-
Shozo KAWAMURA
2018 Volume 84 Issue 861 Pages
18-pre02
Published: 2018
Released on J-STAGE: May 25, 2018
JOURNAL
FREE ACCESS
-
Junya KATO, Shota YABUI, Kentaro TAKAGI, Tsuyoshi INOUE
2018 Volume 84 Issue 861 Pages
17-00227
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: March 13, 2018
JOURNAL
FREE ACCESS
In design of rotating machines, analysis of external force is important for stable rotating operation. The various external forces such as unbalance force, seal contact force and rotor dynamic fluid force effect on the rotor system, dynamic characteristics of rotating system is changed by the external forces. The external force can vary depending on a rotor trajectory. In previous studies, a mathematical model of the dynamic characteristics had been formulated for small amplitude orbit around the equilibrium point for the rotor trajectory. However, the formulation hasn't been yet established in the rotor trajectory with large amplitude or eccentricity caused by the external forces. In this study, an experimental system using active magnetic bearing (AMB) is developed to achieve the formulation. The system can generate any arbitrary trajectory assuming various external forces and the rotor system follow the generated trajectory. The system can estimate the external force at the same time. Current flowing through coil of the AMB is controlled by a controller designed based on the frequency response to follow the arbitrary orbit. Then, the external forces are estimated from the control signal by the disturbance observer. Experiments were performed by assuming unbalance forces generated in the elastic rotor. From the results it was confirmed experimentally that high precision tracking control and estimation of external force are possible. The various rotor trajectory under the action of the external forces can be repeated by using the system, and the external force can be analyzed by the experimental data.
View full abstract
-
Ryoya TANAKA, Shinji WAKUI
2018 Volume 84 Issue 861 Pages
17-00424
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: January 18, 2018
JOURNAL
FREE ACCESS
This paper considers the implementation of a cascade type PIS compensator for the pneumatic anti-vibration apparatuses (AVA) control system. In precedence research the parallel type PIS compensator was used. This is composed of a PI and S compensators connected in parallel. However a PIS compensator is interpreted as a special case of what is used in repetitive control. In this case, a cascade connected compensators is used. According to this, the PIS compensator should be in series type. Also, parallel type PIS compensator generates swing of the output signal. Through above problems, cascade type PIS compensator is considered. However, the AVA control system with the compensator causes collision and steady-state deviation. In order to resolve these problems, we improve the structure of the compensator and its switching method. This experimental result shows that the normal operation of the AVA control system with cascade type PIS compensator. From the above, we show that the implementation of cascade type PIS compensator for the AVA control system.
View full abstract
-
Yasutomo KANEKO, Seita KISHIMOTO, Kazushi MORI, Hiroharu OOYAMA
2018 Volume 84 Issue 861 Pages
17-00447
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: January 18, 2018
JOURNAL
FREE ACCESS
Although, in designing blades, it is assumed that all blades on a disk are identical (tuned system), the vibration characteristics of the blade is slightly different due to the manufacturing tolerance, the deviation of the material property, and so on (mistuned system). As a result, in the forced response of an actual bladed disk caused by the flow distortion, the responses of all the blades on a disk become different, and the response of a certain blade may become extremely large, due to the split of the duplicated natural frequencies, the distortion of the vibration modes, and so on. On the other hand, it is suggested by many researchers that the mistuning suppresses the blade flutter, because the complete travelling wave mode is not formed in a disk. In other words, the effect of the mistuning acts on the dangerous side for the forced vibration, while on the safety side for the blade flutter. In this study, the stability analysis and the frequency response analysis of mistuned bladed disks are carried out using the reduced model with high fidelity, in order to research the vibration characteristics of typical mistuned bladed disks. Based on the analysis results, an optimal design procedure of mistuned bladed disks considering both the forced response and the self-excited vibration is proposed.
View full abstract
-
Shohei UEMURA, Etsujiro IMANISHI
2018 Volume 84 Issue 861 Pages
17-00468
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: February 02, 2018
JOURNAL
FREE ACCESS
This paper presents a dynamic simulation technique for the rigid body system coupled with the hydraulic system considering the digging behavior of the soil. The rigid body system and hydraulic system is modeled based on the Newton-Euler formulation, while the soil is modeled by the discrete element method (DEM) using the cohesive model proposed by Utili and Nova(2008). The co-simulation is carried out for the rigid body/hydraulic coupling system and the soil. Firstly, the digging simulation of the soil for the bucket of the hydraulic excavator is carried out for the cohesive soil and the sandy soil. The digging behavior of the soil and the digging force are discussed. Secondly, the co-simulation technique for the rigid body/hydraulic coupling system and the soil is presented. Finally, the dynamic simulation of the hydraulic excavator is carried out for the digging operation, the behavior of the hydraulic system and the soil is discussed for the cohesive soil and the sandy soil. It is shown that the digging power of the arm driving system for the sandy soil can be reduced by considering the cohesive force. It is clarified that the present technique can evaluate the hydraulic system of the hydraulic excavator for any characteristics of the soil.
View full abstract
-
Kippei MATSUDA, Kenichiro TANAKA, Hideyuki IMAI, Tatsuhiko GOI, Yasuka ...
2018 Volume 84 Issue 861 Pages
17-00472
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: January 18, 2018
JOURNAL
FREE ACCESS
The traction drive - integrated drive generator (T-IDG®) has been developed since 1999 to replace current hydrostatic transmission drive generators. The T-IDG® consists of a generator and a half-toroidal traction-drive continuously variable transmission (CVT), which maintains a constant output speed of 24,000 rpm. In terms of coping with recent trends of high-power electric drive aircraft (MEA) and the need for weight reduction, a high-speed traction-drive CVT is advantageous over current hydro-static drive transmissions. To control a speed ratio of the high-speed CVT accurately, it is essential to know the speed-changing response. In conventional study, the speed-changing response is approximately proportional to a rotational speed; however, in the high speed CVT, a minute deformation during the speed change affects its response. This paper describes the analysis and a developed theory of the speed-changing response of a toroidal CVT, with showing test results which verify the response of the high speed CVT, whose input speed is 20,000 rpm at maximum with a peripheral speed of traction contact of 70 m/s.
View full abstract
-
Yuto ARAKI, Akane UEMICHI, Yudai YAMASAKI, Shigehiko KANEKO
2018 Volume 84 Issue 861 Pages
17-00507
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: February 02, 2018
JOURNAL
FREE ACCESS
As a method for mining offshore gas fields, a floating production, storage and offloading (FPSO) system is attracting attention. However, sloshing in the oil-gas separator installed in FPSOs excited by sea waves is expected to cause significant difficulties. To suppress sloshing wave heights, one possibility may be to install perforated plates in a tank. In this study, a method is proposed for the accurate estimation of the first resonant wave height in the horizontal cylindrical tank with a perforated plate under pitching excitation in less time. To accomplish this purpose, the pressure loss due to the perforated plate in the open channel must be estimated accurately. Therefore, the pressure loss is modeled using steady CFD calculations considering the effects of the distribution of the flow velocity and the distribution of the inflow angle. The first order sloshing wave height is calculated in the theoretical analysis by substituting the pressure loss calculated in steady CFD. The wave heights determined using the pressure loss utilized by steady CFD are compared with the experimental value measured with a small-scale model. Using the method proposed in this study, the first resonant wave height of sloshing wave height is calculated accurately in less time.
View full abstract
-
Masashi YASUDA, Eiji SATO, Manabu YAMADA, Koichi KAJIWARA, Masaki HAYA ...
2018 Volume 84 Issue 861 Pages
17-00509
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: May 07, 2018
JOURNAL
FREE ACCESS
Research on seismic isolation technology was also a question of how much restoring force can be reduced. The seismic isolation rubber with thin film like rubber and metal plates stacked in multiple stages to reduce the restoring force has achieved great success. However, there still exists restoring power, measures against long-period earthquakes are not perfect and vertically unprotected. This research is an effort to make three-dimensional seismic isolation more realistic with higher performance by further minimizing resilience in all directions. The developed three-dimensional seismic isolation mechanism consists of an air levitation mechanism that isolates horizontal vibration and a spring link mechanism that isolates vertical vibration. Excitation experiments of the prototype were carried out using real-scale three-dimensional seismic waves by the E-defense shaking table. As a result, excellent characteristics of horizontal periodicity and vertical natural period of 5 s were confirmed. The vibration isolation performance at 1 Hz was about 20 dB in all three directions, and the high isolation performance not found in conventional equipment was verified. They were also supported by analytical models.
View full abstract
-
Akira SANADA, Yoshio TSUJI, Kazuhiro IWATA, Michinori KAWANO, Hitoshi ...
2018 Volume 84 Issue 861 Pages
17-00511
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: February 16, 2018
JOURNAL
FREE ACCESS
Hydraulic breakers, which are used to demolish concrete structures or rocks etc., make a loud noise. It is considered that one of the major noise sources of the breaker is the longitudinal vibration resonance of the breaker's chisel. Hence, in order to suppress the noise, a chisel in which a dynamic damper is integrated is proposed in this paper. The proposed dynamic damper consists of ring-shaped weight and ring-shaped plastic spacers. To install it on the chisel, a portion of the chisel must be made slender because the diameter of the chisel is limited by size of the chisel holder of the breaker. Because of this structure, the resonance frequencies of longitudinal vibration modes of the chisel are changed with parameters of the dynamic damper, such as the sizes and the position, etc. Therefore, it is difficult to design the dynamic damper with conventional ways. First, vibration response of the proposed chisel is derived with the transfer matrix method theoretically. Second, experimental results of the frequency response are shown and confirm the validity of the theoretical model. Then, effects of the parameters of the dynamic damper are investigated with the model. Finally, the experimental results of the impact noise during demolishing work are shown. These results show that the proposed chisel is valid and feasible for reducing the noise from hydraulic breakers.
View full abstract
-
Kolawach CHALERMPONG, Hiroshi YAMAURA, Kensuke HARA
2018 Volume 84 Issue 861 Pages
17-00512
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: May 07, 2018
JOURNAL
FREE ACCESS
This research studied an influence of the inertia of the hoisting rope on the dynamics of a mobile crane system. Two dynamics models of the mobile crane were formulated with the inertia included rope model and the massless rope model, and their dynamics response were compared. The floating frame of reference formulation was used in formulating the model of the deformable components. In the simulations, we variated the length of the rope and the mass of the hoisted load then applied the slewing motion to the boom for 10 seconds and let the system underwent free vibration for another 10 seconds while the boom angle was fixed. The deformation of the rope and the comparison of the hoisted load motion between two models were considered. The results illustrated that the rope model with included inertia was able to illustrated its bending during the crane operation and this deformation increased with the length of rope. It appeared that the deformation of the boom tip had influences on the deformation of the rope. In the motion of the hoisted load, the time - history data illustrated that the inertia included rope model had slightly higher frequency than the massless rope model during the free motion, and the trajectory also showed the slightly larger sway. In addition, the total calculation time of the inertia included rope model was around 13 times longer. The difference in the motion of the hoisted load from both models increased with the length of rope but decreased when the mass of load increased. In conclusion, the model with included inertia of rope showed different response to the massless rope model at long rope and light load condition, and this difference was decreased at short rope and heavy load condition.
View full abstract
-
Akane UEMICHI, Ippei KANETSUKI, Shigehiko KANEKO
2018 Volume 84 Issue 861 Pages
17-00514
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: April 12, 2018
JOURNAL
FREE ACCESS
Hydrogen combustion is attracting attentions because of zero CO2 emission. Recently, a gas turbine which uses hydrogen-rich fuel is being developed. In our previous study, we examined the influence of hydrogen-containing ratio on combustion oscillation for fuel mixtures of hydrogen and town gas (13A) experimentally. In the experiment, pressure oscillations were measured by a sensor which is installed at the bottom of the combustor. It is found that two oscillation frequencies near 200 Hz and 400 Hz were simultaneously detected in the case of hydrogen-containing fuels, whereas single oscillation frequency around 350 Hz was observed in the case of only 13A fuel. To understand this difference of oscillating frequencies, we conducted acoustic analysis using one-dimensional different diameter acoustic model. However, this simplest model could not reproduce three types of oscillating frequencies obtained by the experiment. Besides, we used an acoustic impedance of the bottom of the combustion chamber as an acoustic boundary condition. The acoustic impedance is measured experimentally under the noncombustion (cold) condition and corrected by combustion temperature obtained by equilibrium calculation. As a result of applying the corrected acoustic impedance, the three types of oscillating frequencies could be reproduced by acoustic analysis. Furthermore, to express the difference among fuel mixtures, delay times, flame positions, and the mean temperature in the chamber were calculated by the CFD simulation. Consequently, it is found that the acoustic analysis result could reproduced the difference among fuel mixtures; hydrogen makes the oscillating frequencies a little higher, because temperature becomes higher and delay time becomes shorter.
View full abstract
-
Soichiro TAKATA, Hirofumi INOUE, Shigeki SHINODA
2018 Volume 84 Issue 861 Pages
17-00522
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: May 07, 2018
JOURNAL
FREE ACCESS
In this paper, deterioration diagnosis for distribution main pipe was studied using the uniform cylindrical shell approximation and in-plane bending mode. The in-plane bending mode is expected to have high accuracy in detection of deterioration, because the eigen frecuency of the mode is proportional to pipe thickness. First, using the finite element method, the characteristics of in-plane bending mode are investigated. It is confirmed that in-plane bending mode has little small dependence on the pipe length and the boundary conditions at the pipe ends, it appears in the audio frequency bands, and it has linear dependence on the pipe thickness. In addition, formula with two dimensional ring approximation is derived. Moreover, the average thickness and the uniform-cylindrical shell approximation are introduced for deal with the deteriorated pipe. Using the thinning pipe thickness of previous study, validity of the average thickness and the uniform-cylindrical shell approximation were confirmed. On the other hand, actual pipeline has the sub-structure, for example, valve, hydrant, and so on. In order to deal with the coupled vibration between the cylindrical shell and the sub-structure, eigenvalue analysis are conducted using the Semi-Analytical Receptance Method (SARM). The experimental consideration were conducted in case of that the sub-structure non-attached case. The in-plane bending mode is observed experimentally on the actual pipe system and its resonant frequency shows good match with the theoretical values.
View full abstract
-
Yoshinori NARISAWA, Takeshi MIZUNO, Masaya TAKASAKI, Yuji ISHINO, Masa ...
2018 Volume 84 Issue 861 Pages
17-00523
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: May 10, 2018
JOURNAL
FREE ACCESS
A basic single-degree-of-freedom magnetic suspension system consists of one floator, one electromagnet and one amplifier. For multi-degrees-of-freedom control, multiple electromagnets and multiple amplifiers are necessary, which increases the cost of total system. As a means of overcoming this problem, parallel magnetic suspension has been proposed which controls multiple floators or multi-degree-of-freedom motions with a single power amplifier. In this system, all of the suspended points move simultaneously even when a disturbance acts on one of the suspended points solely because all electromagnet's coils are connected. This paper studies the moving direction of each suspended point with respect to a step disturbance in double parallel magnetic suspension system. The analytical study shows that the response direction is determined by the system parameter that relates the response speed of each subsystem. In the slower subsystem, the suspended point moves in the same direction as the applied force while in the faster subsystem, the suspended point moves in the opposite direction. In other words, the slower subsystem has positive stiffness while the faster system has negative stiffness. To confirm this prediction, step responses are measured in the experimental apparatus.
View full abstract
-
Tadao TAKIGAMI, Yuki AKIYAMA, Mineyuki ASAHINA, Katsuya YAMAMOTO
2018 Volume 84 Issue 861 Pages
17-00531
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: May 08, 2018
JOURNAL
FREE ACCESS
It is one of the important issues to investigate the vibration behavior of railway bogies, since the vibration of the bogies may result in loosening bolts which fix the parts to the bogie frames or/and fatigue fracture of the parts themselves. A technique for predicting the vibration of bogie parts is proposed by which the acceleration power spectral densities (PSDs) at evaluated points are predicted with the use of frequency response functions (FRFs) between the axle boxes and the evaluated points, together with the use of measured accelerations of axle boxes. Stationary excitation tests are conducted to identify the FRFs, and the axle boxes or rails were hit with impulse hammers to excite the bogies. Alternatively, the new approach without the stationary tests is also proposed in this study. In this case, the FRFs are identified with the accelerations acquired in the preliminary running tests in car depots. The proposed technique is applied to the vibration prediction of the bogies for several types of railway vehicles including electric cars and a diesel car, and the differences or ratio between the predicted and actually measured PSDs are evaluated. It is confirmed that the preliminary running tests are preferable to stationary excitation tests for improving the prediction accuracy. It is also verified that the prediction error can be reduced in the case where not only the vertical but the lateral and longitudinal accelerations of axle boxes are considered as the excitation inputs under the conditions that the principal component regression is applied to identify the FRFs.
View full abstract
-
Fumihiko TANIGUCHI, Chihiro NAKAGAWA, Atsuhiko SHINTANI, Tomohiro ITO
2018 Volume 84 Issue 861 Pages
17-00534
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: April 12, 2018
JOURNAL
FREE ACCESS
Inverted pendulum vehicles controlled by movement of driver's center of gravity (COG), such as Winglet or Segway are the examples of Personal Mobility Vehicles (PMV). PMV is sometimes expected to be used in pedestrian spaces. When a driver brakes an inverted pendulum vehicle suddenly, the driver has to move his/her COG backward largely and has the risk to lose his/her balance due to the characteristics of vehicle control. Therefore, we aim to achieve a vehicle control system that is friendly to drivers in emergency. In the previous study, the coupling model of a vehicle and a human had been built on Multibody Dynamics and the technique to brake an inverted pendulum vehicle automatically had been proposed using that model. In this study, we carried out two experiments to decide the timing of the automatic braking system defined as Time To Collision (TTC). We carried out two experiments about stopping distance when a driver brakes an inverted pendulum vehicle suddenly and when the automatic braking system is operated, and we compared those results. Then, it was shown that stopping distance operated by the automatic braking system is shorter than by human driver's sudden braking operations. In addition, we derived TTC1 ( 0.7 s ) of inverted pendulum vehicles from these experiments about stopping distance by human drivers' sudden braking. Then, we derived reaction time ( 0.4 s ). Finally, we proposed a safety system using TTC1 and the reaction time. When TTC reaches 1.1[s], the alarm makes a human brake an inverted pendulum vehicle suddenly. Then if a human doesn't brake an inverted pendulum vehicle suddenly and TTC reaches 0.7[s], the automatic braking is operated.
View full abstract
-
Shunsuke SHIOMI, Yoshikazu OSHIMI, Koji NUMATA
2018 Volume 84 Issue 861 Pages
17-00568
Published: 2018
Released on J-STAGE: May 25, 2018
Advance online publication: May 08, 2018
JOURNAL
FREE ACCESS
Object detection function of turnout and switch mechanism is one of an important function for safety of railway system. An object between a tongue rail and a stock rail on a turnout is detected by a lock mechanism of a switching machine and circuit controllers, which are applied on high-speed railway. Designer of switch mechanism has checks his detecting function design by experiments, which were sole way to check it, using real turnout and switch mechanism. In this paper, we described an equation of motion of the switch mechanism and the turnout using multi-body dynamics and flexible multi-body. Moreover, we described a method, which calculate shape of tongue rails inserted an object between rails. By results of calculations, we confirmed that the proposed method could simulates the shape of rails, which is affected by object. Computing time is 40% shorter than an experiment, however, the result includes an error which causes that the model was assumed deformation of tongue rails as 2-d deformation.
View full abstract
Design, Machine Element & Tribology, Information & Intelligent Technology, Manufacturing, and Systems