Kita Kyushu, Japan
Kita Kyushu, Japan

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Matsuzaki K.,Kyushu University | Ryu T.,Oita University | Sueoka A.,Kyushu Polytechnic College | Tsukamoto K.,Ayabo Co. | Honda T.,Oita University
International Conference on Noise and Vibration Engineering 2012, ISMA 2012, including USD 2012: International Conference on Uncertainty in Structure Dynamics | Year: 2012

BTA deep hole drilling is used for producing holes of high aspect ratio. In this process, a chatter vibration sometimes occurs and a rifling mark is formed on the surface of a hole. The rifling mark generating phenomenon was considered as a self-excited vibration caused by time delay. In a real machine for BTA drilling, the boring bar is supported at the oil pressure head and at the intermediate support as well as at the base. The analytical model was proposed considering the supporting condition of the boring bar in detail, and the stability of the self-excited vibration was analyzed numerically. According to the result, the followings are confirmed. The natural frequency and the natural mode of the boring bar change complexly depending on the hole depth. The rifling mark of odd number sided polygon only occurs. The occurrence of the rifling mark is closely related to the natural frequency and the natural mode of the boring bar. Under the condition of the actual machine, 3-sided and 5-sided polygonal rifling mark is easy to occur. © (2012) by the Katholieke Universiteit Leuven Department of Mechanical Engineering All rights reserved.


Rosbi S.,Oita University | Ryu T.,Oita University | Nakae T.,Oita University | Matsuzaki K.,Kagoshima University | And 3 more authors.
MOVIC 2014 - 12th International Conference on Motion and Vibration Control | Year: 2014

This paper analyzes a suppression method for nonlinear vibration called subharmonic vibration of order 1/2 in car powertrains by using a dynamic absorber. In car powertrains, the torsional forced vibration caused by engine combustion leads to reduced ride quality. Thus, in the torque converter of an automatic transmission car, a piecewise-linear spring called a damper is used to reduce the transmission of the forced vibration into the vehicle frame. However, subharmonic vibration occurs in the actual vehicle when the spring restoring characteristics are around the switching point. The fundamental vibration frequency of the subharmonic vibration is half of the engine forced vibration frequency. Although the design of the dynamic absorber used to suppress the forced vibration has been established for linear systems, the optimum design for suppressing subharmonic vibration of order 1/2 has not yet been investigated. In this study, the powertrain is modeled using a multi-degree-of-freedom system for the actual vehicle, including the engine, torque converter, transmission gears, and wheels. An equation of motion is developed by also considering the restoring force of the piecewise-linear spring. The numerical result shows that subharmonic vibration occurs when the engine excitation frequency is almost twice the second mode of the natural frequency, and the result shows good agreement with the experimental data. Then, the dynamic absorber is introduced to suppress the occurrence of subharmonic vibration. In this paper, the optimum design of the dynamic absorber used to suppress the subharmonic vibration is discussed. The numerical results show that with the appropriate natural frequency and damping ratio, the optimally designed dynamic absorber is capable of suppressing the occurrence of subharmonic vibration. © 2014 The Japan Society of Mechanical Engineers.


Makino T.,Nippon Steel & Sumitomo Metal Corporation | Kato T.,Nippon Steel & Sumitomo Metal Corporation | Hirakawa K.,Kyushu Polytechnic College
Engineering Fracture Mechanics | Year: 2011

Railway axles are one of the most important components in railway systems since a fail-safe design is not available. In the present paper, the fatigue tolerance of the high-speed railway axle in Japan is reviewed. To maintain the safety, the fatigue strength of the axle has been extensively studied. Theses case histories and consequent improvements in manufacturing process are presented. The crack propagation behavior of the induction hardened axle is studied based on the fracture mechanics. Concerning the powered railway axles, the fatigue design method in Japan is compared with that in Europe and the effect of the train velocity on the allowable load is discussed. © 2010 Elsevier Ltd.


Makino T.,Nippon Steel & Sumitomo Metal Corporation | Kato T.,Nippon Steel & Sumitomo Metal Corporation | Hirakawa K.,Kyushu Polytechnic College
International Journal of Fatigue | Year: 2012

Shelling is one of the typical rolling contact fatigue (RCF) failures of railway wheels. Creepage between wheels and rails due to rolling radius difference in curves is inevitable on railway tracks. Therefore, there are tangential stresses and slip phenomena on wheel treads. Eventually, initiation of RCF cracks being the origin of shelling is accelerated by creepage. The objective of the present paper is to evaluate RCF property of railway wheel steel. The effect of the slip ratio on the RCF strength of the railway wheel steel was evaluated. RCF tests were conducted using two cylindrical contact specimens under water lubrication at a slip ratio of 0.0-1.0%. The range of slip ratio is determined to assume a creepage between wheel and rail during curving. As a result, it was found that the traction coefficient increased with the increase in the slip ratio, and the fatigue strength decreased simultaneously. The results were evaluated by a shakedown map and Hirakawa's RCF map. Experimental fatigue limits could be expressed more precisely by the criterion of Hirakawa's RCF map than that expressed by the well-known shakedown map. Stress intensity factors (SIFs) of the cracks produced by the RCF test were calculated by finite element (FE) analysis where the effect of water pressure due to the penetration of water into the cracks is taken into account. Two peaks of the maximum tangential SIF occurred during one cycle of rolling contact. The direction of the crack propagation was estimated by the maximum tangential stress criteria. The results of the RCF test showed that the cracks were initiated at the surface, propagated obliquely in the depth direction and then branched into two directions. One was towards the surface and the other was towards the depth. These two crack directions were inspected experimentally, corresponding to the estimated crack directions from the two peaks of SIF by FE analysis. The effect of slip ratio on RCF crack propagation was discussed by using the SIFs of the RCF cracks where water penetration into the cracks was considered. © 2011 Published by Elsevier Ltd.


Matsuzaki K.,Kagoshima University | Ryu T.,Oita University | Sueoka A.,Kyushu Polytechnic College | Tsukamoto K.,Ayabo Corporation 1 Hosogute
International Journal of Machine Tools and Manufacture | Year: 2015

Boring and Trepanning Association (BTA) deep hole drilling is used for producing holes with high aspect ratios. In this process, chatter vibration sometimes occurs, and a rifling mark is formed on the bore surface. The rifling mark generating phenomenon is considered to be a result of self-excited vibration caused by time delay. An analytical model is proposed considering the supporting condition of the boring bar in detail. In a real machine for BTA drilling, the boring bar is supported at the oil pressure head and the supporting pad, as well as at the base. The stability of the self-excited vibration is analyzed numerically, and the result is compared with the experiment. The theoretical and experimental results agree well with each other. Furthermore, the effect of an additional guide pad proposed by the authors as a countermeasure is evaluated theoretically and experimentally. © Elsevier Ltd. All rights reserved.


Seama N.,Kobe University | Seama N.,Japan Agency for Marine - Earth Science and Technology | Tada N.,Japan Agency for Marine - Earth Science and Technology | Goto T.-N.,Kyoto University | Shimoizumi M.,Kyushu Polytechnic College
Earth, Planets and Space | Year: 2013

We propose to use an approximately vertical bipole electric current towed by a ship as a source for a Magnetometric Resistivity (MMR) method. This proposal requires the precise positioning of the bottom electrode for the bipole source, and our newly developed MMR system achieved this. We conducted an MMR experiment in the central Mariana Trough, and we obtained data using two different methods along a survey line: one method towed a bipole source transmitting continuously along the survey line, and the other used a conventional vertical bipole source transmitting at several stationary transmission stations along the survey line. We found that the towed bipole source tilted from the vertical by an angle of 8 degrees at the maximum during the MMR experiment. We compared the results from the two methods to evaluate the towed bipole source method. Our results indicate that the tilted bipole source approximates well with the vertical bipole source at the mid-point between the surface and the bottom electrodes. Since the towed bipole source method requires much less survey time and the results show a higher spatial resolution, it is a powerful tool for MMR experiments to image a shallow oceanic crustal resistivity structure efficiently. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS).


Nishii K.,Kyushu Polytechnic College | Furukawa A.,Kyushu University | Watanabe S.,Kyushu University | Miyake K.,Kyushu University
AIP Conference Proceedings | Year: 2010

The labyrinth seal is one of non-contact seals, which is used as a seal device of rotary machines from reasons of the lubrication free and small losses. So far, many researchers have investigated the characteristics and suitable geometries of labyrinth seals, though only one directional flow of the seal has been focused up to now. As flow direction in the seal becomes changeable depending on the gas-purge system and the inner pressure variation of machines for recent applications, a guideline of designing labyrinth seal with changeable flow directions is required. In the present report, effects of seal characteristics and internal flow behaviors on various shapes of asymmetric convexity in labyrinth seals are experimentally investigated and relations between pressure loss and convexity geometries are discussed for designing a suitable seal. © 2010 American Institute of Physics.


Nakae T.,Oita University | Ryu T.,Oita University | Sueoka A.,Kyushu Polytechnic College | Ikebe Y.,Oita University | Rosbi S.,Kyushu Polytechnic College
International Conference on Noise and Vibration Engineering 2012, ISMA 2012, including USD 2012: International Conference on Uncertainty in Structure Dynamics | Year: 2012

Disc brake squeal is classified in terms of its generation mechanism. It has been found in previous studies that two types of squeal exist in disc brakes. One is called out-of-plane squeal, and the other is called inplane squeal. There are many reports that treat the out-of-plane squeal as coupled out-of-plane vibration modes among the disc and caliper due to Coulomb friction. Previously, the authors have experimentally and analytically confirmed the out-of-plane squeal generation mechanism and countermeasures in rigid and floating types of car disc brakes. Recently, the occurrence of in-plane squeal has been increasing, and the mechanism of in-plane squeal is not yet fully understood. This paper deals with two types of disc brakes that generate both out-of-plane squeal and in-plane squeal. The vibration modes of the brake units during squealing are also investigated. Additionally, the relationship between the rate of squeal occurrence and both the direction of disc rotation, the disc rotation speed and the pad pressure are investigated. And the effect of the rubber installation to the pads on squeal is also investigated. From these experiments, the generation mechanisms of in-plane squeal and out-of-plane squeal are compared and confirmed. © (2012) by the Katholieke Universiteit Leuven Department of Mechanical Engineering All rights reserved.


Yatsuzaki T.,Kyushu Polytechnic College
Proceedings of the 11th International Conference of the European Society for Precision Engineering and Nanotechnology, EUSPEN 2011 | Year: 2011

The purpose of this study is to clarify the possibility of the eco-cutting process for the super heat-resistant alloy Inconel 718. In particular, the effects of the oil mist application were examined with reference to the cutting process, through observation and measurement of the form of the generated chips in a series of experiments under various cutting conditions. As a result of these experiments, and through observations of the cross-sections of the chips, it was quantitatively possible to measure and confirm the effects of the oil mist application.


Kondo Y.,Kyushu University | Yamanouchi T.,Kyushu Polytechnic College
Fatigue and Fracture of Engineering Materials and Structures | Year: 2010

It is well known that earthquakes can damage structures and machinery. After an earthquake, those components, which have been obviously damaged are scrapped and replaced, and most of the components which have not been obviously damaged will continue to be used even after earthquakes. However, as will be shown, the earthquake may have severely impaired the fatigue strength of such components by introducing unfavourable residual stresses and short cracks at stress raisers. In addition, if such components should contain hydrogen, an increasingly possible scenario for the hydrogen economy in the future, then it is shown that the loss of fatigue strength can be even greater. This paper explores the extent of fatigue degradation due to overloads and to absorbed hydrogen. It was shown that generation of small crack and tensile residual stress imposed by overloads caused substantial decrease of residual fatigue strength compared with that in the initial state. It was also shown that hydrogen enhanced more reduction. Hydrogen enhanced reduction in two ways. The crack generated by overloads grew deeper in hydrogen charged material. In addition to this, the reduction of ΔKth also occurred in hydrogen charged material. These two factors worked together to reduce the residual fatigue strength after multiple overloads. © 2010 Blackwell Publishing Ltd.

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