping, high frequency excitation magnet was developed. Damping characteristics of the non-synchronous mode of nodal diameter 12 and 4 were measured in the rotation test. For comparison, synchronous mode of nodal diameter 4 was measured. From these results, it was concluded as follows. (1) It is possible to excite non-synchronous mode by high frequency excitation magnet and measure the damping ratio. (2) According to the measurement results of non-synchronous mode of nodal diameter 12 and 4, damping ratio is increased if the excitation force become large. Synchronous mode of nodal diameter 4 is also a similar trend. (3) Nodal diameter 4 damping ratio of non-synchronous mode(Resonance speed : 100%) was lower than synchronous mode(Resonance speed : 75%). (4) When evaluating flutter which occurs at rated speed, it is necessary to measure structural damping ratio at rated speed.
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  • 竹村 英孝, 中村 正幸
    82 巻 (2016) 838 号 p. 15-00604
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/03
    ジャーナル フリー
    Stepping motors, together with the micros-stepping drive, are widely used in many motion control applications, given their low cost and high reliability. However, even with the use of micro-stepping drive, the rotor vibration of stepping motor is not easy to be avoided, especially due to the presence of a large cogging torque. It is also well known that the motor energy consumption with the micro-stepping drive is large, in order not to be concerned with the load torque but to control the motor current at the rated maximum value. This paper presents research on a new micro-stepping drive method for stepping motors. A new method for stepping motor controllers, which cancels out the cogging torque without using any additional electronic devices and mechanical parts and reduces the motor energy consumption, is proposed. This paper is organized as follows. First, the method using cogging torque compensation is derived. Next, computer simulation on the cogging torque of a stepping motor in the micro-stepping drive is described to verify effectiveness of our proposed method. Then, experiments for the motor drive controller conducted to evaluate the rotor vibration and energy consumption are presented. Finally, it is concluded that simulation and experimental results show that our proposed method is effective in the vibration suppression and energy saving.
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  • 武田 真和, 渡辺 昌宏
    82 巻 (2016) 838 号 p. 16-00015
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/03
    ジャーナル フリー
    This paper presents experiments and an analysis on the self-excited vibration of a plate supported by air pressure. The instability conditions are examined using a theoretical analysis considering the effect air compressibility in a chamber. The system's characteristic equation is derived from the plate motion coupled with equations of the gap flow between the plate and the chamber surface. The vibration characteristics and the unstable conditions of the self-excited vibration are examined through experiments. The unsteady fluid force acting on the plate (bottom surface) is investigated by measuring the unsteady pressure. The local work done by the unsteady fluid force is also clarified. Lastly, the unstable mechanism of the self-excited vibration is discussed based on the theoretical model and experimental results.
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  • 木村 弘之, 滝前 祐紀
    82 巻 (2016) 838 号 p. 16-00035
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/31
    ジャーナル フリー
    A vibration suppressor is used to change the natural frequency of an elevator rope, and to prevent resonance. The elevator rope is modeled using a string. Linear string vibration is well known. However, the vibration of the string that has a vibration suppressor has been studied for a few conditions because of its geometric nonlinearity. Let the position of the vibration suppressor be 1/N of the string. In the case where N is an even number, an exact solution of the free vibration of the string has been obtained. However, in the case where N is an odd number, no exact solution of the free vibration has yet been obtained. In this paper, an exact solution of the free vibration of this case (N is an odd number) is presented. Finite difference analysis of the string vibration with a vibration suppressor is performed. The calculated results obtained from the finite difference analysis are in good agreement with those of the exact solution.
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  • 山下 透, 平野 良樹, 杉山 勉, 吉積 敏昭
    82 巻 (2016) 838 号 p. 16-00050
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/26
    ジャーナル フリー
    Braking characteristics of piston-dashpot system in a hydraulic operating device for circuit breaker was investigated by the measurement and numerical analysis. Braking force against piston motion is generated in the use of pressure drop of gap flow through annular dashpot formed at the end of the piston. One-dimensional flow and motion of piston-dashpot system were modeled and analyzed dynamically to evaluate this force and piston displacement. Formulas of pressure drop in dashpot gap flow which distinguishes turbulent flow from laminar flow by Reynolds number were used in the analysis. A piston moving part was modeled by two particles model system in consideration of elastic link mechanism. The validity of the hydraulic and dynamic analysis was confirmed by the comparison with experiments of a testing device. The effect of dashpot dimension such as annular gap, dashpot diameter, dashpot length and the number of gap stage on braking characteristics was surveyed and the range of effective braking characteristics was showed. These results are useful for the proper design of dashpot dimension of hydraulic operating device.
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  • 中川 智皓, 森田 悠介, 新谷 篤彦, 伊藤 智博
    82 巻 (2016) 838 号 p. 16-00052
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/26
    ジャーナル フリー
    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.
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  • 安田 裕矢, 渡邉 鉄也, 鞆田 顕章
    82 巻 (2016) 838 号 p. 16-00061
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/26
    ジャーナル フリー
    The rocking vibration with friction is focused in this study. The fall down conditions of the rocking system with friction are clarified. Rocking vibration is the rotational motion around the both ends of the structure and occurs when the structure is excited. In this report, the behavior of single-degree-of-freedom rocking system and two-degree-of-freedom rocking system with friction are taken into consideration. An analysis model is proposed and the response is calculated in the case that the structure is excited by sinusoidal wave and seismic wave. In order to estimate the parameters to prevent the fall down in a simple manner, two state judgement maps are proposed. One is the “Input variation map” focusing on the parameters of input sinusoidal wave and the other is the “Form variation map” focusing on the parameters of the structure form. From the analysis results, it was possible to clarify the basic characteristics of the rocking vibration with friction from the aspect of the input waves and the dimensions of the structure.
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  • 木村 弘之
    82 巻 (2016) 838 号 p. 16-00086
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/31
    ジャーナル フリー
    A vibration suppressor is used to change the natural frequency of an elevator rope, and to prevent resonance. The elevator rope is modeled using a string. Linear string vibration is well known. However, the vibration of the string that has a vibration suppressor has been studied for a few conditions because of its geometric nonlinearity. An exact solution of the free vibration of a string with a vibration suppressor located at 1/N from one end of the string has been obtained. However, in the case when vibration suppressors are installed at 1/N from both ends of the string, no exact solution of the free vibration has yet been obtained. In this paper, an exact solution of the free vibration of this case is presented. Further, to verify the validity of this exact solution, a finite difference analysis of the string vibration with vibration suppressors is performed. The calculated results obtained from the finite difference analysis are in good agreement with those of the exact solution.
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計算力学
設計,システム,製造
  • 長山 格
    82 巻 (2016) 838 号 p. 15-00278
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/10
    ジャーナル フリー
    This paper describes a high performance parallel image retrieval system for mechanical drawings management. The system is designed with PC-cluster that consistes of one master node and eight slave nodes. In order to achieve a higher performance, parallel processing and precise searching process are introduced to the proposed system. The parallel processing uses many rotated templates of a target symbol to perform pattern matching by each slave node. The precise searching is newly designed by analyzing our previous study for image retrieval of mechanical drawings. Object detection in many kind of images continues to be one of the most common application for image processing and understanding. We first discuss some essential issues to be considered conventional object detection with large digital images. Experimental results by using the proposed system are also described. The good performance of the system is shown.
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  • 大久保 光, 福田 宙央, 坪井 涼, 田所 千治, 佐々木 信也
    82 巻 (2016) 838 号 p. 15-00679
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/10
    ジャーナル フリー
    Tribological properties of a diamond-like carbon film were investigated under lubrication with commercial fully formulated oils. Friction tests were carried out for a hydrogenated amorphous carbon (a-C:H)/steel tribopair under lubrication with the four types of fully formulated oil using a reciprocating type ball-on-disk tribo-tester. To clarify the friction and wear mechanisms, surface analysis, such as Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS) and atomic force microscopy (AFM), were conducted on the wear tracks of a-C:H disks. The results of friction tests and surface analysis show that the properties of tribofilms on DLC films play important roles in determining the tribological properties of DLC films under lubrication with fully formulated oils.
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生体工学,医工学,スポーツ工学,人間工学
  • 田中 瑞穂, 梅沢 侑実, 土井 幸輝, 藤本 浩志
    82 巻 (2016) 838 号 p. 16-00001
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/03
    ジャーナル フリー
    Identification of the hardness of an object in a human hand is different according to the hardness of the object. For example, chiropractors identify stiffness in the muscle by using their thumb, which can press more forcefully than the forefinger. However, it has not been shown experimentally if the characteristics of hardness discriminability are different according to fingers. In this study, to clarify the relation between different fingers pressing elastic objects and the characteristics of hardness discriminability, we investigated the differential threshold of hardness using the forefinger and thumb. Additionally, the influence of press force and press displacement on the characteristics of hardness discriminability was clarified. We used 7 elastic test pieces with different Young’s moduli as the presented stimuli. We also used the test pieces with hardness sensation judged as ‘hard’ in our previous research. We conducted the experiment using the constant stimuli method to calculate differential threshold of hardness as one evaluation index of hardness discriminability when using the forefinger and thumb. The results of this experiment showed that the hardness discriminability of the thumb was better than that of the forefinger. In addition, these results suggested that press displacement but not press force should be used to estimate the hardness discriminability and that the thumb is better than the forefinger to discriminate the displacement. These findings clarify the mechanism underlying hardness discriminability in the human hand.
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  • 近藤 良, 鈴木 利充, 峯岸 祐太, 岡田 養二, 松田 健一
    82 巻 (2016) 838 号 p. 16-00088
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/05/31
    ジャーナル フリー
    A wearable leg support system for hemiplegia has been proposed in this paper. Power assist suits, which are studied by many researchers lately, are not applicable to those people with lower limb paralysis caused by spinal cord injury or stroke. We have developed a wearable leg support system, Manipuleg-2, that has actuators at hip, knee, and ankle, and has a special control lever mounted on the unaffected shoulder. The postures of user's arm and wrist are detected by the lever with 3 DOF, and are transformed to the actuator joint angles for manipulation of the exoskeleton leg. Walking experiments have been conducted for an able-bodied subject with the developed system on a level floor and a certain uneven floor, and the results show that the subject has mastered how to manipulate the control lever to walk properly.
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環境工学,化学機械,システム安全
  • 白石 裕司, 中塚 記章, 宮内 隆志, 林 潤, 赤松 史光
    82 巻 (2016) 838 号 p. 15-00601
    公開日: 2016/06/25
    [早期公開] 公開日: 2016/06/07
    ジャーナル フリー
    Low NOX emission combustion technology is required for Municipal Solid Waste (MSW) incinerators. Comparing investigation between simplified 1D combustion experiment and 1D numerical analysis has been performed to decide detailed reaction mechanism suited for NO emission prediction in MSW combustion. Effects of H2/CO ratio and H2O/CO2 ratio in the modeled pyrolysis gas to NO formation were evaluated in the primary combustion and the subsequent secondary combustion by Premixed Laminar Burner-Stabilized Flame Model. Comparison between measured NO concentration and calculated NO concentration indicated that calculation results obtained by using Kilpinen97 reaction were within a certain error range compared with experimental results in a wider condition range of fuel composition and excess air ratio than the modified GRI-mech3.0. Increased H2/CO and H2O/CO2 led to the decrease in NO mole flux in the primary combustion, respectively by different reaction paths, which increased both H2/CO and H2O/CO2 showed an additive effect on the decrease in NO mole flux. NO conversion ratios after the secondary combustion from NH3 in the modeled pyrolysis gas were still reduced by the increased H2/CO and H2O/CO2 in the modeled pyrolysis gas although the NO conversion ratios after the secondary combustion were larger than those after the primary combustion because of the conversion to NO in the secondary combustion from HCN, NH3 and HCNO remained in the primary combustion. Conversion ratio from HCN, NH3 and HCNO to NO in the secondary combustion can be reduced by the decreased temperature at inlet of the secondary combustion area. Based on the findings above, it is possible to design lower NOX emission MSW incinerators by considering the conditions of the exhaust gas recirculation affecting H2/CO and H2O/CO2 in the primary combustion, and the cooling structure of the primary combustion flue gas.
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