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  2. Akama Makoto

Akama Makoto

  (赤間 誠)

Profile Information

Affiliation
Professor, Faculty of Engineering, Department of Mechanical Engineering for Transportation, Osaka Sangyo University
Degree
Doctor Engineering(Tohoku University)
博士（工学）(東北大学)
Researcher number
70425867
J-GLOBAL ID
201301098055797812
researchmap Member ID
7000005156

Research Areas

 1

Education

 3

Committee Memberships

 2

Papers

 32
  • Wijitpatima Chawanat, Makoto Akama
    Tribology Online, 19(4) 277-286, Jul 7, 2024  Peer-reviewed
    A railway wheel flat occurs when the wheel locks and slides along the rail, forming a white etching layer (WEL) just under the flat surface where rolling contact fatigue cracks often form that can propagate into the wheel and spall during service. This study comprehensively investigated the influencing factors on wheel crack propagation that lead to spalling. Experiments were conducted to test wheel specimens with WELs of various dimensions, and simulations were performed to evaluate the stresses near the WELs as well as the rate and direction of crack propagation.
  • WANG Wutong, AKAMA Makoto, TSUKAHARA Masahiro, MISAKA Yoshitaka, MATSUDA Shinya, GUENNEC Benjamin, SAKAI Tatsuo
    Journal of the Society of Materials Science, Japan, 72(3) 161-167, Mar 15, 2023  Peer-reviewed
    Rotating bending fatigue tests were performed to investigate the effect of induction hardening (HQI) on the very high cycle fatigue (VHCF) properties of the axle steel. In addition, finite element analyses (FEA) and scanning electron microscope (SEM) observations were conducted to elucidate the fundamental behavior. The results obtained are summarized as follows; (1) It was found that the fatigue strength of the axle steel was improved by almost 300 MPa in VHCF region by HQI, (2) A lot of specimens of the HQI had fractured in VHCF region, therefore, the consideration of VHCF properties should be taken into account in the design of railway axles, (3) Crack initiation sites can be classified into three forms; the surface of the HQI layer in the minimum section, the base metal beyond the HQI layer in the axial direction, and the internal base material in the minimum section. These can be reconfirmed through the comparison between the local fatigue strength distribution and the bending stress distribution obtained by FEA.
  • TAKAHASHI Yuma, AKAMA Makoto
    JOURNAL OF JAPANESE SOCIETY OF TRIBOLOGISTS, 67(8) 567-580, Aug 15, 2022  Peer-reviewed
    Trains often operate as a shuttle service. When a train arrives at the terminal station, its direction of travel is reversed, and therefore so is the rolling direction of the wheels. It is therefore important to investigate how the crack propagation, and wear on the wheel tread are changed by reversing the rolling direction. In this study, twin disc wear-fatigue tests were carried out under various conditions to study the effect on the behaviour of rolling contact fatigue (RCF) cracks and wear. Also, finite element analyses (FEA) were performed in order to clarify the results of these tests. In the lubricated condition, the cumulative wear tended to increase when the rolling direction of the wheel specimen was reversed if the slip ratio was 1%. On the other hand, in the dry condition, there was almost no change in the wear before and after reversing. FEA suggested that, when the wheel specimen was reversed, lubricant was trapped in the RCF crack and the friction coefficient between the crack faces was reduced, leading to shear mode crack growth and increased the fatigue wear.
  • Makoto AKAMA, Kiyoshi MATSUBARA
    Transactions of JSCES, (20200017), Sep 10, 2020  Peer-reviewed
    鉄道レールのシェリングは、列車の車輪が繰り返し通過することにより発生する表面の転がり接触疲労き裂である。本研究では、シェリングの水平裂の進展について数値シミュレーションを実施した。成長は、ヘルツ接触圧が負荷される2次元傾斜き裂の応力拡大係数（K値）の境界要素解析に基づいて行った。このような2次元き裂を複数並列に配置し、その先端を結ぶことで、3次元半楕円水平裂のK値を近似的に求めることができる。この方法は、完全な3次元で解析された方法と比較して、計算速度で優位性がある。進展はモードI/II及びモードI/IIIの非比例混合モード試験のデータを用いて、Richardによって提案された等価K値範囲を用いるパリス型き裂進展則で求めた。分岐の方向はHourlier-Pineau規準で予測した。
  • Makoto AKAMA, Takafumi KIMATA
    Wear, 448-449(15), Jan 28, 2020  Peer-reviewed
    A numerical model is developed to simulate the competition between RCF-initiated short crack propagation and wear in a wheel tread. The crack is assumed to initiate when the total accumulated plastic shear strain reaches the critical value. In the early crack growth simulations, the two-stage short crack growth model proposed by Hobson is applied. With regard to wear, the Archard model is adopted as the basis. The model is shown to operate properly when applied to the results of unidirectional twin disc tests. When an outward route comprising a 1000 km straight run is simulated based on the Shinkansen routes, it is found that the tread is hardly damaged. The results obtained from the rolling reversal fatigue tests show that if the rolling direction of the wheel is reversed, the delamination wear becomes dominant.
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Misc.

 4

Books and Other Publications

 2
  • 赤間誠, 阿部豊, 石塚弘道, 于強, 織田伸吾, 加藤肇彦, 河本洋, 小熊規泰, 酒井達雄, 桜井茂雄, 佐藤憲一, 白木渡, 白鳥正樹, 鈴木誠, 坪井学, 服部成雄, 藤山一成, 吉永隆治, 吉村達彦 (Role: Joint author)
    養賢堂, Nov, 2008 (ISBN: 9784842504452)
    信頼性工学の基礎概念・基礎理論・試験及び設計法など、実製品の信頼性保証技術が纏められており、産業界の現場で実際に信頼性工学を応用する際に必要となる具体的な応用手法を中心テーマとしている。私の担当部分では、新幹線電車車軸の輪座で発生するき裂の不確かな進展速度の値を評価するために、ベイズ解析を行なった。その結果、破壊確率のより信頼性のある値が得られた。
  • M. Akama, H. Ishizuka, E. Andersson, H.V.Bahr, E.Berg, H.Bj?rck, J.Blomerius, A.H.Kaas, J.Madejski, J.Grabczyk, L.Hhoudour, D.Dooze, J.L.Bruyelle, A.Filip (Role: Joint author)
    WITPRESS, 1999 (ISBN: 1853127841)
    鉄道の安全性は、特に最近の高速鉄道における速度向上により、関心が高まっている。そこでこの本は、各国の専門家による広範囲にわたる安全性の評価手法の適用例を含んだものである。第一章は私による確率論的破壊力学の新幹線車軸への適用、第二章はステンレス車体の衝突解析、第三章はドイツ浮上式鉄道トランスラピッドの安全性技術などが収録されている。

Presentations

 57
  • Makoto AKAMA, Yuma TAKAHASHI
    The Fifth International Conference on Railway Technology (Railways 2022), Aug 23, 2022, Elsevier, Civil-Comp Press
    In this study, we conducted a series of twin-disc wear and fatigue tests and FE simulations of the tests. The results are as follows. In the wet conditions, the wear rate increased when the rolling direction of the wheel disc was reversed. In contrast, in the dry conditions, the wear rate was much higher than in the wet conditions, however, it changed little before and after the reversal. The Archard model could not explain the increase in wear rate after the reversal in wet conditions, because the model does not take into account the delamination wear induced by the fluid. Some discs after the test were sectioned and photographed to observe the crack morphologies and microstructural changes by optical metallography. In wet conditions, when the wheel disc was reversed, the cracks clearly tended to propagate parallel to the surface, and the resulting long and thin wear sheets delaminated. In this case, the crack is filled with fluid just before its mouth reaches the contact area between the wheel and rail discs, whereupon the mouth is sealed. Therefore, the fluid is trapped in the crack and acts as a lubricant to reduce the friction coefficient, and cracks tend to propagate easily and large delamination sheets are apt to form. In order to explain the increase in wear rate after the reversal under wet conditions, CTSDs were obtained by FE analyses. In the wet conditions, the ΔCTSD after the reversal was almost twice as large as that before the reversal. This means that the amount of crack propagation after the reversal is higher than that before the reversal. In contrast in the dry conditions, the ΔCTSD is almost the same before and after the reversal. Therefore, the amount of crack propagation before and after the reversal is considered to be almost the same.
  • 王 呉桐, 赤間 誠, 塚原真宏, 三阪佳孝, 松田伸也, GUENNEC Benjamin, 酒井達雄
    日本材料学会 第71期通常総会・学術講演会, May 30, 2022, 日本材料学会
    本研究では，高周波表面焼入れを施した車軸鋼相当試験片を用いた超高サイクル領域までの回転曲げ疲労試験を行ってS-N曲線を作製した。同時にFEM解析を行い，試験結果を考察した。またSEMによって破面観察を実施した。その結果，未焼入れ材の10^7時間強度はほぼ300MPaであるのに対して，焼入れ材の同時間強度はほぼ700MPaであり，高周波焼入れによって疲労強度は，ほぼ400MPaも向上すること，焼入れ材では10^7サイクル以上で破断した試験片がかなり存在し，表面焼入れを行っている新幹線車軸は超高サイクル領域での疲労特性の解明が不可欠であることなどがわかった。
  • 高橋優雅, 赤間誠
    日本トライボロジー学会トライボロジー会議予稿集(CD-ROM), Oct 29, 2021
  • Yuuma TAKAHASHI
    日本機械学会 関西学生会2020年度学生員卒業研究発表講演会, Mar 16, 2021, The Japan Society of Mechanical Engineers
    鉄道車両は運用中に様々な損傷を受ける．その中でき裂と摩耗は車輪の寿命を決定することが知られている．本研究では，車輪の転がり方向逆転によるき裂と摩耗の挙動への影響を研究するため，西原式二円筒摩耗試験機による試験及び有限要素法(FEM)を用いた数値解析を実施した．
  • 赤間誠, WANG Wutong, 塚原真宏, 三阪佳孝, 松田伸也, 酒井達雄
    信頼性シンポジウム講演論文集, 2021
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Professional Memberships

 6
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Research Projects

 1

Industrial Property Rights

 3

研究テーマ

 2
  • 研究テーマ（英語）
    転がり接触疲労に関する研究
    キーワード（英語）
    転がり接触疲労，車輪，レール，数値解析
    概要（英語）
    車輪とレールには，接触によってき裂が発生する場合がある。そのき裂の発生時期，き裂の進展速度などを，数値解析手法で予測する。
    研究期間（開始）（英語）
    2001/04/01
  • 研究テーマ（英語）
    鉄道部材の健全性評価に関する研究
    キーワード（英語）
    健全性評価，車軸，車輪，レール，数値解析
    概要（英語）
    車軸，車輪，レールなどの鉄道車両部品，軌道部材について，数値解析的手法で発生応力などを解析し，それらの構造健全性を評価する。
    研究期間（開始）（英語）
    2001/04/01
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