研究者詳細 - 石原　大輔

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Modeling of cambering in insect’s flapping wings using finite element shell elements 査読有り

Minato Onishi, Daisuke Ishihara

Proceedings of the 38th JSST Annual International Conference on Simulation Technology 271 - 274 4pages 2019年11月

Computational control for strongly coupled Piezoelectric-Structure-Interaction 査読有り

Vinay Shankar, Daisuke Ishihara, Prakasha Chigahalli Ramegowda, Rei Takata, Tomoyoshi Horie

Proceedings of the 38th JSST Annual International Conference on Simulation Technology 275 - 278 4pages 2019年11月

昆虫羽ばたき飛行の特徴的な翼先端軌跡における流体構造連成現象の役割招待有り

石原大輔

昆虫と自然 ( ニュー・サイエンス社 ) 54 ( 8 ) 32 - 34 2019年07月

A novel coupling algorithm for the electric field–structure interaction using a transformation method between solid and shell elements in a thin piezoelectric bimorph plate analysis 査読有り

Ramegowda P., Ishihara D., Niho T., Horie T.

Finite Elements in Analysis and Design 159 33 - 49 2019年07月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Elsevier B.V. Thin piezoelectric bimorph cantilever is increasingly employed throughout the field of actuator and sensor applications in the microelectromechanical system (MEMS). Generally for finite element analysis of piezoelectric bimorph cantilever, three–dimensional (3D)solid element can accurately takes into account a linear or quadratic distribution of electric potential over the thickness for various electric configurations of the actuator and sensor applications. As the MEMS structures usually are quite thin and undergo large deformations, shell elements are very well suited for the structural discretization. This paper is focused on the development of a novel coupled algorithm to analyze the electromechanical coupling in a piezoelectric bimorph actuator and sensor using the shell and solid elements to simulate the structural and electric fields, respectively. The electric force induced by the inverse piezoelectric effect is transformed from the solid elements to the shell elements as an equivalent external force and moment, and the resultant displacements are transformed from the shell elements to the solid elements to evaluate the direct piezoelectric effect. Two different approaches were developed to analyze the electric field–structure interaction. In the first approach, for each block Gauss–Seidel (BGS)iteration, multiple full Newton–Raphson (N–R)iterations are executed until the tolerance criteria are satisfied. In the second approach, the BGS and N–R loops are unified into a single loop. A piezoelectric bimorph actuator and sensor were analyzed for various electrical configurations to demonstrate the accuracy of the proposed method.

DOI： 10.1016/j.finel.2019.02.001

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昆虫羽ばたき翼に生じるキャンバー生成のピクセルモデリング

大西南斗, 石原大輔, 二保知也, 堀江知義

第65回理論応用力学講演会・第22回土木学会応用力学シンポジウム講演論文集 331 - 332 2019年06月

Cycles of triply coupled mechanical contact, current, and thermal conduction phenomena during resistance spot welding 査読有り

Horie T., Niho T., Hayashi N., Ishihara D.

Welding in the World 63 ( 3 ) 701 - 713 2019年05月

記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019, International Institute of Welding. The characteristics of the cycles of coupled phenomena that occur among elastic-plastic contact deformation, current distribution, heat generation, and thermal conduction during resistance spot welding are examined using coupled finite element analyses. The current density peak that appears at the center of the interface moves outward along the interface to the high-contact resistance region, then the peaks in the current density, contact resistance, Joule heat generation, and temperature migrate outward with the contact edge followed by the melting zone during the welding process. The influence of welding parameters on the cycles of coupled phenomena is also examined. When the weld current is increased, the current density within the contact surface does not increase but enlarges the high-temperature region instead of heating the central part of the interface. When a small electrode force is applied, the nugget formation is initially enhanced not due to the increased contact resistance but rather because of the increase in the current density through the interface with a reduced contact area.

DOI： 10.1007/s40194-018-00699-5

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薄く柔軟な複合材圧電バイモルフのソリッド圧電‐シェル逆圧電分離反復型解法

石原大輔, プラカシャチガハリラメゴウダ, 高田黎, 二保知也, 堀江知義

計算工学講演会論文集 24 E-10-01 (2pages) 2019年05月

3枚重ね抵抗スポット溶接の構造・電流・熱伝導3 連成現象および接合強度におよぼす鋼板材質・板組の影響

二保知也, 金城喜己, 石原大輔, 堀江知義

計算工学講演会論文集 24 E-12-01 (2pages) 2019年05月

A Computational Study on the Fluid-Structure Interaction Mechanism in Insect Flapping Wings 査読有り

Daisuke Ishihara

Proceedings of The International Conference on Computational & Experimental Engineering and Sciences 21 ( 3 ) 66 - 66 2019年05月

構造‐圧電‐回路連成現象に対する有限要素解析手法の提案

高田黎, 石原大輔, Prakasha Chigahalli Ramegowda, 二保知也, 堀江知義

計算力学講演会講演論文集 ( 一般社団法人日本機械学会 ) 2019 ( 0 ) 2019年01月

記述言語：日本語掲載種別：研究論文（その他学術会議資料等）

A piezoelectric bimorph for actuators and sensors is usually connected to a circuit. The piezoelectric bimorph is affected by charge from the circuit in its mechanical behavior, and it also plays a role of a capacitor in the circuit. Therefore, the coupling of the piezoelectric bimorph and circuit as well as the structure - piezoelectric coupling should be taken into account in the design process of the actuators and sensors using the piezoelectric bimorph. Here, the novel finite element analysis method is proposed for this structure – piezoelectric – circuit coupled problem. Structural and piezoelectric analyses are performed using the finite element method with the shell and solid elements, respectively. Circuit analysis is a single degree of freedom. The coupled equations for the piezoelectric – circuit coupling is proposed from the continuous conditions for the electric potential and charge. The coupled algorithm is based on the block Gauss-Seidel method and a novel transformation method between the solid and shell variables. In the structural analysis, the rule of mixtures about the bending rigidity and the mass is used. In the piezoelectric analysis, the pseudo-piezoelectric evaluation method is used.

DOI： 10.1299/jsmecmd.2019.32.276

その他リンク： https://ci.nii.ac.jp/naid/130007817403

Pseudoelastic mesh–moving using a general scenario of the selective mesh stiffening 招待有り査読有り

Ishihara Daisuke, Goto Atsushi, Onishi Minato, Niho Tomoya, Horie Tomoyoshi

日本シミュレーション学会英文誌 ( 一般社団法人日本シミュレーション学会 ) 6 ( 1 ) 67 - 74 2019年01月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

The selective mesh stiffening in this study changes the stiffness of the element based on both the element area and shape. It includes the stiffening in the previous studies as a specific case, and leads to a general scenario in the pseudoelastic mesh–moving. This scenario gives better mesh quality in the mesh-moving of a rectangular domain with a structure consisting of a square and a fin undergoes large rotations. This is because the shear deformation of the element is adaptively considered.

DOI： 10.15748/jasse.6.67

その他リンク： https://ci.nii.ac.jp/naid/130007611945

抵抗スポット溶接の接触変形・電流・熱伝導3連成解析における変形効果の重要性

二保知也, 易新宇, 石原大輔, 堀江知義

計算力学講演会講演論文集 ( 一般社団法人日本機械学会 ) 2019 ( 0 ) 2019年01月

記述言語：日本語掲載種別：研究論文（その他学術会議資料等）

Resistance spot welding is widely used in manufacturing industries such as automotive industry. In this paper, we propose electric current analysis and thermal conduction analysis with deformation effect for resistance spot welding analysis. Effect of deformation on bonding strength and triply coupled effect for contact deformation, electric current and thermal conduction are discussed.

DOI： 10.1299/jsmecmd.2019.32.227

その他リンク： https://ci.nii.ac.jp/naid/130007817379

Partitioned method of insect flapping flight for maneuvering analysis 査読有り

Onishi M., Ishihara D.

CMES - Computer Modeling in Engineering and Sciences 121 ( 1 ) 145 - 175 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 Tech Science Press. All rights reserved. This study proposed a partitioned method to analyze maneuvering of insects during flapping flight. This method decomposed the insect flapping flight into wing and body subsystems and then coupled them via boundary conditions imposed on the wing’s base using one-way coupling. In the wing subsystem, the strong coupling of the flexible wings and surrounding fluid was accurately analyzed using the finite element method to obtain the thrust forces acting on the insect’s body. The resulting thrust forces were passed from the wing subsystem to the body subsystem, and then rigid body motion was analyzed in the body subsystem. The rolling, yawing, and pitching motions were simulated using the proposed method as follows: In the rolling simulation, the difference of the stroke angle between the right and left wings caused a roll torque. In the yawing simulation, the initial feathering angle in the right wing only caused a yaw torque. In the pitching simulation, the difference between the front- and back-stroke angles in both the right and left wings caused a pitch torque. All three torques generated maneuvering motion comparable with that obtained in actual observations of insect flight. These results demonstrate that the proposed method can adequately simulate the fundamental maneuvers of insect flapping flight. In the present simulations, the maneuvering mechanisms were investigated at the governing equation level, which might be difficult using other approaches. Therefore, the proposed method will contribute to revealing the underlying insect flight mechanisms.

DOI： 10.32604/cmes.2019.06781

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A coupled finite element analysis approach combining in-house and general-purpose codes 査読有り

Horie T., Niho T., Ishihara D.

IUTAM Bookseries 35 117 - 129 2019年01月

記述言語：英語掲載種別：研究論文（学術雑誌）

© Springer Nature Switzerland AG 2019. Coupled finite element analysis is expected in several fields of research and development, where necessity of coupled analysis of not only two phenomena but also three or more phenomena is increasing. The demand for multiscale and multiphysics analyses is also increasing. A coupled analysis approach that combines an in-house code and a general-purpose commercial finite element analysis code using a message passing interface is very promising for these analyses. To examine the practical usefulness and effectiveness, this approach was applied to the triply coupled and multiscale analyses of a resistance spot welding problem and to the dynamic coupled analysis of an ultra sonic piezoelectric motor. The approach is effective to perform various types of coupled finite element analyses of multiphysics and multiscale problems.

DOI： 10.1007/978-3-030-14883-6_7

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Solid piezoelectric-shell inverse piezoelectric partitioned analysis method for thin piezoelectric bimorph with conductor layers 査読有り

Takata R., Ishihara D., Ramegowda P., Niho T., Horie T.

Transactions of the Japan Society for Computational Engineering and Science ( 一般社団法人日本計算工学会 ) 2019 ( 0 ) 20190011 - 20190011 2019年01月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2019 by the Japan Society for Computational Engineering and Science. Piezoelectric bimorph for actuators and sensors is usually thin and includes conductor layers such as the electrode and the shim plate. Therefore, this study deals with the coupled piezoelectric and inverse-piezoelectric analysis of thin piezoelectric bimorph with the conductor layers. Solid elements can describe the various types of distributions of electric potential along the thickness, while shell elements are more appropriate to analyze the thin structures. Therefore, instead of using piezoelectric solid elements or piezoelectric shell elements for both the piezoelectric and inverse-piezoelectric analyses, the solid and shell elements are used to simulate the electrical and structural fields, respectively. The coupled algorithm is based on the block Gauss-Seidel method and the transformation method between the solid and shell variables. In the structural analysis, the rule of mixtures for the bending rigidity and the mass is used. A pseudo-piezoelectric evaluation method for the conductor is proposed in order to use the existing programs for the piezoelectric and inverse-piezoelectric analyses without any modification. Finally, it is demonstrated that the proposed method shows very accurate potential distributions in the actuator and sensor modes of the thin piezoelectric bimorph with the conductor layers.

DOI： 10.11421/jsces.2019.20190011

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昆虫羽ばたき翼に生じるキャンバー生成のピクセルモデリング

大西南斗, 石原大輔, 二保知也, 堀江知義

理論応用力学講演会講演論文集 ( 日本学術会議「機械工学委員会・土木工学・建築学委員会合同IUTAM分科会」 ) 65 ( 0 ) 2019年01月

記述言語：日本語掲載種別：研究論文（その他学術会議資料等）

昆虫羽ばたき翼におけるキャンバーは，空力性能の向上に重要な役割を果たす．ゆえにその生成メカニズムを解明する事は，昆虫はばたき飛行を理解するために重要である．昆虫はばたき翼のキャンバー生成における翅脈の力学的役割を解明するために，はりとシェルの有限要素を用いた形状簡略化モデルが提案されている．このモデルでは，必然的に不均一な要素分割を用いているため，流体構造連成解析の場合，ロバストなメッシュ制御方法が必要となり，計算コストがかなり高くなることが予想される．そこで本研究では，メッシュ制御を簡易化できるように，均一な要素分割を用いるピクセルモデルを提案する．本モデルでは，メッシュを均一なシェル要素により構成し，その剛性の違いにより，翅脈と翼膜の役割りを与える．先行研究のモデルとの比較を通じて，提案モデルの基本的妥当性について検討する．

DOI： 10.11345/japannctam.65.0_331

その他リンク： https://ci.nii.ac.jp/naid/130008100946

Finite element modeling of flexible piezoelectric energy harvester operating in air

RAMEGOWDA Prakasha Chigahalli, ISHIHARA Daisuke, TAKATA Rei, NIHO Tomoya, HORIE Tomoyoshi

計算力学講演会講演論文集 ( 一般社団法人日本機械学会 ) 2019 ( 0 ) 2019年01月

記述言語：日本語掲載種別：研究論文（その他学術会議資料等）

Piezoelectric energy harvesting from the mechanical vibrations has attracted considerable research interest in the last decade. This work presents a finite element modeling of forced vibration of flexible piezoelectric devices (FPED). The successful design of the FPED depends on the identification of the optimal geometry, material configurations, and loading conditions to achieve maximum power efficiency at a specific band of excitation frequencies. A piezoelectric energy harvesting (PEH) process from the mechanical vibration takes the form of two-way coupling between piezoelectric and inverse piezoelectric effect, while the piezoelectric energy harvesting from the ocean waves takes the form of three-way coupling between fluid, piezoelectric, and inverse piezoelectric effects. There are some experimental and theoretical studies about piezoelectric energy harvesting from the mechanical vibrations as-well as ocean waves in literature. Meantime, performing design optimization via experimental studies is very expensive. An accurate FE modeling of the coupling effects between the fluid, piezoelectric, and inverse piezoelectric effect will reduce the cost-effective design optimization and increase the energy efficiency of the PEH. In the present study, the FE analysis of FEPD is presented. The result obtained with the FE model is compared with the experimental model reported in the literature.

DOI： 10.1299/jsmecmd.2019.32.279

その他リンク： https://ci.nii.ac.jp/naid/130007817401

Role of fluid-structure interaction in generating the characteristic tip path of a flapping flexible wing 査読有り

Ishihara D.

Physical Review E 98 ( 3 ) 2018年09月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

© 2018 American Physical Society. This study shows that characteristic modes, such as the figure-eight mode, can be created in the path of the wing tip, which is caused by the fluid-structure interaction, using a flapping model wing with two lumped flexibilities describing the elevation motion as well as the pitching motion. A direct numerical simulation based on the three-dimensional finite element method for fluid-structure interaction (FSI) analyzes the behaviors of the model wing, the surrounding air, and their interaction, where the dynamic similarity law for the FSI is used to incorporate actual insect data, and the parallel computation algorithm is used to perform the systematic parametric study. Characteristic modes, such as the figure-eight mode, are observed in the path of the wing tip from the elevation motion of the simulated wing. This motion is considered as the forced vibration caused by the interaction with the surrounding fluid excited by the flapping of the wing. Therefore, this motion can be modulated by the flexibility to change the natural frequency, which can be controlled by the muscles at the base of the wing in the actual insect. The present simulation shows that the selection between these modes in the path of the wing tip depends on the ratio between the natural frequency of the elevation motion and the flapping frequency. In the case of the figure eight, the upward elevation motion of the wing acts on the leading-edge vortex (LEV) so as to keep its momentum upon stroke reversal. Therefore, this LEV can remain in the wake of the wing after stroke reversal and enhance the next LEV. Because of this effect, the lift increases significantly as the mode of the wing tip path shifts to the figure-eight mode. This understanding will contribute to a developed field of bioinspired micro air vehicles; i.e., it will reduce the complexity of electromechanical devices that prescribe entire motions of their wings.

DOI： 10.1103/PhysRevE.98.032411