研究者データベース

藤村 奈央(フジムラ ナオ)
工学研究院 機械・宇宙航空工学部門 機械材料システム
助教

基本情報

所属

  • 工学研究院 機械・宇宙航空工学部門 機械材料システム

職名

  • 助教

学位

  • 博士(工学)(北海道大学)

J-Global ID

研究分野

  • ものづくり技術(機械・電気電子・化学工学) / 材料力学、機械材料

職歴

  • 2014年 - 現在 北海道大学 工学(系)研究科(研究院) 助教

所属学協会

  • 日本材料学会   日本機械学会   

研究活動情報

論文

  • Initiation and propagation processes of internal fatigue cracks in β titanium alloy based on fractographic analysis
    Gaoge Xue, Takashi Nakamura, Nao Fujimura, Kosuke Takahashi, Hiroyuki Oguma
    Applied Sciences (Special Issue: Advances in Very-High-Cycle Fatigue) 11 2021年 [査読有り]
  • Effect of vacuum pressure on small crack propagation in Ti-6Al-4V
    Fumiyoshi Yoshinaka, Gaoge Xue, Nao Fujimura, Takashi Nakamura
    International Journal of Fatigue 142 2021年 [査読有り]
  • Surface modification of machine-finished magnesium alloy AZ31 using a scanning cyclic press
    Nao Fujimura, Koyo Ooga, Kosuke Takahashi, Takashi Nakamura, Tatsuki Wajima
    Mechanical Engineering Journal 7 2020年 [査読有り]
  • N. Fujimura, T. Nakamura, M. Ueno
    Mechanical Engineering Letters 4 2018年12月 [査読有り][通常論文]
  • 藤村奈央, 西塚祐斗, 髙橋航圭, 中村孝
    日本機械学会論文集 84 864 2018年08月 [査読有り][通常論文]
  • Nao Fujimura, Takashi Nakamura, Kosuke Takahashi
    MATEC Web of Conferences 165 2018年05月25日 [査読有り][通常論文]
     
    To quantitatively investigate the cause of the changes in arithmetic mean roughness Ra and arithmetic mean waviness Wa of austenitic stainless steel under low-cycle fatigue loading, precise observation focusing on persistent slip bands (PSBs) and crystal grain deformations was conducted on SUS316NG. During the fatigue tests, the specimen's surface topography was regularly measured using a laser microscope. The surface topographies were analysed by frequency analysis to separate the surface relief due to PSBs from that due to grain deformation. The height caused by PSBs and that by grain deformation were measured respectively. As a result, both of the heights rose with the increase of usage factor (UF). The amount of increase in the heights with respect to UF increased with strain range. The trend of development of both heights was similar with the trend of Ra and Wa. A comparison between Ra and the height caused by PSBs showed that these values strongly correlated with each other. A comparison between Wa and the height caused by grain deformation also showed that these values strongly correlated with each other. Consequently, the surface texture parameters Ra and Wa represent the changes in the heights of surface reliefs due to PSBs and grain deformation.
  • 藤村 奈央, 中村 孝, 髙橋 航圭, 和島 達希
    材料 66 12 906 - 912 公益社団法人 日本材料学会 2017年12月01日 [査読有り][通常論文]
     
    A new surface modification technique, scanning cyclic press (SCP), was developed. SCP scans a metal surface with a vibrating indenter under precise loading control based on servo fatigue testing machine and can apply a variable cyclically compressive load. This study applied SCP to magnesium alloy AZ31 to investigate the effect on fatigue properties. After applying SCP, the surfaces of specimens were observed by using a laser scanning microscope and uniaxial push-pull fatigue tests were conducted. As a result, surface roughness of SCP-treated specimens slightly increased; however, the fatigue life became longer than that of untreated specimens. To clarify the reason for the improvement effect, fracture surfaces of the specimens were investigated in detail on the basis of SEM observation. SEM observation showed differences between the fracture surfaces of the untreated and SCP-treated specimens. The origin of fracture was at the surface in the untreated specimen. In the SCP-treated specimen, however, the fracture origins were sub-surface and a band-like layer just beneath the surface was observed on fracture surface, whereas the layer did not exist on that of untreated specimen. The surface hardness of SCP-treated specimen increased to almost twice as much after applying SCP. The result suggests that SCP modified surface layer of specimen and this layer suppressed crack initiation from surface.
  • Tomoki Shinko, Takashi Nakamura, Nao Fujimura, Yasutaka Nakata
    Zairyo/Journal of the Society of Materials Science, Japan 64 11 910 - 917 2015年 [査読有り][通常論文]
     
    Low-cycle fatigue tests of SUS316NG austenitic stainless steel were conducted for several strain ranges (0.76, 1.26, 2.1, 4.1, and 8.1%) in which the specimen’s surface topography was regularly measured using a laser scanning microscope. The surface topographies obtained were analyzed by frequency analysis to separate the surface relief due to persistent slip bands (PSBs) from that due to crystal grain deformation. The PSBs-induced surface relief evolution and the grain-deformation-induced one were quantitatively evaluated by using arithmetic mean roughness Ra and arithmetic mean waviness Wa, respectively. The Î"Ra and Î"Wa, the increments in Ra and Wa from the initial values, increased with the usage factor (UF) for each strain range. Moreover, the rates of increase in Î"Ra and Î"Wa with respect to UF increased with the strain range. Î"Wa/Î"Ra was larger for higher strain ranges. This tendency of Î"Wa/Î"Ra indicates that the surface relief due to grain deformation develops more prominently than that due to PSBs for larger strain ranges. The results for Ra and Wa agree with the results of surface topography observation. On the basis of these results, a method was developed for estimating the UF of fatigued material and the applied strain range by using only the measured Ra and Wa.
  • Nao Fujimura, Takashi Nakamura, Hiroyuki Oguma
    PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE - 2013, VOL 5 2014年 [査読有り][通常論文]
     
    Changes in the surface roughness of SUS316NG during cyclic loadings were investigated, and the relations between those changes and the crack initiation and propagation processes are discussed on the basis of microscopic observations and cellulose acetate replica observations. Strain-controlled fatigue tests were conducted at three constant strain ranges. Surface roughness was measured periodically during the tests, and three roughness parameters were calculated: arithmetic mean roughness R-a, surface profile maximum height R-max, and maximum valley depth R-v. Until the middle of fatigue life, all three increased linearly with the number of cycles regardless of the strain range, and their rates of increase became smaller with decreasing strain range. Surface observation revealed that small cracks initiated very early in fatigue life, propagated slowly until the middle of fatigue life, and then grew rapidly. Changes in surface roughness are therefore sensitive to fatigue loading even when cracks are very small and crack detection is difficult. The results suggest that surface roughness can probably be used to assess fatigue damage because until the middle of fatigue life it increases linearly with the number of cycles. The definition of each roughness parameter and the changes show that R-max and R-v are suitable for damage assessment.
  • 藤村奈央, 中村孝, 小熊博幸, 中島智広, 信耕友樹
    材料 62 12 750 - 755 The Society of Materials Science, Japan 2013年12月 [査読有り][通常論文]
     
    Changes in the surface roughness of SUS316NG during cyclic loadings were investigated, and the relationship between those changes and the fatigue damage processes, including evolution of surface relief due to active slip systems, were discussed on the basis of microscopic observations. Strain-controlled fatigue tests were conducted at three constant strain ranges Δε = 8, 4, and 1%. During the tests, surface roughness was measured periodically at cycles determined with respect to the usage factor UF, and then the surface was observed directly to clarify the surface morphology. As a result, until the middle of fatigue life, the arithmetic mean roughness R<font size="-1">a</font> increased linearly with the number of cycles regardless of the strain range conditions. Clear changes in surface roughness were obtained even at a strain range as small as 1%. The results suggest that the surface roughness measurement can probably be used to assess fatigue damage because it increases linearly with the number of cycles until the middle of fatigue life. The rate at which surface roughness increased with UF became smaller with decreasing applied strain range. In the damage process, the surface became uneven because of active slip systems and the asperity became larger when the number of cycles increased. Surface observations revealed that the number of slip bands decreased and the development of the asperity became more difficult with decreasing applied strain range. The change tendencies of surface roughness were similar to those of the density of slip bands at each strain range. This shows that the rate at which surface roughness increased with UF is affected by the number of slip bands at each strain range condition.
  • Nao FUJIMURA, Takashi NAKAMURA, Hiroyuki OGUMA
    Journal of Solid Mechanics and Materials Engineering 7 3 372 - 380 2013年 [査読有り][通常論文]
  • Nao Fujimura, Hiroyuki Oguma, Takashi Nakamura
    PROCEEDINGS OF THE ASME PRESSURE VESSELS AND PIPING CONFERENCE VOL 1 1061 - 1067 2012年 [査読有り][通常論文]
     
    The effects of cyclic pre-strain on low cycle fatigue properties of austenitic stainless steel were investigated, and the fatigue damage was assessed based on several parameters such as the full width at half maximum (FWHM) of diffracted X-ray profile and surface roughness of specimens. The strain-controlled tests were conducted under strain ratio R epsilon = -1 and various constant total strain ranges. Also the change in remnant fatigue lives were investigated when the cyclic pre-strain were applied to the specimens under the different number of cycles which were determined with reference to the usage factor UFpre ranged from 0.2 to 0.8. As a result, the remnant fatigue life of the pre-strained samples became shorter than that of the sample without pre-strain as the UFpre increased. The relationship between the pre-strain damage expressed in UFpre and the remnant fatigue damage in UFpost was roughly described by the cumulative linear damage law: UTpre + UFpost = 1. Namely, the cyclic pre-strain affected the remnant fatigue lives. In order to evaluate the effects of cyclic pre-strain on fatigue lives more precisely, the damage in the cyclic pre-straining processes was estimated by using FWHM and surface roughness. The FWHM of the specimens with pre-strain once decreased with increase in UFpre, and then increased after showing a minimum value. The surface roughness of specimens increased linearly with an increase of the number of pre-straining cycles. These results suggested that the damage due to pre-strain can be assessed by means of FWHM and surface roughness of specimens.

講演・口頭発表等

  • Improvement of the fatigue property of magnesium alloy AZ31 through a new surface modification technique: scanning cyclic press  [通常講演]
    Nao Fujimura, Suzuka Abe, Koyo Ooga, Takashi Nakamura, Kosuke Takahashi, Tatsuki Wajima
    Eighth International Conference on Very High Cycle Fatigue (VHCF8) 2021年07月 口頭発表(一般)
  • Sanning Cyclic Pressを用いたマグネシウム合金の表面改質に及ぼす負荷繰返し数の影響
    阿部すずか, 藤村奈央, 大賀向陽, 髙橋航圭, 中村孝, 和島達希
    日本機械学会 2020年度年次大会 2020年09月
  • 微小内部き裂の発生・進展挙動に基づくα+β型チタン合金の疲労寿命分布解析
    森下弘法, 中村孝, 藤村奈央, 髙橋航圭
    日本材料学会第69期学術講演会 2020年05月
  • 表面改質技術Scanning Cyclic Pressを施した低炭素鋼S25Cの疲労特性
    藤村奈央, 丹野椋子, 宮﨑数則, 中村孝
    日本材料学会 第69期学術講演会 2020年05月
  • Scanning Cyclic Pressを施したマグネシウム合金の疲労特性と表層組織観察  [通常講演]
    藤村奈央, 大賀向陽, 大久保賢二, 中村孝, 髙橋航圭, 和島達希
    日本材料学会第68期学術講演会 2019年05月 口頭発表(一般)
  • Ti-6Al-4Vにおける表面および内部微小疲労き裂の開閉口挙動  [通常講演]
    友田悠太, 中村孝, 藤村奈央, 吉中奎貴, 小熊博幸, 竹内晃久, 上椙真之, 上杉健太朗
    日本材料学会第68期学術講演会 2019年05月 口頭発表(一般)
  • 接着継手強度に及ぼす両面テープ併用の効果  [通常講演]
    髙橋航圭, 菊澤卓馬, 藤村奈央, 中村孝
    日本材料学会第68期学術講演会 2019年05月 口頭発表(一般)
  • 大気および真空環境における微小疲労き裂の進展・停留挙動  [通常講演]
    塚越拓摩, 石原梨沙, Paras MEHENDIRATTA, 中村孝, 藤村奈央, 髙橋航圭
    日本材料学会第68期学術講演会 2019年05月 口頭発表(一般)
  • Changing mechanisms of surface relief and the damage evaluation of low cycle fatigued austenitic stainless steel  [通常講演]
    N. Fujimura, T. Nakamura, K. Takahashi
    12th international fatigue congress Fatigue 2018 2018年05月
  • 加熱修復機能を有する樹脂材料の硬化成形温度の検討  [通常講演]
    岸本繁人, 高橋航圭, 中村孝, 藤村奈央
    日本材料学会 第3回材料WEEK 若手学生研究発表会 2017年10月 ポスター発表
  • Scanning Cyclic Pressによるアルミニウム合金のナノ微細化表面改質  [通常講演]
    髙栁伊吹, 中村孝, 藤村奈央, 高橋航圭, 和島達希
    2017年10月 ポスター発表
  • 走査型 Cyclic Press “SCP”の開発と低炭素鋼の表面改質  [通常講演]
    水谷一皓, 中村孝, 藤村奈央, 高橋航圭, 和島達希
    日本材料学会 第3回材料WEEK 若手学生研究発表会 2017年10月 ポスター発表
  • 振動圧縮荷重を用いた表面改質技術“Cyclic Press”の提案とチタン合金への適用  [通常講演]
    上遠野寛, 中村孝, 吉中奎貴, 藤村奈央, 高橋航圭, 和島達希
    日本材料学会 第3回材料WEEK 若手学生研究発表会 2017年10月 ポスター発表
  • OS0527 低サイクル疲労を受けたSUS316NGの表面性状変化機構と損傷評価  [通常講演]
    藤村奈央, 西塚祐斗, 中村孝, 髙橋航圭
    M&M2017材料力学カンファレンス 2017年10月 口頭発表(一般)
  • PS32 Ti-22V-4Al における疲労き裂発生過程の観察  [通常講演]
    鹿島彰太, 髙梨圭, 吉中奎貴, 中村孝, 藤村奈央, 髙橋航圭
    M&M2017材料力学カンファレンス 2017年10月 ポスター発表
  • PS29 Ti-22V-4Alにおける疲労き裂発生・進展特性  [通常講演]
    髙梨圭, 鹿島彰太, 吉中奎貴, 中村孝, 藤村奈央, 髙橋航圭
    M&M2017材料力学カンファレンス 2017年10月 ポスター発表
  • PS27 AZ31の疲労特性に及ぼすScanning cyclic pressの影響  [通常講演]
    大賀向陽, 藤村奈央, 中村孝, 髙橋航圭, 和島達希
    M&M2017材料力学カンファレンス 2017年10月 ポスター発表
  • J1310106 Scanning cyclic pressを用いた金属表層の組織制御  [通常講演]
    中村孝, 藤村奈央, 水谷一皓, 髙栁伊吹, 和島達希
    日本機械学会年次大会 2017年09月 口頭発表(一般)
  • 155 Development of a new surface modification technique: scanning cyclic press and its application for the improvement of fatigue life of magnesium alloy  [通常講演]
    Nao FUJIMURA, Takashi NAKAMURA, Tatsuki WAJIMA
    Seventh International Conference on Very High Cycle Fatigue 2017年07月 口頭発表(一般)
  • Scanning Cyclic Pressを用いたマグネシウム合金AZ31の表面改質と疲労特性改善効果  [通常講演]
    藤村奈央, 中村孝, 上遠野寛, 宮崎数則, 柴山環樹, 和島達希
    第33回疲労シンポジウム・第1回生体・医療材料シンポジウム 2016年11月 口頭発表(一般)
  • OS0510 ポリイミドフィルムにおける膜厚方向破壊靱性の計測と評価  [通常講演]
    南雲慶憲, 坂本悠介, 中村孝, 藤村奈央, 髙橋航圭
    M&M2016材料力学カンファレンス 2016年10月 口頭発表(一般)
  • J1610203 ナノ微細化表面改質を目的とするScanning Cyclic Pressの開発と低炭素鋼への適用  [通常講演]
    宮崎数則, 中村孝, 藤村奈央, 柴山環樹, 和島達希
    日本機械学会年次大会 2016年09月 口頭発表(一般)
  • J1610202 Cyclic Press による低炭素鋼のナノ微細化表面改質  [通常講演]
    中村孝, 中谷建太朗, 宮崎数則, 藤村奈央, 柴山環樹, 和島達希
    日本機械学会年次大会 2016年09月 口頭発表(一般)
  • J0310101 SUS316NGの低サイクル疲労における表面性状変化とその機構  [通常講演]
    西塚祐斗, 藤村奈央, 中田康敬, 上遠野寛, 中村孝
    日本機械学会年次大会 2016年09月 口頭発表(一般)
  • 藤村 奈央, 中村 孝, 信耕 友樹
    M&M材料力学カンファレンス 2015年11月 
    To statistically investigate the changes and the distributions in surface roughness, strain controlled low cycle fatigue tests of austenitic stainless steel were conducted under strain range Δε=8, 4%. During the tests, the specimen's surface topography was regularly measured using a laser scanning microscope. The surface topographies obtained were analyzed by frequency analysis to separate the surface relief due to persistent slip bands. The persistent-slip-bands-induced surface relief evolution was quantitatively evaluated by using arithmetic mean roughness R_a. As a result, R_a at Δε=8, 4% increased with the increase of UF (Usage Factor). The R_a data were plotted roughly linearly on a log-normal probability paper. It suggests that R_a likely follows a log-normal distribution. On the probability papers, the slope of R_a plots and the average value at Δε=8, 4% were clearly different. It shows that the distribution form of R_a varies between different Δε. The slopes of R_a plots at each UF were similar on the paper. It showed that the dispersion of R_a data didnot change even if UF increases.
  • 中田 康敬, 西塚 祐斗, 信耕 友樹, 藤村 奈央, 中村 孝
    年次大会 : Mechanical Engineering Congress, Japan 2015年09月 
    To investigate the effects of change in loading amplitude on surface topography, two-step loaded low-cycle fatigue tests of SUS316NG austenitic stainless steel were conducted. During the tests, the specimen's surface topography was regularly measured using a laser scanning microscope. The surface topographies obtained were analyzed by frequency analysis to separate the surface relief due to persistent slip bands from that due to crystal grain deformation. The persistent-slip-bands-induced surface relief evolution and the grain-deformation-induced one were quantitatively evaluated by using arithmetic mean roughness R_a and arithmetic mean waviness W_a, respectively. As a result, the rates of increase in R_a and W_a changed obviously after changing loading amplitude. The results for R_a and W_a agree with the results of surface observation, the increases in the numbers of slip bands and deformed crystal grains changed after changing loading amplitude.
  • 中田 康敬, 信耕 友樹, 藤村 奈央, 中村 孝
    北海道支部講演会講演概要集 2014年09月
  • 堀川 紀孝, 濱口 萌愛, 藤村 奈央, 中村 孝
    M&M材料力学カンファレンス 2014年07月 
    Austenite stainless steel is widely used in power plants and nondestructive damage estimation method is required to determine the damage on the structure due to fatigue or earthquake. Eddy current method is one of the nondestructive inspection technique, and it reflects the surface condition of the metal. Surface roughness of the specimen increased by the deformation and the roughness change is used to estimate the damage by the low cycle fatigue. This report deals with the eddy current signal change due to the surface roughness. Test pieces of SUS316 with 6mm in diameter were prepared, and the surface was ground with emery paper. Eddy current testing was carried out with two types of the probe and testing frequency of 200kHz and 1MHz. Eddy current signal, which is output of the eddy current instrument, were measured. Eddy current signal was changed by surface grinding. Grinding on the surface showed significant effect on the eddy current signal. It is caused by removal of residual stress near the surface of the test piece that induced by the drawing process. Difference in the eddy current signal by the surface roughness within 1μm in Ra is quite small and higher testing frequency is required to distinguish the difference.
  • 藤村 奈央, 中村 孝, 小熊 博幸, 新沼 賢基
    M&M材料力学カンファレンス 2014年07月 
    Changes in surface roughness of SUS316NG during cyclic variable loadings were investigated. Strain controlled two-step fatigue tests were conducted under two different strain ranges. In the tests, strain range was switched from Δε_H=4% to Δε_L=2% or from Δε_L=2% to Δε_H=4% at the usage factor UF=0.2. The specimen's surface was observed by a laser scanning microscope to clarify the surface profile and surface roughness R_a. As a result, R_a increased with UF during the first and second steps in the two-step tests. The increasing rate of R_a at the second step became smaller after strain range was changed from 4% to 2%, whereas it became larger after strain range was changed from 2% to 4%. The increasing tendencies of Ra at each step were similar to those in fatigue test under constant strain ranges Δε=4% and 2%, respectively. The results suggest that changes in surface roughness under two-step variable loadings can be described by superimposing R_a values in order of loading, which were obtained under constant strain range tests. Surface observation revealed that the height change in surface profile during each loading step varied depending on the strain range. This shows that the history of strain range affected the changes in surface profile, and it is the reason that the increasing rate of R_a changed in the two-step tests.
  • 信耕 友樹, 藤村 奈央, 中田 康敬, 小熊 博幸, 中村 孝
    M&M材料力学カンファレンス 2014年07月 
    Low-cycle fatigue tests of SUS316NG were conducted under conditions of strain range Δε=2, 4 and 8%. During the fatigue tests, changes in surface relief of specimen were measured by a laser scanning microscope. The surface roughening due to slip bands and deformation of grains was quantitatively evaluated by using arithmetic average roughness R_a and arithmetic average waviness W_a respectively. As a result, R_a and W_a increased with the increase of UF (Usage Factor), and the increasing rates of R_a and W_a with respect to UF became larger in larger strain ranges. The ratio of increasing rate of W_a to R_a also became larger in larger strain ranges. This result indicates that the surface roughening due to deformation of grains is caused more significantly than that due to slip bands is in larger strain ranges. Based on the different tendencies of R_a and W_a, we suggested a new damage evaluation method which can estimate UF and applied strain range of fatigued material.
  • 藤村奈央, 信耕友樹, 中村孝
    疲労シンポジウム講演論文集 2014年
  • Nao Fujimura, Takashi Nakamura, Hiroyuki Oguma
    American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP 2013年12月 
    Changes in the surface roughness of SUS316NG during cyclic loadings were investigated, and the relations between those changes and the crack initiation and propagation processes are discussed on the basis of microscopic observations and cellulose acetate replica observations. Strain-controlled fatigue tests were conducted at three constant strain ranges. Surface roughness was measured periodically during the tests, and three roughness parameters were calculated: arithmetic mean roughness Ra, surface profile maximum height R max, and maximum valley depth Rv. Until the middle of fatigue life, all three increased linearly with the number of cycles regardless of the strain range, and their rates of increase became smaller with decreasing strain range. Surface observation revealed that small cracks initiated very early in fatigue life, propagated slowly until the middle of fatigue life, and then grew rapidly. Changes in surface roughness are therefore sensitive to fatigue loading even when cracks are very small and crack detection is difficult. The results suggest that surface roughness can probably be used to assess fatigue damage because until the middle of fatigue life it increases linearly with the number of cycles. The definition of each roughness parameter and the changes show that Rmax and Rv are suitable for damage assessment. Copyright © 2013 by ASME.
  • 新沼 賢基, 藤村 奈央, 信耕 友樹, 中村 孝, 小熊 博幸
    M&M材料力学カンファレンス 2013年10月 
    A strain controlled two step test was conducted to investigate changes in the surface features of SUS316NG during cyclic variable loading. In the two step test, strain range was switched from Δ_<εH> = 4% to Δ_<εL> = 2% at the usage factor UF= 0.2. The specimen surface was observed by a laser microscope to clarify the surface morphology and surface roughness R=a. Initiation and propagation of the main crack was also observed by using cellulose acetate replica The results in the two step test were compared with those obtained in fatigue tests under constant strain ranges. As a result changes in surface features such as slip bands and surface asperities clearly depended on the value of strain ranges even under the same UF value. Small cracks initiated very early in the fatigue life, however, they hardly propagated until the middle of fatigue life. In contrast, Ra clearly increased from the beginning to the middle of fatigue life. These results suggest that surface roughness can be an effective parameter for fatigue damage assessment. In addition, the increasing rates of Ra during the first and second steps in two step test were similar to those in fatigue tests under constant strain ranges Δ_ε = 4% and Δ_ε = 2%, respectively. Therefore, the history of strain range under cyclic variable loadings can probably be described from the value of R_a and the increasing rate of R_a in the fatigue tests under constant strain ranges.
  • 新沼賢基, 藤村奈央, 信耕友樹, 中村孝, 小熊博幸
    日本機械学会M&M2013材料力学カンファレンス(CD-ROM) 2013年10月
  • 信耕 友樹, 藤村 奈央, 新沼 賢基, 小熊 博幸, 中村 孝
    北海道支部講演会講演概要集 2013年09月
  • 信耕友樹, 藤村奈央, 新沼賢基, 小熊博幸, 中村孝
    日本機械学会北海道支部講演会講演概要集 2013年09月
  • 藤村奈央, 中村孝, 小熊博幸, 中島智広, 信耕友樹
    日本材料学会学術講演会講演論文集 2013年05月
  • 中島 智広, 藤村 奈央, 新沼 賢基, 小熊 博幸, 中村 孝
    北海道支部講演会講演概要集 2012年10月
  • 中島智広, 藤村奈央, 新沼賢基, 小熊博幸, 中村孝
    日本機械学会北海道支部講演会講演概要集 2012年10月
  • 藤村 奈央, 中村 孝, 小熊 博幸
    M&M材料力学カンファレンス 2012年09月 
    The effects of surface roughness on low cycle fatigue properties were investigated by strain-controlled fatigue tests using specimens of austenitic stainless steel finished by two different methods: machining and mirror polishing. During fatigue tests, the surface roughness of each specimen was measured, and crack initiation and propagation were observed using cellulose acetate replicas. As a result, the fatigue life of mirror polished specimen was longer than that of machined one. It was shown that the surface roughness affected the fatigue life. The change of surface roughness of each specimen showed the same increasing tendency with respect to the number of cycles. However, around the end of fatigue life, the surface roughness of mirror polished specimen became larger than that of machined one. In the damage process, the crack initiated at the very early stage of fatigue life. The crack growth rate was small until the middle of fatigue life; however, it increased rapidly after that. The surface roughness affected the crack initiation, and that is the reason why the fatigue life and the change of surface roughness were different between each specimen.
  • 藤村奈央, 小熊博幸, 中村孝
    日本材料学会学術講演会講演論文集 2012年05月
  • 藤村奈央, 中村孝, 小熊博幸
    日本機械学会M&M2012材料力学カンファレンス(CD-ROM) 2012年
  • Nao Fujimura, Hiroyuki Oguma, Takashi Nakamura
    American Society of Mechanical Engineers, Pressure Vessels and Piping Division (Publication) PVP 2011年12月 
    The effects of cyclic pre-strain on low cycle fatigue properties of austenitic stainless steel were investigated, and the fatigue damage was assessed based on several parameters such as the full width at half maximum (FWHM) of diffracted X-ray profile and surface roughness of specimens. The straincontrolled tests were conducted under strain ratio Rε = -1 and various constant total strain ranges. Also the change in remnant fatigue lives were investigated when the cyclic pre-strain were applied to the specimens under the different number of cycles which were determined with reference to the usage factor UFpre ranged from 0.2 to 0.8. As a result, the remnant fatigue life of the pre-strained samples became shorter than that of the sample without pre-strain as the UFpre increased. The relationship between the pre-strain damage expressed in UFpre and the remnant fatigue damage in UFpost was roughly described by the cumulative linear damage law: UFpre + UFpost = 1. Namely, the cyclic pre-strain affected the remnant fatigue lives. In order to evaluate the effects of cyclic pre-strain on fatigue lives more precisely, the damage in the cyclic pre-straining processes was estimated by using FWHM and surface roughness. The FWHM of the specimens with pre-strain once decreased with increase in UF pre, and then increased after showing a minimum value. The surface roughness of specimens increased linearly with an increase of the number of pre-straining cycles. These results suggested that the damage due to pre-strain can be assessed by means of FWHM and surface roughness of specimens. © 2011 by ASME.
  • 中島智広, 藤村奈央, 小熊博幸, 中村孝
    日本機械学会北海道支部講演会講演概要集 2011年10月
  • 中島 智広, 藤村 奈央, 小熊 博幸, 中村 孝
    北海道支部講演会講演概要集 2011年10月
  • 藤村 奈央, 小熊 博幸, 中村 孝
    北海道支部講演会講演概要集 2010年11月
  • 藤村奈央, 水門恵理, 中村孝, 小熊博幸
    日本材料学会学術講演会講演論文集 2010年05月

受賞

  • 2020年06月 日本材料学会 令和元年度学術奨励賞
     
    受賞者: 藤村奈央
  • 2017年03月 日本材料学会 疲労部門委員会 第33回疲労シンポジウム・第1回生体・医療材料シンポジウム 優秀研究発表賞
     
    受賞者: 藤村奈央
  • 2013年07月 21st Rudy Scavuzzo Student Paper Symposium Competition at the 2013 ASME Pressure Vessels Piping Conference Honorable Mention (Ph. D. Category)
     
    受賞者: 藤村奈央
  • 2011年07月 Student Paper Competition 2011 ASME Pressure Vessels and Piping Conference The First Runner-Up Student Paper, Student Paper Competition
     
    受賞者: 藤村奈央

共同研究・競争的資金等の研究課題

  • 表面改質技術Scanning Cyclic Pressによる金属の疲労特性改善
    日本学術振興会:科研費 若手研究
    研究期間 : 2019年04月 -2022年03月 
    代表者 : 藤村奈央
  • 繰返し負荷を受けた金属材料における表面性状の変化機構と疲労損傷評価
    日本学術振興会:科学研究費補助金(若手研究(B))
    研究期間 : 2017年04月 -2019年03月 
    代表者 : 藤村奈央
  • 日本学術振興会:科学研究費補助金(研究活動スタート支援)
    研究期間 : 2014年04月 -2016年03月 
    代表者 : 藤村 奈央

教育活動情報

主要な担当授業

  • 機械加工学実習
    開講年度 : 2020年
    課程区分 : 学士課程
    開講学部 : 工学部
    キーワード : 鋳造、溶接、塑性加工、切削加工、研削加工、先端加工

大学運営

委員歴

  • 2019年04月 - 2021年03月   日本溶接協会DFC3小委員会   中立委員
  • 2017年04月 - 2019年03月   日本溶接協会 FQA3小委員会   中立委員
  • 2017年04月 - 2017年10月   日本機械学会 M&M2017材料力学カンファレンス 実行委員会   実行委員
  • 2015年04月 - 2017年03月   日本溶接協会 FQA2小委員会   中立委員
  • 2014年09月 - 2015年09月   日本機械学会 2015年度年次大会 実行委員会   実行委員
  • 2014年07月 - 2015年03月   日本溶接協会 FQA小委員会   中立委員


Copyright © MEDIA FUSION Co.,Ltd. All rights reserved.