Papers - Omiya, Masaki

Impact-induced fracture mechanisms of immiscible PC/ABS (50/50) blends

Machmud M., Omiya M., Inoue H., Kishimoto K.

IOP Conference Series: Materials Science and Engineering (IOP Conference Series: Materials Science and Engineering)  334 ( 1 )  2018.04

ISSN  17578981

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© Published under licence by IOP Publishing Ltd. This paper presents a study on fracture mechanisms of polycarbonate (PC)/acrylonitrile-butadiene-styrene (ABS) (50/50) blends with different ABS types under a drop weight impact test (DWIT) using a circular sheet specimen. Formation of secondary crack indicated by a stress-whitening layer on the mid-plane of scattered specimens and secondary surface of fracture perpendicular to primary fracture surface were captured under scanning electron microscope (SEM). Although the both blends finally failed in brittle modes, SEM observation showed that their secondary fracture mechanisms were completely different. Observation through the thickness of the etched PC/ABS specimen samples using SEM also clearly showed that PC and ABS were immiscible. The immiscibility between PC and ABS was indicated by presence of their layer structures through the thickness of the blends. It was revealed that layer of ABS structure was influenced by size of rubber particle and this latter parameter then affected microstructure and fracture mechanisms of the blends. Impact-induced fracture mechanisms of the blends due to such microstructures are discussed in this paper. It was also pointed out that the secondary cracking was likely caused by interface delamination between PC and ABS layers in the core due to transverse shear stress generated during the impact test.

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構造物の位相最適化における荷重伝達指標 Ustar (U*)の適用 (2) 荷重伝達U*エントロピーによる経路の明瞭化

高橋邦弘, 大宮正毅, 宮下朋之, 藤田知樹, 本田正徳

日本機械学会 IIP2018 情報・知能・精密機器部門（IIP 部門）講演会 講演論文集 (日本機械学会)  18 ( 9 ) 1B02(4pages) 2018.03

Research paper (conference, symposium, etc.), Joint Work

構造物の位相最適化における荷重伝達指標Ustar (U*)の適用，(1) 荷重伝達指標Ustar (U*) を考慮したレベルセット法

藤田知樹, 宮下朋之, 大宮正毅, 高橋邦弘, 本田正徳

日本機械学会 IIP2018 情報・知能・精密機器部門（IIP 部門）講演会 講演論文集 (日本機械学会)  18 ( 9 ) 1B01(4pages) 2018.03

Research paper (conference, symposium, etc.), Joint Work

Development of head protector for judo practice considering neck extension suppression

Takeshi KAMITANI, Natsuko ONIDANI, Masaki OMIYA, Atsuhiro KONOSU

Journal of Biomechanical Science and Engineering (The Japan Society of Mechanical Engineers)  13 ( 1 ) 1 - 11 2017.12

Research paper (scientific journal), Joint Work, Accepted,  ISSN  18809863

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© 2018 The Japan Society of Mechanical Engineers. Severe head injuries-and even deaths-have been reported in the practice of judo, often resulting from inexperience in using the appropriate falling technique (ukemi). In this study, we developed a novel head protector that protects the head and suppresses the neck extension during impact with the mat. The head protector was fabricated for this purpose and consists of a head support structure and shock-absorbing materials. The effectiveness of the head protector was tested experimentally with an apparatus with head and neck components that were based on a Hybrid III dummy. Several configurations of the support structure characteristics and the shock-absorbing materials were evaluated. The proposed head protector was capable of reducing the head angular velocity variation range-which is an important evaluation index for the onset of acute subdural hematoma -by 29% using the devices alone, by 21% using shock-absorbing materials alone, and by 47% using a combination of both. These results show that the proposed structures are highly effective in suppressing extensions at the cervical-thoracic joint (C7-T1), whereas the shock-absorbing materials are highly effective in suppressing rotations at the atlanto-occipital joint (O-C1). It is concluded that wearing the proposed head protector-which combines both effects-can reduce the risk of severe head injuries, even those resulting from severe impacts such as those associated with the judo ukemi practice.

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Comparison by stress analysis of growth period and adult elbow joint under Judo motion

Natsuko ONIDANI,Masaki OMIYA, Naomichi OGIHARA, Takeshi KAMITANI

Proceedings of 2017 INTERNATIONAL JUDO SYMPOSIUM, 5th Judo Medical and Scientific Research Conference, Tokyo  2017.12

Research paper (international conference proceedings), Joint Work

2リンクモデルを用いた柔道における頭部保護具の検討

佐々木 貴弘，大宮 正毅，星野 裕昭

日本機会学会シンポジウム：スポーツ工学・ヒューマンダイナミクス2017　講演論文集 (日本機械学会)  U0041   1 - 6 2017.11

Research paper (conference, symposium, etc.), Joint Work

柔道動作時における成長肘関節の応力解析

鬼谷奈津子，大宮正毅，荻原直道，紙谷武

日本機会学会シンポジウム：スポーツ工学・ヒューマンダイナミクス2017　講演論文集 (日本機械学会)  U0030   1 - 6 2017.11

Research paper (conference, symposium, etc.), Joint Work

On the way to the Tokyo Summer Olympic Games (2020). Prevention of severe head and neck injuries in judo: it's time for action

Kamitani T, Malliaropoulos NG, Omiya M, Otaka Y, Inoue K, Onidani N

British Journal of Sports Medicine (BMJ Publishing Group Ltd & British Association of Sport and Exercise Medicine)  51 ( 22 ) 1581 - 1582 2017.11

Research paper (scientific journal), Joint Work, Accepted

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Prediction of Shear Length in Blanking Process by Numerical Analysis

Shusuke SATO, Masaki OMIYA

Materials Science Forum (Trans Tech Publications)  920   181 - 186 2017.10

Research paper (international conference proceedings), Joint Work, Accepted,  ISSN  9783035713039

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© 2018 Trans Tech Publications, Switzerland. Blanking process has high productivity compared with other cutting processes. Because of this feature, the blanking process is used for the manufacture of automobile parts, electronic parts and so on. However, the blanking process is the process that leads to fracture. When the cutting surface are used as the functional surface, such as gears or cams, the precision of cutting surface is important and it can be improved by applying appropriate process conditions. The appropriate process conditions have been determined by repeating many experiments and this process is very inefficient. Owing to this background, the determination of the optimal process condition by numerical method such as the finite element method (FEM) is expected. In the previous studies, blanking process analyses of round blanking process which were modeled as 2D axisymmetric problem have been carried out and the cutting surface that coincided well with the experimental result was obtained. However, the blanking shape was not taken into consideration and they were not considering whether it can be applied to complicated shape expected to be applied in the future. In this study, blanking process analysis of quadrilateral blanking process was modeled as 2D plane strain problem and the applicability of various ductile fracture criteria was examined by comparing numerical results with experimental results based on shear length. As a result, there was little difference in the applicability of Cockcroft and Latham, Ayada, Brozzo ductile fracture criterion to the prediction of shear length under the current conditions.

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荷重伝達指標Ustar(U*)を用いた位相最適化

藤田知樹, 宮下朋之, 大宮正毅, 高橋邦弘

日本設計工学会2017年度秋季大会研究発表講演会講演論文集 (日本設計工学会)     71 - 74 2017.10

Research paper (conference, symposium, etc.), Joint Work

画像相関法を用いた接着継手の混合モード破壊挙動解析

志水健人，大宮正毅，米山聡

日本機械学会M&M2017材料力学カンファレンス (日本機械学会)  17-5   70 - 73 2017.10

Research paper (conference, symposium, etc.), Joint Work

数値シミュレーションを用いたせん断加工におけるせん断面長さの予測

佐藤 秀祐，大宮 正毅

日本機械学会M&M2017材料力学カンファレンス (日本機械学会)  PS05   1 - 2 2017.10

Research paper (conference, symposium, etc.), Joint Work

柔道における頭部外傷を防止するための保護具の検討

佐々木 貴弘, 大宮 正毅

日本機械学会M&M2017材料力学カンファレンス (日本機械学会)  PS06   1 - 2 2017.10

Research paper (conference, symposium, etc.), Joint Work

自動車用接着継手を対象とした混合モードJ積分の簡易評価法の検討

小川 賢介，前田 隆世，小林 卓哉，横井 栄一郎，古沢 透流，高田 賢治，大宮 正毅

計算工学講演会論文集 (日本計算工学会)  22 ( E-09-3 ) 1 - 5 2017.05

Research paper (conference, symposium, etc.), Joint Work

延性破壊条件を求めるための簡易試験片形状の検討

田原 孝浩, 大宮 正毅

日本機械学会関東支部第23期総会・講演会講演論文集 (一般社団法人日本機械学会関東支部)  OS0501-06   1 - 2 2017.03

Research paper (conference, symposium, etc.), Joint Work

頭部物理モデルを用いた柔道における後頭部衝突時の頭蓋内挙動観察実験

紙谷武，宮崎祐介，稲次基希，大宮 正毅

日本臨床スポーツ医学会誌 (日本臨床スポーツ医学会)  24 ( 3 ) 443 - 450 2016.08

Research paper (scientific journal), Joint Work, Accepted,  ISSN  1346-4159

A Proposal of Ground Power Operated Gondola Type Space Elevator

SASAKI Hidemi, OMIYA Masaki

Proceedings of The ISEC 2016 Space Elevator Conference (International Space Elevator Consortium)   2016.08

Research paper (international conference proceedings), Joint Work

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This paper shows a new operation method of the space elevator and the detailed features. This plan has considerable advantages such as being able to use electricity without restriction, however, the construction period is long and a tether with comparatively high strength is required. Then, a relation between strength of available tether and construction period will be considered.

Anion Effects on the Ion Exchange Process and the Deformation Property of Ionic Polymer Metal Composite Actuators

Wataru AOYAGI, Masaki OMIYA

Materials (MDPI)  9 ( 6 ) 479 2016.06

Research paper (scientific journal), Joint Work, Accepted

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An ionic polymer-metal composite (IPMC) actuator composed of a thin perfluorinated ionomer membrane with electrodes plated on both surfaces undergoes a large bending motion when a low electric field is applied across its thickness. Such actuators are soft, lightweight, and able to operate in solutions and thus show promise with regard to a wide range of applications, including MEMS sensors, artificial muscles, biomimetic systems, and medical devices. However, the variations induced by changing the type of anion on the device deformation properties are not well understood; therefore, the present study investigated the effects of different anions on the ion exchange process and the deformation behavior of IPMC actuators with palladium electrodes. Ion exchange was carried out in solutions incorporating various anions and the actuator tip displacement in deionized water was subsequently measured while applying a step voltage. In the step voltage response measurements, larger anions such as nitrate or sulfate led to a more pronounced tip displacement compared to that obtained with smaller anions such as hydroxide or chloride. In AC impedance measurements, larger anions generated greater ion conductivity and a larger double-layer capacitance at the cathode. Based on these mechanical and electrochemical measurements, it is concluded that the presence of larger anions in the ion exchange solution induces a greater degree of double-layer capacitance at the cathode and results in enhanced tip deformation of the IPMC actuators.

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合金化溶融亜鉛めっき鋼板における接着継手の混合モード破壊試験

大宮 正毅，中村憲一郎，前田隆世，小川賢介，小林卓哉，古沢透流，横井栄一郎，高田賢治

日本材料学会第65期学術講演会講演論文集 (日本材料学会)  No.406   97 - 98 2016.05

Research paper (scientific journal), Joint Work

後頭部衝突時における頭蓋内挙動のマルチボディダイナミクスモデル

大宮 正毅，鈴木 隆太郎，紙谷 武，星野 裕昭

日本機械学会関東支部第22期総会講演会講演論文集 (日本機械学会)  OS1302   1 - 2 2016.03

Research paper (scientific journal), Joint Work