Details of the Researcher

PHOTO

Keisuke Otsuka
Section
Graduate School of Engineering
Job title
Associate Professor
Degree

  • 博士（工学）（東北大学）

  • 修士（工学）（東北大学）

e-Rad No.
20881189
Profile

We are developing simulation methods for large deformation structures, such as next-generation aerospace systems. In particular, we are working on multibody and aeroelastic simulations using the Absolute Nodal Coordinate Formulation (ANCF), a type of large deformation finite element method. For details on ANCF, please see this open access paper.

https://doi.org/10.1115/1.4054113

 

Research History 6

  • 2023/04 - Present
    Tohoku University　Department of Aerospace Engineering　Associate Professor

  • 2024/01 - 2024/11
    The University of Iowa (US)　Visiting Scholar

  • 2020/04 - 2023/03
    Tohoku University　Department of Aerospace Engineering　Assistant Professor

  • 2019/06 - 2019/09
    Imperial College London (UK)　Visiting Research Student

  • 2017/04 - 2019/03
    Japan Society for the Promotion of Science　Research Fellow DC2

  • 2014/08 - 2015/06
    KTH Royal Institute of Technology (Sweden)　Exchange Student

Show all Show first 5

Education 3

  • Tohoku University　Graduate School of Engineering　Department of Aerospace Engineering, Doctoral Program

    2016/04 - 2020/03

  • Tohoku University　Graduate School of Engineering　Department of Aerospace Engineering, Master's Program

    2014/04 - 2016/03

  • Tohoku University　School of Engineering　Department of Mechanical and Aerospace Engineering

    2010/04 - 2014/03

Committee Memberships 7

  • 12th Asian Conference on Multibody Dynamics (ACMD2026) Scientific Committee

    2024/12 - Present

  • 35th International Symposium on Space Technology and Science (ISTS2025) Program Organizer　Session Organizer

    2024/11 - Present

  • 21st International Conference on Flow Dynamics (ICFD2024)　Session Organizer

    2024/01 - 2024/11

  • 20th International Conference on Flow Dynamics (ICFD2023)　Session Organizer

    2023/01 - 2023/11

  • 34th International Symposium on Space Technology and Science (ISTS2023) Program Organizer

    2022/11 - 2023/06

  • The 34th Symposium on Electromagnetics and Dynamics (SEAD34)　Organizer

    2021/12 - 2022/05

  • 14th International Conference on Flow Dynamics (ICFD2017)　Session Organizer

    2017/05 - 2017/10

Show all ︎Show first 5

Professional Memberships 4

  • American Society of Mechanical Engineers (ASME)

  • American Institute of Aeronautics and Astronautics (AIAA)

  • The Japan Society for Aeronautical and Space Sciences

  • The Japan Society of Mechanical Engineers

Research Interests 11

  • Planetary Exploration Aircraft

  • Mars Aircraft

  • AI

  • Deep Learning

  • Machine Learning

  • High Altitude Platform Station (HAPS)

  • Topology optimization

  • Wind tunnel experiment

  • Aeroelasticity

  • Floating Wind Turbine

  • Multibody dynamics

Research Areas 1

  • Aerospace, marine, and maritime Engineering / Aerospace engineering /

Awards 15

  1. Best Presentation Award for Young Researchers

    2023/11　20th International Conference on Flow Dynamics (ICFD2023)　"Simulation Framework for Wake-Induced Aeroelastic Phenomena"

  2. Intelligent Cosmos Research Award

    2023/05　Intelligent Cosmos Foundation　"Strain-Based Beam Model for Very Flexible Floating Wind Turbine"

  3. Trasnportation and Logistics Division Competition Award

    2023/03　The Japan Society of Mechanical Engineers　"Unified Flexible Multibody Dynamics for Transportation Systems"

  4. Best Poster Presentation Award

    2022/11　The 22ned International Symposium on Advanced Fluid Information (AFI-2022)　"Geometrically Nonlinear Beam Model for Slender Multibody Wings"

  5. R&D Award

    2022/11　NF Foundation　"Aeroelastic Analysis of Very Flexible Floating Wind Turbine"

  6. Research Award of The Japan Society of Mechanical Engineers

    2022/04　The Japan Society of Mechanical Engineers　"Multifidelity Analysis and Experiment of Deployable Wing Aircraft"

  7. Research Award

    2021/12　Aoba Foundation for Promotion of Engineering　"Movably-Nonlinear Modeling for Successive Analysis of Next-Generation Aircraft"

  8. Inoue Research Award for Young Scientists

    2021/02　Inoue Science Promotion Foundation　"Flexible Multibody Dynamics of Deployable Wing Aircraft"

  9. Best Presentation Award for Young Researchers

    2020/12　17th International Conference on Flow Dynamics (ICFD2020)　"Flexible Wing Fluid-Structure Interaction Model Coupling Unsteady Vortex Lattice Method and Absolute Nodal Coordinate Formulation"

  10. Audience Award

    2019/08　JSME Dynamics and Design Conference 2018　"Flexible Multibody Simulation for Deployable Morphing Wings"

  11. Young Researcher Award

    2018/08　The Japan Society for Aeronautical and Space Sciences　"Three-Dimensional Multibody Simulation Method based on Absolute Nodal Coordinate Formulation for Flexible Deployable Wings"

  12. Best Presentation Award for Students Session

    2016/10　13th International Conference on Flow Dynamics (ICFD2016)　"Deployment Simulation of Morphing Wing"

  13. Student Research Award

    2016/03　The Japan Society of Mechanical Engineers　"MBD Simulation of Morphing Wing Subjected to Unsteady Aerodynamic Force"

  14. Global Hagi Scholarship Award

    2014/07　Tohoku University　"KTH Royal Institute of Technology (Sweden) Exchange Study"

  15. Student Award

    2014/02　The Japan Society for Aeronautical and Space Sciences

Show all ︎Show 5

Papers 47

  1. Data-Driven Real-Time Topology Optimization Using Consistent Rotation-Based Moving Morphable Components International-journal Peer-reviewed

    Hirotani, S., Yaji, K., Makihara, K., Otsuka, K.

    AIAA Journal　(in press)　2025/12

    Publisher: AIAA

  2. Deep Learning for Constructing Ordinary Differential Equations in Hamiltonian Formulation of Multibody Systems International-journal Peer-reviewed

    Dong, S., Kuzuno, R., Makihara, K., Otsuka, K.

    Mechanics Research Communications　(in press)　2025/10

    Publisher: Elsevier

  3. Nonlinear Dynamic Analysis Framework for Slender Structures Using the Modal Rotation Method International-journal Peer-reviewed

    Shizuno, Y, Dong, S, Kuzuno, R, Okada, T, Kawashima, S, Makihara, K, Otsuka, K

    ASME Journal of Computational and Nonlinear Dynamics　20　(2)　021002　2025/03

    Publisher: ASME

    DOI： 10.1115/1.4067201 　

    More details Close

    Owing to their low induced drag, high-aspect-ratio wings are often applied to aircraft, particularly high-altitude long-endurance (HALE) aircraft. An analytical method that considers geometrical nonlinearity is necessary for the analysis of high-aspect-ratio wings as they tend to undergo large deformations. Nonlinear shell/plate or solid finite element methods are widely used for the static analysis of wing strength. However, an increase in the number of elements drastically increases the computational costs owing to the complexity of wing shapes. The modal rotation method (MRM) can avoid this additional expense by analyzing large deformations based on modes and stiffness matrices obtained from any linear or linearized model. However, MRM has only been formulated as a static analysis method. In this study, a novel modal-based dynamic analysis framework, referred to as dynamic MRM (DMRM), is developed to analyze slender cantilever structures. This paper proposes a method to discretize dynamics by capitalizing on the fact that MRM considers geometrical nonlinearity based on deformed shapes. The proposed method targets slender structures with small strains and large displacements and considers geometrical nonlinearity, but not material nonlinearity. Additionally, a formulation method for the work performed by a follower force is proposed. The energy stored in the structure agreed with the work performed by an external force in each performed simulation. DMRM achieved a 95% reduction in the calculation time compared with a nonlinear plate finite element method in a performed simulation.

  4. Moving Morphable Components Using Strain-Based Beam Geometry Description for Topology Optimization International-journal International-coauthorship Peer-reviewed

    Otsuka, K, Yamashita, H, Sugiyama, H, Dong, S, Kuzuno, R, Makihara, K

    AIAA Journal　62　(12)　4846-4854　2024/12

    Publisher: AIAA

    DOI： 10.2514/1.J064272 　

  5. Piezoelectric Flutter Energy Harvesting: Absolute Nodal Coordinate Formulation Model and Wind Tunnel Experiment International-journal International-coauthorship Peer-reviewed

    Mukogawa T., Shimura, K., Dong, S., Fujita, K., Nagai, H., Kameyama, M., Shi, Y., Jia, Y., Soutis, C., Kurita, H., Narita, F., Hara, Y., Makihara, K., Otsuka, K.

    Mechanics Research Communications　143　104351　2024/11

    Publisher: Elsevier BV

    DOI： 10.1016/j.mechrescom.2024.104351 　

    ISSN： 0093-6413

    More details Close

    This study proposes a new flutter harvesting analysis framework based on an absolute nodal coordinate formulation (ANCF) model that includes a nonlinear finite element method, a three-dimensional unsteady vortex lattice method that considers nonlinearities, and a piezoelectric equation. Because conventional studies assumed no extensionality of the neutral axis, use of flutter harvester configurations was restricted. However, this framework using the ANCF model can be applied to different configurations (e.g., extensible harvesters with fixed-fixed boundaries or multibody harvesters). The feasibility of the proposed method was verified by conducting wind tunnel experiments. The frequencies, root mean square (RMS) displacements, and RMS voltages of the analysis and experiment were compared. The difference between experiment and analysis was 23% in terms of frequencies. One of the reasons for the difference was viscous drag. Although the results were not a perfect match, the introduction of a viscous drag model will be considered in future studies to enhance this framework.

  6. Moving Morphable Multi Components Introducing Intent of Designer in Topology Optimization International-journal International-coauthorship Peer-reviewed

    Otsuka, K, Dong, S, Kuzuno, R, Sugiyama, H, Makihara, K

    AIAA Journal　61　(4)　1720-1734　2023/04

    Publisher: AIAA

    DOI： 10.2514/1.J062210 　

    More details Close

    Topology optimization based on moving morphable components efficiently generates a topology that is expressed by a few geometrical design variables. However, conventional moving morphable components have three problems: lack of C1 continuity between components, difficulty in describing a smooth rollup shape, and difficulty in generating a rigid joint to an optimized topology. In this study, a novel topology optimization framework was developed by introducing theories devised for multibody analysis. First, an adaptive moving morphable component based on absolute nodal coordinate formulation was proposed. Because both the position and gradient are used as design variables, C1 continuity is ensured. Second, a position and gradient connection algorithm leveraging the linear constraint of the absolute nodal coordinate formulation was proposed to describe the smooth rollup shape. Third, a rigid joint was generated by introducing the gradient constraint equation in an optimizer. The developed framework exhibited superior convergence as compared with the conventional one in the benchmark short beam problem. It successfully generated an optimal topology with the intent of a designer (that is, designer-selected topology continuity and rigid joints), which facilitated the assembly and manufacturing of topologically optimized structural members to construct an entire aerospace structure.

  7. Joint Parameters for Strain-Based Geometrically Nonlinear Beam Formulation: Multibody Analysis and Experiment International-journal Peer-reviewed

    Otsuka, K, Dong, S, Fujita, K, Nagai, H, Makihara, K

    Journal of Sound and Vibration　538　(117241)　2022/11

    DOI： 10.1016/j.jsv.2022.117241 　

    More details Close

    A novel singularity-free, tuning-free, and reduced-order strain-based beam formulation is developed for analyzing slender multibody systems such as folding wing aircraft and offshore wind turbines that perform large rigid body motions and geometrically nonlinear deformations. Conventional linear deformation models are not suitable for the analysis, whereas the strain-based beam formulation has a potential to describe the geometrically nonlinear deformation efficiently using a small number of strain variables and a constant stiffness matrix obtained from a recursive equation. However, it suffers from singularity, penalty-coefficient tuning, and many variables when applied to multibody systems. This study addressed these problems by proposing joint parameters. Singularity-free joint parameters introduced in the recursive equation produce a novel velocity transformation that removes coefficient tuning and achieves model reduction. We demonstrate that the proposed method can perform a more stable multibody analy is compared to that using the conventional method. Further, we measured the strain of the folding wing during deployment in a wind tunnel at the Institute of Fluid Science, Tohoku University to validate the strain-based beam formulation with the proposed joint parameters. The strain of the proposed method is in good agreement with that of the wind tunnel experiment, wherein the folding wing performed multibody dynamic motion with geometrically nonlinear deformation.

  8. Consistent Strain-Based Multifidelity Modeling for Geometrically Nonlinear Beam Structures International-journal International-coauthorship Peer-reviewed

    Otsuka, K, Wang, Y, Fujita, K, Nagai, H, Makihara, K

    ASME Journal of Computational and Nonlinear Dynamics　17　(11)　111003　2022/11

    DOI： 10.1115/1.4055310 　

    More details Close

    Conventional multifidelity modeling for slender structures such as folding-wing aircrafts and offshore wind turbines does not allow the generation of multiple fidelity models that consistently use the same external force model, which complicates simulation program and design process. Although consistent absolute nodal coordinate formulation (ANCF)-based multifidelity modeling was recently proposed to address this inconsistency, it still has the following four problems: (1) a large number of generalized coordinates, (2) a large number of Lagrange multipliers, (3) difficulty in constraining high-frequency axial deformation, and (4) a lack of lower-fidelity models. The lower-fidelity models that have not yet been developed are torsion-only beam, extension-only truss, and bending-only beam models. The objective of this study was to develop a novel consistent strain-based multifidelity modeling framework that addresses these problems by leveraging new vector-strain transformations from ANCF to the strain-based beam formulation. We employed a hydrodynamic force model based on Morison's equation as an example to demonstrate all fidelity models obtained from the proposed strain-based framework consistently use the same external force model. We conducted five simulations to verify the proposed models. The consistent external force model for the hydrodynamic force was then validated by comparison with experimental data. The simulation results concurred with those of conventional models and experiments. Low-fidelity models exhibited over 98% reduction in calculation time compared to high-fidelity models, which helps in conceptual and initial designs that require a large number of parametric simulations.

  9. Strain-Based Geometrically Nonlinear Beam Formulation for Rigid-Flexible Multibody Dynamic Analysis International-journal International-coauthorship Peer-reviewed

    Otsuka, K, Wang, Y, Palacios, R, Makihara, K

    AIAA Journal　60　(8)　49-4968　2022/08

    DOI： 10.2514/1.J061516 　

    More details Close

    Geometrically nonlinear strain-based beam formulation has the potential to analyze flexible slender components in multibody systems efficiently owing to the minimum number of variables and constant stiffness matrix. The objective of this study is to develop a multibody dynamic analysis framework based on the strain-based beam formulation. To this end, we describe the constraint equation using the vector variables of the absolute nodal coordinate formulation that exhibits a velocity-transformation relationship with the strain-based formulation. Subsequently, we divide the Jacobian of the constraint equation into two terms. One term is equivalent to the velocity transformation matrix that is currently implemented in the existing strain-based analysis framework. The other term is a simple constant or linear Jacobian defined based on the orthonormal vectors of the absolute nodal coordinate formulation. This simple Jacobian description integrates the strain-based beam formulation with multibody dynamic theories to handle open- and closed-loop joints. The obtained numerical results validate that the proposed strain-based multibody dynamic analysis method concurs well with and exhibits a better convergence than the conventional flexible multibody dynamic analysis method.

  10. Recent Advances in the Absolute Nodal Coordinate Formulation: Literature Review from 2012 to 2020 International-journal International-coauthorship Peer-reviewed

    Otsuka, K, Makihara, K, Sugiyama, H

    ASME Journal of Computational and Nonlinear Dynamics　17　(8)　080803　2022/08

    DOI： 10.1115/1.4054113 　

    More details Close

    Absolute nodal coordinate formulation (ANCF) is a non-incremental nonlinear finite element procedure that has been successfully applied to the large deformation analysis of multibody systems for more than two decades. Although a comprehensive review on ANCF was conducted by Gerstmayr, et al. in 2013, significant theoretical developments have been made since then at a much faster pace to improve the element accuracy and computational efficiency. In order to overview recent advances in ANCF simulation capabilities that are not covered in the first review paper, this paper aims to conduct a comprehensive review of 259 papers concerning ANCF published from 2012 through 2020. It is shown that the ANCF element library has grown substantially for beam, plate/shell, solid elements, eliminating drawbacks of ANCF elements developed earlier. The application areas have extended, especially in the aerospace field, and the enhanced ANCF simulation capabilities have been demonstrated in solving challenging engineering problems. Research efforts have been made continually to integrate computer-aided design (CAD) and analysis with ANCF elements. Furthermore, computational improvements and multiphysics simulations have become major research topics for ANCF. It is also demonstrated that the accurate ANCF geometry description can be exploited to facilitate structural optimization of multibody systems.

  11. Aeroelastic Simulation of High-Aspect Ratio Wings with Intermittent Leading-Edge Separation International-journal International-coauthorship Peer-reviewed

    Wang, Y., Zhao, X., Palacios, R., Otsuka, K.

    AIAA Journal　60　(3)　1769-1782　2022/03

    DOI： 10.2514/1.J060909 　

    More details Close

    We present a medium-fidelity aeroelastic framework for computing intermittently separating three-dimensional (3-D) flows around high-aspect ratio wings with a significantly reduced computational cost compared to the computational-fluid- dynamics-based method. To achieve that, we propose a modified three-dimensional vortex panel method with leading-edge separation controlled by leading-edge suction parameter theory, and its incorporation in a coupled aeroelastic solver for the dynamic response of these systems. Numerical verifications and simulations are presented on both attached and separated aeroelastic test cases, demonstrating the method on postflutter limit-cycle oscillation of a cantilever wing, and leading-edge separation on a deploying wing, a complex kinematic response. In both cases we were able to capture three-dimensional interactions on intermittently separating dynamic flowfields using a low computational cost.

  12. Nonlinear Aeroelastic Analysis of High-Aspect-Ratio Wings with a Low-Order Propeller Model International-journal International-coauthorship Peer-reviewed

    Otsuka, K., Del Carre, A., Palacios, R.

    AIAA Journal of Aircraft　59　(2)　293-306　2022/03

    DOI： 10.2514/1.C036285 　

    More details Close

    A nonlinear aeroelastic analysis framework for high-aspect-ratio wings that includes the aerodynamic effects of propellers is described. The high computational cost required for modeling aerodynamic interaction between the wing and propeller wake is reduced by taking advantage of the relatively slow dynamics of the wing. Consequently, the propeller wake is modeled as a straight vortex cylinder that does not require a computationally expensive wake updating process. By leveraging the smallness of the propeller, an averaged vortex cylinder method is proposed that calculates the induced velocities of the propeller vortex cylinder efficiently without suffering from a numerical singularity and loss of accuracy. The induced velocities are considered in the wing aerodynamic force calculation using an unsteady vortex lattice method. An efficient propeller cylinder coordinate generation method modeling the propeller-attached wing by absolute nodal coordinate formulation with a multibody dynamic theory is also proposed. The developed framework is validated by comparison with other formulations. A static aeroelastic analysis on a low-speed high-aspect-ratio wing demonstrates that the propeller-induced axial velocity causes the deflection change of 5.4%. A nonlinear dynamic result shows that the propeller decreases the vibration amplitude by 6.7% because the propeller-induced axial velocity enhances the aerodynamic damping.

  13. Three-Dimensional Aeroelastic Model for Successive Analyses of High-Aspect-Ratio Wings International-journal International-coauthorship Peer-reviewed

    Otsuka, K., Wang, Y., Makihara, K.

    ASME Journal of Vibration and Acoustics　143　(6)　061006　2021/12

    Publisher: ASME International

    DOI： 10.1115/1.4050276 　

    ISSN： 1048-9002

    eISSN： 1528-8927

    More details Close

    Next-generation civil aircraft and atmospheric satellites will have high-aspect-ratio wings. Such a design necessitates successive analysis of static, frequency, and time-domain dynamic responses based on a three-dimensional nonlinear beam model. In this study, a new successive-analysis framework based on an absolute nodal coordinate formulation with mean artificial strains (ANCF-MAS) is developed. While retaining the advantages of other 3D ANCF approaches, such as constancy of the mass matrix and absence of velocity-dependent terms, ANCF-MAS uses the elastic force of the mean artificial strains to remove cross-sectional deformations that cause locking problems. The equation becomes a differential equation with an easily linearized elastic force that enables not only static and dynamic analyses but also frequency analysis using standard eigenvalue solvers. The solutions converge to the analytical frequencies without suffering from locking problems. A proposed successive-analysis method with model-order reduction reveals that the frequencies vary with the nonlinear static deformation because of the 3D deformation coupling. This reduced-order model agrees well with nonlinear models even when the wing experiences a large nonlinear dynamic deformation.

  14. Absolute Nodal Coordinate Formulation with Vector-Strain Transformation for High Aspect Ratio Wings International-journal International-coauthorship Peer-reviewed

    Otsuka, K., Wang, Y., Makihara, K.

    ASME Journal of Computational and Nonlinear Dynamics　16　(1)　011007　2021/02

    DOI： 10.1115/1.4049028 　

    More details Close

    High aspect ratio wings are potential candidates for use in atmospheric satellites and civil aircraft as they exhibit a low induced drag, which can reduce the fuel consumption. Owing to their slender and light weight configuration, such wings undergo highly flexible aeroelastic static and dynamic deformations that cannot be analyzed using conventional linear analysis methods. An aeroelastic analysis framework based on the absolute nodal coordinate formulation (ANCF) can be used to analyze the static and dynamic deformations of high aspect ratio wings. However, owing to the highly nonlinear elastic force, the statically deformed wing shape during steady flight cannot be efficiently obtained via static analyses. Therefore, an ANCF with a vector-strain transformation (ANCF-VST) was proposed in this work. Considering the slender geometry of high aspect ratio wings, the nodal vectors of an ANCF beam element were transformed to the strains. In this manner, a constant stiffness matrix and reduced degrees of freedom could be generated while capturing the highly flexible deformations accurately. The ANCF-VST exhibited superior convergence performance and accuracy compared to those of analytical approaches and other nonlinear beam formulations. Moreover, an aeroelastic analysis flow coupling the ANCF-VST and an aerodynamic model based on the unsteady vortex lattice method was proposed to perform the static and dynamic analyses successively. The proposed and existing aeroelastic frameworks exhibited a good agreement in the analyses, which demonstrated the feasibility of employing the proposed framework to analyze high aspect ratio wings.

  15. Versatile Absolute Nodal Coordinate Formulation Model for Dynamic Folding Wing Deployment and Flutter Analyses International-journal International-coauthorship Peer-reviewed

    Otsuka, K., Wang, Y., Makihara, K.

    ASME Journal of Vibration and Acoustics　141　(1)　011014　2019/02/01

    DOI： 10.1115/1.4041022 　

    ISSN： 1048-9002

    eISSN： 1528-8927

  16. Multifidelity Modeling of Deployable Wings: Multibody Dynamic Simulation and Wind Tunnel Experiment International-journal International-coauthorship Peer-reviewed

    Otsuka, K., Wang, Y., Fujita, K., Nagai, H., Makihara, K.

    AIAA Journal　57　(10)　4300-4311　2019

    DOI： 10.2514/1.J058676 　

    ISSN： 0001-1452

  17. Absolute Nodal Coordinate Beam Element for Modeling Flexible and Deployable Aerospace Structures International-journal Peer-reviewed

    Otsuka, K., Makihara, K.

    AIAA Journal　57　(3)　1343-1346　2019

    DOI： 10.2514/1.J057780 　

    ISSN： 0001-1452

  18. Deployment Simulation Using Absolute Nodal Coordinate Plate Element for Next-Generation Aerospace Structures International-journal Peer-reviewed

    Otsuka, K., Makihara, K.

    AIAA Journal　56　(3)　1266-1276　2018

    DOI： 10.2514/1.J056477 　

    ISSN： 0001-1452

  19. Deployable Wing Model Considering Structural Flexibility and Aerodynamic Unsteadiness for Deployment System Design International-journal International-coauthorship Peer-reviewed

    Otsuka, K., Wang, Y., Makihara, K.

    Journal of Sound and Vibration　408　105-122　2017/11/10

    DOI： 10.1016/j.jsv.2017.07.012 　

    ISSN： 0022-460X

    eISSN： 1095-8568

  20. Aeroelastic Deployable Wing Simulation Considering Rotation Hinge Joint Based on Flexible Multibody Dynamics International-journal Peer-reviewed

    Otsuka, K., Makihara, K.

    Journal of Sound and Vibration　369　147-167　2016/05/12

    DOI： 10.1016/j.jsv.2016.01.026 　

    ISSN： 0022-460X

    eISSN： 1095-8568

  21. Parametric Studies for the Aeroelastic Analysis of Multibody Wings International-journal Peer-reviewed

    Otsuka, K., Makihara, K.

    Transactions of JSASS, Aerospace Technology Japan　14　(ists30)　Pc_33-Pc_42　2016

    Publisher: THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

    DOI： 10.2322/tastj.14.Pc_33 　

    More details Close

    Air density on Mars is much lower than that on Earth. To generate sufficient lifting force to fly, Mars-airplanes need to have a larger wing area than Earth-airplanes. The recently developed Mars-airplanes have multibody wings that can be folded and deployed to realize larger wing area and compactness. Aeroelastic analyses of the wings are necessary to avoid catastrophic behaviors, such as flutter or divergence. However, conventional aeroelastic analysis methods cannot be applied to the multibody wing because these wings have mechanical joints for connecting wing bodies, and thus, they differ significantly from conventional wings. In this paper, a new analysis method that can be applied to the multibody wing is explained. The method combines aerodynamics, multibody dynamics theory, and absolute nodal coordinate formulation. By using this method, we simulate the aeroelastic motion of multibody wings. We investigate the changes in aeroelastic motion when we change the number of the wing bodies and the structural parameters.

  22. Reduced-Order Modeling of Hamiltonian Formulation in Flexible Multibody Dynamics: Theory and Simulations International-journal Peer-reviewed

    Dong, S., Kuzuno, R., Otsuka,K., Makihara,K.

    Applied Mathematical Modelling　114　116055　2025/08

    Publisher: Elsevier

    DOI： 10.1016/j.apm.2025.116055 　

    More details Close

    Flexible multibody dynamics has been developed as an effective method for analyzing mechanical structures, wherein the Hamiltonian formulation draws attention for advantages such as the systematic handling of systems with varying mass. However, the utilization of the finite element method typically results in a large number of variables, which deteriorates computational efficiency. An effective method to reduce the number of variables (coordinates and canonical conjugate momentum) in Hamiltonian formulation needs to be presented. This paper proposes a novel reduced-order modeling of the Hamiltonian formulation based on the component mode synthesis method. A novel definition of momentum is proposed to construct the equation of motion. Compared with conventional Hamiltonian formulations, not only generalized coordinates but also momentum is reduced. By combining the absolute nodal coordinate formulation with the proposed formulation, it is applicable to analyze nonlinear structures with large deformation and rotations. Four numerical simulations were conducted to evaluate the performance of the proposed formulation, and calculation time reductions of 52.1 %, 83.6 %, 93.4 %, and 81.5 % were achieved. Overall, the proposed Hamiltonian formulation exhibits high calculation efficiency, good numerical stability, and high accuracy.

  23. Support Vector Machine Framework for Detecting Ambiguous Contours of Space Debris Cloud International-journal Peer-reviewed

    Morimoto, D, Takahashi, H, Sugiyama, Y, Otsuka, K, Ohtani, K, Hasegawa, S, Makihara, K

    AIAA Journal of Spacecraft and Rockets　(in press)　2025/01

    Publisher: AIAA

  24. Statistically-Oriented Optimal Control and Disturbance Prediction for Piezoelectric Semi-Active Vibration Suppression International-journal Peer-reviewed

    Abe, M, Mishima, K, Hara, Y, Otsuka, K, Makihara, K

    IEEE Transactions on Control Systems Technology　(in press)　2025/01

    Publisher: IEEE

  25. System Identification of Multi-Degree-of-Freedom Structures Subject to Unmeasurable Periodic Disturbances Using a Piezoelectric Device International-journal Peer-reviewed

    Tang, T, Hara, Y, Meng, Z, Otsuka, K, Makihara, K

    Journal of Evolving Space Activities　(in press)　2025/01

  26. Semi-Active Structural Excitation Method to Realize Energy-Saving On-Orbit Identification International-journal Peer-reviewed

    Hara, Y, Tang, T, Otsuka, K, Makihara, K

    Journal of Evolving Space Activities　2　125　2024/12

    Publisher: JSASS

    DOI： 10.57350/jesa.125 　

    More details Close

    On-orbit identification has more stringent technical constraints than on-ground identification due to the operational environment. In particular, the amount of energy consumption is severely limited. This study proposes a novel identification method that does not consume a lot of energy and does not use input sequence information. The proposed method adopts piezoelectric semi-active control to excite a structural vibration and a covariance-driven stochastic subspace identification (SSI-COV) method. The piezoelectric semiactive control temporarily converts mechanical energy into electrical energy and then excites structural vibration using the temporarily converted electrical energy. Therefore, this is an energy-saving excitation method. Since the SSI-COV method identifies the structural model under the assumption that the input sequence is white noise, it identifies the structural model without any input information. We proposed a semi-active input generation method such that the properties of the semi-active input will be equivalent to those of the white noise. We validated the proposed method through numerical simulations and experiments. To explore the feasibility of the proposed method, this study employs a simple two-degree-of-freedom structure instead of a complex continuum structure. The proposed method identified the modal parameters of the structure and consumed only 68 mJ.

  27. High-Fidelity Flexible Multibody Model Considering Torsional Deformation for Nonequatorial Space Elevator International-journal Peer-reviewed

    Kuzuno, R, Dong, S, Takahashi, Y, Okada, T, Xue, C, Otsuka, K, Makihara, K

    Acta Astronautica　220　504-515　2024/07

    Publisher: Elsevier

    DOI： 10.1016/j.actaastro.2024.05.008 　

    More details Close

    Space elevators are a promising technology for future space transportation. The primary component of a space elevator is a tether deployed from a geostationary orbit towards the Earth and into deep space. Payloads can be transported using a climber moving along the tether. However, obtaining a deeper comprehension of the precise dynamics of a space elevator is challenging. The tether could have various deformations such as elongation, bending, and torsion owing to its flexible nature and the low level of vibration damping in space. Therefore, understanding those effects on the tether is essential for the design concept of a space elevator. Reproducing the behavior of space tether systems on the ground is challenging, which is primarily due to the scale of the system and the difficulty of accurately replicating a space environment. Thus, high-fidelity numerical analysis methods are required to analyze the dynamic response of space elevators precisely. Previously proposed analysis models of space tether systems with climbers have focused on elongation, bending, and rigid body motion of the tether, and the effect of torsional deformation has been neglected. However, a tether can be twisted easily owing to its low torsional stiffness. This study established high-fidelity numerical simulation models for space elevators considering large deformations including the torsion of a tether. This study developed a flexible multibody model with a moving climber using the absolute nodal coordinate formulation with 14 degrees of freedom. Further, the gravitational perturbation caused by the non-sphericity of the Earth was considered. Using the constructed model, the motion and deformation of nonequatorial space elevators caused by the climber motion and the disturbance in the space environment were investigated. The obtained results indicate that gravitational perturbation can induce torsional deformation, particularly at higher anchor latitudes.

  28. State Observer of Multibody Systems Formulated Using Differential Algebraic Equations International-journal Peer-reviewed

    Okada, T, Dong, S, Kuzuno, R, Takahashi, Y, Shizuno, Y, Hara, Y, Otsuka, K, Makihara, K

    Multibody System Dynamics　61　(2)　2024/06

    Publisher: Springer

    DOI： 10.1007/s11044-024-09995-z 　

    More details Close

    Multibody dynamics comprises methodologies for the design and analysis of mechanical systems, with Kalman filters being the principal state estimation methods. The Kalman filters are generally formulated for unconstrained systems, the dynamics of which are described by ordinary differential equations in state-space models. However, multibody systems are constrained systems, and the commonly used method to describe their dynamics involves using differential algebraic equations (DAEs) comprising differential and algebraic equations. The differential equations also include the Lagrange multipliers. Hence, incorporating multibody systems, described by DAEs into the scheme of Kalman filters, cannot be achieved straightforwardly, which facilitates different strategies being addressed. This study develops a novel method for converting DAEs into a state-space model. A transition model of the time derivatives of Lagrange multipliers and a Lagrange multiplier constraint vector are devised and used in the state and output equations, respectively. The continuous- and discrete-time extended Kalman filters (CEKF and DEKF) are constructed using the proposed state-space model, and state estimations are simulated on the benchmark planar four- and five-bar linkages. Further, a demonstration of system observability is conducted, and sensitivity to the initial state estimates is studied. These tests demonstrate that the proposed state-space model achieves observable systems and that both the CEKF and DEKF, constructed using the proposed state-space model, can estimate the states with a wide range of initial conditions.

  29. A Novel and Efficient Hamiltonian Dynamic Analysis Approach for Constraint Force Determination in Flexible Multibody Systems International-journal Peer-reviewed

    Dong, S, Kuzuno, R, Otsuka, K, Makihara, K

    Journal of Sound and Vibration　588　118517　2024/05

    Publisher: Elsevier

    DOI： 10.1016/j.jsv.2024.118517 　

    More details Close

    In the dynamic analysis of flexible multibody systems, Hamiltonian formulations offer advantages in numerical stabilization and systematic handling of systems with varying mass. However, current approaches face challenges. Differential algebraic equations (DAEs) can directly express constraint forces but are computationally inefficient, while ordinary differential equations (ODEs) are more computationally efficient but cannot directly represent constraint forces due to the elimination of the Lagrange multiplier. This paper presents an innovative and efficient dynamic analysis approach based on the Hamiltonian formulation, incorporating velocity transformation and open-constraint coordinate methods. Compared to conventional DAE-based Hamiltonian formulations, our approach conducts analysis efficiently using only independent variables. Compared to conventional ODE-based Hamiltonian formulations, our approach effectively expresses constraint forces through Lagrange multiplier reformulation. Furthermore, when compared to the traditional ODE-based Lagrangian formulation, our approach exhibits superior computational efficiency. Numerical simulations assess our proposed formulation, showing agreement with conventional formulations, shorter calculation time, and alignment with analytical results, confirming the accuracy and usefulness of our approach.

  30. Comparison of Magnetostrictive-Actuated Semi-Active Control Methods Based on Synchronized Switching International-journal Peer-reviewed

    Li, A, Kobayashi, Y, Hara, Y, Otsuka, K, Makihara, K

    Actuators　13　(4)　143-143　2024/04/12

    Publisher: MDPI

    DOI： 10.3390/act13040143 　

    eISSN： 2076-0825

    More details Close

    Three distinct synchronized switching circuits based on a magnetostrictive actuator are compared in this paper to examine their control mechanisms and circuit characteristics. These circuits include a semi-active shunt circuit, a semi-active current inversion and amplification circuit, and a semi-active automatic current inversion and amplification circuit. Each circuit type employs an additional electronic switch. The synchronized switching method enables the rational control of the circuit current generated by the magnetostrictive actuator to fulfill any desired control strategy. Simulation and experimental results on a 10-bay truss structure reveal that the three circuits can effectively adjust the polarity of the induced current as needed. The three circuits are then compared to thoroughly analyze their unique characteristics and explain their respective advantages and dis-advantages. Using the comparison results, various options available for control circuit design are demonstrated.

  31. Numerical Study Using Nonlinear Finite-Element Methods Based on Green–Lagrange Strain for Dynamics and Statics of Nonequatorial Space Elevator International-journal Peer-reviewed

    Kuzuno, R, Dong, S, Takahasi, Y, Okada, T, Shizuno, Y, Otsuka, K, Makihara, K

    Journal of Evolving Space Activities　2　197　2024

    DOI： 10.57350/jesa.197 　

    More details Close

    A space elevator consists of a climber, counterweight, and primary structure: the tether. Recently, a nonequatorial space elevator has gained attention owing to its ability to extend the construction range and avoid collisions with spacecraft in the geostationary orbit. Previous research on the tether of the nonequatorial space elevator constructed low-fidelity models, such as a rigid body or a spring–mass system, despite the complexity of its dynamics. This study newly introduced a nonequatorial space elevator model using the Green–Lagrange strain in a nodal position finite-element method and flexible multibody dynamics model for a nonequatorial space elevator formulated via the absolute nodal coordinate formulation, which ensures C1 continuity and bending in the element. Based on the constructed models, this study investigated the primary geometrical factors in the analysis of a nonequatorial space elevator. It also examined the static effect of climber position and the dynamics of the climber's descent in a nonequatorial space elevator. The investigation revealed the cause of the higher-order oscillations occurring in the tether of the nonequatorial space elevator, which are absent in the equatorial configuration.

  32. Fractional-Order Modelling and Dynamic Analysis on a Typical Beam Structure with a Semi-active Particle Damping Equipment International-journal International-coauthorship Peer-reviewed

    Xue, C, Ye, J, Kuzuno, R, Otsuka, K, Makihara, K, Xia, Z

    Powder Technology　433　119219　2024/01

    Publisher: Elsevier

    More details Close

    Semi-active particle damping equipments exhibit considerable adaptability when implemented in flexible structures. However, their dynamic characteristics become complex due to the presence of a substantial quantity of particles within the damping equipment, and the influence of the internal magnetic field necessitates careful consideration. The fractional-order model of this kind of equipment is established, wherein the designed parameters kp and α are respectively associated with the filling ratio and the input current. Depending on the Hertz-Mindlin contact model, the multi-body dynamic issues inner the damping equipment are addressed using the Discrete Element Method, and then the fractional-order parameters kp and α are identified based on the energy distribution observed within a single vibration period. The numerical simulations, conducted using the fractional-order model, show a fundamental consistency with the experimental results. This alignment serves to validate the accuracy and feasibility of the fractional-order model. Finally, the fractional-order model is utilized to investigate the optimized value of the input current and to analyze the motion trajectory of the damping equipment under various scenarios. The results indicate that the optimized input current is approximately 2.5 A; and as the parameter kp and α increase, the motion trajectory of the system will rotate in a counterclockwise direction, accompanied by a gradual outward displacement of the outermost curve relative to the origin position.

  33. Establishment of Iterative Modeling Method for Spherical Tensegrity Structure Using Rotational Symmetry and Regular Polyhedron Configuration International-journal Peer-reviewed

    Mori, E, Matsumoto, Y, Kawabata, N, Otsuka, K, Makihara, K

    Mechanics Research Communications　135　104217　2024/01

    Publisher: Elsevier

    DOI： 10.1016/j.mechrescom.2023.104217 　

    More details Close

    Tensegrity structures are attractive light-weight structures. In particular, spherical tensegrity structures are expected to be applied in various fields. This article proposes a simple method for modeling spherical tensegrities. Firstly, the nodal coordinates of the spherical tensegrity are systematically determined based on rotational symmetry and regular polyhedral configuration. This approach enables the systematic acquisition of the nodal coordinates of spherical tensegrities of all sizes by introducing a three-dimensional rotation matrix and the dihedral angle of the regular polyhedron. Secondly, the prestress ratio is determined iteratively. For the stability analysis of the spherical tensegrity, nonlinear analysis with prestress is required. For the analysis considering the prestress, a tangent stiffness matrix is applied in this study. The simple determination method enables the modeling of spherical tensegrities. The natural frequencies and mode shapes of the spherical tensegrity are identified by frequency analysis. A vibration experiment is conducted as a verification experiment. The natural frequencies from the analysis are compared to the resonance frequencies from the experiment. This comparison confirms the validity of the frequency analysis results, based on the two proposed methods.

  34. Magnetostrictive-Based Induced Current Inversion and Amplification: Semi-Active Vibration Suppression for Multiple-Degree-of-Freedom Flexible Structures with Zero Energy Consumption International-journal Peer-reviewed

    Li., A, Kobayashi, Y, Hara, Y, Otsuka, K, Makihara, K

    Journal of Sound and Vibration　568　118069　2024/01

    Publisher: Elsevier

    DOI： 10.1016/j.jsv.2023.118069 　

    More details Close

    Vibration suppression technology is indispensable in the operation of multiple-degree-of-freedom (MDOF) structures. Properties such as a light weight and reliability are essential for an MDOF structure. However, truss structures tend to be flexible and susceptible to vibration from external influences. Hence, vibration suppression for MDOF flexible structures is necessary. This paper proposes a new semi-active vibration suppression method with a magnetostrictive transducer that can be applied to vibration suppression of an MDOF flexible structure. The proposed method is achieved through an electrical control circuit consisting a magnetostrictive transducer, an inversion capacitor, an electronic switch, and diodes. The control input of the proposed method is considered the induced current. With strategic selection of the circuit statuses, the amplitude of the induced current can be inversed and amplified. Our proposed control strategy is to control the circuit statuses so that the vibration suppression performance can be as effective as possible. The control strategy is determined based on the vibration displacement and velocity of the structure. Numerical simulations were performed to predict the vibration suppression performance. Subsequently, validation experiments were performed using a vibrating cantilevered truss structure, which was considered an MDOF structure composed of many aluminum bar members and iron joints. Under various experimental conditions, the proposed method achieved suppression rates of 12.1–26.7%. The results validated that the proposed method is more effective than a conventional passive method for the vibration suppression of an MDOF flexible structure. The proposed method may aid in ensuring the safe operation of MDOF flexible structures, such as trusses, under extreme conditions.

  35. Multibody Constraints in the Geometrically-Nonlinear Intrinsic Formulation International-journal International-coauthorship Peer-reviewed

    Wang, Y, Otsuka, K

    ASME Journal of Computational and Nonlinear Dynamics　18　(12)　121007　2023/12

    Publisher: ASME

    DOI： 10.1115/1.4063724 　

    More details Close

    The intrinsic formulation for geometrically-nonlinear beam dynamics provides a compact and versatile description of slender beam-like structures. With nonlinearities limited to second-order couplings in the formulation, it has been an attractive choice in formulating nonlinear reduced-order models for dynamic analysis and control design in aeroelasticity problems involving large displacements and rotations. Owing to its rotation-free formalism, the intrinsic formulation has not been formulated to accommodate multibody constraints, limiting its use against multibody structures with kinematic constraints. This work aims to address such weakness as we present developments in introducing multibody constraints into the full and reduced-order intrinsic equations while still preserving the beneficial traits of the method. We describe the resolution of displacement-level constraints using index-1 approach and adaptation of constraint stabilisation strategies to the intrinsic formulation using state projection. The numerical behaviour of the full- and reduced-order implementations are assessed using test cases with large static and dynamic deformations with time-domain simulations to demonstrate validity of the approach.

  36. Performance of Magnetostrictive Small Wind Turbine using Fe–Co Base Clad Films International-journal Peer-reviewed

    Ueno, T, Nakaki, T, Mukogawa, T, Dong, S, Kurita, H, Otsuka, K, Makihara, K, Narita, F

    Advanced Engineering Materials　25　(19)　2300185　2023/07

    Publisher: John Wiley

    More details Close

    In this study, the Fe–Co alloy was combined with cobalt ferrite (CoFe2O4) and nickel (Ni) to form Fe–Co/CoFe2O4 and Fe–Co/Ni clad sheets and their energy-harvesting performance was evaluated. The Fe–Co/CoFe2O4 clad sheet exhibited an output voltage of 4.229 mV and an output power of 6.89 nW at a wind speed of 10 m/s. The energy-harvesting performance of both these clad sheets could not be quantitatively compared owing to their different thicknesses, which result in varying volume and distance from the neutral plane. Nevertheless, the values of output voltage and power for Fe–Co/CoFe2O4 were higher than those for Fe–Co/Ni (2.107 mV and 0.294 nW).

  37. Energy Harvesting Using Magnetostrictive Transducer Based on Switch Control International-journal International-coauthorship Peer-reviewed

    Li, A, Goto, K, Kobayashi, Y, Hara, Y, Jia, Y, Shi, Y, Soutis, C, Kurita, H, Narita, F, Otsuka, K, Makihara, K

    Sensors and Actuators: A. Physical　355　114303　2023/06

    Publisher: Elsevier

    DOI： 10.1016/j.sna.2023.114303 　

    ISSN： 0924-4247

  38. Hamiltonian Formulation with Reduced Variables for Flexible Multibody Systems Under Linear Constraints: Theory and Experiment International-journal Peer-reviewed

    Dong, S, Otsuka, K, Makihara, K

    Journal of Sound and Vibration　547　117535　2023/03

    Publisher: Elsevier

    DOI： 10.1016/j.jsv.2022.117535 　

    More details Close

    Mechanical structures, such as robot arms in space stations and rockets that are used to support futuristic activities and carry loads in modern society, tend to be flexible owing to their reduced weight. Flexible multibody dynamics is an effective method for analyzing the dynamic motion of flexible structures. Although the Hamiltonian formulation based on the canonical theory is commonly used in multibody dynamics, certain drawbacks exist, such as complexity and computational cost. In this study, a novel flexible multibody dynamics formulation based on canonical theory is proposed with reduced variables to improve computational efficiency. This method formulates the equation of motion using only independent generalized coordinates with the assumption of linear constraint equations and the introduction of the first derivative of the constraint condition. The proposed method is combined with absolute nodal coordinate formulation and the motions of flexible structures are simulated to verify its accuracy and effectiveness. In comparison with the conventional methods, the proposed method requires less calculation time while maintaining accuracy. In addition, a wind tunnel experiment was conducted to validate the proposed method. The concurrence between the simulation and experimental results further verifies the accuracy of the proposed method.

  39. Low-Energy-Consumption Structural Identification with Switching Piezoelectric Semi-Active Input International-journal Peer-reviewed

    Hara, Y, Otsuka, K, Makihara, K

    Mechanical Systems and Signal Processing　187　(109914)　2023/03

    Publisher: Elsevier

    DOI： 10.1016/j.ymssp.2022.109914 　

    More details Close

    Herein, we propose a structural system identification method that uses semi-active inputs generated from piezoelectric transducers. Previous onsite structure identification methods consumed significant amounts of energy to generate input signals and thus could not be actively implemented. The proposed method consumes less energy to generate input signals during identification. Two problems limit the use of semi-active inputs for identification purposes: (1) a control strategy to generate semi-active inputs suitable for identification does not exist, and (2) the polarity of the semi-active input cannot be freely controlled. To solve the first issue, we constructed a semi-active input generation strategy that matches the polarities of semi-active inputs with target signals appropriate for identification. To address the second problem, the mechanism by which polarity control is possible and impossible is clarified based on an analytical solution of a semi-active input generation circuit. A data calibration method focusing on sign similarity was proposed to improve the identification accuracy when polarity control cannot be implemented. The proposed semi-active identification method successfully identified the frequency response of a structure using 98% lesser energy than that used by conventional active methods. The proposed method was validated through simulations and experiments. The proposed method achieved accurate identification and can be used for onsite structural health monitoring.

  40. Strategy for Performance Improvement in Piezoelectric Semi-Active Structural System Identification by Excluding Switching Failures using Pseudo-State Feedback International-journal Peer-reviewed

    Hara, Y, Tang, T, Otsuka, K, Makihara, K

    Mechanical Systems and Signal Processing　187　(109906)　2023/03

    Publisher: Elsevier

    More details Close

    System identification in vibrating structures is useful for structural health monitoring. Onsite structural system identification must be achieved with low energy consumption. Accordingly, semi-active inputs should be considered to apply onsite system identification because they can be generated with low energy consumption. However, conventional identifications that use semi-active inputs could not continuously generate inputs suitable for system identification because of switching failure. Switching failure is caused by the mechanism of the semi-active input generation circuit. Due to switching failure, properties of semi-active inputs deviate from the property suitable for identification. Their results deviate from the results obtained using suitable inputs. Moreover, semi-active identification could not be used for structural health monitoring because they cannot determine the cause of significant variations in the identification results (either because of system identification faults from switching failure or because of structural damage). To solve these drawbacks of semi-active identification, we propose a new strategy to generate semi-active inputs that can realize ideal identification. The proposed strategy has two novelties compared to conventional semi-active identification methods: (1) The strategy prevents switching failures and continuously provides semi-active inputs suitable for identification. (2) The strategy is modeled as an optimization problem and provides appropriate circuit control to generate semi-active inputs suitable for identification by solving binary search. Numerical simulations and experiments confirm that the proposed strategy exhibits better identification performance than the conventional strategies. In addition, small variances are observed in the identification results in all time domains. The semi-active inputs generated by the proposed strategy can contribute to precise structural health monitoring using onsite structural identification because it provides accurate identification results with less variation and energy consumption.

  41. Semi-Active Switching Vibration Control with Tree-Based Prediction and Optimization Strategy International-journal Peer-reviewed

    Abe, M, Hara, Y, Otsuka, K, Makihara, K

    Journal of Intelligent Material Systems and Structures　34　(4)　440-460　2023/03

  42. Self-Sensing Method for Semi-Active Structural Identification by Removing Piecewise Bias from Piezoelectric Voltage International-journal Peer-reviewed

    Hara, Y, Tang, T, Otsuka, K, Makihara, K

    Sensors and Actuators A: Physical　347　113907-113907　2022/11

    Publisher: Elsevier

    DOI： 10.1016/j.sna.2022.113907 　

    ISSN： 0924-4247

    More details Close

    Structural system identification (SSI) that uses many actuators and sensors will be more accessible as a sensing technology if the number of these devices decreases. Recently, a semi-active SSI using a piezoelectric transducer and a unique semi-active input generation circuit was proposed. The semi-active SSI outperforms conventional SSIs with low energy consumption. If the semi-active input and its vibration response are estimated from the voltage generated by a piezoelectric transducer, some sensors will become redundant. Conventional self-sensing methods estimate structural vibrations without using vibration sensors. The semi-active SSI in combination with the self-sensing method will be more accessible than current technologies from the perspectives of a lower energy consumption and fewer number of devices. However, the following two problems exist: (1) A semi-active input generation circuit cannot introduce conventional hardware-based self-sensing methods with additional electric circuits because the electrical components in the additional circuits degrade the performance of the piezoelectric transducer. (2) Software-based self-sensing methods, such as the Kalman filter, cannot be used in system identification scenarios because the electromechanical parameters and models are unknown. To overcome these drawbacks, a novel software-based self-sensing method that does not require electromechanical models is proposed in this paper, and the effectiveness of the proposed method is thoroughly investigated using both simulations and experiments. The identification performance of the proposed method using the estimated input and output is the same as that using directly measured data. The proposed method can especially contribute to the predictive maintenance of structures in isolated environments.

  43. Dynamics and Energy Analysis of Nonequatorial Space Elevator Using Three-Dimensional Nonlinear Finite Element Method Extended to Noninertial Coordinate System International-journal Peer-reviewed

    Kuzuno, R, Dong, S, Okada, T, Otsuka, K, Makihara, K

    IEEE Access　10　43964-43980　2022/05

    Publisher: IEEE

    DOI： 10.1109/ACCESS.2022.3168666 　

    More details Close

    A space elevator is a futuristic space transportation technology that enables low-cost and versatile payload transportation using climbers on a tether deployed from the geostationary orbit (GEO). In particular, a nonequatorial space elevator, which contains an anchor in a region with latitudes on the Earth, has recently attracted attention. It has several advantages, such as extending the construction range and avoiding collisions with spacecraft in the GEO. Prior research has focused on rigid-body or spring-mass models with low fidelity. This paper proposes a modeling method for nonequatorial space elevators using a nodal-position finite element method (NPFEM) extended to a rotational coordinate system. The NPFEM is a three-dimensional finite element method that considers geometric nonlinearity. Conventional NPFEMs have only been formulated using inertial coordinate systems. This paper proposes a method to formulate the NPFEM in a noninertial coordinate system and derive the inertial forces and Jacobian matrices. In addition, a three-dimensional analysis of a nonequatorial space elevator was performed based on the proposed method. After determining the equilibrium position of the NPFEM, the dynamic response of the tether during climber ascent was analyzed. Moreover, parametric studies were conducted by varying several properties of the nonequatorial space elevator. Furthermore, the energy exchange between the components was analyzed to validate the proposed method and to discuss the energy perspective of the space elevator. The results revealed that the proposed nonequatorial space elevator model experienced a more tensioned equilibrium and exhibited a more significant dynamic response than conventional models.

  44. Comprehensive Predictive Control for Vibration Suppression Based on Piecewise Constant Input Formulation International-journal Peer-reviewed

    Takamoto, I., Abe, M., Hara, Y., Otsuka, K., Makihara, K.

    Journal of Intelligent Material Systems and Structures　33　(7)　901-917　2022/04

    DOI： 10.1177/1045389X211038703 　

    More details Close

    We propose a novel semi-active vibration suppression method based on model predictive control (MPC). Semi-active vibration suppression provides excellent damping performance, energy consumption, and stability during control. As the semi-active control input is often discontinuous, it may be difficult to predict. Hence, we combine semi-active vibration suppression and MPC to determine the control input trajectory arbitrarily. The proposed method, called predictive switching based on piecewise constant input (PSPCI), assumes that the piezoelectric charge remains constant when the control circuit is in the open state. Under this assumption, the future system state can be predicted for semi-active vibration suppression while reducing the computational load. The PSPCI method predicts the future work done by the transducer and effectively suppresses vibrations. Its effectiveness and robustness are demonstrated through simulations and experiments. The proposed PSPCI method enables the prediction of the semi-active control input and diversifies the control input determination for effective semi-active vibration suppression.

  45. Adaptive and Robust Operation with Active Fuzzy Harvester under Nonstationary and Random Disturbance Conditions International-journal Peer-reviewed

    Hara, Y., Otsuka, K., Makihara, K.

    Hara, Y.; Otsuka, K., ;Makihara, K.　21　(11)　3913　2021/06

    Publisher: MDPI

    DOI： 10.3390/s21113913 　

    More details Close

    The objective of this paper is to amplify the output voltage magnitude from a piezoelectric vibration energy harvester under nonstationary and broadband vibration conditions. Improving the transferred energy, which is converted from mechanical energy to electrical energy through a piezoelectric transducer, achieved a high output voltage and effective harvesting. A threshold-based switching strategy is used to improve the total transferred energy with consideration of the signs and amplitudes of the electromechanical conditions of the harvester. A time-invariant threshold cannot accomplish effective harvesting under nonstationary vibration conditions because the assessment criterion for desirable control changes in accordance with the disturbance scale. To solve this problem, we developed a switching strategy for the active harvester, namely, adaptive switching considering vibration suppression-threshold strategy. The strategy adopts a tuning algorithm for the time-varying threshold and implements appropriate intermittent switching without pre-tuning by means of the fuzzy control theory. We evaluated the proposed strategy under three realistic vibration conditions: a frequency sweep, a change in the number of dominant frequencies, and wideband frequency vibration. Experimental comparisons were conducted with existing strategies, which consider only the signs of the harvester electromechanical conditions. The results confirm that the presented strategy achieves a greater output voltage than the existing strategies under all nonstationary vibration conditions. The average amplification rate of output voltage for the proposed strategy is 203% compared with the output voltage by noncontrolled harvesting.

  46. Piezoelectric Energy Enhancement Strategy for Active Fuzzy Harvester with Time-Varying and Intermittent Switching International-journal Peer-reviewed

    Hara, Y., Zhou, M., Li, A., Otsuka, K., Makihara, K.

    Smart Materials and Structures　30　(1)　015038　2021/01/01

    Publisher: IOP Publishing

    DOI： 10.1088/1361-665x/abca08 　

    ISSN： 0964-1726

    eISSN： 1361-665X

    More details Close

    This study aims to increase the amount of electrical energy harvested from a piezoelectric vibration energy harvester under unloaded and high-load resistance conditions. Although increased piezoelectric charge due to the synchronized switch harvesting on inductor (SSHI) strategy damps mechanical vibrations, the mechanical vibration amplitude of a mechanical element in a harvester is assumed to be constant for most discussions regarding the active harvester with SSHI strategy. However, this assumption is not valid under excessive switching actions, in which case the performance of the harvester deteriorates. This problem is known as the vibration suppression effect. To address this problem, in this study, two switching strategies for the charge inversion circuit—namely, switching considering vibration suppression-threshold (SCVS-t) and adaptive SCVS-t (ASCVS-t)—are proposed through intermittent switching actions. During the harvesting process, intermittent switching using these strategies is performed based on the output voltage threshold, thus maintaining high mechanical vibration amplitude and excellent harvesting performance by avoiding excess switching. The ASCVS-t adopts a tuning algorithm for the time-varying threshold and can achieve appropriate intermittent switching and effective harvesting under various vibration conditions without pre-tuning. Experimental comparisons with conventional strategies confirm that the proposed strategies achieve 2.9 times and 2.0 times greater harvested energy storages than a standard harvester and conventional switching strategy, respectively.

  47. Predictive Switching Vibration Control Based on Harmonic Input Formulation International-journal Peer-reviewed

    Takamoto, I., Abe, M., Hara, Y., Nakahara, T., Otsuka, K., Makihara, K.

    Sensors and Actuators, A: Physical　315　112271　2020/11/01

    Publisher: Elsevier

    DOI： 10.1016/j.sna.2020.112271 　

    ISSN： 0924-4247

Show all ︎Show first 5

Books and Other Publications 1

  1. Analysis Model Selection to Capture Important Physics "What is Fidelity?"

    Keisuke Otsuka

    The Japan Society of Mechanical Engineers　2022/06

    DOI： 10.1299/jsmemag.125.1243_40 　

Presentations 126

  1. Moving Wide Bezier Components with Constrained Ends-Based Evolutionary Topology Optimization for Turbulent Pipe Systems International-presentation

    Kazuya Urata, Kentaro Yaji, Kikuo Fujita, Keisuke Otsuka

    The 16th World Congres of Structural and Multidisciplinary Optimization (WCSMO-16)　2025/05/20

  2. Analysis of Thermal Problems Using Machine Learning

    Ryo Kato, Atsuto Okuyama, Soraki Eguchi Yushin Hara, Kanjuro Makihara Keisuke Otsuka

    JSME conference　2025/03/17

  3. MMC-Based Topology Optimization Using Machine Learning

    Motonobu Kawai, Shuonan Dong, Ryo, Kuzuno Yoshitaka Shizuno Taiki, Okada Naruya Nagai, Shugo Kawashima, Kanjuro Makihara Keisuke Otsuka

    JSME conference　2025/03/17

  4. Thermal Load Estimation Using Machine Learning International-presentation

    Atsuto Okuyama, Ryo Kato, Soraki Eguchi, Yushin Hara, Kanjuro Makihara, Keisuke Otsuka

    21st International Conference on Flow Dynamics (ICFD2024)　2024/11/18

  5. Nonlinear Aeroelastic Simulation Framework with Machine Learning for High Aspect Ratio Wings International-presentation International-coauthorship

    Kento Shimura, Hao He, Hiroki Yamashita, Hiroyuki Sugiyama, Yoshiaki Abe, Takanori Haga, Keisuke Otsuka

    21st International Conference on Flow Dynamics (ICFD2024)　2024/11/18

  6. Absolute Nodal Coordinate Formulation for Nonlinear Multibody Modeling of Flared Hinged Wings International-presentation International-coauthorship

    Keisuke Otsuka, Chi Wing Cheng, Rafael Palacios

    34th Congress of the International Council of the Aeronautical Sciences (ICAS2024)　2024/09/09

    More details Close

    The wings of transport jets are becoming high aspect ratio to reduce induced drag. Because of the high aspect ratio configuration with lightweight, the wings may undergo nonlinear large deformations induced by aerodynamic forces. To alleviate excessive large deformation under gust conditions, flared hinged wings have been developed. This study develops a new multibody simulation framework for the flared hinged wings based on absolute nodal coordinate formulation (ANCF). In this framework, the constraint equation to describe the flared hinge joint can be written in a simple linear equation. We show that the simulation results of ANCF simulation framework is in good agreement with those of a second simulation framework, namely SHARPy, based on a conventional geometrically-exact beam formulation (GEBF)

  7. Multibody Analysis Comparison between Strain-Based Beam Formulation and Absolute Nodal Coordinate Formulation International-presentation International-coauthorship

    Keisuke Otsuka, Hiroyuki Sugiyama

    International Conference on Multibody System Dynamics (IMSD2024)　2024/06/12

    More details Close

    he wings of recent regional jet tend to have high aspect ratio to reduce induced drag. Because of the high aspect ratio configuration with lightweight, the wings undergo large deformations induced by aerodynamic forces. In addition, such high aspect ratio wings experience very high wing root bending moment when they encounter gust. To alleviate the gust response, a folding wing concept was proposed. When designing the high aspect ratio wings with the folding wing mechanism, a multibody simulation considering geometric nonlinearity is necessary. Owing to the slenderness of the high aspect ratio wing, geometrically nonlinear beam formulations are suitable for the simulation. In this study, two geometrically nonlinear beam formulations are compared in multibody simulations. One is absolute nodal coordinate formualtion (ANCF) and the other is strain-based beam formulation (SBBF). The major difference of them is that ANCF has a constant mass matrix, while SBBF has a constant stiffness matrix.

  8. Moving Morphable Components based on Strain-Based Beam Formulation for Topology Optimization International-presentation International-coauthorship

    Keisuke Otsuka, Shuonan Dong, Ryo Kuzuno, Hiroyuki Sugiyama, Kanjuro Makihara

    AIAA SciTech 2024 Forum　2024/01/08

    More details Close

    Moving morphable component (MMC) framework is a topology optimization method that can directly impose geometrical constraints by using geometrical parameters as design variables, which can enhance the manufacturability of topologically optimized structures. Curvature is a significant geometrical parameter in designing structures because curved topology tends to have less stress concentration than sharp topology, and it is difficult to manufacture excessively curved topology. Therefore, imposing specific constraints on curvature is important. However, conventional MMCs cannot impose curvature constraints directly because they do not use curvature as a design variable. To address this issue, we propose a curvature-based component that possesses curvature as a design variable. The proposed component leverages the curvilinear geometry representation of the strain-based beam formulation, which was originally developed to analyze large deformation of slender structures. However, the geometry representation produces poor convergence and asymmetric topology even when symmetric boundary and load conditions are considered because the origin of the curvilinear coordinate is placed on a curved geometry asymmetrically. Therefore, we propose a symmetric curvature-based component that considers curvilinear coordinates in the negative and positive directions symmetrically. Further, it is demonstrated that the use of a direction vector is better suited than that of a trigonometric function to define the direction of the curvilinear coordinates. We extend the components to multi-curvature-based components that can express more complicated topology. We demonstrate that the proposed components can easily impose the curvature constraints in a benchmark problem, which could enhance the manufacturability of topologically optimized structures.

  9. Analysis-Oriented Moving Morphable Components for Topology Optimization International-presentation

    Keisuke Otsuka, Shuonan Dong, Ryo Kuzuno, Kanjuro Makihara

    AIAA SciTech 2023　2023/01/25

    More details Close

    Topology optimization based on moving morphable components efficiently generates a topology that is expressed by a few geometrical design variables. However, conventional moving morphable components have three problems: lack of C1 continuity between components, difficulty in describing a smooth roll-up shape, and difficulty in generating a rigid joint to an optimized topology. In this study, a novel topology optimization framework was developed by introducing theories devised for multibody analysis. First, an adaptive moving morphable component based on absolute nodal coordinate formulation was proposed. Because both the position and gradient are used as design variables, C1 continuity is ensured. Second, a position and gradient connection algorithm leveraging the linear constraint of the absolute nodal coordinate formulation was proposed to describe the smooth roll-up shape. Third, a rigid joint is generated by introducing the gradient constraint equation in an optimizer. The developed framework exhibited superior convergence compared with the conventional one in the benchmark short beam problem. It successfully generated an optimal topology with the intent of a designer, that is, designer-selected topology continuity and rigid joints, which facilitates the assembly and manufacturing of topologically optimized structural members to construct an entire aerospace structure.

  10. Strain-Based Geometrically Nonlinear Beam Formulation for Multibody Dynamic Analysis International-presentation International-coauthorship

    Keisuke Otsuka, Yinan Wang, Rafael Palacios, Kanjuro Makihara

    AIAA Scitech 2022 Forum　2022/01/04

    More details Close

    The geometrically nonlinear strain-based beam formulation has the potential to analyze flexible multibody systems efficiently due to the minimum number of variables and the constant stiffness matrix. The objective of this paper is to extend the strain-based beam formulation to a generic multibody dynamic analysis. To achieve this objective, we describe the constraint equation by using the vector variables of the absolute nodal coordinate formulation that has a velocity-transformation relationship with the strain-based formulation. Then, we divide the Jacobian of the constraint equation into two terms. One term is equivalent to the velocity transformation matrix that has been implemented in the existing strain-based analysis framework. Therefore, additional programming effort and calculation are not needed. The other term is a simple constant or linear Jacobian defined by the orthonormal vectors of the absolute nodal coordinate formulation. This simple Jacobian description enables not only efficient analysis but also various choice of a time-integration method. We demonstrated that the proposed framework can be used with the explicit Runge-Kutta method and the implicit generalized-α method. The proposed strain-based multibody dynamic analysis method exhibited good agreement with and a better convergence than a conventional flexible multibody dynamic analysis method.

  11. Unsteady Aeroelasticity of Slender Wings with Leading-Edge Separation International-presentation International-coauthorship

    Yinan Wang, Xiaowei Zhao, Rafael Palacios, Keisuke Otsuka

    AIAA Scitech 2021 Forum　2021/01

    More details Close

    We present a medium-fidelity aeroelastic framework for computing intermittently separating 3D flows around slender aero-structures with a significantly reduced computational cost than CFD-based method. In which, we propose a modified 3D vortex panel method with leading-edge separation controlled by the leading-edge suction parameter theory, and demonstrate its incorporation in a coupled aeroelastic solver for the dynamic response of these systems. Numerical verifications and simulations are presented on both attached and separated aeroelastic test cases, demonstrating the capability of the proposed method.

  12. Nonlinear Static and Dynamic Analysis Framework for Very Flexible Multibody Aircraft with Propellers International-presentation International-coauthorship

    Keisuke Otsuka, Alfonso del Carre, Rafael Palacios

    AIAA Scitech 2021 Forum　2021/01

    More details Close

    A nonlinear static and dynamic aeroelastic analysis framework for high aspect ratio wings with propellers is described. The aerodynamic effect of propellers is considered. The high computational cost required for modeling aerodynamic interaction between the wing and propeller wake is reduced by taking advantage of the relatively slow dynamics of the wing. Consequently, the propeller wake is modeled as a straight vortex cylinder that does not require a computationally expensive wake updating process. By leveraging the smallness of the propeller, we propose an averaged vortex cylinder method that calculates the induced velocities of the propeller vortex cylinder efficiently without suffering from a numerical singularity and loss of accuracy. The induced velocities are considered in the wing aerodynamic force calculation using an unsteady vortex lattice method. We also propose an efficient propeller cylinder coordinate generation method modeling the propeller-attached wing by absolute nodal coordinate formulation with a multibody dynamic theory. The developed framework is validated by comparison with other frameworks and formulations. A nonlinear static analysis on a representative high-aspect-ratio wing demonstrates that the propeller-induced axial velocity has a larger effect on the increase in deflection than the tangential velocity. The nonlinear dynamic results show that the propeller may decrease the deflection amplitude.

  13. Deployable Wing Model Using ANCF and UVLM: Multibody Dynamic Simulation and Wind Tunnel Experiment International-presentation International-coauthorship

    Keisuke Otsuka, Yinan Wang, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    AIAA SciTech 2020 Forum　2020/01/09

    More details Close

    This paper presents a deployable-wing multifidelity modeling method based on an asymmetrically gradient-deficient absolute nodal coordinate formulation coupled with unsteady vortex lattice method. Slender deployable wings are composed of multiple bodies connected by hinge joints and can be deployed or folded spanwise during flight. Low-fidelity and high-fidelity deployment simulation models are required for the conceptual and actual design phases of the wings, respectively. The presented multifidelity modeling method can be used for computationally efficient low-fidelity rigid multibody simulation and more realistic high-fidelity flexible multibody simulation. These multi-fidelity simulations are accomplished using a consistent modeling process and the same simulation program architecture. In addition, a consistent methodology can be used to couple an aerodynamic model with the low-fidelity and high-fidelity structural models. To demonstrate the effectiveness of the presented method, we newly present simulations using benchmark slender wing parameters in this paper. To validate the proposed modeling method, wing deployment experiments were performed in a wind tunnel at the Institute of Fluid Science, Tohoku University. Good agreement was found between the simulation using the presented method and the wind tunnel experiments, even when the wings experienced large geometrically nonlinear deformations.

  14. ANCF-ICE Beam Element for Modeling Highly Flexible and Deployable Aerospace Structures International-presentation

    Keisuke Otsuka, Kanjuro Makihara

    AIAA SciTech 2019 Forum　2019/01/07

  15. Deployment Simulation Model Based on ANCF Plate Element for Next-Generation Aerospace Structures International-presentation

    Keisuke Otsuka, Kanjuro Makihara

    AIAA SciTech 2018 Forum　2018/01

  16. Modal Rotation Methodによる柔軟構造の大変形解析

    Naruya Nagai, Yoshitaka Shizuno, Shuonan Dong, Ryo Kuzuno, Taiki Okada, Motonobu Kawai, Shugo Kawashima, Kanjuro Makihara, Keisuke Otsuka

    JSME conference　2025/03/17

  17. Buffeting-Induced Vibration Energy Harvesting using Flexible Plates with Piezoelectric Film International-presentation International-coauthorship

    Kento Shimura, Mizuki Ishigami, Yu Jia, Yu Shi, Constantinous Soutis, Hiroki Kurita, Fumio Narita, Yushin Hara, Kanjuro Makihara, Keisuke Otsuka

    21st International Conference on Flow Dynamics (ICFD2024)　2024/11/18

  18. Dynamic Analysis Method for High-Aspect-Ratio Wings Using Curvature Modes International-presentation

    Yoshitaka Shizuno, Shuonan Dong, Ryo Kuzuno, Taiki Okada, Naruya Nagai, Motonobu Kawai, Shugo Kawashima, Kanjuro Makihara, Keisuke Otsuka

    2024/11/18

  19. Numerical Study on Aerodynamic Interaction Between Propeller Wake and Wing in Low-Reynolds Number Flow International-presentation

    Nana Hasegawa, Masahiro Kanazaki, Keisuke Otsuka, Hiroki Nagai

    Asia-Pasific International Symposium on Aerospace Technology (APISAT2024)　2024/10/29

  20. Simple Shape Finding for Spherical Tensegrity Based on Rotational Location International-presentation

    Kanjuro Makihara, Yuta Matsumoto, Daiki Suzuki, Keisuke Otsuka

    75th International Astronautical Congress (IAC-2024　2024/10/14

  21. Dependance of Structural Variables and Initial Self-Stress Derivation in Form-Finding of Spherical Tensegrity

    Yuta Matsumoto, Daiki Suzuki, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2024/09/28

  22. Torsional Effect of Flexible Tether by Eccentric Climber in Space Elevator Including Nonequatorial Anchor International-presentation

    Ryo Kuzuno, Shuonan Dong, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    The 11th Asian Conference on Multibody Dynamics 2024 (ACMD2024)　2024/08/26

  23. Constraint Force in Focus: An Efficient Hamiltonian Dynamic Analysis for Flexible Multibody Systems International-presentation

    Shuonan Dong, Ryo Kuzuno, Keisuke Otsuka, Kanjuro Makihara

    The 17th International Conference on Motion and Vibration (MoViC2024)　2024/08/06

  24. Shape Determination Method for Spherical Tensegrity Using Spherical Symmetry and Rotational Manipulation

    Kanjuro Makihara, Yuta Matsumoto, Keisuke Otsuka

    2024/07/31

  25. Vibration Energy Harvesting from Aeroelastic Phonomena

    Kento Shimura, Taisei Mukogawa, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2024/03/15

  26. High Precision Three Dimensional Dynamic Analysis for Nonequatorial Space Elevator

    Ryo KUZUNO, Shuonan DONG, Yuya TAKAHASHI, Taiki OKADA, Keisuke OTSUKA, Kanjuro MAKIHARA

    Space Engineering Conference　2023/11/23

  27. Simulation Framework for Wake-Induced Aeroelastic Phenomena International-presentation

    Keisuke Otsuka, Yoshiaki Abe, Tomoki Yamazaki, Takanori Haga

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/07

  28. Aeroelastic Simulation Framework for Membrane Wings International-presentation

    Keisuke Otsuka, Shuonan Dong, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/08

  29. Arbitrary Lagrangian-Eulerian Non-liner Finite Element Analysis of Tethered Structure with Large Deformation International-presentation

    Yuya Takahashi, Ryo Kuzuno, Shuonan Dong, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/06

  30. Flutter Harvester Using Flexible Plates with Piezoelectric Film International-presentation International-coauthorship

    Taisei Mukogawa, Shuonan Dong, Yu Jia, Yu Shi, Constantinous Soutis, Hiroki Kurita, Fumio Narita, Keisuke Otsuka, Kanjuro Makihara

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/06

  31. State Estimation of Multibody Model Using State Observer Based on Differential Algebraic Equation International-presentation

    Taiki Okada, Shuonan Dong, Ryo Kuzuno, Yuya Takahashi, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/06

  32. Effective Semi-Active Energy Harvesting from Structural Vibration Using Magnetostrictive Transducer International-presentation

    Yuusuke Kobayashi, An Li, Keisuke Otsuka, Kanjuro Makihara

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/06

  33. Structural Optimization of Flexible Multibody Systems with Deployment Mechanism International-presentation

    Satoshi Watanabe, Shuonan Dong, Keisuke Otsuka, Kanjuro Makihara

    20th International Conference on Flow Dynamics (ICFD2023)　2023/11/06

  34. High-Precision Multibody Model for Space Elevator Including Torsional Deformation International-presentation

    Ryo Kuzunoa, Shuonan Dong, Yuya Takahashi, Keisuke Otsuka, Kanjuro Makihara

    74th International Astronautical Congress (IAC)　2023/10/03

  35. Semi-Active Predictive Vibration Control Based on Input Formulation Considering Periodic Disturbances

    Koyo Mishima, Meng Zhou, Tiayi Tang, Zingzhi Li, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2023/09/30

  36. Evaluation of Protection Performance against Orbital Debris of Partially Curing Inflatable Structures

    Hikaru Takahasi, Daisuke Morimoto, Yoshihiro Sugiyama, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2023/09/30

  37. Energy Saving Structural Health Monitoring Using Semi-Active Identification International-presentation

    Yushin Hara, Tianyi Tang, Keisuke Otsuka, Kanjuro Makihara

    Asia Pacific Conference of the Prognostics and Health Management Society (PHMAP 2023)　2023/09/12

  38. Switching Control Methods for Efficient Energy Harvesting of Large-scale Vibration Structure Using Magnetostrictive Transducer

    An Li, Yuusuke Kobayashi, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    Dynamics and Design Conference 2023　2023/08/31

  39. Energy-Saving Modal Parameter Identification Using Semi-Passive Control

    Yushin Hara, Tianyi Tang, Keisuke Otsuka, Kanjuro Makihara

    Dynamics and Design Conference 2023　2023/08/30

  40. MMC Topology Optimization with Geometrical Constraints

    Keisuke Otsuka, Shuonan Dong, Kanjuro Makihara

    2023/08/10

  41. Reduced Order Modeling and Experimental Validation of Flexible Multibody Dynamics in Hamiltonian Formulation

    Shuonan Dong, Keisuke Otsuka, Kanjuro Makihara

    2023/08/08

  42. System Identification of Space Structures Subjected to Unknown Disturbances Using Piezoelectric Device International-presentation

    Tianyi Tang, Yushin Hara, Meng Zhou, Mizuki Abe, Keisuke Otsuka, Kanjuro Makihara

    The 34th International Symposium on Space Technology and Science (ISTS2023)　2023/06/07

  43. Dominant Geometrical Factor in Non-Equatorial Space Elevator Dynamics International-presentation

    Ryo Kuzuno, Shuonan Dong, Yuya Takahashi, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    The 34th International Symposium on Space Technology and Science (ISTS2023)　2023/06/06

  44. Piezoelectric Semi-Active Structural Identification Method to Realize Energy-Saving On-Orbit Identification International-presentation

    Yushin Hara, Tianyi Tang, Keisuke Otsuka, Kanjuro Makihara

    The 34th International Symposium on Space Technology and Science (ISTS2023)　2023/06/07

  45. Phase-Delay Switching Strategy for Piezoelectric Vibration Energy Harvesting International-presentation International-coauthorship

    Meng Zhou, Yushin Hara, Tianyi Tang, Yu Jia, Yu Shi, Constantinos Soutis, Hiroki Kurita, Fumio Narita, Keisuke Otsuka, Kanjuro Makihara

    The 34th International Symposium on Space Technology and Science (ISTS2023)　2023/06/06

  46. Non Liner Finite Element Analysis of Tethered Structure with Large Deformation

    Yuya Takahashi, Ryo Kuzuno, Shuonan Dong, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2023/03/17

  47. Semi-Active Energy Harvesting Using Magnetostrictive Transducers

    Yusuke Kobayashi, An Li, Keiju Goto, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2023/03/17

  48. Structure optimization of deployable structure with large deformation

    Satisshi Watanabe, Shuonan Dong, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2023/03/17

  49. Structural Modal Parameter Identification Incorporating with Semi-Active Piezoelectric Control International-presentation

    Hara, Y, Asanuma, H, Otsuka, K, Makihara, K

    SPIE Conference, Smart Structures + Nondestructive Evaluation　2023/03/15

  50. Unified Flexible Multibody Dynamics for Transportation Systems

    Keisuke Otsuka, Shuonan Dong, Ryo Kuzuno, Kanjuro Makihara

    TRANSLOG2022　2022/12/01

  51. Unsteady Characteristics of Membrane Wing Applied Dielectric Elastomer Actuator International-presentation

    Tatsuya Kobayashi, Koji Fujita, Keisuke Otsuka, Hiroki Nagai

    19th International Conference on Flow Dynamics (ICFD2022)　2022/11/10

  52. Structural Parameter Estimation for Health Monitoring and Damage Detection based on Subspace Identification International-presentation

    Tianyi Tang, Mizuki Abe, Meng Zhou, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    19th International Conference on Flow Dynamics (ICFD2022)　2022/11/10

  53. Geometrically Nonlinear Beam Model for Slender Multibody Wings International-presentation International-coauthorship

    Keisuke Otsuka, Yinan Wang, Kelvin Cheng, Shuonan Dong, Koji Fujita, Rafael Palacios, Hiroki Nagai, Kanjuro Makihara

    19th International Conference on Flow Dynamics (ICFD2022)　2022/11/10

  54. Damage Evaluation for Hollow Cylindrical Tethers with Cross-Shaped Keepers International-presentation

    Nanami Karasawa, Daisuke Morimoto, Hikaru Takahash, Kiyonobu Ohtani, Kesuke Otsuka, Kanjuro Makihara

    19th International Conference on Flow Dynamics (ICFD2022)　2022/11/10

  55. Investigation of Flutter Velocity and Power Generation with Piezoelectric Film International-presentation International-coauthorship

    Shuonan Dong, Taisei Mukogawa, Yushin Hara, Keisuke Otsuka, Boyue Chen, Yu Shi, Yu Jia, Constantinos Soutis, Hiroki Kurita, Fumio Narita, Kanjuro Makihara

    19th International Conference on Flow Dynamics (ICFD2022)　2022/11/10

  56. Semi-Active Energy Harvesting with Magnetostrictive Transducer from Structural Vibration International-presentation International-coauthorship

    Keiju Goto, An Li, Yushin Hara, Keisuke Otsuka, Hiroki Kurita, Fumio Narita, Paul Lohmuller, Pascal Laheurte, Kanjuro Makihara

    19th International Conference on Flow Dynamics (ICFD2022)　2022/11/09

  57. Extended Nonlinear Finite Element Method for Three-Dimensional Non-Equatorial Space Elevator Analysis

    Ryo Kuzuno, Shuonan Dong, Yuya Takahashi, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    The 66rd Space Technology Conference　2022/11/01

  58. Flexible Rotating Multibody Analysis Using Extended NPFEM for NonEquatorial Space Elevator International-presentation

    Ryo Kuzuno, Shuonan Dong, Yuya Takahashi, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    The 6th International Conference on Multibody System Dynamics (IMSD)　2022/10/17

  59. Effect of Pre-Strain on Dielectric Elastomer Actuator Wing at Low Reynolds Number International-presentation

    Tatsuya Kobayashi, Koji Fujita, Keisuke Otsuka, Hiroki Nagai

    The 2022 Asia-Pacific International Symposium on Aerospace Technology　2022/10/12

  60. Detection Method of Debris-Cloud Contour by Machine Learning Focused on Positional Relation of Feature Points

    Daisuke Morimoto, Nanami Karasawa, Hikaru Takahashi, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2022/10/08

  61. Application of the Force Density Method in Tensegrity Structures and Analysis of Mechanical Properties through Excitation Experiments

    Takuma Goto, Nariyuki Kawabata, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2022/10/08

  62. Flutter Analysis of Flat Plate and Flutter Power Generation Experiment Using Piezoelectric Film

    Taisei Mukogawa, Shuonan Dong, Keisuke Otsuka, Kanjuro Makihara

    JSME conference　2022/10/08

  63. Experimental Investigations: Dynamic Analysis of 150-Member Spherical Tensegrity to Identify its Characteristics for Space Application International-presentation

    Kanjuro Makihara, Takuma Goto, Nariyuki Kawabata, Keisuke Otsuka

    73rd International Aeronautical Congress (IAC2022)　2022/09/18

  64. インフラ構造物の振動エネルギを用いた磁歪スイッチング制御エネルギハーベスティングの研究

    An Li, Keiju Goto, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    2022/09/13

  65. モデル縮約したハミルトニアン形式の柔軟マルチボディシステム解析

    Shuonan Dong, Ryo Kuzuno, Taiki Okada, Yoshitaka Shizuno, Keisuke Otsuka, Kanjuro Makihara

    2022/09/12

  66. 予測木に基づくモデル予測・最適化アル ゴリズムによるセミアクティブ振動制御 International-coauthorship

    Mizuki Abe, Tianyi Tang, Meng Zhou, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    Dynamics and Design Conference 2022　2022/09/08

  67. Nonlinear Aeroelastic Analysis of High-Aspect-Ratio Wings with Propeller-Wing Aerodynamic Interaction

    Keisuke Otsuka, Shuonan Dong, Kanjuro Makihara

    2022/08/05

  68. Energy Conversion Vibrating Structure Identification Using Piezoelectric Semi-Active Inputs

    Yushin Hara, Tianyi Tang, Meng Zhou, Keisuke Otsuka, Kanjuro Makihara

    2022/08/03

  69. System Identification Using Semi-Active Method with Piezoelectric Material

    Tianyi Tang, Meng Zhou, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    2022/03/11

  70. Semi-Active Vibration Energy Harvesting of Flexible Structures with Magnetostrictive Transducer

    Keiju Goto, An Li, Taishi Watanabe, Yushin Hara, Kanjuro Makihara, Keisuke Otsuka

    2022/03/11

  71. Energy Harvesting Using Magnetostrictive Material Based on Active Control International-presentation International-coauthorship

    An Li, Taishi Watanabe, Yushin Hara, Yu Jia, Yu Shi, Constantinos Soutis, Keisuke Otsuka, Kanjuro Makihara

    33rd International Symposium on Space Technology and Science (ISTS2022)　2022/03/03

  72. Development of Multibody Dynamics Formulation Based on Canonical Theory International-presentation International-coauthorship

    Shuonan Dong, Keisuke Otsuka, Yinan Wang, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    33rd International Symposium on Space Technology and Science (ISTS2022)　2022/03/01

    More details Close

    In modern society, the application of space structures, such as rockets and space stations, are becoming increasingly frequent into the exploration of outer space. Multibody dynamics is an effective method to analyze the dynamic motion of the space structures. As the weight reduction is important for space structures, the flexibility needs to be considered. In this paper, we introduce the Lagrangian formulation and Hamiltonian formulation to describe the multibody systems with use of the Lagrange’s undetermined multipliers method. Lagrangian formulation uses the genialized coordinates as the variables to derive the equation of motion. On the other hand, based on the canonical theory, Hamiltonian formulation uses the generalized coordinates and canonical conjugate momentum. Each formulation is combined with Absolute Nodal Coordinate Formulation, one of the nonlinear finite element methods, to describe the elastic deformation. We compare the behavior of Lagrangian formulation and Hamiltonian formulation by performing the numerical simulation. Two methods show good agreement in the simulation results of the generalized coordinates. However, different methods show different results of generalized momentum in the Hamiltonian formulation, which leads to the careful awareness of selecting constraint levels.

  73. Nonlinear Aeroelastic Analysis Coupling Unsteady Vortex Lattice Method and Strain-Based Beam Formulation International-presentation International-coauthorship

    Keisuke Otsuka, Shuonan Dong, Yinan Wang, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/29

  74. Shape Keepers of Hollow Cylindrical Tethers for Space Debris Removal International-presentation

    Mayumi Suzuki, Ryohei Kobayashi, Nanami Karasawa, Daisuke Morimoto, Kiyonobu Ohtani, Keisuke Otsuka, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/29

  75. Penetration Evaluation of Inflatable Space Structure with Heat Curing at Hypervelocity Impact International-presentation

    Ryohei Kobayashi, Mayumi Suzuki, Nanami Karasawa, Daisuke Morimoto, Keisuke Otsuka, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/28

  76. Iterative Modeling and Dynamic Analysis of Spherical Tensegrity International-presentation

    Erina Mori, Takuma Goto, Nariyuki Kawabata, Keisuke Otsuka, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/27

  77. New MMC-Based Topology Optimization Method with Curvilinear Representation International-presentation

    Shunsuke Hirotani, Shuonan Dong, Ryo Kuzuno, Taiki Okada, Keisuke Otsuka, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/27

  78. Experimental Investigation of Flutter Power Generation with Piezoelectric Film International-presentation International-coauthorship

    Kei Imagawa, Keisuke Otsuka, Yu Jia, Yu Shi, Constantinos Soutis, Hiroki Kurita, Fumio Narita, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/27

  79. Enhancing Piezoelectric Harvested Energy of an Advanced Switching Interface by Tunable Switching Intervals International-presentation International-coauthorship

    Meng Zhou, Yushin Hara, Yu Jia, Yu Shi, Constantinos Soutis, Hiroki Kurita, Fumio Narita, Keisuke Otsuka, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/27

  80. Optimization of Electromechanical Dynamic Vibration Absorber for Flexible Space Structure International-presentation

    Taishi Watanabe, An Li, Keiju Goto, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    18th International Conference on Flow Dynamics (ICFD2021)　2021/10/27

  81. Battery-Less Soft Sensor of Spacecraft Vibration with Advanced Piezoelectric Energy Harvester

    Yushin Hara, Li An, Meng Zhou, Keisuke Otsuka, Kanjuro Makihara

    72nd International Aeronautical Congress (IAC2021)　2021/10/29

  82. Model Predictive Control for Switching Vibration Suppression Using Future Trajectory International-presentation

    Kanjuro Makihara, Mizuki Abe, Yushin Hara, Keisuke Otsuka

    72nd International Aeronautical Congress (IAC2021),　2021/10/29

  83. Risk Assessment of Space Debris Collisions Considering Severed Tethers

    Nanami Karasawa, Ryohei Kobayashi, Mayumi Suzuki, Daisuke Morimoto, Keisuke Otsuka, Kanjuro Makihara

    2021/10/02

  84. Three-Dimensional Nonlinear Analysis of Tether for Non-Equatorial Space Elavator

    Ryo Kuzuno, Dong Shuonan, Shunsuke Hirotani, Keisuke Otsuka, Kanjuro Makihara

    2021/10/02

  85. Absolute Nodal Coordinate Formulations for Aeroelastic Analysis of Next-Generation Aircraft Wings International-presentation International-coauthorship

    Otsuka, K., Dong, S., Makihara, K.

    17th International Conference on Multibody Systems, Nonlinear Dynamics, and Control (MSNDC)　2021/08/17

  86. 歪を要素変数とする非線形梁要素の柔軟マルチボディ解析への拡張

    Otsuka, K., Dong, S., Makihara, K.

    2021/08/06

  87. ファジィ適応制御を用いた間欠スイッチングハーベスタ

    Hara, Y., Zhou, M., Otsuka, K., Makihara, K.

    2021/08/04

  88. Evaluation of Penetration of Inflatable Space Habitat with Heat Curing at Hypervelocity Impact

    Ryohei Kobayashi, Honoka Tomizaki, Mayumi Suzuki, Nanami Karasawa, Keisuke Otsuka, Kanjuro Makihara

    JSASS Northern Branch 2021 Annual Meeting　2021/03/19

  89. Vibration Control of Flexible Space Structure using Dynamic Vibration Absorber with Magnetostrictive Material

    Taishi WATANABE, An LI, Yushin HARA, Keisuke OTSUKA, Kanjuro MAKIHARA

    2021/03/12

  90. Research on Shape Keepers of Hollow Cylindrical Tether for Removing Space Debris

    Mayumi SUZUKI, Honoka TOMIZAKI, Ryohei KOBAYASHI, Nanami KARASAWA, Keisuke OTSUKA, Kanjuro MAKIHARA

    2021/03/12

  91. Energy Harvesting Based on Synchronous Inversion and Charge Extraction Circuit Considering Vibration Suppression Effect

    Meng Zhou, Yushin Hara, Ikuya Takamoto, Keisuke Otsuka, Kanjuro Makihara

    2021/03/12

  92. Research on Plate Vibration with Large Deformation

    Kei Imagawa, Keisuke Otsuka, Kanjuro Makihara

    2021/03/12

  93. Multibody Modeling Using Absolute Nodal Coordinate Plate Element for Deployable Aerospace Structures International-presentation

    Keisuke Otsuka, Shuonan Dong, Shunsuke Hirotani, Ryo Kuzuno, Kanjuro Makihara

    The 15th International Conference on Motion and Vibration Control (MoViC2020)　2020/12/08

    More details Close

    Future aerospace structures, such as Mars aircraft and flapping wing aircraft, have deployable/foldable and thin plate-like components connected by hinge joints. A deployment simulation is necessary to design the structures. Multibody dynamics (MBD) to model the joints coupled with a nonlinear finite element method is an effective approach to perform the simulation. In this study, a plate element based on absolute nodal coordinate formulation (ANCF) is coupled with MBD. ANCF plate element can express large rigid body motion and large elastic deformation including wing-chord deformation, and thus it is suitable for modeling low aspect ratio and very thin wings. However, the ANCF plate element has highly nonlinear elastic force leading to computational inefficiency. To overcome this computational inefficiency, we modify the elastic force formulation of the ANCF plate element by taking advantage of the wing characteristic. By using the ANCF plate element with the modified elastic force, we simulate the deployment motion of a multibody system.

  94. Flexible Multibody Dynamics Using Absolute Nodal Coordinate Formulation with Internal Constraint Equation International-presentation

    Keisuke Otsuka, Shuonan Dong, Shunsuke Hirotani, Ryo Kuzuno, Kanjuro Makihara

    The 15th International Conference on Motion and Vibration Control (MoViC2020)　2020/12/08

    More details Close

    Next-generation aerospace structures, such as deployable wing aircraft, consist of very flexible bodies connected by joints because they are required to be lightweight. In designing the structures, a deployment simulation considering the high flexibility and joint is necessary. Multibody dynamics with absolute nodal coordinate formulation (ANCF) is effective for the simulation. ANCF is a nonlinear finite element method that can easily describe flexible deformation and constraint joint equations. However, ANCF cannot be easily applied to complicated cross-sectional structures such as a wing. This is because the volume integral necessary for the elastic force derivation is difficult for complicated structural shapes. To solve this problem, we present an ANCF beam element with internal constraint equations (ICE). ICE restricts the non-dominant deformation. Consequently, a line integral can be used instead of the volume integral. We demonstrate that the ANCF-ICE beam element can describe the very flexible deformation of a complicated cross-sectional structure in a flying wing simulation.

  95. Multibody Dynamic Analysis Based on Canonical Theory

    Shuonan Dong, Keisuke Otsuka, Kanjuro Makihara

    17th International Conference on Flow Dynamics (ICFD2020)　2020/10/29

  96. Flexible Wing Fluid-Structure Interaction Model Coupling Unsteady Vortex Lattice Method and Absolute Nodal Coordinate Formulation International-presentation International-coauthorship

    Keisuke Otsuka, Shuonan Dong, Yinan Wang, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    17th International Conference on Flow Dynamics (ICFD2020)　2020/10/29

  97. Motion Analysis Based on ANCF/CRBF Beam Model with Simplified Elastic Force

    Shunsuke Hirotani, Keisuke Otsuka, Shuonan Dong, Kanjuro Makihara

    JSME Conference　2020/09/26

  98. Establishment of Modeling Method of Spherical Tensegrity Using Rotational Symmetry

    Erina Mori, Yushin Hara, Keisuke Otsuka, Kanjuro Makihara

    JSME Conference　2020/09/26

  99. Multifidelity Aeroelastic Analysis of Folding Wings Invited

    Keisuke Otsuka

    JSME Annual Conference 2020　2020/09/15

  100. Nonlinear Structural Analysis Using Absolute Nodal Coordinate Formulation for Very Flexible Wings

    Keisuke Otsuka, Shuonan Dong, Kanjuro Makihara

    2020/08/05

  101. 正準理論に基づく柔軟マルチボディシス テムについての研究

    Dong Shuonan, Keisuke Otsuka, Shunsuke Hirotani, Takahiro Suzaki, Kanjuro Makihara

    JSME　2020/03/13

  102. New Framework of Strain Based Beam Formulation for Rigid Body Motion International-presentation

    Takahiro Suzaki, Keisuke Otsuka, Shunsuke Hirotani, Shuonan Dong, Kanjuro Makihara

    16th International Conference on Flow Dynamics (ICFD2019)　2019/11/08

  103. Comparison of 2D and 3D Simulation Models for Deployable Wing International-presentation International-coauthorship

    Keisuke Otsuka, Takahiro Suzaki, Yinan Wang, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    16th International Conference on Flow Dynamics (ICFD2019)　2019/11/08

  104. Multibody Dynamic Analysis of Birdlike Folding Wing

    Keisuke Otsuka, Takahiro Suzaki, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    2019/10/16

  105. Improved Method of Strain Based Beam Formulation for Considering Constraints

    SUZAKI Takahiro, OTSUKA Keisuke, ONUKI Satoru, MAKIHARA Kanjuro

    The Proceedings of Conference of Tohoku Branch　2019/03/12

  106. Simulation and Control of Flexible Aero-Structures using Nonlinear Reduced-Order Models International-presentation International-coauthorship

    Yinan Wang, Keisuke Otsuka, Koji Fujita, Hiroki Nagai, Kanjuro Makihara

    15th International Conference on Flow Dynamics (ICFD2018)　2018/11/09

  107. Semi-Active Vibration Suppression Using Predictive Theory International-presentation

    Masumi Ueno, Ikuya Takemoto, Keisuke Otsuka, Kanjuro Makihara

    15th International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  108. Motion Analysis of Flexible Folding Wing with a Hinge Joint Loaded by Gust International-presentation

    Satoru Onuki, Keisuke Otsuka, Takahiro Suzaki, Hiroki Nagai, Koji Fujita, Kanjuro Makihara

    15th International Conference on Flow Dynamics (ICFD2018)　2018/11/08

  109. Dynamic Simulation of Deployable Wing Mars Airplane International-presentation International-coauthorship

    Keisuke Otsuka, Yinan Wang, Koji Fujita, Kanjuro Makihara, Hiroki Nagai

    15th International Conference on Flow Dynamics (ICFD2018)　2018/11/07

  110. Three Dimensional Beam Elements Based on Strain

    Suzaki Takahiro, OTSUKA Keisuke, ONUKI Satoru, MAKIHARA Kanjuro

    The Proceedings of Autumn Conference of Tohoku Branch　2018/09/07

  111. Flexible Multibody Simulation for Deployable Morphing Wings

    OTSUKA Keisuke, MAKIHARA Kanjuro

    The Proceedings of the Dynamics & Design Conference　2018/08

    More details Close

    <p>Morphing wing technology is to change the wing shape during flight. The technology has a potential to improve aircraft performance dramatically. One of the attractive morphing wings is the wing that can deploy or fold in the wing span direction. Such a morphing wing is called a deployable wing. The wing consists of several wing bodies jointed by hinges. A deployment actuator and a latching system are attached to the hinge. To obtain the good design of the deployable wing, the deployment simulation using a numerical model is necessary. We have proposed the numerical model comprising flexible multibody dynamics using absolute nodal coordinate formulation (ANCF) and unsteady aerodynamics. The model expresses the coupled motion of large aeroelastic deformation and large rigid body rotation. The model has a constant mass matrix, which means that there is no need to consider imaginary forces. However, it is difficult to model the deployment torque considering relative rotation angle between bodies because ANCF uses vectors expressed in a global coordinate system as nodal variables instead of rotation angles. This paper presents a modeling method to overcome this difficulty. Additionally, we model a lathing mechanism that is necessary for the deployment simulation. Finally, parametric deployment wing simulations are conducted to show the applicability of the model.</p>

  112. Three-Dimensional Multibody Simulation Method based on Absolute Nodal Coordinate Formulation for Flexible Deployable Wings

    Keisuke Otsuka, Kanjuro Makihara

    2018/08/01

  113. Predictive Semi-Active Vibration Control for Multiple DOF Space Structure

    Masumi Ueno, Kei Asahina, Keisuke Otsuka, Kanjuro Makihara

    2018/03/06

  114. Motion Analysis of Flexible Folding Wing with a Hinge Joint Loaded by Gusts

    Satoru Onuki, Keisuke Otsuka, Takahiro Suzaki, Kanjuro Makihara

    2018/03/06

  115. Multibody Analysis of Morphing Wing Considering Aeroelastic Deformation

    Keisuke Otsuka, Kanjuro Makihara

    2018/03/06

  116. Based on predictive control theory semi-active control for multiple DOF system

    Ueno Masumi, Asahina Kei, Otsuka Keisuke, Makihara Kanjuro

    Proceedings of the Japan Joint Automatic Control Conference　2017/11/10

  117. Deployable Wing Simulation Using Flexible Multibody Dynamics International-presentation

    Keisuke Otsuka, Kanjuro Makihara, Hiroki Nagai

    14th International Conference on Flow Dynamics (ICFD2017)　2017/11/02

  118. Aeroelastic Analysis of Deployable Wing using Reduced Order Multibody Structural Model

    OTSUKA Keisuke, MAKIHARA Kanjuro

    The Proceedings of the Dynamics & Design Conference　2017/08/31

    More details Close

    Aviation organizations around the world are developing deployable wings. The wing is composed of some bodies connected by hinge joints with actuators, and thus it can be transformed in the span direction during the flight. Aeroelastic analysis using structural and aerodynamic models is important for the design of the deployable wing. The aeroelastic analysis takes a long calculation time because the structural deformation and unsteady aerodynamic force must be calculated at the same time. This study presents a deployable wing structural model based on multibody dynamics and absolute nodal coordinate formulation for the aeroelastic analysis. To reduce the calculation time, we propose a reduced order structural model of the deployable wing. The reduced order model provides the 18% reduction of the calculation time compared to the full model within 1% error. Additionally, we propose the method of the flutter speed determination in the time-domain using the reduced order structural model. The method can reflect the nonlinearity caused by the mixed motion between the elastic deformation and the rigid body rotation around the hinge joint in the flutter speed determination. In the method, the total energy of the wing is utilized as an index to determine the flutter speed. As a result, we can evaluate all deformations related to the flutter by using one scalar.

  119. Deployable Wing Model for Deployment Simulation and Aeroelastic Analysis

    Keisuke Otsuka, Kanjuro Makihara

    2017/08/04

  120. Semi-Active Vibration Control with Predictive Control Theory

    UENO Masumi, ASAHINA Kei, OTSUKA Keisuke, MAKIHARA Kanjuro

    The Proceedings of Autumn Conference of Tohoku Branch　2017

  121. Frequency-Domain Flutter Analysis of Folding Wing based on Flexible Multibody Dynamics International-presentation

    Keisuke Otsuka, Kanjuro Makihara

    The 2016 Asia-Pacific International Symposium on Aerospace Technology (APISAT2016)　2016/10/26

  122. Deployment Simulation of Morphing Wing International-presentation

    Keisuke Otsuka, Hiroaki Miyazawa, Kanjuro Makihara

    13th International Conference on Flow Dynamics (ICFD2016)　2016/10/11

  123. Flutter Analysis of Deployable Wing Using Flexible Multibody Dynamics International-presentation

    Keisuke Otsuka, Kanjuro Makihara

    The first International Symposium on Flutter and its Application (ISFA2016)　2016/05/17

  124. MBD Simulation of Morphing Wing Subjected to Unsteady Aerodynamic Force

    OTSUKA Keisuke, MAKIHARA Kanjuro

    The Proceedings of Conference of Tohoku Branch　2016/03/11

  125. Aeroelastic Simulation Using Absolute Nodal Coordinate Formulation International-presentation

    Keisuke Otsuka, Kanjuro Makihara

    12th International Conference on Flow Dynamics (ICFD2015)　2015/10/28

  126. Aeroelastic Simulation for Deployable Wing using Flexible Multibody Dynamics International-presentation

    Keisuke Otsuka, Kanjuro Makihara

    30th International Symposium on Space Technology and Science (ISTS2015)　2015/07/09

Show all Show first 5

Research Projects 27

  1. Data-Driven High-Fidelity Fluid Structure Interaction Simulation Method for Next-Generation Aircraft Design Competitive

    Yoshiaki Abe, Keisuke Otsuka, Takanori Haga, Yu Kawano

    Offer Organization: Japan Society for the Promotion of Science

    System: KAKENHI

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2024/04 - 2029/03

  2. Connection between 3D Static and 1D Dynamic Analyses -Wind Tunnel and Flight Test- Competitive

    Keisuke Otsuka, Naoto Morita, Kento Shimura

    Offer Organization: Sumitomo Foundation

    System: Research Grant

    Institution: Tohoku University

    2024/11 - 2026/10

  3. AI to Generate Equation of Motion for Next-Generation Robot Competitive

    Keisuke Otsuka, Kento Shimura, Haruta Hirao

    Offer Organization: Toyota Physical and Chemical Research Institute

    System: Toyota Physical and Chemical Research Scholar

    Institution: Tohoku University

    2025/04 - 2026/03

  4. AI Fusing Reality and Virtual for Real-Time Aeroelastic Simulation of Floating Wind Turbine Competitive

    Keisuke Otsuka

    Offer Organization: ENEOS

    System: Research Grant

    Institution: Tohoku University

    2025/04 - 2026/03

  5. AI Bridging Robotics and Multibody Dynamics Other

    Keisuke Otsuka, Kanjuro Makihara, Yushin Hara

    Offer Organization: Hagiwarra Foundation

    System: Research Grant

    Institution: Tohoku University

    2025/04 - 2026/03

  6. Seamless Connection between Topology Optimization and Computer Aided Design Competitive

    Keisuke Otsuka

    Offer Organization: Suzuki Foundation

    System: Research Grant

    Institution: Tohoku University

    2025/04 - 2026/03

  7. Linear Curvilinear Modes for Nonlinear Structural Analysis Competitive

    Keisuke Otsuka

    Offer Organization: Japan Society for the Promotion of Science

    System: KAKENHI

    Category: Young Researcher

    Institution: Tohoku University

    2024/04 - 2026/03

  8. Thermal Monitoring of Spacecraft by Using Wireless Sensor Network Competitive

    Keisuke Otsuka

    Offer Organization: The Thermal and Electric Technology Foundation

    System: Research Grant

    Institution: Tohoku University

    2024/12 - 2025/12

  9. Energy Harvesting from Nonlinear Aeroelastic Vibration Competitive

    大塚 啓介

    Offer Organization: Kurita Water and Environment Foundation

    System: Research Grant

    Institution: Tohoku University

    2024/10 - 2025/09

  10. Low-Speed Aeroelastic Buffeting of Tail Wings: Theory and Analysis Competitive

    Keisuke Otsuka, Yoshiaki Abe, Takanori Haga, Kento Shimura

    Offer Organization: Institute of Fluid Science, Tohoku University

    System: General Collaborative Resarch Project

    Institution: Tohoku University

    2023/04 - 2025/03

  11. Aeroelastic Analysis of Membrame Wings Based on Absolute Nodal Coordinate Formulaiton Competitive

    Keisuke Otsuka

    Offer Organization: Nohmura Foundation for Membrane Structure’s Technology

    System: Research Grant 2022

    2023/04 - 2025/03

  12. Construction of probabilistic predictive theory to realize low-energy-consumption vibration control for deployable truss observation satellite

    Kanjuro Makihara, Haruhiko Asanuma, Keisuke Otsuka

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Scientific Research (B)

    Institution: Tohoku University

    2022/04 - 2025/03

  13. Absolute Nodal Coordinate Formulation for Nonlinear Multibody Modeling of Flared Hinged Wings Competitive

    Keisuke Otsuka

    Offer Organization: Suzuki Foundation

    System: Research Grant for International Research Activity

    Institution: Tohoku University

    2024/09 - 2024/09

  14. Moving-Nonlinearity Modeling for Structural Optimization of Soft Robot Competitive

    Keisuke Otsuka

    Offer Organization: Mazak Foundation

    System: Research Grant 2022

    Institution: Tohoku University

    2023/05 - 2024/03

  15. Modal Curve Method to Connect 3D Static and 1D Dynamic Analyses of Very Flexible Aircraft Competitive

    Keisuke Otsuka

    Offer Organization: Suzuki Foundation

    System: Research Grant 2022

    2023/04 - 2024/03

  16. A new theory, vectorial and rotational canonical transformation, overcomes a barrier separating structural and mechanism analyses Competitive

    Kanjuro Makihara, Keisuke Otsuka, Hiroki Nagai

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research

    Category: Grant-in-Aid for Challenging Research (Exploratory)

    Institution: Tohoku University

    2022/06 - 2024/03

  17. Aeroelastic Model of Very Flexible Membrane Wings: Theory and Experiment Competitive

    Keisuke Otsuka, Koji Fujita, Hiroki Nagai, Kanjuro Makihara, Rafael Palacios, Yinan Wang

    Offer Organization: Institute of Fluid Science, Tohoku University

    System: General Collaborative Resarch Project

    Institution: Tohoku University

    2021/04 - 2024/03

  18. Movable-Nonlinearity Modeling for Successive Analyses of Very Flexible Structures Competitive

    Keisuke Otsuka

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Early-Career Scientists

    Institution: Tohoku University

    2021/04 - 2024/03

  19. Aeroelastic Control for Offshore Wind Turbine Using Strain-Based Modeling and Sensing Competitive

    Keisuke Otsuka

    Offer Organization: The Ebara Hatakeyama Memorial Foundation

    System: Research Grant 2022

    Institution: Tohoku University

    2022/06 - 2023/03

  20. Aeroelastic Theory and Wind Tunnel Experiment for Very Flexible Floating Wind Turbine Competitive

    Keisuke Otsuka

    Offer Organization: TEPCO Memorial Foundation

    System: Research Grant (General Research)

    Institution: Tohoku University

    2022/04 - 2023/03

  21. Nonlinear Aeroelastic Analysis of Floating Wind Turbine with Very Flexible Blade Competitive

    Keisuke Otsuka

    Offer Organization: The Iwatani Naoji Foundation

    System: The 48th (2021) Iwatani Science Technology Funding

    Institution: Tohoku University

    2022/04 - 2023/03

  22. Vector-Strain Transformation Theory for Analysis and Control of Next-Generation Aircraft Wings Competitive

    Keisuke Otsuka, Kanjuro Makihara

    Offer Organization: Mazda Foundation

    System: The 36th Mazda Research Funding

    Institution: Tohoku University

    2020/11 - 2022/03

  23. Vector-Strain Transformation for Control and Analysis of Next-Generation Deployable Structures Competitive

    Keisuke Otsuka

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for Research Activity Start-up

    Category: Grant-in-Aid for Research Activity Start-up

    Institution: Tohoku University

    2020/09 - 2022/03

    More details Close

    With the increasing demand for telecommunication, renewable energy, and disaster monitoring, high-altitude platform station with deployable wings, large wind turbines, and space robot arms are expected to be developed. To develop these next-generation structures, which have slender bodies with nearly 100 meters and undergo large deformation, deformation and deployment control using a numerical model is necessary. The model should be based on variables that can be measured in actual operation for the purpose of control. In this research, we proposed an innovative modeling method based on strain variables, which are easy to measure in actual operation even when large deformation occurs. The analysis performance of the proposed model was demonstrated through a large wind tunnel experiment at the Institute of Fluid Science, Tohoku University.

  24. Real-Time Strain-Based Control of Very Flexible Aircraft Competitive

    Keisuke Otsuka

    Offer Organization: CASIO Science Promotion Foundation

    System: The 38th Research Funding

    Institution: Tohoku University

    2020/12 - 2021/11

  25. Interdisciplinary Modeling for Three-Dimensional Morphing-Flight Controller Design of Flexible and Deployable Wing Aircraft

    Keisuke Otsuka, Rafael Palacios

    Offer Organization: Japan Society for the Promotion of Science

    System: Overseas Challenge Program for Young Researchers

    Institution: Imperial College London

    2019/06 - 2019/09

  26. Development of Morphing Wing Modeling Fusing Interdisciplinary Fields: Fluid/Structure/Control (2017-2018) Competitive

    Keisuke Otsuka

    Offer Organization: Japan Society for the Promotion of Science

    System: Grants-in-Aid for Scientific Research Grant-in-Aid for JSPS Fellows (DC2)

    Category: Grant-in-Aid for JSPS Fellows

    Institution: Tohoku University

    2017/04 - 2019/03

  27. Deployment Simulation Model based on ANCF Plate Element for Next-Generation Aerospace Structures

    Keisuke Otsuka

    Offer Organization: Society for Promotion of Space Science

    System: 2017 Financial Support to Attend International Conferences

    Institution: The American Institute of Aeronautics and Astronautics (AIAA)

    2018/01 - 2018/01

Show all Show first 5

Teaching Experience 6

  1. Design and Drawing I　Tohoku University

  2. Mathematics and Physics II　Tohoku University

  3. Structural Mechanics　Tohoku University

  4. Introduction to Aerospace Engineering　Tohoku University

  5. Experiment II　Tohoku University

  6. Experiment I　Tohoku University

Show all Show first 5

Social Activities 3

  1. Lecture at Namiki School

    2023/09/20 -

  2. Mathematical Model Programming

    2022/12/12 -

  3. Seminar of MALTAB Parallel Computing Process Using AOBA-B

    2022/11/16 -