TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C
Online ISSN : 1884-8354
ISSN-L : 1884-8354
Volume 77, Issue 774
Displaying 1-30 of 30 articles from this issue
Mechanical Systems
Regular Paper
  • Takafumi MOCHIZUKI, Ichiro HAGIWARA
    2011 Volume 77 Issue 774 Pages 246-256
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Modal differential sub-structure that can quickly predict effects of structural modifications has been proposed by the author. This method is a kind of the component modal synthesis and utilizes modal analysis results of the model before the structural modification. Because the method does not require the user to decide the component to be modified beforehand, the user can determine the component to be modified after checking the calculation result of the full structure. This method can be applied to free structural modifications such as substitution of a structural part. In a certain case, however, where the model has to handle very many modes, the eigenvalue problem becomes insoluble due to singularity of the mass matrix. This paper elucidates the reason of the problem and shows a procedure to avoid it.
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  • Takahiro MURAKAMI, Michiya SAKAI, Masami NAKANO
    2011 Volume 77 Issue 774 Pages 257-269
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    A novel MR damper which has the same variable damping characteristics as an existing semi-active control but no active component has been proposed and developed. The damping force changes in response to the sign of the displacement and the velocity, which is effective in reducing vibrations. Moreover, the damper has an advantage in high reliability, since the damper is composed of only passive components such as MR fluid, permanent magnets, and check valves. The prototype has been manufactured and the dynamic performance has been verified experimentally by an excitation test and a shaking table test with single-degree-of-freedom (SDOF) system. The experimental results show that the damping force changes depending on the displacement and the velocity and the damper has excellent performance in reducing the vibration of the SDOF system over a wide range of frequency. In addition, the analytical evaluation method for the damping characteristics is developed, in which the static magnetic field analysis and the algebraic equations of simplified fluid flow model are employed. Comparing the analytical results with the experimental results, it is found that the developed evaluation method can adequately simulate the characteristics of the damper.
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  • Kunihiko ISHIHARA, Kosuke TAJIMA, Ryuta MARUYAMA
    2011 Volume 77 Issue 774 Pages 270-279
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    The FDC (Flow Dynamics Conveyer) has been often used in power plants and iron works because of superiority in quiet compared with a roller type conveyer and it is excellent in a low noise and low power. The FDC consists of a trough and a belt, and the air is supplied from a lot of holes provided on the trough. However, large vibrations occur when the flow rate becomes a certain value. This abnormal vibration is defined to be self-excited vibration caused by leakage flow induced vibration here. It is well known that the abnormal vibration occurs when the tapered flow channel is formed. The purpose of this study is to clarify the generation mechanism of the abnormal vibration. The experiment was carried out to examine the effect of various parameters such as taper angle θ, floating amount H on the abnormal vibration. As a result, the damping ability becomes small with increase in the taper angle and decrease in the floating amount. Furthermore it was clarified that the abnormal vibration occurs inθ>αH (α:constant value)
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  • Gaku KUDO, Masahiro WATANABE, Kensuke HARA
    2011 Volume 77 Issue 774 Pages 280-289
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    This paper deals with an experimental study of flow-induced wave generated on a thin film under shear loading. The experiment is carried out to investigate the deformed shape of the thin film with various values of shear loading, and the wave propagation due to the interaction of the deformed shape of the thin film with the fluid flow in the narrow passage. As a result, it is clarified that the flow-induced wave occurs to the thin film caused by the interaction of the deformed shape of the corrugation due to the shear loading with the fluid flow in the narrow passage. The critical flow velocity of the flow-induced wave drastically decreases caused by the generation of the corrugation on the thin film due to shear loading. Moreover, it is clarified that the traveling direction of the flow-induced wave is determined by the deformed shape of the corrugation and fluid flow direction. The flow-induced wave propagates diagonally, almost across the fluid flow direction.
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  • Keisuke MINAGAWA, Satoshi FUJITA, Shingo KANAEDA, Rokuro ENDO, Mitsuhi ...
    2011 Volume 77 Issue 774 Pages 290-299
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    In recent years, seismic evaluation and design techniques which are able to evaluate cumulative damage have been required. Authors have dealt with this issue from the viewpoint of the energy balance equation. The energy balance equation expresses cumulative information of response, so that the energy balance equation is adequate for the evaluation of the influence of cumulative load such as seismic response. Authors have already clarified qualitative relationships between input energy and fatigue failure of simple single degree of freedom system. However, in order to apply energy balance equation on actual structure for seismic evaluation, expansion of it to multiple degree of freedom systems is required. Therefore this paper proposes three types of energy balance equation for multiple degree of freedom systems, that is a matrix method, an each mass method and a modal method. Energy balance equation by the matrix method indicates energy of a whole system. The equation by the each mass method indicates energy of each mass. The equation by the modal method indicates energy of each mode. In this paper, behaviors and features are investigated by numerical simulation and vibration experiment.
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  • Kenji OKADA, Shinichi MARUYAMA, Ken-ichi NAGAI, Takao YAMAGUCHI
    2011 Volume 77 Issue 774 Pages 300-308
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    This paper presents experimental results on chaotic vibrations of an annular plate with initial deflection. The effect of modal interaction on chaotic vibrations is main scope in this paper. The plate is free on the outer edge and clamped on the inner edge. The initial deflection of the plate is nine thousandth times to the difference between the outer radius and the inner radius. The lowest and the third modes with one nodal-diameter have different natural frequencies due to the initial deflection. The second mode corresponds to the mode without nodal-diameter. The fourth and fifth modes have two cross nodal-diameters. The linear natural frequencies of the second and the third modes coincide with a slight deviation. The plate is subjected to lateral periodic acceleration. Sweeping the excitation frequency, nonlinear response curves of the plate are recorded. In the wide frequency ranges, non-periodic responses are generated. The responses are inspected by the Fourier spectrum, the Poincaré projection, the maximum Lyapunov exponent and the principal component analysis. The predominant non-periodic response is confirmed as the chaotic response generated from one-to-one and two-to-three internal resonances. The lowest, the second and the third modes are coupled in the internal resonances. The principal component analysis is applied to the chaotic response selected with short-time intervals sequentially collected from the long-time response. It is found that exchanges of the contribution ratio are observed among the lowest, the second and the third modes. Furthermore, the nodal diameters of the fourth and the fifth modes are fluctuated along the circumferential direction in the chaotic response.
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  • Hideto AIZAKI, Shinji WAKUI
    2011 Volume 77 Issue 774 Pages 309-318
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    In the field of precision positioning and measurement, air-type active anti-vibration apparatuses are widely used. This apparatus equips an actively controlled air spring which has anti-resonance and resonance characteristic on frequency response. Due to this characteristic, it is known that deformation of main body occurs because of the difference of pressure in each air spring. In order to avoid the deformation of main body supported by the air springs and to manage their driving forces, the pressure feedback was especially implemented as a minor loop. However, it is undesirable to install pressure sensors in the field of industrial application because it takes cost and the sensors have low resolution for the management of the driving force. Then, this paper proposes a minimum order observer that estimates inner pressure of the air spring without a pressure sensor. Some correction gains for the observer are usually set by pole assignment method, however these gains depend on the parameters of the plant. Therefore, the observer needs adjustment of correction gains for implement. Then, this paper proposes a minimum order observer which is able to be adjusted with monitoring the measured frequency response, and clears the role of the correction gains.
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  • Yuichi KOIDE, Hirokuni ISHIGAKI, Hiromitsu MATSUNAGA, Naoki FUKUSHI, T ...
    2011 Volume 77 Issue 774 Pages 319-328
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    In the seismic design of the boiling water reactor, we need to estimate the dynamic insertion behavior of control rods into the core region to secure the safety of the reactor under seismic events. In particular, estimation of the insertion time is one of the most important design tasks affecting the scrammability of the reactor. We developed a numerical analysis model to predict the control rod insertion time under seismic events using multibody dynamics. The effect of the interaction force between the control rod and the fuel assemblies is considered in three-dimensional contact analysis. This interaction force causes resistance force acting on the control rod under insertion. The hydraulic control unit and the control rod drive, which provide the control rod with driving force, were modeled in the concentrated parameter system considering dynamic characteristics, such as the inertance of the working fluid in the scram piping and the capacitance of the working gas in the accumulator. The numerical analysis can simulate the realistic insertion behavior of the control rod by coupling these models together and using an interactive process to calculate how they interact. The validity of the numerical analysis model was confirmed by comparing the analytical results with the experimental ones. The results of our analysis showed that the numerical analysis model provides good agreement with the insertion time of the control rod.
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  • Yoshitaka TAKAHASHI, Nobuyuki SHIMIZU
    2011 Volume 77 Issue 774 Pages 329-341
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    There are several formulations for the beam element in the large deformation and displacement problem. Recently, Absolute Nodal Coordinate Formulation (ANCF) is studied for such problems. In this formulation, the mass matrix and the stiffness matrix are described as simple equations, even in the case of the large deformation and displacement problem. However, degree of freedom of the beam element of ANCF increases from conventional finite element method, since the beam element is formulated by 8 absolute nodal coordinates. In this paper, the authors propose a formulation and an assembling method of the beam element formulated by 6 absolute nodal coordinates considering the calculation efficiency. In this method, the number of nodal coordinates of the assembling point of beam elements is same as nonlinear finite element method. The effect of the proposed method is verified by the numerical simulations.
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  • Makoto IWAMURA, Peter EBERHARD, Werner SCHIEHLEN, Robert SEIFRIED
    2011 Volume 77 Issue 774 Pages 342-355
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    The aim of this study is to develop a general purpose optimal trajectory planning algorithm for multibody systems. Multibody systems may be divided into two groups, i.e., open loop systems and closed loop systems. In this paper, a general purpose optimal trajectory planning algorithm for open loop multibody systems is proposed. Firstly, the optimal trajectory planning problem is formulated as an optimal control problem. Then, a method to compute the partial derivatives of the state equation with respect to the state or the control variables that are necessary for optimal control calculation is developed based on a recursive dynamics computational algorithm for multibody systems. After that, a general purpose optimal trajectory planning algorithm is formulated by connecting the method for computing the partial derivatives and the robust optimal control algorithm called hierarchical gradient method. An optimal trajectory planning problem of a planar space robot with two arms is shown to demonstrate the effectiveness of the proposed algorithm.
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  • Makoto IWAMURA, Peter EBERHARD, Werner SCHIEHLEN, Robert SEIFRIED
    2011 Volume 77 Issue 774 Pages 356-369
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    The aim of this study is to develop a general purpose optimal trajectory planning algorithm for multibody systems. Multibody systems may be divided into two groups, i.e., open loop systems and closed loop systems. In a previous paper, a general purpose optimal trajectory planning algorithm for open loop systems was suggested. In this paper, optimal trajectory planning algorithms for closed loop systems are proposed by extending the algorithm for open loop systems. Two types of methods are presented by using the dynamics computational algorithms for closed loop systems. The first method is based on the generalized coordinate partitioning and embedding techniques. The second method is based on the augmented formulation with Lagrange multipliers. The validity of these methods for optimal trajectory planning is confirmed by computational results and their features are compared.
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  • Yasutaka SATOU, Hiroshi FURUYA
    2011 Volume 77 Issue 774 Pages 370-380
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    A fold process of a deployable space membrane with retraction mechanisms is examined to reduce wrinkles and to improve the fold precision of the membrane retracted repeatedly. The properties of the fold process are investigated experimentally with experimental retraction mechanisms which wrap and fold the membrane with tensile forces and rotation of the center hub. To reduce wrinkles, and to improve the fold precision, hinge mechanisms which are stiffened elements attached on the membrane are proposed. To examine the effects of the hinge mechanisms, fold patterns, and configuration of the center hub on the properties of the fold process, the retraction experiments are performed. The experimental results indicate that the distribution of the tensile forces and the hinge mechanisms mainly determine the fold process. Introducing the mixed spiral fold which consists of Z-folds and spiral folds, the membrane is successfully folded with fewer wrinkles and higher precision than the rotationally skew fold.
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  • Takahiro HOSOI, Katsuya TANIFUJI
    2011 Volume 77 Issue 774 Pages 381-391
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Due to the lightening of railway vehicles and the improvement of operation speeds, the reduction of running safety by cross winds is becoming an important problem. In particular, the running safety tends to reduce when the vehicles are running on curved sections. When a cross wind acts on the vehicle running on a curve from the outer side, a flange climbing phenomenon can occur. In this study, a full vehicle model was constructed using a multi-body software, SIMPACK, and the running simulation on a curve was carried out to examine the running safety under the condition that a cross wind acted on the vehicle from the outer side of the curve. As a result, it is verified that the derailment coefficient of the first wheelset becomes large in the exit transition curve and that of the third wheelset does in the entrance transition curve and this trend is pronounced by larger wind forces. Here, the derailment coefficients at the timing the derailment occurs are different between the first and third wheelsets, and those derailment coefficients are much larger than the critical derailment coefficients obtained by Nadal's formula. Then an equivalent friction coefficient which depends on an attack angle is introduced in Nadal's formula. Consequently, the critical derailment coefficient considering the equivalent friction coefficient came close to the actual derailment coefficient.
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  • Hiroyuki OHNO, Akira MATSUMOTO, Yasuhiro SATO, Makoto SHIMIZU, Masao T ...
    2011 Volume 77 Issue 774 Pages 392-400
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    A new measuring method introduced in this paper can measure contact forces between wheel and rail without special wheel-set with slip rings or telemeters. In this method the lateral contact force is measured from the lateral distortion of wheel measured directly by several non-contact gap sensors. Normal and longitudinal contact forces are also measured from the deflection of spring or the strain of parts of the bogies except special wheel-set. This new method, unlike the conventional method, is able to store the data everyday on every curve of commercial lines, which change according to friction coefficient and train running speed and so on. In this paper the authors describe the new measuring method without strain-gauge-equipped wheel-set, estimations of comparing the new method and the conventional method, and data analysis of measurements by commercial service trains. Practicable use of this new method enables us to easily obtain the statistical data of derailment coefficients with an on-board measuring method. Statistically analyzing the variation of rail-lubrication conditions and characteristics of wheel-rail contact force on every curve with this new system can help to improve track conditions for maintenance.
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  • Kei TAKENAKA, Yasuhiko SASAKI, Hisao INAMI, Hideki NAKAMOTO, Yusuke WA ...
    2011 Volume 77 Issue 774 Pages 401-410
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    We developed the rapid live bacteria counter (RLBC) with the disposable cassette to count live bacteria rapidly, simply and accurately for the food security. The RLBC has the following features: (1) The RLBC performs automatically following processes in the cassette: removing residues, staining live and dead bacteria and counting live bacteria by flow cytometry techniques. (2) This uses the multi staining to distinguish easily the fluorescence of live bacteria from the different fluorescence of foreign substances. (3)For accurate counting and the cassette breakage prevention , the micro flow-cell for the flow cytometry satisfies following conditions that the coincidence loss of live bacteria is below 0.05 and the pressure drop is below 1×105 Pa. The live bacteria count obtained with the RLBC and the classical cultural method for the test samples are highly correlated (R2 (E-Coli) = 0.97, R2 (Spinach) = 0.96, R2 (Carrot) = 0.91, R2 (Red cabbage) = 0.90).
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  • Daisuke YAJIMA, Akiko FUKUDA, Koji IKUTA
    2011 Volume 77 Issue 774 Pages 411-420
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Our group has been developing an active catheter that can be used safely in human blood vessels. Earlier studies have proposed a hydraulic active catheter with active segments that can be independently driven with water pressure alone. The system can be achieved with a "Band Pass Valve (BPV)," a micro valve with an inner flow path set to open within a specific pressure range for the supply of fluid into a bending soft actuator inside. A prototype BPV was fabricated by hybrid micro stereolithography and tested in experiments to verify its function. During the design of the BPV, the complex interaction between fluid and elastomer made it quite difficult to set the driving pressure range theoretically. This paper proposes a quantitative design method for the BPV based on a dimensional analysis. With this method, dimensionless numbers and design charts can be provided for any kind of micro valve. This method enabled the development of a hydraulic active catheter with a minimal configuration and simplified valve composition. The valve thus designed was fabricated and tested for verification of its driving performance.
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  • Daisuke FURUKAWA, Tarou HAYASHI, Souichi SAEKI, Takashi SAITO
    2011 Volume 77 Issue 774 Pages 421-428
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    A reconstruction technique, such as Fluorescence Molecular Tomography or Fluorescence Diffusion Optical Tomography, permits us to detect a tumor genesis, cancer detection and so on using the Photo Dynamic Diagnosis(PDD) images. However, these techniques require huge computational cost and the introduction into intra operation has some difficulty about the surgical possibility in real time and narrow field. In this study, we propose a method to identify the fluorescence source simulated as a tumor in real time process using Near Infrared(NIR) fluorescence images, the optimization approach with Weighted Residual Method (WRM). In order to verify the location accuracy of the proposed method, we demonstrated the tumor identification using tissue phantom and a fluorescence tube filled with fluorescence dye (AlPcS). The absolute errors between the true positions and the estimated positions in the experiments were less than 1mm. The estimated time was about seventy mill-seconds. To confirm the validity for living bodies, we carried out the experimental identification using small animals. The fluorescent micro-tubes (diameter 0.4mm) filled with AlPcS were inserted in the brains of the euthanized mice. The errors between the true positions and the estimated positions in the animal experiments were about 1.6mm. Consequently, we confirm that this proposed method is effective as an assisted system in a navigation surgery.
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  • Takuro HATSUKARI, Norihisa MIYAKE, Yasuhisa HIRATA, Kazuhiro KOSUGE
    2011 Volume 77 Issue 774 Pages 429-438
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    A person can employ various standing-up strategies depending on his/her physical ability and personal habit. Physically-handicapped persons have abilities as well to stand-up, with the help of caregivers or devices. There is not so much relationship between physical ability of a person and the standing-up strategy being employed, which leads to the fact that the devices or the care method might not be appropriately chosen. A method for choosing among standing-up strategies based on a newly defined ADL(Activity of Daily Living) index for standing-up function has therefore been proposed. Then, these strategies are derived from standing-up strategy classification focused on human joints' degree-of-freedom, and can be classified into 7 categories. In the cases where multiple strategies correspond to the same index, the differences are studied experimentally. In the cases where no existing device is known to the corresponding category, prototype model of the support devices are made experimental use. The result of the experiments shows that an appropriate standing-up strategy can be chosen in accordance with the ADL index.
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  • Tomohiro HAYASHI, Koichi IWATSUKI, Yoshiyuki SANKAI
    2011 Volume 77 Issue 774 Pages 439-449
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Recent studies have revealed the importance of voluntary exercise in rehabilitation training after spinal cord injury and cerebrovascular diseases. However, the voluntary exercise has been an impossible task for severe paraplegic patients who cannot move their lower limbs by themselves. If a robot suit can assist walking of such patients by estimating their intention from neuromuscular activities, it can provide an opportunity for voluntary exercise to them. Because the patients have difficulty in controlling neuromuscular activities, the robot suit is required to estimate the intention from deficient neuromuscular activities and to execute gait motions in place of their paralyzed limb muscles. The purpose of this study is to assist gait of severe paraplegic patients with the robot suit by estimating their intention of swinging legs. To this end, we developed a method to estimate the intention of swinging leg from both deficient bioelectrical signals and foot-ground reaction force. In order to move a patient's paralyzed limbs, we combined the estimation method with an autonomous control method for the robot suit. Walking trials on a treadmill with partial body weight support were performed with two complete paraplegic patients. The robot suit was able to estimate the patients' intention from deficient bioelectrical signals and to move their lower limbs. Consequently, the robot suit succeeded in assisting gait of the patients on the treadmill. This result shows that the robot suit can provide an opportunity for voluntary exercise to severe paraplegic patients having difficulty to move their lower limbs.
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  • Shoichi MAEYAMA, Yasuhiro UWAI, Keigo WATANABE
    2011 Volume 77 Issue 774 Pages 450-459
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    A lifting judgment for a robust dead reckoning system is proposed for a wheeled mobile robot when the robot is carried by the person. In this system the position of the robot on the ground is estimated by an odometry, whereas that in the air is estimated by an inertial sensor. The estimation mode is switched by the lifting judgment. Neither enough accuracy nor reliability is actually obtained though it is thought that the lifting judgment can be decided by only height information. This is attributed to the fact that there are cumulative errors due to the bias drift in the height calculation from the integration of the value of the acceleration sensor. Therefore, a PSD distance sensor was installed for only the lifting judgment in the previous implementation. This paper proposes a lifting judgment method with a boosting algorithm by using the information on the internal sensors such as accelerometer, gyro sensor, and wheel encoder without the PSD distance sensor. Furthermore, experimental results using an actual mobile robot are given to demonstrate the effectiveness of the present method.
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  • Atsushi OZATO, Noriaki MARU
    2011 Volume 77 Issue 774 Pages 460-469
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    We propose position and orientation control method of Omnidirectional Mobile Robot by Liner Visual Servoing(LVS). We define both the new binocular visual space which represent attitude of the target using binocular visual coordinate of two markers and the new motion space of omnidirectional mobile robot to realize position and orientation control by LVS. It is robust to calibration error of camera angles, because it does not use camera angles to calculate feedback command. Simulation results are presented to demonstrate the effectiveness of the proposed method.
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  • Kiyoshi HIROSE, Hitoshi DOKI, Shinsuke KODA, Kiyoshi NAGASAKU
    2011 Volume 77 Issue 774 Pages 470-480
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    This paper proposes the motion measurement system and the dynamic analysis methods of the skiing turn on an outside actual snowfield. This motion measurement system that consists of inertial and magnetic field sensors provides 3-axis angular velocity, acceleration and intensity of magnetic field. This motion analysis method provides joint angle of lower body in skier using information from the motion measurement system, extended Kalman filter and inverse kinematics. In addition, this dynamic analysis method provides joint torque using joint angle, angular velocity, angular acceleration, acceleration, reaction force from the snow surface obtained from 6-axis force sensor and inverse dynamics. In order to indicate the performance of our proposed system, we have performed the measurement experiment of the skiing turn on an actual snowfield. It is found that the proposed method is able to analyze the major features of skiing turn and to evaluate quantitatively the skill and characteristics of skiers.
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Translated Paper
  • Takashi NAKAE, Atsuo SUEOKA, Takahiro RYU
    2011 Volume 77 Issue 774 Pages 481-492
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    The squeal phenomenon is often generated in bicycle disc brakes. This paper deals analytically with the generation mechanism and the criterion of whether or not the squeal occurs. According to the experimental studies, it has been made clear that the squeal is mainly in-plane vibration in the direction of disc surface with the frequency about 1kHz caused by frictional characteristics with negative slope with respect to the relative velocity. An analytical model of the bicycle disc brake system has been devised to confirm the experimental results, in which a coupled in-plane and out-of-plane vibrating system is composed of the disc, hub, caliper and spokes. The resulting frequency of squeal and the unstable vibration modes of the disc and spokes from the analytical model agreed well with the experimental results.
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  • Takashi NAKAE, Takahiro RYU, Atsuo SUEOKA
    2011 Volume 77 Issue 774 Pages 493-504
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Squeal and chatter phenomena are often generated in bicycle disc brakes. The squeal is in-plane unstable vibration along the disc surface caused by dry friction with negative slope with respect to the relative velocity. The squeal is generated in the vibrating system including the brake unit, spokes and hub. According to experiments, the chatter is generated in a certain limited range at high disc temperatures, and is nonlinear frictional vibration in which the out-of-plane unstable vibration of the disc due to Coulomb friction and the squeal are combined through the internal resonance relationship between the out-of-plane and in-plane vibrations caused by the increase in disc temperature during braking. First, we propose a simple nonlinear system with three degrees of freedom which possesses the essential vibration factors included in a bicycle disc brake system to investigate whether or not the coupled nonlinear vibration due to the internal resonance occurs. Then, we numerically confirm the mechanism of the chatter generated in a bicycle disc brake by nonlinear analysis.
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Machine Elements, Design and Manufacturing
Regular Paper
  • Hiroyuki OMURA, Takabumi FUKUDA, Koichi FUTSUHARA, Noboru SUGIMOTO
    2011 Volume 77 Issue 774 Pages 505-513
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    The most characteristic point of food processing machines is that they require hygiene measures for risk reduction against contamination of manufactured food products for consumers, as well as safety measures for risk reduction to ensure safety for operators. The measures of risk reduction for safety aspects do not always match the risk reduction measures for hygiene aspects. The protective measures of safety aspects may increase the hygiene risk. Therefore, ISO 14159 has defined to decide the suitable protective measures for risk reduction by comparing both safety and hygiene. However, not only ISO14159 but also other standards do not illustrate a concrete method by comparing safety risk and hygiene risk. Harm contents differ between safety risk and hygiene risk, so methods of safety risk estimation are inapplicable to hygiene risk estimation. Consequently it has been an important issue in Food-processing machine industry to develop method of risk assessment by comparing the safety risk and hygiene risk, because of these circumstances. Authors devise the reduction measure of the hygiene aspects to be included in the process of the limits of the machine. We consider it is possible to perform both risk assessments, according to risk reduction process described in ISO 12100-1, without comparing both different risks. This paper mentions about the unprecedented assessment method including different risks.
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  • Yohichi NAKAO, Hajime NIIMIYA, Takuya OBAYASHI
    2011 Volume 77 Issue 774 Pages 514-526
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    The present paper describes the rotary-type flow control valve that is developed for controlling the rotational speed of the fluid-driven spindle. The valve controls water or oil flow, depending on the spindle application. The structure of the designed flow control valve is first introduced with brief explanation on the spindle. Mathematical models are then derived in order to consider the control performance of the valve. Flow control performance of the valve is examined through calculations and experiments. In addition, the performance of the rotational speed control of the spindle by the valve is studied via experiments and calculations. Finally, it is verified that the developed flow control valve successfully controls the rotational speed of the spindle with desired resolution of the rotational speed. The calculation results using linearized models are also compared with the experimental results, showing that it will be useful to design a feedback control system.
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  • Takeshi NAKAMOTO, Yoji HAGITA
    2011 Volume 77 Issue 774 Pages 527-536
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Sapphire has high hardness and chemical stability. When a sapphire is used as a product, it must be machined into a desired shape. However, it is very difficult to machine the sapphire because of its high hardness. By the way, the sapphire reacts with silica at high temperature and under high pressure. Using this phenomenon, a single crystal sapphire is machined by tool wear during cutting of glass which contains the silica because the cutting point attains the high temperature and high pressure. The rake faces of the sapphires are a-plane, c-plane and r-plane in the cutting experiments. The removal rate is small when the rake surface is c-plane. The glass chips during the machining are inspected by EPMA. The elements of the sapphire exist around the glass chips. The mechanisms and removal rate of the machining of the sapphire are examined by a simple model from these results.
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  • Taira OGITA, Shigeru TADANO, Masahiro TODOH, Masaru KANAOKA
    2011 Volume 77 Issue 774 Pages 537-544
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    Orthopaedic implants have been fixed to bone tissue by other artificial materials such as bone cement or clinical screws. It is important to develop the bonding technique between bone and implant materials directly. Laser technique with high energy density is effective tool for bonding the different materials in short duration precisely. In this study, the laser technique for the bonding of bone and implant material has been proposed. The applications of laser technique were examined for the sintered (HAp), glass-added hydroxyapatite (G-HAp) and bone tissue. As a result of laser irradiation on brittle HAp, the cracks appeared near the melting region. However, on G-HAp containing cordierite-glass ceramics with a low linear expansion coefficient, crack-generation was reduced and performance of laser processing improved. The application for the bonding of bone and G-HAp showed that a sufficient bonding was achieved by the generation of melting region of HAp and bone with cavities by the evaporation of bone tissue.
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Translated Paper
  • Hiromu HASHIMOTO, Puttha JEENKOUR, Mongkol MONGKOLOWONGROJN
    2011 Volume 77 Issue 774 Pages 545-555
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    This paper describes the novel optimization method of wind-up tension to prevent wound roll defects, mainly star defect (wrinkling) and telescoping (slippage), based on the optimum design technique. Modified Hakiel model with air entrainment effects is applied to analyze in-roll stress distributions in the radial and tangential directions. In the present optimization method, the wind-up tension is gradually changed in the radial direction to minimize the tangential stresses under the constraint of nonnegative tangential stresses. At the same time, we consider the friction conditions to prevent the slippage between web layers due to a decrease of radial stresses and friction force. Successive quadratic programming, which is a typical mathematical programming method, is used as the optimization technique. The optimized wind-up tensions are obtained for various winding conditions, and we confirmed theoretically and experimentally that the in-roll stress distributions are very much improved for preventing both wrinkling and slippage simultaneously by the optimization method being proposed.
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  • Shinji HIKITA, Hiromu HASHIMOTO
    2011 Volume 77 Issue 774 Pages 556-567
    Published: 2011
    Released on J-STAGE: February 25, 2011
    JOURNAL FREE ACCESS
    We describe an entirely new method of improving the slippage between web and roller. First, the concept of a micro-grooved roller is introduced, and then a theoretical model for estimating the slip onset velocity under the transport of web by the micro-grooved roller is formulated. The predicted results are compared with the experimental data to verify the applicability of the prediction model of slippage. Moreover, the web-wrinkling condition, which is in a trade-off relationship with the slippage condition, is also considered in the model. From the theoretical and experimental results, it is confirmed that the optimized micro-grooved roller is very effective in improving the slippage and wrinkling of thin web under the high-speed transport with low tension at the actual production line.
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