Details of a Researcher - Omiya, Masaki

Papers - Omiya, Masaki

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混合モード負荷下における接着継手破壊じん性値に及ぼす接着長さの影響

大宮正毅，北川絢，今中誠，河野洋輔

日本材料学会第69期学術講演会講演論文集 (日本材料学会) 1 - 2 2020.05

Research paper (conference, symposium, etc.), Joint Work, Lead author, Corresponding author

A phase-field ductile fracture model with a variable regularization length parameter

Han J., Nishi S., Takada K., Muramatsu M., Omiya M., Ogawa K., Oide K., Kobayashi T., Murata M., Moriguchi S., Terada K.

Transactions of the Japan Society for Computational Engineering and Science (Transactions of the Japan Society for Computational Engineering and Science) 2020 1 - 15 2020

© 2020 by the Japan Society for Computational Engineering and Science. In the last decade, one of the gradient damage models called “phase-field fracture model” has been receiving attention. The model for brittle fractures has acquired great success, but that for ductile fractures is still under development. In this context, we propose a novel phase-field model with a variable regularization length parameter that is defined as an increasing function of the measure of the plastic strain. Since the regularization length parameter l representing the width of a diffuse crack is known to determine the damaged region around the crack, it has been modified so as to increase depending on the amount of plastic deformation. Thanks to this variable regularization length parameter l∗, the phase-field parameter d is calculated in consideration of the damage due to plastic deformation. The conventional elasto-plastic model with J2 theory in plasticity is employed and couple to our proposed phase-field model. Several numerical examples are conducted to demonstrate the capability of our proposed model and validate the introduction of l∗ in comparison with the experimental result.

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Role of size of rubber particles on failure mode and impact resistance characteristics of pc/abs blends and their abs constituents with a higher rubber content

M. Nizar M., Masaki O., Hirotsugu I., Kikuo K.

Defect and Diffusion Forum (Defect and Diffusion Forum) 402 DDF 1 - 6 2020

ISSN 10120386

© 2020 Trans Tech Publications Ltd, Switzerland. This study presents an experimental study on failure modes and resistances of polycarbonate (PC)/Acrylonitrile Butadiene Styrene (ABS) blends and their ABS constituents under a drop weight impact test (DWIT). Failure modes and impact resistances such as impact strength and impact toughness of such blends are generally influenced by molecular weight of the PC, rubber content and size of rubber particle in ABS system. A preliminary study on ABS materials using a DWIT showed that size of rubber particle not only determining their failure modes but also influencing their resistance characteristics. However, in a previous study performed using the similar DWIT on PC/ABS blends with a 10 wt% rubber content, it was revealed that size of rubber particle did not significantly influence their resistances. Their failure modes were even macroscopically very difficult to be distinguished. This study, hence, is aimed to further explore role of the size of rubber particle on failure mode and impact resistance characteristics of the PC/ABS blends and their ABS constituents with a higher rubber content. The impact test results have revealed that with a 20 wt% rubber content, size of rubber particle only influenced the resistances of the PC/ABS blends. It did not significantly contribute to affect failure mode of the PC/ABS blends. Whilst, it significantly influenced failure modes and resistances of the ABS. The DWIT results also re-confirmed that blending a brittle ABS into PC led to produce a tougher PC/ABS blend.

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R-curve behavior of adhesively bonded composite joints with highly toughened epoxy adhesive under mixed mode conditions

Kouno Y., Imanaka M., Hino R., Omiya M., Yoshida F.

International Journal of Adhesion and Adhesives (International Journal of Adhesion and Adhesives) 105 2020

ISSN 01437496

© 2020 Elsevier Ltd The fracture toughness of an adhesively bonded carbon fiber reinforced plastic joint under mixed mode (I and II) conditions was determined by means of the Fernlund–Spelt type double cantilever beam (DCB) test, where a rubber-modified epoxy adhesive was used. The R curves were determined by calculating the energy release rates, GI and GII, based on the beam theory, along with a finite element analysis. The total energy release rate GT (= GI + GII) strongly depended on the I–II mixed mode. This means that it remarkably increased with increasing mode-II component; furthermore, it varied with crack growth from GTC (at the onset of cracking) to GTS (at the steady crack-propagation region). The difference between GTC and GTS increased with the increase in the mode II component. Such R-curve characteristics were discussed based on observation of the fracture surfaces with a scanning electron microscope and the corresponding crack propagation-path behavior.

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Modelling and hydrogen-induced stress characterization of hydrogen-driven soft actuator using water splitting

Omiya M., Kurokawa M.

International Journal of Hydrogen Energy (International Journal of Hydrogen Energy) 46 ( 2 ) 2835 - 2843 2020

ISSN 03603199

© 2020 Hydrogen Energy Publications LLC Hydrogen production by water splitting is expected to be a significant power source in future because of its cleanness and environment-friendliness. In this study, an actuator driven by hydrogen produced by water splitting is studied and a hydrogen-induced stress model for a bimorph-type hydrogen actuator is developed. From the examination of the soft actuator having electrodes made of polyvinyl chloride with palladium electrode (Pd-PVC), the stress and bending moment induced by hydrogen absorption during water splitting are quantitatively evaluated. The results show that the thickness of the palladium electrode affects the mechanical performance of the Pd-PVC actuator, with the thinner palladium electrode showing a larger bending moment and tip displacement. A simple mechano-electro-chemical coupling equation is proposed to describe the relationship between bending moment, stress, and the electric charge used for water splitting. A palladium electrode soft actuator can work as a hydrogen generator/storage mechanism and as a mechanical actuator, and it can be useful for the power source of small systems or micro- or nano-devices.

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高分子基材上のパラジウム薄膜における水素吸蔵に伴うはく離解析

大宮正毅

日本機械学会M&M2019材料力学カンファレンス講演論文集 (日本機械学会) OS0211 1 - 4 2019.11

Research paper (conference, symposium, etc.), Single Work, Lead author, Last author, Corresponding author

画像相関法による混合モード下におけるCFRP/アルミニウム合金接着継手の破壊力学的強度評価

島本翔太，大宮正毅

日本機械学会2019年度年次大会講演論文集 (日本機械学会) J04116P 1 - 3 2019.09

Research paper (conference, symposium, etc.), Joint Work, Last author, Corresponding author

水素吸蔵型IPMCアクチュエータの変形特性

黒川正人，大宮正毅

日本機械学会2019年度年次大会講演論文集 (日本機械学会) S03136P 1 - 3 2019.09

Research paper (conference, symposium, etc.), Joint Work, Last author, Corresponding author

複数の3軸加速度センサを用いたトラック荷台挙動の推定

大宮正毅，梅原佑太，星野裕昭，高木雅広

日本包装学会第28回年次大会研究発表会予稿集 (日本包装学会) b-07 130 - 131 2019.07

Research paper (conference, symposium, etc.), Joint Work, Lead author, Corresponding author

Modelling of intracranial behaviour on occiput impact in judo

Suzuki R., Omiya M., Hoshino H., Kamitani T., Miyazaki Y.

Computer Methods in Biomechanics and Biomedical Engineering (Computer Methods in Biomechanics and Biomedical Engineering) 22 ( 8 ) 797 - 805 2019.06

ISSN 10255842

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. Acute subdural hematoma (ASDH) sometimes occurred in judo because of the bridging veins’ failure by rotation of the brain in the skull. However, the relationship between intracranial behaviour and the motion of the body on occiput impact has not yet been clarified. In this study, we developed an intracranial mechanical model based on multibody dynamics and compared it with experimental results. The results show the importance of modelling bridging veins and cerebral spinal fluid to the relative displacement between brain and skull. The proposed model will contribute to accident analyses or the optimum design of supporting devices.

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温度サイクル下における樹脂材料の疲労き裂進展特性

大宮正毅，渡辺悠介，榎本利章，小川賢介，小林卓哉

日本材料学会第68期学術講演会講演論文集 (日本材料学会) 704 1 - 2 2019.05

Research paper (bulletin of university, research institution), Joint Work, Lead author, Corresponding author

Determination of traction-separation laws on an acrylic adhesive under shear and tensile loading

Imanaka M., Omiya M., Taguchi N.

Journal of Adhesion Science and Technology (Journal of Adhesion Science and Technology) 33 ( 6 ) 646 - 659 2019.03

ISSN 01694243

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. Structural acrylic adhesives are of special interest because those adhesives are cured at room temperature and can be bonded to oily substrates. To use those adhesives widely for structural bonding, it is necessary to clarify the methodology for predicting strengths of bonding structures with those adhesives. Recently, cohesive zone models (CZMs) have been receiving intensive attentions for simulation of fracture strengths of adhesive joints, especially when bonded with ductile adhesives. The traction-separation laws under mode I and mode II loadings require to estimate fracture toughness of adhesively bonded joints. In this paper, the traction-separation laws of an acrylic adhesive in mode I and mode II were directly obtained from experiments using Arcan type adhesively bonded specimens. The traction-separation laws were determined by simultaneously recording the J-integral and the opening displacements in the directions normal and tangential to the adhesive layer, respectively.

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Estimation of static strength of adhesively bonded single lap joints with an acrylic adhesive under tensile shear condition based on cohesive zone model

Imanaka M., Omiya M., Taguchi N.

Journal of Adhesion Science and Technology (Journal of Adhesion Science and Technology) 33 ( 6 ) 660 - 674 2019.03

ISSN 01694243

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. In this study, the tensile shear and bending tests of adhesively bonded single lap joints with the acrylic adhesive was evaluated experimentally and numerically. In the previous paper, the traction-separation laws in mode 1 and mode 2 for an acrylic adhesive were directly obtained from the observation of failure process using Arcan type adhesively bonded specimens: simultaneous measurements of the J-integral and the opening displacements in the directions normal, δ n and tangential to the adhesive layer, δ s respectively. The experimental results were compared with numerical simulations conducted in ABAQUS including cohesive damage model. The cohesive laws obtained in the previous paper were simplified to trapezoidal shape from the experimentally obtained ones which were indicated in the previous paper. A good agreement was found between the experimental and numerical results. Then, to investigate the damage evolution in the adhesive layer for some lap joints, microscopic video observation was conducted near the end of the adhesive layer, and the video image have been compared with the contours of damage variable obtained by FEM corresponding to the video images. The observed damage evolution also agrees with the trend of damage variable.

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Development of fast computation algorithm for load transfer Ustar (U*) calculation in structures with slidable supports

高橋邦弘，櫻井俊彰，大宮正毅，槇徹雄

日本機械学会論文集 (日本機械学会) 85 ( 870 ) 18-00374 - 12 2019.01

Research paper (scientific journal), Joint Work, Accepted

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Investigation on simplified equation for estimating J-integral of adhesive joint and its application to galvannealed steel plate<sup>+</sup>1

Ogawa K., Maeda R., Kobayashi T., Yokoi E., Furusawa T., Takada K., Omiya M.

Materials Transactions (Materials Transactions) 60 ( 9 ) 1928 - 1935 2019

ISSN 13459678

© 2019 The Society of Materials Science, Japan Structural adhesives have been used to reduce weight and increase rigidity in recent automotive developments. This study focuses on the fracture behaviors of the cohesive zone under mixed-mode conditions, and a method for evaluation of the J-integral parameters using the displacement of the crack tip opening is proposed. The method is an application of the Dugdale model, which is known as an ideal model to work with a localized plasticity ahead of the crack tip. The validity of the method is verified through finite element analysis. Furthermore, the method is applied to adhesive joints on galvannealed steel, and its fracture mechanism is investigated.

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Investigation on simplified equation for estimating J-integral of adhesive joint and its application to galvannealed steel plate

Ogawa K., Maeda R., Kobayashi T., Yokoi E., Furusawa T., Takada K., Omiya M.

Zairyo/Journal of the Society of Materials Science, Japan (Zairyo/Journal of the Society of Materials Science, Japan) 67 ( 12 ) 1042 - 1049 2018.12

ISSN 05145163

2018 The Society of Materials Science, Japan Structural adhesives are used for the purpose of weight saving and rigidity improvement in recent automotive development. In this study, fracture behaviors of a cohesive zone under mixed-mode conditions were focused on, and an evaluation method for the parameters of J-integral using the crack tip opening displacement was proposed. The method is an application of the Dugdale model which is known as an idea to deal with localized plasticity region of a crack tip for adhesive joints. Validity of the method was verified using finite element analysis. Furthermore, the method was applied for adhesive joint on galvannealed steel and its fracture mechanism was investigated.

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Optimization of Vehicle Body Local Structure Using Load Transfer Ustar(U*) Calculation

本田正徳，秋間総，大宮正毅，高橋邦弘，櫻井俊彰，槇徹雄，中川興也

自動車技術会論文集 (自動車技術会) 49 ( 6 ) 1249 - 1254 2018.11

Research paper (scientific journal), Joint Work, Accepted

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Development of Theoretical Prediction Method Using Ustar (U*) for Stiffening Effect of Structures and Application to Determination of Stiffener Location for Passenger Car Bodies under Rapid Steering

高橋邦弘，依田叡門，南部佑太，櫻井俊彰，槇徹雄，大宮正毅

自動車技術会論文集 (自動車技術会) 49 ( 6 ) 1243 - 1248 2018.11

Research paper (scientific journal), Joint Work, Accepted

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Measurement of Output Force of Stacked Ionic Polymer Metal Composites (IPMC) Actuators

M. Kurokawa, M. Omiya

Proceedings of the Sixth Asian Conference on Mechanics of Functional Materials and Structures ，ACMFMS 2018 201 - 203 2018.10

Research paper (international conference proceedings), Joint Work, Last author, Corresponding author

画像相関法を利用した接着継手の破壊力学的強度評価

島本翔太，志水健人, 大宮正毅, 米山聡

日本機械学会2018年度年次大会講演論文集 (日本機械学会) J0470304 1 - 4 2018.09

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

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