Transactions of the JSME (in Japanese)
Online ISSN : 2187-9761
ISSN-L : 2187-9761
Volume 88, Issue 915
Displaying 1-26 of 26 articles from this issue
TRANSLOG2021&J-RAIL2021
  • Keisuke MINAGAWA, Ryuzo HAYASHI
    2022 Volume 88 Issue 915 Pages 22-pre03
    Published: 2022
    Released on J-STAGE: November 25, 2022
    JOURNAL OPEN ACCESS
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  • Taizo MAKINO, Takanori KATO, Shoichi HASEGAWA, Yosuke YAMAZAKI, Satosh ...
    2022 Volume 88 Issue 915 Pages 22-00102
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: July 12, 2022
    JOURNAL OPEN ACCESS

    The present study aimed to clarify the relationship between the fatigue life under in-service conditions and the failure probability of welded joints in a railway bogie frame. Considering the effects of the stress ratio and weld toe radius, the authors determined the PSN curves by applying the fatigue data of cruciform as-welded joints to the Smith Watson Topper method. An estimation method for the probability of fatigue failure was proposed based on the partial safety factor method (JIS B 9955, 2017, JSME S 018, 2018). Subsequently, the following two concepts were introduced to the fatigue failure issue: one employed the accumulated fatigue damage and its criterion as an evaluation parameter, and the other employed the interval estimation of the scatter of the aforementioned damages based on the t-distribution. Therefore, the proposed method enabled the consideration of the deviation of the in-service cyclic stress. The method was applied to a vehicle using the modified Miner’s rule and the aforementioned PSN curves. Consequently, the failure probability increased with an increase in the mileage of the vehicle, and the relationship between the failure probability and the mileage varied because of the deviation of the in-service stress.

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  • Daisuke YAMAMOTO
    2022 Volume 88 Issue 915 Pages 22-00119
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 14, 2022
    JOURNAL OPEN ACCESS

    This paper describes the relationship between a tangential contact force and a slip ratio under various wet condition. In previous studies, the effect of difference in watering amount on the tangential contact force characteristics under wheel/rail contact condition has not been clarified quantitatively. In this study, to investigate the effects of various experimental condition such as circumferential velocity of a test wheel, the amount of water, and contact pressure on the tangential contact force characteristics, a tangential contact force measurement experiment was conducted under the condition of maximum circumferential velocity of 130km/h. As a result, if a small amount of water intervenes on the contact surface, we confirm that the tangential contact force under wet condition sharply becomes small about 30% or less of that under dry condition until the circumferential velocity increases to 30km/h; also, we confirm that the faster the circumferential velocity is the smaller the decrease in tangential force becomes. This tendency is the same under all contact pressure conditions and is qualitatively consistent with the actual phenomenon. Furthermore, to investigate the relationship of tangential contact force characteristics between on laboratory experiments and on test runs, we evaluated the relationship using Polach’ evaluation formula with wet model parameters and an adhesive coefficient planning formula. As a result, it is clarified that tangential contact force characteristics of wheels/rails under wet condition can be estimated on laboratory experiments by correctly evaluating a water film on the contact surface between actual wheels and rails.

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  • Takatoshi HONDO, Shoya KUNIYUKI, Hisayo DOI
    2022 Volume 88 Issue 915 Pages 22-00128
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 14, 2022
    JOURNAL OPEN ACCESS

    Instrumented wheelsets are widely used in the railway industry for the purpose of measurement of the wheel-rail interaction forces, which are crucial factors in a running safety assessment. Information on lateral contact position between wheel and rail is also an important factor when discussing the wheel-rail contact condisions, such as the friction coefficient at the contact point. However, it is difficult to measure the contact position by using ordinary instrumented wheelsets since they are specialized only for the measurement of interaction forces. Although some configurations of the instrumneted wheelset have been proposed for the measurement of the contact position, those methods require some additional bridge circuits specilized for the contact position measurement. This paper proposes three types of signal processing procedure to extract the information of the contact position from a configuration of bridge circuits constructed for the measurement of the lateral forces between wheel and rail.

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  • Hideki SAKAI
    2022 Volume 88 Issue 915 Pages 22-00154
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: August 09, 2022
    JOURNAL OPEN ACCESS

    Experienced drivers sometimes explain vehicle transient behavior to steering as "after the front wheels start to turn, the rear wheels start to turn with a delay" or "the rear wheels swing around the front wheels like a pendulum. In this paper, the former is called two-stage motion and the latter is called pendulum motion. In order to realize more fun handling performance, it would be effective to physically understand these motions and to reflect these understanding into vehicle developments. Thus, these motions were studied using equations of motion. In these studies, however, since the yaw moment of inertia has been limited to a special case, the valid ranges to which these studies results can be applied are unknown. Therefore, this paper studies these motions for general cases of yaw moments of inertia. Firstly, this paper yields the equations of motion for two-stage motion by algebraically manipulating the equations for, so-called, bicycle model whose yaw moment of inertia is not limited. These yielded equations mean that the front wheels begin to turn immediately after steering, and then the point a, where one of impact centers locates, begins to turn with a delay. Secondly, these equations are transformed into form of the true pendulum equation, whose one of the variables is the attitude angle at position e, where the attitude angle is zero on steady turn. By interpreting these equations, finally, it is pointed out that the pendulum motion is a phenomenon in which the point a accelerates toward the extension of the speed vector at the point e.

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  • Masahiro TSUJIE, Tomoki KUSHIJIMA, Masaharu KONO, Yoshiaki TERUMICHI
    2022 Volume 88 Issue 915 Pages 22-00166
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 14, 2022
    JOURNAL OPEN ACCESS

    The gauge corner cracking (GCC) occurs on heat treated rails of the high rail in curved sections with a radius of 600 to 800m. In case of GCC propagates deeply, it may cause rail breakage. Therefore, it is very important to prevent the occurrence of GCC for the safety transportation of railways. In the previous research, the countermeasure method for suppressing the occurrence of GCC by applying worn profiles of rails to the high rail in curved sections due to the relief of contact pressure between wheel and rail. Since the wear development of rails is closely related to the contact conditions of wheels and rails, predicting of worn profiles of rail will be changed complexly due to various contact conditions. The aim of this study is to examine the cross-sectional rail profile that is the most effective in suppressing crack initiation for the high rail in curved sections with a radius of 600 to 800m where the occurrence of GCC is a concern. In the beginning of this study, a wear development analysis with multibody dynamics which was modeled in various radii at the appearance of GCC was conducted. Secondly, a wheel and rail contact analysis using a predicted rail worn profiles was conducted, and the occurrence of cracks was evaluated based on wheel and rail contact conditions. Finally, the optimum rail cross-sectional profile was searched by machine learning with neural network using the analysis results as a teacher data. In summary, the optimal rail cross-sectional profile with highly effective for the suppression of GCC initiation was determined and evaluated the suppression effect for crack initiation.

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  • Hiroharu ENDOH, Fumitoshi KIKUCHI, Ayano SAITO, Shota ENAMI, Sachiko Y ...
    2022 Volume 88 Issue 915 Pages 22-00172
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 21, 2022
    JOURNAL OPEN ACCESS

    The purpose of this study is to clarify the seasonal characteristics of the thermal sensation and comfort of occupants in a main line vehicle in Japan. In addition to the summer and winter experiments conducted in our previous research, we carried out the subjective experiments in the autumn and the spring. The participants rode a main line vehicle stationed at a rolling stock center, and they experienced the non-steady-state thermal environment ranging from around 20℃ to 30℃ and answered questionnaires about their thermal sensation and comfort. Based on the experimental results obtained in the four seasons, the seasonal characteristics of the relationships between the thermal indices called PMV/PPD and the subjective evaluation values were analyzed, and the seasonal differences in the prediction accuracy of PMV/PPD was also examined. The mean thermal sensation has strong correlation with the PMV in all seasons, and the seasonal differences in the relation between them were not found. Furthermore, the percentage of the participants who felt cold/hot sensation in all seasons got good agreement with the PPD. These results support the validity of PMV/PPD as the prediction indices for thermal sensation in railway vehicles. On the other hand, the seasonal differences were found in the relation between the PMV and the percentage of the participants who felt dissatisfied and the relation between the PMV and the percentage of the participants who felt sweaty – in the summer, the percentage of the participants who felt sweaty and dissatisfied was higher than in the other seasons. The root mean square errors of the PPD in the spring, summer, autumn and winter experiments were 12.9pt, 20.4pt, 17.8pt and 11.0pt, respectively. These results suggest, in order to use the PPD as a highly accurate indicator of thermal comfort in Japan all the year around, it should be corrected taking into account the seasonal characteristics of thermal comfort.

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Solid Mechanics and Materials Engineering
  • Kazuhiro GOKAN, Kazuhiro MIZUTA, Koji KAKEHI
    2022 Volume 88 Issue 915 Pages 22-00114
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 26, 2022
    JOURNAL OPEN ACCESS

    In the aviation industry, materials are being developed to improve the performance of jet engines. TiAl is used in turbine blades because of its high strength at high temperatures and its light weight. However, due to the difficulty of machining TiAl, additive manufacturing has been expected in recent years. Electron-beam-melted TiAl4822 has a unique layered microstructure composed of duplex-like fine-grain layers and a band of coarser γ-grains. This unique microstructure is known to bring about the anisotropy of mechanical properties. This study investigated the effects of building direction on creep properties. The creep test was conducted in accordance with the ASTM standard. The creep life of an additive manufacturing specimen was longer than that of a cast specimen due to the higher percentage of lamellar structure in the former. A specimen with building angle θ = 0° (vertical direction) had the longest creep life, which is attributed to the deformation of layers. When the building angle is θ = 45° or 90°, slip occurs between the layers, resulting in the formation of a large void along the vertical grain boundary of the γ band, which may cause high creep elongation.

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  • Kota ASAUMI, Kuniharu USHIJIMA
    2022 Volume 88 Issue 915 Pages 22-00200
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 13, 2022
    JOURNAL OPEN ACCESS

    In this paper, the bending collapse behavior of sandwich U-shaped beam with lattice core has been investigated by using finite element analysis. In particular, the effects of geometric properties of lattice core and faceplate on the maximum bending moment Mmax and the critical angle θcr were discussed. The existence of lattice core could prevent the elastic buckling of the surrounding U-shaped beam, and enhance Mmax to the fully plastic moment of these plates. Based on numerical investigation, the mode map for θcr was obtained as a function of the relative thickness of the plate t/h and the relative density of the lattice core ρ/ρs.

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  • Toshiki NAKAMURA, Kuniharu USHIJIMA
    2022 Volume 88 Issue 915 Pages 22-00204
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 13, 2022
    JOURNAL OPEN ACCESS

    In this paper, the large deflection of a circular mesh tube was investigated by using a finite element method. During this investigation, it is assumed that the tube is deformed elastically, and its structural nonlinearity due to large deflection was considered. In addition, a theoretical model of an arc-shaped beam is proposed in order to predict the equivalent stiffness. The equivalent stiffness can be used to estimate the nonlinear large deflection response of the tube. In particular, the effects of the number of spirals and the number of turns on the prediction accuracy was discussed.

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  • Fuminori IWAMATSU, Katsumasa MIYAZAKI
    2022 Volume 88 Issue 915 Pages 22-00225
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 14, 2022
    JOURNAL OPEN ACCESS

    Stress corrosion cracking (SCC) has been detected in the welded components of nuclear power plants. The components of nuclear power plants consist of highly ductile materials such as austenitic stainless steels, and their failure mode is expected to be plastic collapse due to ductile fracture. Limit load at plastic collapse can be evaluated based on net-section approach. The ASME Boiler and Pressure Vessel Code Section XI (ASME Section XI) and The Japan Society of Mechanical Engineers (JSME) Rules on Fitness-for-Service for Nuclear Power Plants (JSME Code) specify limit load analysis for a single flaw based on a net-section stress approach. When the maximum applied stress is lower than the allowable stress evaluated by limit load analysis considering structural factors, flaws are considered acceptable and the components can be used continuously until the end of the evaluation period, such as the next inspection time. According to flaw characterization rules in the code, if adjacent flaws are close to each other, non-aligned flaws are considered aligned flaws on a collapse cross-section. If not, none of the flaws consider the existence of any others. These code rules were determined based on linear fracture mechanics, such as fatigue crack growth and brittle fracture. Thus, the technical bases for the code rules are unclear in terms of plastic collapse due to ductile fracture. In this study, we performed fracture tests on plates and cylinders with two or three non-aligned through-wall flaws in order to develop the evaluation procedure of a collapse load for non-aligned multiple flaws. The evaluation procedure for non-aligned multiple flaws was developed based on the test results.

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  • Shigeru KUROSAKI, Jyo SHIMURA, Syuusaku YAMAJI, Mitsutaka KANEHIRA, Ta ...
    2022 Volume 88 Issue 915 Pages 22-00245
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 09, 2022
    JOURNAL OPEN ACCESS

    Previously, the authors developed a strain gage (K-value gage) that can analyze the open mode stress intensity factor exclusively. This K-value gage was designed as a one-element strain gage with a gage width of 1 mm and a grid angle of 104° curvature. This paper presents an analysis method that can extract only the opening mode stress intensity factor from mixed mode (opening + shearing) cracks using the developed K-value gage. The extraction analysis method using this K-value gage was derived for the case of Poisson's ratio of the material to be measured 0.3. At the same time, Poisson's ratio led to use other than 0.3. Furthermore, this paper verified the validity of the proposed analysis method from experiments using a K-value gage. In the comparative verification experiment with the theoretical value, a tensile test was performed by inserting simulated cracks of the same length with only the inclination angle changed in a flat plate test piece. As a result, the experimental values of the aperture mode stress intensity factors were obtained within ±10% of the theoretical values.

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Thermal, Engine and Power Engineering
  • Takasumi DOI, Tadashige KAWAKAMI
    2022 Volume 88 Issue 915 Pages 22-00069
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 02, 2022
    JOURNAL OPEN ACCESS

    The component proportion of gasoline varies depending on the mining time of crude oil, the mining place, and so on. Because it has effects on the engine performance and emission characteristics, studying the effects of the fuel properties on combustion characteristics is important. And a study of power generation for small gasoline engine by using alcohol fuel is extremely important from the viewpoint of stable power supply in the event of a disaster. These points, this experiment has been conducted to examine the reduction of combustion products of power generation for small gasoline engine by using standard fuel with Iso-Octane and Toluene in wide open throttle and throttle opening 2/3, especially about the effects of fuel properties by changing the addition ratio of 1-Butanol, 2-Butanol, Isobutanol, and t-Butanol with a high addition range. The main conclusions are as follows: 1) Standard fuel with Iso-Octane and Toluene is sufficiently possible to use as a alternative standard fuel of power generation for small gasoline engine. 2) It is possible to reduce CO and HC emissions remarkably compared with gasoline by addition of 1-Butanol, 2-Butanol, Isobutanol, and t-Butanol. 3) The CO and HC emissions of 1-Butanol can be reduced more than 31.6 % and 17.5 %, respectively compared with 2-Butanol, Isobutanol, and t-Butanol in the no- and low/medium load ranges. 4) 1-Butanol is most effective for reduction of combustion products when adding each of 1-Butanol, 2-Butanol, Isobutanol, and t-Butanol to standard fuel. 5) It is possible to control CO emissions at a low level, and the reduction of HC and NOx emissions can accomplish by controlling the addition ratio of 1-Butanol in the medium/high load range.

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Dynamics & Control, Robotics & Mechatronics
  • Kazuhiro NISHIWAKI, Masahiro IEZAWA, Masaki TAKAHASHI
    2022 Volume 88 Issue 915 Pages 22-00026
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 04, 2022
    JOURNAL OPEN ACCESS

    Merging in a highway is one of the most difficult driving tasks. In lane changing and merging, drivers consider about safety and longitudinal ride comfort. In addition, drivers must finish merging in the merging zone. The jerk, which is the rate of change of acceleration, is important factor for longitudinal ride comfort. Suppressing the jerk improves ride comfort. On other hand, it causes the possibility of merging failure because of the increase of travel distance. In order to improve the longitudinal ride comfort, this paper presents the merging support system suppressing the jerk under the constraint of the merging zone. It consists of the merging decision maker, the merging planner and the vehicle controller. The merging decision maker compares the selectable merging positions and selects one with smallest acceleration considering the constraint of the merging zone. The merging planner generates the velocity plan and the lateral path plan to reach to the selected merging position. These plans suppressing the longitudinal and lateral jerk by applying the 3-sgate moving average filter. The vehicle controller follows the velocity plan and the lateral path plan accurately. This controller considers the vehicle delay by applying the model predictive control. The performance of the proposed system is tested by simulations. These simulations show that the proposed merging support system contributes safe and comfortable merging.

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  • Yuichi MATSUMURA, Haruto KATSUNO, Tomo YAMADA, Masashi KOMADA, Hidenor ...
    2022 Volume 88 Issue 915 Pages 22-00052
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 01, 2022
    JOURNAL OPEN ACCESS

    This paper addresses a method of controlling the nodal positions of mode shapes as desired. The method is developed to calculate reflection and transmission coefficients at discontinuities and ends required for shaping mode shapes. The method is based on the one-dimensional Ray-Tracing method, which is a method that has been used to obtain eigenfrequencies, mode shapes, frequency response functions of a structure, based on the analysis of wave propagation on three-dimensional beam structures. Natural vibration in an undamped system refers to a state in which waves propagating on a structure are superimposed and become standing waves everywhere on the structure. Therefore, the mode shape indicates the shape of this standing wave. In the paper, a method is derived to estimate the reflection and transmission coefficients at discontinuities and ends, which is necessary to change the nodal points of the mode shape of interest. This method requires a matrix operation that changes only the values of the reflection and transmission coefficients at discontinuities and ends without changing the shape of the structure. Therefore, a rank-one reduction method via similarity transformation of matrices is developed. Finally, the effectiveness of the proposed method is confirmed through numerical examples.

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  • Takeshi TAKIYAMA, Junichi FUJITA
    2022 Volume 88 Issue 915 Pages 22-00074
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 01, 2022
    JOURNAL OPEN ACCESS

    Recently, an automated driving of four-wheeled vehicle such as an automobile have been expanding in terms of various viewpoints such as a safety and an economy driving. Therefore, this paper investigated about the application of the control system for automated driving in order to run on the target turning trajectory. A feedback control is required to compensate a disturbance effect to a vehicle motion for automated turning driving to coinside with the target trajectory. However, comparing the control systems are little investigated because the designing a control system for the motion control of four-wheeled vehicle is complicated. From view point of evaluating a suitable control for automated turning drive, two control system were investigated in simulation study and experimentally. At first, this paper investigated a control system by using a backstepping method after converting the non-holonomic system to the chained system. Also, as a comparison target, this paper designed a control system using a kanayama’s method, which is well known control algorithm to the underactuated mechanism, adding a compensation control. In addition, in order to evaluate the robustness of the control system when the trajectory changes, this paper used an algorithm proposed by authors that make easy setting of the target turning trajectory consisting of clothoid curve. In these way, the comparison between the feedback control system using the backstepping method and the integrated control system using the kanayama’s algorithm was conducted, then, the characteristics of each system was shown by means of simuation study and experimental results.

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  • Shigeru YAMAMOTO, Kosei HIGASHI, Sanga TAKAGI, Tokujiro HORIKAWA, Yuki ...
    2022 Volume 88 Issue 915 Pages 22-00097
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 04, 2022
    JOURNAL OPEN ACCESS

    Strip walking is an unstable lateral movement in a hot strip finishing mill that causes the strip to crash into the side guides, resulting in a tail pinch where the strip is rolled in a folded state. Strip walking should be appropriately controlled to prevent tail pinches, and an adequate mathematical model is essential to design the strip steering control. In this paper, the traditional model and a recently proposed model representing strip walking are numerically compared, and the latter is shown to characterize the details of the actual phenomenon. Such a mathematical model derivation makes it possible to use model predictive control to optimally control the strip walking, considering the rate limit constraint of the actuator. However, model predictive control requires time-consuming optimization computation. Thus, control performance deteriorates with longer control periods. In this paper, we propose a new model prediction control method to reduce optimization computation time with discretized control input that enables fast discrete optimization instead of slow continuous optimization. It is also shown that fixing the misalignment between the roll and steel strip centers is insufficient to prevent the tail pinch. Moreover, it is vital to suppress the rotational motion of the steel strip by using numerical simulations.

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  • Ryota SHIOYA, Daisuke MATSUURA, Yusuke SUGAHARA, Yukio TAKEDA
    2022 Volume 88 Issue 915 Pages 22-00205
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 24, 2022
    JOURNAL OPEN ACCESS

    In order to develop a cable-driven continuum robot having a large workspace without using a large number of segments, which leads to construction complexity and requires the use of many actuators, this paper presents a mechanism design for increasing the orientation workspace volume of a one-segment continuum robot by realizing multiple elastic rod shapes of different lengths, which have one inflection point. The proposed design is that an elastic rod of variable length is used as a backbone and two cables are routed in parallel to the elastic rod and the other two cables are connected to the tip of the elastic rod attachment point on the end disk. This design was obtained by deriving cable routings that meet the necessary conditions for the elastic rod to be in static equilibrium in the shape with one inflection point. Then, numerical analysis and experiments were performed to investigate the effectiveness of the proposed design on the increase of the orientation workspace volume. Considering that the length of the elastic rod is variable and the elastic rod deforms into the shape with one inflection point, the procedure for static analysis to derive the relationship between the length of the elastic rod, each cable tension and the position, orientation of the end disk, was presented. By this procedure, forward and inverse static analyses were conducted. Through the numerical calculation of the orientation workspace based on the static analysis, it was shown that the orientation workspace volume was increased by the proposed design. Furthermore, using the experimental apparatus based on the proposed design, a large orientation workspace was realized and measured configurations were in good agreement with the numerical calculation results.

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  • Yuta OGASAWARA, Hiroyuki IWAMOTO, Shotaro HISANO
    2022 Volume 88 Issue 915 Pages 22-00217
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 04, 2022
    JOURNAL OPEN ACCESS

    Low-frequency noise is difficult to suppress by passive control using a sound absorbing material. Active noise control is expected to be an effective method against low-frequency noise. Minimizing the total acoustic power emitted by a sound source causes a zero control power phenomena. In the zero control power phenomena, the absorption and blowout of sound energy around the control source are balanced, and the time average of the control power becomes zero. Therefore, control power suppression may be able to minimize total sound power. Previous studies have assumed that the sound source is a monopole sound source or a piston embedded in an infinite baffle, so there are restrictions on the sound source. In this research, we aim to generalize the zero control power phenomena the sound sources are regarded as flat plate structures embedded in an infinite baffle, and the conditions under which the zero control power phenomena occurs are examined. We clarify the occurrence conditions for zero power phenomenon when one noise source and n control sound sources are used. The specific conditions for the zero control power phenomena in multiple sound sources which are the newly defined in this paper inter source mobility reciprocity are established between the noise source and each control sound sources. In addition, numerical calculations are performed based on the derived control law to clarify the effect of the number of control sound sources and the sound sources position on the acoustic power. In addition, the relationship between the wavelength and the suppression effect is examined from a numerical point of view.

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  • Hisashi TAJIMA, Kohei SHINTANI, Azuki OGOSHI, Shota KITANO, Motofumi I ...
    2022 Volume 88 Issue 915 Pages 22-00219
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 19, 2022
    JOURNAL OPEN ACCESS

    The drivability is one of the important aspects of vehicle dynamic performances. To ensure quality of the drivability performance, comprehensive screening evaluation is necessary by controlling both complicated driver operation and vehicle behavior. However, it is not straightforward for engineers to handle all combinations of test patterns with limited resources while considering complex control logic and program carefully. This paper proposes a novel automated drivability screening and exploration system by introducing Bayesian active learning (BAL). The proposed system is composed of two key elements such as automated evaluation sub-system and screening and exploring sub-system. In the automated evaluation sub-system, driver model is used to mimic various operation patters of expert drivers and corresponded drivability performance is evaluated automatically using Power-Train Virtual and Real Simulator (PT-VRS). The automated exploring sub-system is used to screen severe condition for drivability and explore feasible region of design space described by control parameters. An effective sampling strategy is introduced based on BAL. In the BAL, Gaussian Process models of drivability performance evaluated by PT-VARS is trained. Based on the posterior distributions of trained Gaussian Processes models, acquisition functions are evaluated and maximized to generate new sampling points. To show effectiveness of the proposed system, an example is demonstrated.

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Computational Mechanics
  • Takuya TOYOSHI, Rekisei OZAWA, Ryuhei TAICHI, Yoshitaka WADA
    2022 Volume 88 Issue 915 Pages 22-00188
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 24, 2022
    JOURNAL OPEN ACCESS

    This paper presents a method for predicting the crack growth shape and the number of cycles of a two-dimensional fatigue crack under cyclic loading using a convolutional neural network. All of data sets for train are generated by s-version FEM for fatigue crack propagation analysis. The crack propagation simulations were simulated with different slant angles. Crack tip coordinates, crack growth vectors, and numbers of cycles are prepared as a set of train data for one prediction step, which is determined by the minimum mesh size of the crack tip in the s-FEM simulation. Data augmentation technique, which adds a slight noise to input data, is introduced as regularization in this work. We'd like to evaluate the effectiveness of the data augmentation. Additionally, the interpolation ability and extrapolation ability of the prediction model are evaluated. The crack growth shapes and the number of cycles in the prediction step can be predicted within 6%, 11.1% difference with the reference.

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Design, Machine Element & Tribology, Information & Intelligent Technology, Manufacturing, and Systems
  • Masahiro SAITO, Shinya TOYOTA, Toshiki HIROGAKI, Eiichi AOYAMA
    2022 Volume 88 Issue 915 Pages 22-00195
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 24, 2022
    JOURNAL OPEN ACCESS

    We have developed a small size and high strength spiral bevel gear fabricated by five-axis controlled machining center. In the present report, we propose a novel spiral bevel gear with the rib at the end of face width to reinforce the tooth bending strength, which is machined with a ball-nose end-mill tool. We investigate the influence of the triangular rib on the bending stress both at the tooth root and around the rib and tooth deflection based on 1DCAE model, and demonstrate the effect of rib reinforcement at the proposed spiral bevel gear. Moreover, we compare the calculated stresses by 1DCAE with experimental ones from fabricated spiral bevel gear. As a result, a novel guideline is found to develop the small size and high strength spiral bevel gear with the rib at the end of face width from a view of rib shape.

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  • Kiyoshi HATAKENAKA, Keitaro UCHIDA
    2022 Volume 88 Issue 915 Pages 22-00234
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 24, 2022
    JOURNAL OPEN ACCESS

    Thermohydrodynamic lubrication (THL) models have been applied to predict the performances of journal bearings that support industrial rotating machineries. The final goal of this study is to propose a THL bearing design method of cylindrical journal bearings with two-axial oil grooves by using the model expressions, which are derived from a database constructed by the THL predictions and can predict the reasonably accurate bearing performances over a wide range of operating conditions and bearing specifications. In the present article, after the previous simplified model, which predicts the bearing performances from only four dimensionless numbers — Sommerfeld number, bearing width-to-diameter ratio, Peclet number and Khonsari number, is shown to poorly predict the performances, a simplified THL model is newly proposed for the database of the bearing performances. This model is derived by modifying the precedent high-accuracy THL model and predicts the bearing performances from the same four dimensionless numbers as the previous simplified model. Compared with some measurements in test rigs of the bearings, the model proposed is found to predict more reasonably accurate performances of the bearing under fully lubricated conditions than the previous simplified model. It is concluded that the new model is appropriate to the database for the simple easy and straightforward bearing design.

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  • Yutaro TAKUMI, Masatoshi SHIMODA
    2022 Volume 88 Issue 915 Pages 22-00240
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 04, 2022
    JOURNAL OPEN ACCESS

    In this paper, we propose a multi-scale optimal design method for determining the member diameters of minute micro-frame structures in a macro-structure. The microstructures and the macrostructure are bridged by the homogenization method. In order to efficiently calculate the homogenized elastic tensors of complicated micro-frame structures consisting of slender members, the NIAH (New implementation of asymptotic homogenization) method is employed instead of the general method with applying the initial strains to the unit cells consisted by SOLID elements. In the NIAH method, the initial displacements equivalent to the initial unit strains are applied to the unit cells consisting of BEAM elements. The objective function is the squared displacements of the loading points. The volume of the macrostructure including the volume of the microstructures and the state equation of the macrostructure are used as the constraints. The micro-frame structures are assigned in the macro structure in advance, and the member diameters of all micro-frame structures are optimized. This multi-scale size optimization problem is formulated as a distributed-parameter optimization problem, and the sensitivity function is derived. The sensitivity function thus obtained is applied to the H1 gradient method for scalar variables to obtain the diameter distribution of all members. The several design problems of multi-scale structures are solved with the proposed method, and the effectiveness and practicality of the method are confirmed.

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Environmental and Process Engineering, Safety
  • Kunihiko ISHIHARA
    2022 Volume 88 Issue 915 Pages 22-00190
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: November 01, 2022
    JOURNAL OPEN ACCESS

    An expanded silencer is well known in all other silencers and widely used in an industry field. As the theory of the expanded silencer has already been established and it is considered to be useful because it has good visibilities of the silencing effect. In general, the performance of silencers is evaluated by the silencing effect(ATT) and insertion loss(IL). When we calculated the silencing effect by using the transfer matrix method, we experienced that the inlet tube length was completely independent of the silencing effect. Is the fact true? It is the motivation of this investigation. There are many studies on the characteristics of the expanded silencer. However, the effects of the inlet and outlet tubes on the silencing effect are different from each other and inconsistent. In this paper, it will be discussed the results of ancestors to find out why there is no unity. As a result, it was clarified to be existed the derivation process of the equation of the silencing effects of ancestors.

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Transportation and Logistics
  • Takahiko ONO
    2022 Volume 88 Issue 915 Pages 22-00194
    Published: 2022
    Released on J-STAGE: November 25, 2022
    Advance online publication: October 21, 2022
    JOURNAL OPEN ACCESS

    A rough road surface produces strong or continuous vibration in an ambulance, which causes feeling of discomfort, severe pain or sometimes deterioration of physical condition to injured or ill persons. With the aim of reducing such harmful vibration for safe and reliable medical emergency transportation services, this paper proposes a method to find out rough road surfaces from drive data of ambulances and to give them the priority for future pavement repair. There are four steps in the prioritization process: The first step is to collect drive data including information on location, speed and vibration with a smartphone. According to ISO2631-1, the vibration is quantified as a running r.m.s of the frequency-weighted acceleration. In the second step, meaningless data such as small vibration and extremely slow speed data are removed. Then, depending on the location and the traveling direction of the ambulance when the data were recorded, the data form clusters, which are candidates of road repair zones. Finally, each cluster is prioritized by the evaluation function. The larger amount of strong-vibration and slow-speed data are included in the cluster, the higher priority is given to it. An example of application to three ambulances is presented. The high priority clusters were well matched to the road surfaces that the ambulance crews were aware of as strong vibration zones. It is also shown that at least one and a half months are required in collection of the drive data to decide on the top ten clusters.

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