日本機械学会論文集
Online ISSN : 2187-9761
ISSN-L : 2187-9761
85 巻 , 872 号
選択された号の論文の26件中1~26を表示しています
スマートマニュファクチャリングの実現に向けた新生産システム
  • 野中 洋一
    2019 年 85 巻 872 号 p. 19-pre01
    発行日: 2019年
    公開日: 2019/04/25
    ジャーナル フリー
  • 日比野 浩典, 久保 直輝, 松本 悠作, 木村 誠, 水上 洋介
    2019 年 85 巻 872 号 p. 18-00148
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/08
    ジャーナル フリー

    It is becoming necessary for agriculture companies to deal with daily stable supplies for farm produces because customers who hope to achieve quality of life (QOL) in daily meal are getting increasing. Therefore, it is increasingly important to research and develop agricultural production systems to deal with daily stable supplies for farm produces. The amount of daily demands for the farm produces fluctuates because customer behaviors have fluctuations. The amount of daily supplies for the farm produces also fluctuates because makespans of the farm produces cultivated in fields have fluctuations. The makespan defines as the time difference between the start and finish of a sequence to harvest the farm produces. Therefore differences between the supply and the demand often occur. By occurring the fluctuations for the makespans, lack of stock and crop loss often occurs in the agriculture companies. The crop loss refers to situations in which goods that could have been consigned were not. This is due to the consignment criteria not being met because of issues such as time delays. In this research, we propose modelling and simulation of the agricultural production system to evaluate and reduce the lack of stock and crop loss due to the uncertainties surrounding the amount and units harvested and produce growth in the cultivated fields. We investigate cultivated field production processes to harvest the farm produces by a multiple-crop rotation. We also investigate various cultivated field data by IoT (Internet of Things) technologies. We propose a cultivated field production process model and crop growth prediction algorithm for application in our proposed simulation. We verify our proposed simulation through case studies.

  • 長沢 仁史, 日比野 浩典, 橋本 元信, 綛 宜史
    2019 年 85 巻 872 号 p. 18-00157
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2018/11/22
    ジャーナル フリー

    For enhancing the energy efficiency of a manufacturing system as a whole, it is critical to optimize energy consumption including that in the utility systems, which supplies compressed air, and that in each production line. Compressed air is used in the manufacturing domain in a wide variety of systems such as those that fix and hold works through pneumatic equipment. Compressed air systems account for approximately 10% of the industrial electricity consumption in the European Union. Therefore, a method for minimizing the energy used in compressed air systems is sought. From the point of view of energy saving in the operation of a compressed air system, a method is available for reducing the output of the compressed air system. However, if the supply of compressed air becomes insufficient by the reduction in the amount supplied, it can result in extension of the cycle time of the production line or in defective products; thus, it can eventually cause lower productivity. Therefore, businesses ensure adequate supply from compressed air systems in order to prevent the adverse impact of insufficient supply of compressed air on productivity; however, this results in wastage of energy. Therefore, it is necessary to simultaneously evaluate productivity and compressed air feed. However, there has been no progress in the research of methods for evaluation. Hence, in this research, a method, which is a hybrid of a manufacturing system simulation and computational fluid dynamics simulation, is proposed for evaluating the operation of both production lines and compressed air systems simultaneously. The proposed method is used to evaluate the deficiencies and excesses in the supply from a compressed air system and the reliability of the supply of a compressed air system in response to the daily production schedule. Moreover, the energy consumption per unit of production throughput is evaluated.

  • 松田 亮, 新堂 正俊, 廣垣 俊樹, 青山 栄一
    2019 年 85 巻 872 号 p. 18-00176
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2018/10/12
    ジャーナル フリー

    Nowadays, a monitoring technology has attracted attention in the factory automation fields regarding IoT (Internet of Things). However, it is difficult to monitor the process information from a round tool during rotating operation in machine tools. We therefore develop a novel tool holder equipped with a wireless communication function to monitor tool temperature and vibration. In the present report, we attempt to measure the inner temperature in drill tool and investigate the influence of feed rate and cutting speed on it. Moreover, we attempt to measure the tool vibrations in the rotational and radial direction in countersinking process. As a result, we demonstrated that the developed method with a wireless system is effective to estimate the tool temperature in drilling processes and the tool vibration in countersinking processes.

材料力学,機械材料,材料加工
  • 金 太成, 林 晏理, 二川 秀史, 細井 厚志, 川田 宏之
    2019 年 85 巻 872 号 p. 18-00408
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/27
    ジャーナル フリー

    Carbon nanotube (CNT) yarn is enables CNTs to be used on macro scale. However, the mechanical properties of CNT yarns are smaller than CNT itself, and improvement of the mechanical properties is a challenge for practical application. In this study, untwisted CNT yarns were fabricated by a dry spinning method, and the yarns were graphitized and combined with polymer for the purpose of development of CNT yarns with high strength. As a result of the graphitized treatment to the as-received yarns under inert atmosphere at 2800°C, impure materials and defect structure on CNTs were removed and strength of the yarn was increased by 19%. After combining the as-received yarns with polyacrylic acid (PAA), the strength was increased by 174% and reached 2.3 GPa. Breaking form of the yarns were changed from pulling out of CNT bundles to rapture of CNT bundles by graphitization and combining with PAA, indicating an increase interactive force between the CNT bundles. However, the strengthening effect was limited when graphitized CNT yarns were combined with PAA. As a result of molecular dynamics simulations, it was revealed force transfer capability of PAA was low when the graphitized yarns was combined with PAA. There were functional groups on as-received CNT such as carboxyl groups. On the other hand, the functional groups were removed from CNTs after the graphitization treatment. Consequently, interaction such as hydrogen bond between as-received CNT and PAA was removed by the graphitization, and it lead to the decrease of the force transfer capability of PAA.

  • 松岡 三郎, 吉田 聡子, 飯島 高志, 濱田 繁, 松永 久生, 山辺 純一郎
    2019 年 85 巻 872 号 p. 18-00415
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/27
    ジャーナル フリー

    In order to clarify the effect of hydrogen-gas pressure on threshold of hydrogen-induced crack growth (KI,H), elasto-plastic fracture toughness tests were performed on JIS-SM490B carbon steel, JIS-SCM435 low-alloy steel and JIS-SUS304 stainless steel. For JIS-SM490B and JIS-SUS304, the values of KI,H at displacement rates of 2×10–5 and 2×10–4 mm/s were almost the same in hydrogen at pressures of pH2= 20, 45 and 115 MPa (KI,H ≒ 80 MPa·m1/2 for JIS-SM490B and 150 MPa·m1/2 for JIS-SUS304). In contrast, for JIS-SCM435, the values of KI,H at displacement rates of 2×10–5 and 2×10–4 mm/s were the same in hydrogen gas at pressures of pH2 = 20, 45 and 80 MPa (KI,H ≒ 100 MPa·m1/2); however, those of KI,H were degraded in 115-MPa hydrogen gas (KI,H ≒ 50 MPa·m1/2). Based on the HISCG (Hydrogen Induced Successive Crack Growth) model, an effect of pH2 on KI,H and an existence of KI,H were also discussed for JIS-SM490B, JIS-SCM435 and JIS-SUS304.

流体工学,流体機械
  • 和田 祥平, 佐藤 明, 二村 宗男
    2019 年 85 巻 872 号 p. 18-00473
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/15
    ジャーナル フリー

    We have developed a simple assessment method for the overlap between spheroidal particles, which is indispensable for performing particle-based simulations of a colloidal suspension. In the present assessment method, the position giving rise to the deepest overlap point between the steric layers of two spheroidal particles is evaluated by using the inscribed sphere of the spheroid that is moved on the major axis line for scanning the surface-to-surface distance of these two spheroids in an effective manner. Moreover, we have developed an evaluation method for the interaction energy due to the overlap of the steric layers covering spheroidal particles. This is based on a sphere-connected particle model, but some modifications are introduced in order to express an appropriate repulsive interaction energy at the deepest overlapping position. Then we have investigated phase change problems in a magnetic spheroidal particle suspension in a two-dimension system by means of Monte Carlo simulations where both the above-mentioned assessment method and the evaluation method for the repulsive interaction energy are combined. In the case of no external magnetic field, as the area fraction is decreased from a large value where chcain-like clusters are formed in the whole area of the system, this internal strucuture changes into raft-like one in a narrow range of the area fraction. Raft-like clusters are preferred in a weak applied magnetic field, but an increase in the field strength induces the phase change from raft-like into chain-like structure.

  • 一柳 隆義, 西海 孝夫
    2019 年 85 巻 872 号 p. 18-00483
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/15
    ジャーナル フリー

    The fluid borne-vibration generated from a hydraulic pump is known to be one of drawbacks in hydraulic systems. In order to decrease the noise and vibration effectively, the simulation tool to predict the pressure ripple at an arbitrary point in the hydraulic circuit must be used at a design stage. Therefore, accurate mathematical models for hydraulic components is required for such simulation. In this research, the target is set to develop a precise mathematical model for the source impedance characteristics of an axial piston pump. In the past research, the simple approximation models have been already developed to be able to express the source impedance characteristics. These models need the parameter identification for the dimension of discharge passageway by the experimental acquired source impedance. Hence, the models can not be used as a design purpose. In this report, the theoretical investigations which consider shapes and dimensions of a discharge passageway inside the pump, as well as the pump chambers with discharge process, are conducted and compared with the experimental results. It was found that the source impedance of axial piston pump can be modeled by the distributed parameter pipe model which takes into account all pump chambers connecting the discharge port.

  • 藤澤 信道, 西山 直道, 太田 有, 後藤 尚志, 加藤 大
    2019 年 85 巻 872 号 p. 18-00493
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/04/03
    ジャーナル フリー

    Work characteristics and loss generation mechanism of a single-stage axial flow compressor at windmill operation were investigated by experiment and CFD analyses. When the inlet flow coefficient is gradually increased from the design point, the rotor blade gradually enters the windmilling operation from the tip toward hub. The research attentions were focused on two windmilling operations, those were free-windmilling and highly loaded windmilling conditions. Total pressure loss under windmilling operations was mainly caused by three flow structures, those were (1) tip leakage flow from suction to pressure surface near the leading edge and that from pressure to suction surface near the trailing edge, (2) the interaction of separation vortices due to the highly negative incidence and the rotor leading-edge vortex, and (3) the boundary layer separation near the hub wall. The distribution of the rotor operating mode was found to exist not only in the span-wise direction but also in the chord-wise direction under the windmilling operations. The turbine mode region was observed near the leading edge, while the compressor mode region was observed near the trailing edge even in the highly loaded windmilling condition. Therefore, driving force of the windmilling was dominated not by the area of the turbine mode on the rotor blade but by the static pressure difference of suction and pressure surfaces on the rotor.

熱工学,内燃機関,動力エネルギーシステム
  • 住 隆博, 黒滝 卓司, 大澤 克幸, 小田 哲也
    2019 年 85 巻 872 号 p. 18-00332
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/11
    ジャーナル フリー

    To obtain qualitative knowledges about an ultra-high-pressure fuel injection process in a future automobile diesel injector, a compressible gas-liquid two-phase flow solver is newly developed and an unsteady numerical analysis on a simple injection system with a two-dimensional micro-hole is performed. The six-equation diffuse interface model with heat and mass transfer is adopted and extended from the original two-phase two-component system to the new two-phase multi-component system. High-order numerical discretization methods in time and space are employed to resolve fine flow structures in the transient injection process. In the numerical results, injection pressure in the high-pressure chamber and back pressure in the low-pressure chamber are systematically changed, and the effects on the injection process are discussed in detail. Under conditions close to real operation, promotion of primary atomization due to jet instability, formation of a detached shock wave at the tip of the fuel jet and generation of cavitation bubbles inside the hole are clearly observed. Moreover, compressible effects in both gas and liquid phases are confirmed to be crucial in the numerical analysis of the ultra-high-pressure fuel injection process, which integrally handles the whole system from the high-pressure section to the low-pressure section.

機械力学,計測,自動制御,ロボティクス,メカトロニクス
  • 古賀 倫子, 佐藤 太一, 蔭山 怜
    2019 年 85 巻 872 号 p. 18-00255
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/26
    ジャーナル フリー

    We investigated the damping mechanism of a granular-material damper for a structure with a high natural frequency. We focused on the flow of the granular-material vibration energy and considered its relationship with the damping characteristics. The movement of spherical granular materials was calculated in the granular-material damper; the power of the collision force and the frictional force exerted by the granular materials on the primary vibration system were obtained and compared with the input energy. In the region in which the total mass of the granular materials was small, the collision force that the granular materials exerted on the primary vibration system affected the damping characteristics of the granular-material damper. Conversely, in the region in which the total mass of the granular materials was large, the frictional force that the granular materials exerted on the primary vibration system in addition to the impact force affected the damping characteristics of the granular-material damper. That is, the vibration of the primary vibration system is primarily affected by the collision of the granular materials on the left and right container walls, and by the energy consumption caused by the friction of the granular materials on the bottom of the container. By using the quantities of energy consumed in both collisions and frictions, it is possible to evaluate the damping characteristics of the granular-material damper.

  • 武田 真和, 小澤 和典, 渡辺 昌宏
    2019 年 85 巻 872 号 p. 18-00289
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/26
    ジャーナル フリー

    This paper presents experiments and an analysis of the self-excited vibration of a floating plate and a support structure. The system in which a floating plate and a support structure vibrate, the elasticity of the support structure influences the stability of the system. Therefore, in this paper, the influence of the elasticity of the support structure on the vibration characteristics and occurrence conditions of the self-excited vibration is examined. In the analysis, the unsteady fluid force is calculated based on the basic equation of a two-dimensional leakage-flow between the plate and the support structure surface. The basic equation of leakage-flow considers the effect of air compressibility. Moreover, the equation of continuous air flow in the chamber includes the effect of air compressibility. The characteristic equation on the stability of the system is derived from the plate and the support structure motion coupled with the unsteady fluid force. The experiment consists of a floating plate and a support structure, where the vibration characteristics are examined. The influence of elasticity of the support structure on the vibration characteristics and occurrence conditions of the self-excited vibration are clarified comparing the analysis with experiments. Lastly, the local work done by the unsteady fluid force acting on the plate surface and the support structure surface is shown, and the instability mechanism is discussed.

  • 南 克樹, 片原田 浩之, 吉武 裕, 串崎 祐樹, 森山 皓太, 山崎 豪
    2019 年 85 巻 872 号 p. 18-00307
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/26
    ジャーナル フリー

    This paper deals with the quenching problem of electromagnetic vibration of the motor stator in the wide frequency region around the natural frequency using two dynamic absorbers. The iron stator of motor is modeled by circular ring, and two dynamic absorbers are installed on the outside of iron stator to quench the forced vibration caused by the rotating distributed electromagnetic force. The solutions of forced vibration are obtained by the theoretical analysis, and those are compared with the solutions obtained by the finite element method and numerical integration. Following was made clear: (1) By installing two dynamic absorbers which have not only different natural frequencies and different damping ratios but also different masses each other, the iron stator is quenched better than by installing the same dynamic absorbers. (2) It is possible to obtain nearly optimum quenching effect with a pair of dynamic absorbers with equal masses. (3) The mechanism of the above-mentioned vibration quenching method using two different dynamic absorbers is made clear. (4) In the case using the dynamic absorbers those have small values of damping ratios, about 25 degrees is better as angle made by the two dynamic absorbers. (5) The characteristics of resonance curves obtained by the theoretical analysis using ring theory and those obtained by the finite element method and numerical integration agreed well each other.

  • 星野 智史, 芳川 知樹
    2019 年 85 巻 872 号 p. 18-00353
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/12
    ジャーナル フリー

    Motion planning for mobile robots considering occluded obstacles is a navigation challenge in dynamic environments. If an obstacle suddenly appears from the occluded area, a robot might collide with the obstacle. This is the occlusion problem. Therefore, this paper proposes a novel motion planner, Velocity Obstacle for Occlusion, VOO. The VOO is based on Velocity Obstacle, VO, which is effective for moving obstacles. In the proposed motion planner, information uncertainties about occluded obstacles, such as position, speed, and moving direction, are quantitatively addressed. Thus the robot based on the VOO is enabled to move in consideration of both observed and occluded obstacles. Through simulations and real robot experiments, we discuss the effectiveness of the VOO for the occlusion problem by comparing to the VO.

  • 菅原 佳城, 大島 俊汰郎, 千田 拓
    2019 年 85 巻 872 号 p. 18-00384
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/11
    ジャーナル フリー

    In recent years, a system with rigid and extremely flexible components (hereinafter called “SREF”) are often employed for satellite systems in order to realize various vast structures in orbit, and flexible components are made of strings, membrane and so on. In general, flexible component of such a system has two states, one is the state with tensional force and the other is without tensional force. Therefore, state transition of the system arises depending on its configuration, and then careful treatments are required for the analysis of such a system, because number of the combination of state increases dramatically depending on the number of mass and flexible component. Eventually, such an increase of components results in the computational difficulty in the analysis of such a system. Authors have found analogy between the state transition of the SREF and contact problem described by linear complementary problem which was developed by Pfeiffer et al., thus similar procedure can be employed for the analysis of the motion of SREF. In this paper, considering such an analogy and introducing some assumptions, state transition problems for SREF are formulated as liner complementarity problem and effective analysis method for dynamic behavior for SREF is proposed. In order to show the validity of the proposed method, some numerical analyses are performed and physical interpretations of the obtained results are discussed. Furthermore, comparison of the numerical analysis between experimental results shows the validity and advantage of the proposed method.

  • 園部 元康, 井上 喜雄, 芝田 京子
    2019 年 85 巻 872 号 p. 18-00412
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/11
    ジャーナル フリー

    Balance evaluation during standing is an important issue for diagnosis of disease and determination of training effect. The purpose of this study is to evaluate personal balance characteristics based on a model from the response of human body when the support surface moves horizontally as an external stimulus. The response of human body was defined as posture angle based on a single-link model and the angle was estimated from two kinds of measurement system. One is a motion capture system and the other is force plates mounted on the support surface. We applied the frequency analysis to the response and identified personal balance characteristics in an assumed balance control model. The balance control model was defined as a multiple feedback loop system which is composed of the delayed state feedback control as an inner-loop and target posture definition according to the velocity of the support surface as an outer-loop. To evaluate personal characteristics from the identified parameters, equivalent damping ratio and natural angular frequency were defined from a pair of conjugate complex roots of the system. As a result, we found that inner-loop characteristics were uniform when the posture angle was estimated from force plates. Outer-loop characteristics contributed to reduce the body sway in the frequency range from 0.1 Hz to 0.2 Hz in theory. The result of seven subjects implied that a subject who has less damping effect tends to use outer-loop system actively.

  • 森 洸太郎, 朝間 淳一, 大岩 孝彰, 鳥居 孝夫
    2019 年 85 巻 872 号 p. 18-00417
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/04/08
    ジャーナル フリー

    This paper introduces a resonance avoidance method for a 2-degrees-of-freedom (DOF) controlled maglev motor using d-axis current. The rotor of the 2-DOF controlled maglev motor has a disk shape, and the rotor radial motion is actively controlled. However, the axial and tilting motions are passively suspended, and hence, the significant rotor vibration is caused during rotation. To avoid the axial and tilting resonances, the motor d-axis current that regulates the strength of the magnetic field is provided for changing the axial and tilting stiffnesses, and hence, resonance points can be avoided during rotation. The axial and tilting stiffnesses with and without d-axis current were calculated by finite element method (FEM), and the rotor resonances were estimated. The rotor vibration was measured using a test machine with and without d-axis current, and the rotor vibrations in the axial and tilting directions were successfully reduced. The experimental results have verified the effectiveness of the proposed resonance avoidance method.

  • 松永 信智, 木村 亮太, 岡島 寛
    2019 年 85 巻 872 号 p. 18-00479
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/26
    ジャーナル フリー

    Recently, welfare vehicles are widely used among the elderly and the aged. However, it is not easy for inexperienced beginners or the aged to control the welfare vehicle in narrow places such as corridors. In this paper, a driving assistance system using Mixed Reality (MR) which has collision avoidance function is proposed using a virtual platoon control scheme. Using the system, it is supposed that the cognitive and driving ability is enhanced from the simulated objective view point. The driver rides on the vehicle and controls using the virtual preceding vehicle on a Head Mounted Display (HMD). The virtual vehicle projected on a HMD is steered from a simulating objective viewpoint, and the welfare vehicle is controlled so as to follow the virtual vehicle using the precise platoon control algorithm. In order to avoid the collision to obstacles by the beginners, the obstacle avoidance function on the assistance system is designed using MR technology. To detect obstacles or the wall, the proposed assistance system uses 3D mapping function of a HMD. As a result, it is confirmed that collision can be avoided safely by driving experiments in the narrow corridor.

  • 河田 雅至, 山田 啓介, 原 進, 宇津野 秀夫, 倉田 純一, 村上 佳広
    2019 年 85 巻 872 号 p. 18-00485
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/26
    ジャーナル フリー

    In this paper, we proposed a momentum exchange impact damper using a solenoidal coil and a capacitor to suppress impact vibration. Noise and vibration generated by forging machines and press machines have been a serious problem. In order to reduce impact vibration, the momentum exchange impact damper has been studied by many researchers. The basic principle of this damper is based on the momentum transfer during the collisions of three rigid bodies. This impact damper is the most effective when the mass of the damper is equal to the mass of the bed of the forging machine. However, the mass of the damper is usually smaller than the mass of the bed for practical use. In this study, this problem was solved by using a solenoidal coil and a capacitor. The electrical charge stored in the capacitor flows through the solenoidal coil when the impact damper passes through the solenoidal coil using a switch. The electromagnetic force is generated by the electrical current, and the electromagnetic force absorbs the kinetic energy of the host structure. The effectiveness of the proposed method was verified through simulations and experiments.

  • 髙木 山河, 来栖 悠太, 涌井 伸二
    2019 年 85 巻 872 号 p. 18-00486
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/04/08
    ジャーナル フリー

    In this paper, we designed a PIS control method that can automatically estimate the disturbance frequency using Schmitt trigger and implemented it in a pneumatic vibration isolator. A pneumatic vibration isolator is used for vibration suppression of the semiconductor exposure apparatus. The pneumatic vibration damping device adopts a structure in which the isolated table is supported by an air spring and compressed air supplied and exhausted from the compressor is supplied to the air spring. As this compressed air is accompanied by pressure fluctuations, it causes vibrations in the isolated table. PIS control using S compensator which suppresses periodic vibration in PI control is used to suppress this flow disturbance. However, in the PIS control, when the frequency of the actual disturbance fluctuates, the vibration suppression effect by the PIS control deteriorates. Therefore, we proposed a PIS controller that can automatically estimate the frequency of disturbance using Schmitt trigger. By implementing this method, we succeeded in improving the vibration suppression effect by comparing displacement of the base of conventional PIS control method and automatic frequency estimation PIS control.

計算力学
  • 若狭 守, 下田 昌利
    2019 年 85 巻 872 号 p. 19-00011
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/20
    ジャーナル フリー

    In this paper, a parameter-free optimization method is proposed for controlling the time-dependent response of a three-dimensional linear elastic structure, where the optimal shape is determined without design parameterization. The design objective is to minimize the vibration displacements or to control the vibration displacement at arbitrary domains and times for an arbitrary time-dependent loading under the volume constraint. The unsteady time-dependent optimum design problems are formulated as distributed-parameter optimization problems and the sensitivity functions with respect to the design velocity field are derived based on the variational method, Lagrange multiplier method and the adjoint method. The derived sensitivity function is applied to the H1 gradient method, a gradient method in the function space to determine the optimal shape variation. With the proposed method, the optimal shape for time-dependent response problems such as a forced-vibration, a free-vibration or a transient response is obtained while minimizing the objective functional and maintaining the smooth surface of a structure. Several numerical design examples including a continuous dynamic force or an impulse force as an input force are shown to confirm the effectiveness of the proposed method, and the results are discussed.

設計,機素・潤滑,情報・知能,製造,システム
  • 藤田 慎之輔, 寒野 善博
    2019 年 85 巻 872 号 p. 18-00160
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/04/09
    ジャーナル フリー

    Advancement of computer technologies as well as the developments of structural materials and construction methods have enabled us to design a so-called free-form shell, which has complex shape and topology that cannot be categorized to traditional shapes. However, the mechanical behavior of such a shell is very complicated, and it is very diffcult for a designer to decide feasible shape of a real-world structure based on his/her experience. Based on such background, in recent years, some shape optimization methods for continuum shell structures, which have a strong relationship between shape and structural rationality, have been proposed actively. On the other hand, thickness distribution is also an important aspect of shell structures. There exist not so many studies on the optimization methods which treat shell shape and plate thickness simultaneously. From the view point of structural feasibility, constructability and topological clarity, it is not acceptable that the plate thickness takes an extremely small value. Therefore, the part with a thin plate thickness should be an opening, which requires to use a topology optimization approach. In this paper, a simultaneous optimization method of shape, thickness, and topology of shell structures is proposed. Efficiency of the proposed approach is investigated through several numerical examples, and the characteristics of the computational results are discussed.

  • 東﨑 康嘉, 後藤 卓也, 奈良 智明, 保阪 瞭太
    2019 年 85 巻 872 号 p. 18-00482
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/15
    ジャーナル フリー

    Helical gears have long been known as one of the most commonly used mechanical components in transmitting power. Recently, the power to be transmitted has become large, and the engine speed is also increasing. However, the lubrication condition and the surface temperature that dominate the failure of the helical gear are complicated and not fully understood. Since the surface failure is influenced by temperatures in the tooth contacts, it is very important to know the surface temperatures of gears in operation. However, measuring the surface temperatures of gears in operation is difficult. As an effective means to measure the surface temperatures, method using dissimilar metals is known. The voltage proportional to surface temperatures was produced by contacting dissimilar metals. This is known as Seebeck effect. In this study, S55C (Carbon steel) and SUS316 (Stainless steel) were selected to dissimilar metals. Both dissimilar metals were heat-treated and surface were hardened. SUS316 was vacuum carburizing process and S55C was performed induction hardening. In order to remove the influence multiple meshing, the gear was designed so that the total contact ratio which is the sum of transverse contact ratio and the overlap contact ratio was less than 2. This result secured the area of a single contact zone. Surface temperatures measurement using hardened helical gears succeeded in the area of single contact zone. When we compared the experimental values and the theoretical values using Blok’s formula considering with lengthwise sliding velocity, surface temperatures on gear teeth were largely same.

生体工学,医工学,スポーツ工学,人間工学
  • 伊丹 琢, 矢野 賢一, 森 一大, 亀田 和弘, 青木 隆明, 岸田 敏嗣, 林 典雄, 松井 愛気, 菅原 政範, 篠田 信之
    2019 年 85 巻 872 号 p. 18-00484
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/03/22
    ジャーナル フリー

    Knee osteoarthritis(Knee-OA) is a disease caused by age-related muscle weakness, obesity, or sport injury, and it has been estimated that approximately one in two people may experience it by the age of 85. Most cases of knee-OA lead to a gait problem due to pain during walking, with the result that knee-OA is a significant cause of reduced personal quality of life (QOL). One of the characteristics of knee-OA who are classified as grade II to III of Kellgren-Lawrence classification is rotation dyskinesia of the knee joint due to the degeneration of the system around the knee. This rotation movement is crucial for impact absorption, balanced walking and stabilization of the knee joint and this movement is one of key elements in walking. In the present study, we focused on the rotation of the lower leg relative to the movement of the ankle joint during walking stance phase, and we developed a mechanical orthosis of the new type of ankle-foot orthosis (AFO), which induces rotation of the lower leg in conjunction with the movement of the ankle joint mechanically. The mechanical induction of rotation movement is used the movement difference due to the angle change of inside and outside bars in conjunction with ankle angle. We verified the effectiveness of the developed orthosis by measuring the amount of rotation, lateral thrust, Womac test while five subjects with knee osteoarthritis. Based on the results, the effectiveness of our developed orthosis was confirmed.

  • 澤田 悠佑, 渡邉 鉄也
    2019 年 85 巻 872 号 p. 19-00008
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/04/08
    ジャーナル フリー

    A flexible string is used at various places. Typical examples are a cable for power transmission and communication and a wire for cranes and elevators. In addition, there are the uses such as a fly-fishing line, climbing rope and a mowing machine to cut turf by turning a nylon string. In the past study, a string pendulum was paid attention as the basic motion of the string. An analysis model of the string pendulum was made and appropriateness of the modeling and the behavior of the string pendulum were clarified. However, axial elongation is not considered. In fact, the axial elongation affects their behavior such as axial micro vibration or restoring force of the elongation. Therefore, it is necessary to consider the axial elongation to grasp the behavior of the string more exactly. In this study, an accelerated motion of the string such as the casting motion is focused on and analyzed in consideration the axial elongation then appropriateness of the modeling is verified by comparing experimental results and analysis results. Furthermore, relations of the axial elongation and an accelerated motion are investigated. In this paper, the behavior is investigated focusing on the velocity of the tip of the string. As a result, strain energy is stored and then converted into kinetic energy, thereby increasing the velocity.

法工学,技術史,工学教育,経営工学など
  • 内田 皓久, 古林 敬顕, 中田 俊彦
    2019 年 85 巻 872 号 p. 18-00122
    発行日: 2019年
    公開日: 2019/04/25
    [早期公開] 公開日: 2019/04/09
    ジャーナル フリー

    Fuel cell vehicles are expected to be a key actor for coming hydrogen society in Japan. However, because of different source of fuel hydrogen, there remains uncertainty of the real value of FCVs. A question arises of what is benefit of introducing FCVs compared with other passenger vehicles such as HEVs and EVs. This study investigates the characteristics of FCVs in Well-to-wheels using inventory analysis and forecast penetration of FCVs into the passenger transportation sector applying an energy-economic model. Analytical results indicate that (1) FCVs have an important benefit of reducing carbon emissions provided carbon free hydrogen fuel by green electricity derived electrolysis. (2) Under the carbon reduction target of -80% in the year 2050, the share of FCVs in the passenger vehicle transportation sector reaches 14%, which is higher than 1% without carbon constraint. (3) In the total cost of ownership, price of FCVs is the dominant expenditure, which suggest the secure of FCV's cost reduction. The result of the study shows that the penetration of FCVs into the passenger transportation market requires competitive price of the vehicle as well as higher carbon reduction target.

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