研究者詳細 - 高野　直樹

Probabilistic prediction of mechanical behavior of additively manufactured product considering geometrical imperfections associated with building direction

Mizuki Maruno, Naoki Takano

Mechanical Engineering Journal （JSME） 8 （ 6 ） 1 - 13 2021年12月

研究論文（学術雑誌）, 共著, 査読有り

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Experimental study on deformability of polymeric dental aligner by digital image correlation method

Naoki Yamaguchi, Kohta Ito, Pietro Oldani, Motoya Shiogama, Moeka Sawamura, Haruhisa Nakano, Koutaro Maki, Naoki Takano

材料（日本材料学会） 70 （ 1 ） 57 - 63 2021年01月

研究論文（学術雑誌）, 共著, 査読有り

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Influence of higher orders of Neumann expansion on accuracy of stochastic linear elastic finite element method with random physical parameters

Lucas Degeneve, Naoki Takano

Mechanical Engineering Letters （日本機械学会） 6 20-00228 2020年10月

研究論文（学術雑誌）, 共著, 査読有り

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鋼材成分のばらつきを考慮した焼入れプロセスの相変態－熱伝導連成解析と温度に対する感度解析

古川達也, 高野直樹, 杉本剛, 木島秀弥, 田村茂之

日本機械学会論文集 86 （ 887 ） 2020年06月

研究論文（学術雑誌）, 査読有り

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Stochastic nonlinear multiscale computational scheme for short fiber reinforced composites to study the influence of microstructural variability on Damage Propagation

Tien-Dat Hoang, Yutaro Abe, Shinya Nakamura, Akio Miyoshi, Naoki Takano

（SN Applied Sciences） 2 （ 182 ） 1 - 16 2020年01月

研究論文（学術雑誌）, 共著, 査読有り

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3Dプリンティング技術により積層造形されたアルミ合金ラティス構造の圧縮特性に関する研究

高野直樹, 瀧澤英男, 伊藤幸太, 小高研人, 松永智, 阿部伸一

材料（日本材料学会） 68 （ 4 ） 351 - 357 2019年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0514-5163

<p>In order to discuss the quality assurance of additively manufactured lattice structure made by aluminum alloy (AlSi10Mg) using 3D printing technology or selective laser sintering technique, compression test, micro-CT imaging and finite element analysis were carried out. The specimens were manufactured by 2 printing service companies with different expertise, which led to the choice of different process parameters such as the building direction, support structure, powder bed temperature and laser scanning speed. The largely scattered compressive peak loads were in good linear positive correlation with the weight, which is the easiest and convenient index for the quality assurance. On the other hand, the apparent density was almost the same. The reason why the weight of the products was largely scattered was investigated by micro-CT image analysis and finite element analysis. Also by comparison with the CAD data, the influence of manufacturer-dependent process parameters on the strength was discussed.</p>

First-order perturbation-based stochastic homogenization method applied to damage prediction for composite materials

Tien-Dat Hoang, Naoki Takano

Acta Mechanica （Acta Mechanica） 230 （ 3 ） 1061 - 1076 2018年12月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00015970

© 2018, Springer-Verlag GmbH Austria, part of Springer Nature. In this paper, a first-order perturbation-based stochastic homogenization method was developed to predict the probabilities of not only macroscopic properties but also microscopic strain damage in multiphase composite materials, considering many random physical parameters. From the stochastic solution of microscopic strains, damage propagation was analyzed to predict where progressive damage would occur in the microstructures of composites subject to a given macroscopic strain. As an example, a short fiber-reinforced plastic, consisting of short fibers, matrix, and interphase, was used to show the influence of random physical parameters for each constituent material on the variability of the homogenized properties and microscopic strain. In another example, a coated particle-embedded composite material was stochastically analyzed to consider even slight influences of uncertainty in the mechanical properties of the coating material and show damage propagation in this coating layer. Characteristic displacements representing material heterogeneity were thoroughly investigated and extensively used with the aim of reducing the computational cost of finding them in a nonlinear analysis of the microscopic damage propagation.

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Biomechanical analysis of likelihood of optic canal damage in peri-orbital fracture

Tomohisa Nagasao, Tadaaki Morotomi, Motone Kuriyama, Motoki Tamai, Yoshiaki Sakamoto, Naoki Takano

Computer Assisted Surgery （Computer Assisted Surgery） 23 （ 1 ） 1 - 7 2018年04月

研究論文（学術雑誌）, 共著, 査読有り

© 2018 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Purpose: Detection of optic canal fractures is often difficult because of the subtleness of the fracture. If we could clarify impact on which region around the orbit is likely to accompany the fracture of the optic canal, the knowledge should be useful to make early diagnosis of optic canal fractures. The present study was conducted to elucidate this issue. Methods: Ten finite element models were produced simulating the skulls of ten humans (8 males and 2 females; 43.8 ± 10.2 y/o). The peri-orbital area of each of the ten models was divided into eight regions in a clockwise fashion per 45 degrees. These regions were defined as Superior-Medial (0–45 degrees), Medial-Superior (45–90 degrees), Medial-Inferior (90 to 135 degrees), Inferior-Medial (135 to 180 degrees), Inferior-Lateral (180–225 degrees), Lateral-Inferior (225 to 270 degrees), Lateral-Superior (270–315 degrees), and Superior-Lateral regions (315–360 degrees), respectively. Dynamic simulation of applying traumatic energy on each of these regions was conducted. Resultant fracture patterns were evaluated using finite element analyses. Thereafter, frequencies of fracture involvement of the optic canal were evaluated for each of the eight regions. Results: The involvement of the optic canal was most frequent for the Superior-Medial region (7/10), followed by the Medial-Superior region (5/10). Conclusion: Optic canal fracture is likely to occur when the area between the supra-orbital notch and the medial canthus are strongly impacted. When evident fracture or serious damage of soft tissue is observed in this area, occurrence of optic canal fracture should be suspected.

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General formulation of the first-order perturbation based stochastic homogenization method using many random physical parameters for multi-phase composite materials

Pin Wen, Naoki Takano, Shusuke Akimoto

Acta Mechanica （Acta Mechanica） 229 （ 5 ） 2133 - 2147 2018年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00015970

© 2018, Springer-Verlag GmbH Austria, part of Springer Nature. In the numerical prediction of the homogenized macroscopic properties of an arbitrary heterogeneous material with periodic microstructure, a general formulation of the first-order perturbation-based stochastic homogenization method is presented in a discretized form based on the finite element method in order to consider the variability or uncertainty of the mechanical properties of the material models. Many random parameters are defined for each material model and for each component of the stress–strain matrix of the constituent’s material model. The first-order terms of the characteristic displacement are thoroughly studied both theoretically and numerically, and are also used in the verification of the developed computer code. The comparison with the Monte Carlo simulation also supports the proposed formulation.

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Stochastic prediction of apparent compressive stiffness of selective laser sintered lattice structure with geometrical imperfection and uncertainty in material property

Naoki Takano, Hideo Takizawa, Pin Wen, Kento Odaka, Satoru Matsunaga, Shinichi Abe

International Journal of Mechanical Sciences （International Journal of Mechanical Sciences） 134 347 - 356 2017年11月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00207403

© 2017 Elsevier Ltd Aiming at the future applications of a lattice structure manufactured by selective laser sintering for bone scaffold in the biomedical field, by putting highlight on the possible imperfections influenced by different manufacturing strategies, a numerical prediction method was studied and compared with compressive test results. To consider the geometrical imperfections as well as the uncertainty in sintered material property, the first-order perturbation based stochastic homogenization (FPSH) method was employed. To be able to compare products made by three different printing service companies, maraging steel was used in this study, which was commonly available. Several geometrical imperfections were categorized into kink, notch and hole, and representative dimensions were parameterized and measured statistically using micro-CT images. They were also correlated to the building direction and support types. The numerical prediction revealed the reduction of stiffness in a stochastic way qualitatively. The constructed database of the geometrical imperfections and the FPSH method will be useful in the next occasion of manufacturing unexperienced product.

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Influence of anisotropic bone properties on the biomechanical behavior of the acetabular cup implant: A multiscale finite element study

Vu-Hieu Nguyen, Giuseppe Rosi, Salah Naili, Adrien Michel, Maria-Letizia Raffa, Romain Bosc, Jean-Paul Meningaud, Christine Chappard, Naoki Takano, Guillaume Haiat

Computer Methods in Biomechanics and Biomedical Engineerin （Computer Methods in Biomechanics and Biomedical Engineering） 20 （ 12 ） 1312 - 1325 2017年10月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10255842

© 2017 Informa UK Limited, trading as Taylor & Francis Group. Although the biomechanical behavior of the acetabular cup (AC) implant is determinant for the surgical success, it remains difficult to be assessed due to the multiscale and anisotropic nature of bone tissue. The aim of the present study was to investigate the influence of the anisotropic properties of peri-implant trabecular bone tissue on the biomechanical behavior of the AC implant at the macroscopic scale. Thirteen bovine trabecular bone samples were imaged using micro-computed tomography (μCT) with a resolution of 18 μm. The anisotropic biomechanical properties of each sample were determined at the scale of the centimeter based on a dedicated method using asymptotic homogenization. The material properties obtained with this multiscale approach were used as input data in a 3D finite element model to simulate the macroscopic mechanical behavior of the AC implant under different loading conditions. The largest stress and strain magnitudes were found around the equatorial rim and in the polar area of the AC implant. All macroscopic stiffness quantities were significantly correlated (R2 > 0.85, p < 6.5 e-6) with BV/TV (bone volume/total volume). Moreover, the maximum value of the von Mises stress field was significantly correlated with BV/TV (R2 > 0.61, p < 1.6 e-3) and was always found at the bone-implant interface. However, the mean value of the microscopic stress (at the scale of the trabeculae) decrease as a function of BV/TV for vertical and torsional loading and do not depend on BV/TV for horizontal loading. These results highlight the importance of the anisotropic properties of bone tissue.

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Parameterization, statistical measurement and numerical modeling of fluctuated meso/micro-structure of plain woven fabric GFRP laminate for quantification of geometrical variability

Kohei Hagiwara, Shintaro Ishijima, Naoki Takano, Akio Ohtani, Asami Nakai

Mechanical Engineering Journal （JSME） 4 （ 4 ） 2017年08月

研究論文（学術雑誌）, 共著, 査読有り

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FRPの確率的RTM成形プロセスシミュレーションにおける裾野分布の解析

高野直樹, 石島慎太郎

日本機械学会論文集 83 （ 851 ） 2017年07月

研究論文（学術雑誌）, 共著, 査読有り

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Stochastic multi-scale finite element analysis of the drilling force of trabecular bone during oral implant surgery

Daisuke Tawara, Naoki Takano, Hideaki Kinoshita, Satoru Matsunaga, Shinichi Abe

International Journal of Applied Mechanics （International Journal of Applied Mechanics） 8 （ 6 ） 1650075 2016年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 17588251

© 2016 World Scientific Publishing Europe Ltd. To avoid procedural accidents during/after oral implant surgery in a jawbone (e.g., perforation of the lingual side due to an inadequate drilling angle or scratching the mandibular canal), it is important for dentists to develop skilled drilling techniques. We have developed a stochastic multi-scale prediction of apparent elastic moduli of the jawbone with modified first-order perturbation-based stochastic homogenization in which individual differences of drilling properties relating to bone quality can be evaluated with a force-sensitive device. To establish drilling properties in various types of jawbone and the perforation case, and for drill diameters, we propose an original computational method that avoids procedural accidents by defining the drilling angle as a parameter and quantifying individual differences and the inner distribution of bone quality in several jawbones as a drilling force. Three samples demonstrated that drilling forces changed depending on the trabecular structure, with the drilling force changing little around the mandibular canal and increasing just before perforation. Drilling force also depended on the drill diameter but did not always match its size. Estimated drilling forces of the expected value and 50% and 90% probability results suggested prominent differences in drilling properties. This information enables dentists to develop a skillful surgical technique.

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Desktop micro-CT image-based dynamic FEM analysis of stress wave pathways between mandibular trabecular bone and cortical bone with comparisons to virtual models with eliminated materials on pathways

Haruhisa Nakano, Naoki Takano, Koutaro Maki

Journal of Biomechanical Science and Engineering （Journal of Biomechanical Science and Engineering） 11 （ 3 ） 1 - 11 2016年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 18809863

© 2016 The Japan Society of Mechanical Engineers. To a nalyze the biomechanical behavior of human bone, micro-CT image-based static FEM analyse s considering trabecular architecture have been carried out. In the field of dental biomechanics, not only the static analysis but also dynamic analysis against impact load is required. In this paper, a desktop micro-CT was used for the right half of a human mandible with 0.103 mm resolution after dissecting. The lost information by a saw was recovered by the homogenization model. The impact load was applied to the implant in the molar part and the load transfer from the implant to the cortical bone and trabecular bone was considered. The stress wave pathways from the implant to the condyle were analyzed by comparison with virtual FEM models with eliminated materials on pathways. It was revealed that the stress wave transferred from the implant neck and end part to peri-implant trabecular bone played a significant mechanical role. It was also found that the apparent wave speed in the trabecular bone region was as fast as that in the cortical bone.

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Numerical prediction of scattered initial fracture load of perforated thin plate under tension by Monte Carlo FEM simulation with stepwise limited sampling

Shusuke Akimoto, Naoki Takano

Mechanical Engineering Letters 2 1 - 8 2016年06月

研究論文（学術雑誌）, 共著, 査読有り

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Quantitative study of force sensing while drilling trabecular bone in oral implant surgery

Mohammad Aimaduddin Atiq bin Kamisan, Hideaki Kinoshita, Fumiya Nakamura, Shinya Homma, Yasutomo Yajima, Satoru Matsunaga, Shinichi Abe, Naoki Takano

Journal of Biomechanical Science and Engineering （Journal of Biomechanical Science and Engineering） 11 （ 3 ） 1 - 9 2016年06月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 18809863

© 2016 The Japan Society of Mechanical Engineers. A survey done recently showed that almost 30 percent of the accidents occurred during oral implant surgery were concerned with the mandibular canal in the trabecular bone region and most of them were related to the drilling process. One of the reasons known is due to the clinicians' lack of knowledge and experience. In order to overcome the problem, through the educational approach, we proposed and developed a new system mainly for dental colleges' students, by focusing on drilling the mandibular trabecular bone. The system comes in the form of an oral implant surgery training simulator that enables student to sense the reaction force during drilling. The developed system was then evaluated by expert clinicians and dental college's students. A total of 8 clinicians and 24 students tested all three samples of drilling force database. The clinicians were asked to describe the drilling force based on a stiffness scale while the students are required to drill two samples first before drilling the third sample. They were asked to sketch the third samples based on the comparison of previous samples. Based on the evaluation done, it was found that the quantification of force sensed during drilling could be derived from the combination of drilling force and speed obtained through the relative value of comparison with the previous or accumulated experience of drilling. The results of this study also indicate that the oral implant surgery training simulator could help students learn the difference of drilling force sense dependent on the bone quality through repeated usage and practices.

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Probabilistic multiscale analysis of three-phase composite material considering uncertainties in both physical and geometrical parameters at microscale

Pin Wen, Daisuke Kurita, Naoki Takano

Acta Mechanica （Acta Mechanica） 227 （ 10 ） 2735 - 2747 2016年05月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00015970

© 2016, Springer-Verlag Wien. A probabilistic multiscale framework is proposed to characterize the probabilistic behaviors of macroscopic elastic properties of multiphase composite materials. The first-order perturbation-based stochastic homogenization method is extended to incorporate inherent randomness existed in multiphase constituents materials on basis of our previous work for porous material. Moreover, a generalized stochastic method is introduced to combine above with morphological nonparametric uncertainties. A numerical example for coated particulate composite material demonstrated the feasibility and effectiveness of proposed methods.

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Prediction of apparent properties with uncertain material parameters using high-order fictitious domain methods and PGD model reduction

Gregory Legrain, Mathilde Chevreuil, Naoki Takano

International Journal for Numerical Methods in Engineering （International Journal for Numerical Methods in Engineering） 109 （ 3 ） 345 - 367 2016年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00295981

Copyright © 2016 John Wiley & Sons, Ltd. This contribution presents a numerical strategy to evaluate the effective properties of image-based microstructures in the case of random material properties. The method relies on three points: (1) a high-order fictitious domain method; (2) an accurate spectral stochastic model; and (3) an efficient model-reduction method based on the proper generalized decomposition in order to decrease the computational cost introduced by the stochastic model. A feedback procedure is proposed for an automatic estimation of the random effective properties with a given confidence. Numerical verifications highlight the convergence properties of the method for both deterministic and stochastic models. The method is finally applied to a real 3D bone microstructure where the empirical probability density function of the effective behaviour could be obtained. Copyright © 2016 John Wiley & Sons, Ltd.

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Macro/micro simultaneous validation for multiscale analysis of semi-periodically perforated plate using full-field strain measurement

Tetsuya Matsuda, Takashi Ito, Shusuke Akimoto, Hiroshi Kobori, Keita Goto, Naoki Takano

International Journal of Mechanical Sciences （International Journal of Mechanical Sciences） 110 34 - 40 2016年03月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00207403

© 2016 Elsevier Ltd. Multiscale analysis of a semi-periodically perforated plate based on a homogenization theory is experimentally validated both macroscopically and microscopically, using a full-field strain measurement. To do this, a plate-fin-type perforated plate with a misaligned microstructure is considered as a semi-periodically perforated plate. Then, a homogenization theory that can analyze macroscopic behavior and microscopic stress and strain distributions of the perforated plate is presented. To validate the theory, a tensile test of a plate-fin-type semi-periodically perforated plate made of epoxy resin is conducted. During the test, the microscopic deformation of the specimen is observed with a digital image correlation (DIC) full-field measurement system, from which microscopic strain distribution of the specimen is calculated. It is shown that the obtained strain distribution satisfies the unit-cell periodicity except at edges of the periodic structure, and that the strain distribution is in good agreement with the result of analysis using the homogenization theory. It is also shown that the macroscopic stress-strain relationships obtained by the experiment and analysis agree well, supporting the macroscopic and microscopic validity of the multiscale analysis using the homogenization theory.

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Drilling force and speed for mandibular trabecular bone in oral implant surgery

Mohammad Aimaduddin Atiq bin Kamisan, Kenichiro Yokota, Takayuki Ueno, Hideaki Kinoshita, Shinya Homma, Yasutomo Yajima, Sinichi Abe, Naoki Takano

Biomaterials and Biomechanics in Bioengineering （TECHNO Press） 3 （ 1 ） 15 - 26 2016年03月

研究論文（学術雑誌）, 共著, 査読有り

Probabilistic homogenization and sensitivity analysis for robust design of coated particulate composite material considering non-parametric geometrical uncertainty at microscale

Pin Wen, Kosho Kamijo, Daichi Kurita, Naoki Takano

Transactions of the Japan Society for Computational Engineering and Science （Transactions of the Japan Society for Computational Engineering and Science） 2016 （ 20160005 ） 1 - 10 2016年02月

研究論文（学術雑誌）, 共著, 査読有り

© 2016 by the Japan Society for Computational Engineering and Science. The aim of this study is that with consideration of geometrical fluctuation, robust design is made to assure performance of material more reliable to fabrication process. Firstly a target microstructure is defined as the optimum solution for coated particulate material. Then a slightly fluctuated computational models are generated in which some random variables are defined. Multiscale analysis is done to obtain homogenized Young’s modulus, shear modulus and an index with respect to strength. Probabilistic sensitivity for those quantities of interest against design variables is analyzed by means of response surface method. For response surface, this paper studies a case where the scattering of sampling points is clustered. The characteristics of cluster sampling points determine the response surface strategy as quadratic polynomial and least square regression method. Finally the numerical result of a specific robust design for coated particulate composite material reveals that when the mean radius of particle is bigger and mean coating thickness is smaller, the less sensitive index is. It will provide a reliable guidance and save cost in the development of wide range of composite materials.

Development of a drilling simulator for dental implant surgery

Hideaki Kinoshita, Masahiro Nagahata, Naoki Takano, Shinji Takemoto, Satoru Matsunaga, Shinichi Abe, Masao Yoshinari, Eiji Kawada

Journal of Dental Education （Journal of Dental Education） 80 （ 1 ） 83 - 90 2016年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00220337

The aim of this study was to develop and evaluate a dental implant surgery simulator that allows learners to experience the drilling forces necessary to perform an osteotomy in the posterior mandibular bone. The simulator contains a force-sensing device that receives input and counteracts this force, which is felt as resistance by the user. The device consists of an actuator, a load cell, and a control unit. A mandibular bone model was fabricated in which the predicted forces necessary to drill the cortical and trabecular bone were determined via micro CT image-based 3D finite element analysis. The simulator was evaluated by five dentists from the Department of Implantology at Tokyo Dental College. The ability of the evaluators to distinguish the drilling resistance through different regions of the mandibular bone was investigated. Of the five dentists, four sensed the change in resistance when the drill perforated the upper cortical bone. All five dentists were able to detect when the drill made contact with lingual cortical bone and when the lingual bone was perforated. This project successfully developed a dental implant surgery simulator that allows users to experience the forces necessary to drill through types of bone encountered during osteotomy. Furthermore, the researchers were able to build a device by which excessive drilling simulates a situation in which the lingual cortical bone is perforated-A situation that could lead to negative repercussions in a clinical setting. The simulator was found to be useful to train users to recognize the differences in resistance when drilling through the mandibular bone.

The “sea” should not be operated on in scar revision for “island-like” scars

Tomohisa Nagasao, Yusuke Hamamoto, Motoki Tamai, Hiroo Kudo, Toshiya Ensako, Tetsukuni Kogure, Naoki Takano, Yoshio Tanaka

Medical Hypotheses 2015年04月

研究論文（学術雑誌）, 共著, 査読有り

Probabilistic analysis of mechanical behaviour of mandibular trabecular bone using a calibrated stochastic homogenization model

Daisuke Tawara, Masahiro Nagahata, Naoki Takano, Hideaki Kinoshita, Shinichi Abe

Acta Mechanica （Acta Mechanica） 226 （ 7 ） 3275 - 3287 2015年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00015970

© 2015, Springer-Verlag Wien. Surgical success of drilling in oral implantology depends on the sense of force on the fingers or feeling of a dental clinician, which is related to the quality of trabecular bone in the jawbone expressed by apparent mechanical characteristics. As the mechanical properties of trabecular bone depend on the bone volume fraction, microstructure, and many other factors closely related to individual differences, a probabilistic numerical procedure to assess drilling force is proposed. Using a micro-CT-based jawbone model, a first-order perturbation-based stochastic homogenization method was employed to estimate the possible scattering of apparent mechanical properties of the trabecular bone region. The complicated drilling problem was simplified to sequential linear static FEAs, to which the predicted apparent Young’s modulus and shearing moduli in the drilling direction were applied. The FEAs demonstrated that the homogenized mechanical properties showed anisotropy, which might lead to differences in the drilling forces at different drilling angles. The numerically estimated drilling forces were shown by the expected value, 50 %-probability result, and 90%-probability result and revealed that one patient among two or ten patients would probably have poor bone quality. There was a remarkable difference in the drilling forces between the expected value and the 90%-probability result.

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Scoring of deformed costal cartilages reduces postoperative pain after Nuss procedure for pectus excavatum

Tomohisa Nagasao, Yusuke Hamamoto, Motoki Tamai, Tetsukuni Kogure, Hua Jiang, Naoki Takano, Yoshio Tanaka

Thoracic and Cardiovascular Surgeon （Thoracic and Cardiovascular Surgeon） 64 （ 1 ） 62 - 69 2015年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 01716425

© 2016 Georg Thieme Verlag KG Stuttgart · New York. Objective The present study aims to elucidate whether or not scoring deformed cartilages reduces postoperative pain after the Nuss procedure for pectus excavatum patients. Methods A total of 46 pectus excavatum patients for whom the Nuss procedure was conducted were included in the study. The patients were categorized into two groups, depending on whether or not the supplementary maneuver of scoring deformed cartilages was performed in addition to the Nuss procedure. Patients for whom deformed costal cartilages were scored were categorized as the Scoring Group (n = 24); those who received no such scoring were categorized as the Non-Scoring Group (n = 22). After evaluating the maximum stresses occurring on the thoraces by means of dynamic simulation using finite element analyses, intergroup comparison of the maximum von-Mises stress values was performed. Furthermore, after quantifying postoperative pain as the frequency with which patients injected anesthetics through an epidural pain-control system within 2 postoperative days, the degree of pain was compared between the two groups. Results The maximum stresses occurring on the thorax were significantly greater for the Non-Scoring Group than for the Scoring Group; injection frequency was also greater for the Non-Scoring Group (average 4.9 times for 2 days) than for the Scoring Group (average 2.5 times for 2 days). Conclusion High stresses occur due to the performance of the Nuss procedure, causing postoperative pain. The stresses can be reduced by performing supplementary scoring on deformed cartilages. Accordingly, postoperative pain is reduced.

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Multiscale stress analysis of trabecular bone around acetabular cup implant by finite element mesh superposition method

Makoto Tsukino, Naoki Takano, Adrien Michel, Guillaume Haiat

Mechanical Engineering Letters （JSME） 1 （ 15-00354 ） 1 - 8 2015年

研究論文（学術雑誌）, 共著, 査読有り

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Stochastic homogenization analysis of FIB-SEM image-based hierarchical model of sprayed porous ZrO2

Yuma Miyauchi, Naoki Takano, Pin Wen

Mechanical Engineering Letters （JSME） 1 （ 15-00389 ） 1 - 8 2015年

研究論文（学術雑誌）, 共著, 査読有り

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Probabilistic prediction of homogenized property and update of prediction for spherical porous material considering microstructural uncertainties

Pin Wen, Kenichiro Yokota, Naoki Takano

Journal of Multiscale Modelling （Imperial College Press） 6 （ 4 ） 1 - 19 2015年

研究論文（学術雑誌）, 共著, 査読有り

Irregular location of major pectoral muscle can be a causativ factor of pectus excavatum

Tomohisa Nagasao, Yusuke Shimizu, Tadaaki Morotomi, Naoki Takano, Hua Jiang, Kazuo Kishi

Medical Hypotheses 82 （ 5 ） 512 - 517 2014年05月

研究論文（学術雑誌）, 共著, 査読有り

Classification and visualization of primary trabecular bone in lumbar vertebrae

Khairul Salleh Basaruddin, Junya Omori, Naoki Takano, Takayoshi Nakano

Advances in Biomechanics and Applications 1 （ 2 ） 111 - 126 2014年04月

研究論文（学術雑誌）, 共著, 査読有り

Estimation of apparent elastic moduli of trabecular bone considering biological apatite (BAp) crystallite orientation in tissue modulus

Khairul Salleh Basaruddin, Naoki Takano

Advanced Materials Research （Advanced Materials Research） 894 167-171 - 171 2014年03月

研究論文（学術雑誌）, 共著

This study presents a prediction of apparent elastic moduli of vertebral trabecular bone using the homogenization method. A micro-finite element (FE) model of trabecular bone was reconstructed from a sequential of cross-section micro-CT image by converting bone voxels to brick elements. Eight regions of interest (ROIs) were extracted from two lumbar vertebra bone specimens of healthy and osteoporotic. The homogenization method and finite element method was employed to analyze the microscopic trabecular bone. Bone tissue property was modeled as orthotropy material considering the biological apatite (BAp) crystallite orientation. This research focuses on the effect of morphological difference between healthy and osteoporotic bones to the apparent elastic moduli. The change of degree of anisotropy was also discussed. Comparison of the calculated Young's moduli in vertical axis with Keyak et al.'s experimental result showed good agreement and proved the reliability of the numerical model. © (2014) Trans Tech Publications, Switzerland.

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Practical Monte Carlo simulation method highlighting on tail probability with application to biomechanics analysis of pressure ulcer

Samuel Susanto Slamet, Kyohei Hatano, Naoki Takano, Tomohisa Nagasao

Transactions of the Japan Society for Computational Engineering and Science （Transactions of the Japan Society for Computational Engineering and Science） 2014 （ 2014 ） Paper No.20140001 2014年02月

研究論文（学術雑誌）, 共著, 査読有り

The Monte Carlo method is a well-known method for calculating uncertainty, but it has the disadvantage of high computational cost because it usually requires 10,000 sampling points. In this paper, a practical sampling algorithm named Stepwise Limited Sampling (SLS) is proposed to obtain both accurate expected values and very accurate tail probability values in the Monte Carlo simulation. This method was then applied to a biomechanics problem concerning the risk prediction of pressure ulcers. It is known that the initial damage that leads to a fatal stage of pressure ulcer occurs in deep muscle, but its location has not been clarified. By modeling assumed damage at the bone-muscle interface in the human buttock as a cutout, and by judging whether the damage propagates or not, sets of material properties of muscle and fat in the tail probability that result in high interface shear strain were obtained as a function of body positioning during nursing. © 2014 by the Japan Society for Computational Engineering and Science.

Association between the peri-implant bone structure and stress distribution around the mandibular canal: A three-dimensional finite element analysis

Hideaki Kinoshita, Ken Nakahara, Satoru Matsunaga, Akinobu Usami, Masao Yoshinari, Naoki Takano, Yoshinobu Ide, Shinichi Abe

Dental Materials Journal （Dental Materials Journal） 32 （ 4 ） 637-642 - 642 2013年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 02874547

The aim of this study was to elucidate the association between the bone structure at implant insertion sites and stress distribution around the mandibular canal by means of three-dimensional finite element (3D FE) analysis. Four FE models were created with slice data using micro-computed tomography (micro-CT), and 3D FE analysis was performed. Mechanical analysis showed that the load reached the mandibular canal via the trabecular structure in all FE models. High levels of stress were generated around the mandibular canal when the distance between the mandibular canal and the implant decreased. High stress levels were also observed when cortical bone thickness and bone volume/total volume (BV/TV) were low. Our findings suggest that load is transmitted to the mandibular canal regardless of differences in the thickness of cortical bone or cancellous bone structure, but excessive load may be generated in bone with thin cortical and coarse cancellous structures.

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Consideration of shear modulus in biomechanical analysis of peri-implant jaw bone: Accuracy verification using image- based multi-scale simulation

Satoru Matsunaga, Hiroyoshi Naito, Yuichi Tamatsu, Naoki Takano, Shinichi Abe, Yoshinobu Ide

Dental Materials Journal 32 （ 3 ） 425-432 2013年08月

研究論文（学術雑誌）, 共著, 査読有り

Transformation of keloids is determined by stress occurrence patterns on peri-keloid regions in response to body movement

Tomohisa Nagasao, Noriko Aramaki-Hattori, Yusuke Shimizu, Sumiko Yoshitatsu, Naoki Takano, Kazuo Kishi

Medical Hypotheses 81 （ 1 ） 136-141 2013年07月

研究論文（学術雑誌）, 共著, 査読有り

Relationship between locations of rib defects and loss of respiratory function - A biomechanical study

Asako Hatano, Tomohisa Nagasao, Yasunori Cho, Yusuke Shimizu, Naoki Takano, Tsuyoshi Kaneko, Kazuo Kishi

Thoracic and Cardiovascular Surgeon （Thoracic and Cardiovascular Surgeon） 62 （ 4 ） DOI:10.1055/s-0033-1338107 - 362 2013年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 01716425

Objective The present study elucidates the relationship between the locations of rib defects and loss of respiratory function. Methods Ten sets of three-dimensional finite element models were produced from computed tomography data of 10 persons and categorized as normal type models. These models were modified by removing part of the ribs, and the resultant models were categorized as defect type models. Varying the location of the defects, six types of defect model were produced from each of the 10 normal models; the defects were made on the anterior-superior, anterior-inferior, lateral-superior, lateral-inferior, posterior-superior, and posterior-inferior regions of the thorax. To simulate respiration, contracture forces were applied to nonlinear springs modeling respiratory muscles for each of the normal and defect models. Difference in volume of the thoracic cavity between inspiration and expiration phases was viewed as the indicator of respiratory function and was defined as ΔV. The values of ΔV were compared between normal type models and their corresponding defect type models. Results Among the six types of defect, the degree of functional loss was greatest with those defects on the lateral-inferior part of the thorax, where ΔV of the affected side hemithorax drops to 38 to 45% of normal values, whereas ΔV was 62 to 88% with other defect models. Conclusion Thoraces that have defects on their lateral-inferior regions present lower respiratory functioning than thoraces with other defect locations. Hence, in treating clinical cases where defects are expected to occur in this region, effort should be made to minimize the area of the defect. © 2014 Georg Thieme Verlag KG Stuttgart New York.

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Uncertainty modeling in the prediction of effective mechanical properties using stochastic homogenization method with application to porous trabecular bone

Khairul Salleh Basaruddin,Naoki Takano, Hikaru Akiyama, Takayoshi Nakano

Materials Transactions （Materials Transactions） 54 （ 8 ） 1250-1256 - 1256 2013年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13459678

A systematic modeling of uncertainty due to image processing, material characteristics and experimental works was developed in order to propose a novel stochastic image-based multi-scale method for heterogeneous media. The effective mechanical properties with application to three porous trabecular bone models were predicted by introducing the correction factor (β) to represent the miscellaneous errors or unknown factors. Finally, the probability density was obtained for the effective mechanical properties, which could evaluate the reliability of scattered experimental results. It has been concluded that variation in effective properties of heterogeneous media can be predicted even when only limited measured values are available by using the present extrapolation technique based on verified simulation results. © 2013 The Japan Institute of Metals and Materials.

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Stochastic multi-scale prediction on the apparent elastic moduli of trabecular bone considering uncertainties of biological apatite (BAp) crystallite orientation and image-based modelling

Khairul Salleh Basaruddin, Naoki Takano, Takayoshi Nakano

Computer Methods in Biomechanics and Biomedical Engineering （Computer Methods in Biomechanics and Biomedical Engineering） 18 （ 2 ） DOI:10.1080/10255842.2013.785537 - 174 2013年04月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 10255842

© 2013 Taylor & Francis. An assessment of the mechanical properties of trabecular bone is important in determining the fracture risk of human bones. Many uncertainty factors contribute to the dispersion of the estimated mechanical properties of trabecular bone. This study was undertaken in order to propose a computational scheme that will be able to predict the effective apparent elastic moduli of trabecular bone considering the uncertainties that are primarily caused by image-based modelling and trabecular stiffness orientation. The effect of image-based modelling which focused on the connectivity was also investigated. A stochastic multi-scale method using a first-order perturbation-based and asymptotic homogenisation theory was applied to formulate the stochastically apparent elastic properties of trabecular bone. The effective apparent elastic modulus was predicted with the introduction of a coefficient factor to represent the variation of bone characteristics due to inter-individual differences. The mean value of the predicted effective apparent Young's modulus in principal axis was found at approximately 460 MPa for respective 15.24% of bone volume fraction, and this is in good agreement with other experimental results. The proposed method may provide a reference for the reliable evaluation of the prediction of the apparent elastic properties of trabecular bone.

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Monte Carlo simulation of dynamic problem using model order reduction technique highlighting on tail probability

Naoki Takano, Mitsuteru Asai, Kohta Okamoto

Journal of Computational Science and Technology 6 （ 3 ） 169-181 2012年09月

研究論文（学術雑誌）, 共著

Morphology analysis of vertebral trabecular bone under dynamic loading based on multi-scale theory

Khairul Salleh Basaruddin, Naoki Takano, Yuto Yoshiwara, Takayoshi Nakano

Medical and Biological Engineering and Computing （Medical and Biological Engineering and Computing） 50 （ 10 ） 1091-1103 - 1103 2012年08月

研究論文（学術雑誌）, 共著, ISSN 01400118

Trabecular bone has a complicated porous microstructure and consists of interconnected plates and rods known as trabeculae. The microarchitecture of the trabeculae contributes to load distribution capacity and, particularly, the optimal bone strength. Many previous studies have shown that morphological parameters are used to characterize the microarchitecture of trabecular bone, but little is known about the mechanical role of trabecular morphology in the context of load-bearing behavior. Therefore, this study proposes a new segmentation method for examining the morphology of trabecular structure foci of load-bearing capability. A micro-finite element model of trabecular bone was obtained from the fourth lumbar vertebra on the basis of a three-dimensionally reconstructed micro-computed tomography (CT) image. We used an asymptotic homogenization method to determine microscopic stress by applying three unidirectional compressive loads in the vertical, anteroposterior, and right-left axes of two trabecular bone volumes. We then classified the complicated trabecular microstructure into three segments: primary and secondary trabeculae and trabeculae of no contribution. Next, a dynamic analysis was conducted by applying a force impulse load. The result indicated that 1/3 of the trabecular volume functions as primary trabecula. The morphology of the trabecular network could be visualized successfully highlighting the percolation of the stress wave in the primary trabecular segment. Further, we found that the role of the plate-like structures was that of a hub in the trabecular network system. © International Federation for Medical and Biological Engineering 2012.

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Biomechanics analysis of pressure ulcer using damaged interface model between bone and muscle in the human buttock

Samuel Susanto Slemet, Naoki Takano, Yoshiyuki Tanabe, Asako Hatano, Tomohisa Nagasao

Journal of Computational Science and Technology 6 （ 2 ） 70-80 2012年06月

研究論文（学術雑誌）, 共著

Calibration of wet etching parameters for sacrifice layer of MEMS

Naoki Takano, Kenichi Sato, Toshiyuki Toriyama, Toru Yamasaki, Seiichi Uesugi

Journal of Computational Science and Technology 5 （ 3 ） 106-119 2011年10月

研究論文（学術雑誌）, 共著

Numerical study on the morphology and mechanical role of healthy and osteoporotic vertebral trabecular bone

Yuto Yoshiwara, Miguel Clanche, Khairul Salleh Basaruddin, Naoki Takano, Takayoshi Nakano

Journal of Biomechanical Science and Engineering （Journal of Biomechanical Science and Engineering） 6 （ 4 ） 270-285 - 285 2011年09月

研究論文（学術雑誌）, 共著, ISSN 18809863

This study presents a numerical methodology to clarify the morphology of complex trabecular network architecture in human lumbar vertebra by means of the new post-processing technique for calculated microscopic stress by the homogenization method. Micro-CT image-based modeling technique is used and careful but intuitive and easy-to-use method for microstructure model, in other words region of interest (ROI), is also presented. The macroscopic homogenized properties that include not only the Young's moduli but also shear moduli could explain the difference of morphology between healthy and osteoporotic bones. This paper focuses on the change of degree of anisotropy. Then, the microscopic stress under three basis load cases was analyzed. In this analysis, the homogenization method has a merit in the computational cost. The trabeculae are classified into eight groups from the viewpoint of load bearing function against three loading conditions in the proposed post-processing of numerical results. It contributes to the understanding of the mechanical role of trabecular bone in vertebra. The primary trabecular bone that has been supposed to support the self-weight and secondary bone that connects the primary bone are successfully visualized. The discussion on the mechanical role of plate-like trabecular bone in the load path network system is also highlighted. © 2011 by JSME.

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Biomechanics of jaw bone considering structural properties of trabecular bone

Satoru Matsunaga, Naoki Takano, Yuichi Tamatsu, Shinichi Abe, Yoshinobu Ide

Journal of Oral Biosciences （Journal of Oral Biosciences） 53 （ 2 ） 143/147 - 147 2011年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13490079

Formation of polymer microneedle arrays using soft lithography

Yoshimichi Ami, Hiroto Tachikawa, Naoki.Takano, Norihisa Miki

Journal of Micro/Nanolithography, MEMS, and MOEMS （Journal of Micro/Nanolithography, MEMS, and MOEMS） 10 （ 1 ） 011503/1-6 2011年03月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 19325150

We demonstrate the fabrication of polymer microneedle arrays using soft lithography. A photomask was designed to use Fresnel diffraction of UV light to create sharp, tapered hollows in SU-8, a negative photoresist, after development. Polymer microneedles were formed using these SU-8 structures as a mold. These polymer needles may be applicable as flexible electrodes in brain-machine interfaces because they are more likely to survive movement of the skin than conventional brittle silicon needles. Similar needles, made from medicinal substances, could be used for transdermal drug administration. For these applications, the needles must be long, sharp, and stiff enough to penetrate the stratum corneum (∼20 m in thickness) and reach the viable epidermis (200-300 m in thickness), but must not reach the dermis, which contains sensitive nerve endings. We successfully manufactured 2020 microneedle arrays of polydimethylsiloxane with a needle length of 200 m. We experimentally verified that these manufactured electrodes successfully penetrated the stratum corneum of a cultured skin. © 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Biomechanical role of peri-implant cancellous bone architecture

Satoru Matsunaga ,Yoshitaka Shirakura, Takashi Ohashi, Ken Nakahara, Yuichi Tamatsu, Naoki Takano, Yoshinobu Ide

International Journal of Prosthodontics （International Journal of Prosthodontics） 23 （ 4 ） 333-338 - 338 2010年07月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 08932174

Purpose: The aim of this study was to investigate the biomechanical role of trabecular bone around dental implants in the mandible. Materials and Methods: The model in this study was made using micro-computed tomography data taken from a cadaver in whom endosseous implants had been in place for 15 years prior to death. Morphologic analysis and three-dimensional (3D) finite element analysis were performed to calculate the peri-implant loading path of the model in which the trabecular structure was accurately simulated. Results: As seen through multiscale analysis using the homogenization method, the trabecular bone architecture around implants was isotropic for the most part. Also, 3D finite element analysis showed that compressive stresses oblique to the implant axis were transmitted to the lower constrained surface; tensile stresses oblique to the implant axis were transmitted to the upper constrained surface, and they intersected each other with vertical loading. The highest stress in cancellous bone was observed on perpendicular loading, and stress produced in trabeculae decreased approaching horizontal loading. Conclusion: Cancellous bone architecture around the implant was generally isotropic. 3D finite element analysis showed that cancellous bone trabeculae around implants dispersed stress by forming load transfer paths. The results suggest that trabecular bone plays a major role in supporting functional pressure exerted via the implant. © 2010 by Quintessence Publishing Co Inc.

マルチスケール応力解析によるヒト椎体海綿骨の力学的評価

田原大輔, 高野直樹, 安達泰治, 中野貴由

日本骨形態計測学会雑誌 20 （ 1 ） S100-S107 2010年05月

研究論文（学術雑誌）, 共著, 査読有り

Effect of tension and curvature of skin on insertion characteristics of microneedle array

Hiroto Tachikawa, Naoki Takano, Kazuaki Nishiyabu Norisisa Miki, Yoshimichi Ami

Journal of Solid Mechanics and Materials Engineering 4 （ 3 ） 470-480 2010年03月

研究論文（学術雑誌）, 共著, 査読有り

Structural strength prediction for porous titanium based on micro-stress concentration by micro-CT image-based multiscale simulation

Naoki Takano, Ken Fukasawa, Kazuaki Nishiyabu

International Journal of Mechanical Sciences （International Journal of Mechanical Sciences） 52 （ 52 ） 229-235 - 235 2010年01月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 00207403

For the design of porous titanium component, differently from its use as functional materials, structural strength prediction algorithm is proposed based on the micro-stress concentration analyzed by the multiscale simulation. The modeling of real microstructure is carried out by the image-based technique with X-ray micro-CT. The multiscale computational method consists of asymptotic homogenization and finite element mesh superposition (FEMS) techniques. A criterion is proposed to predict the nonlinearity initiation point in the load and displacement curve by means of micro-stress distribution expressed by histogram. Only the constituent's yield strength is referred regardless of the microscopic morphology. The originality of this paper lies in the validation of the homogenization process, the modeling guideline of micro-mesh superposition onto macro-mesh in FEMS, and the strength prediction algorithm. L-shaped components with different pore diameter were discussed in both experiment and simulation. © 2009 Elsevier Ltd. All rights reserved.

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Biomechanical role of peri-implant trabecular structures during vertical loading

Takashi Ohashi, Satoru Matsunaga ,Ken Nakahara, Shinichi Abe, Yoshinobu Ida, Yuichi Yamatsu, Naoki Takano

Clinical Oral Investigations （Clinical Oral Investigations） 14 （ 5 ） 507-513 - 513 2009年08月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 14326981

The aim of this study was to identify the load transfer paths in cortical bone and trabecular structure of cancellous bone in the jawbones for loads from endosseous implants. Maxillae were resected from beagle dogs 6 months after implant surgery and imaged using micro-computed tomography (micro-CT). A three-dimensional structure was produced based on the CT data and peri-implant trabecular structure was observed. Load transfer paths were analyzed from the results of three-dimensional finite element analysis. Furthermore, buffer actions in bone trabeculae when strain increased during stress analysis and when loads were applied were observed. Peri-implant bone trabeculae were seen extending into the upper and lower cortical bone from the fixture. The direction of bone trabecular alignment corresponded with the load transfer paths. In addition, analysis with increased strain confirmed that trabecular structures could serve as load buffers. These results suggest that bone trabeculae supporting load transfer from implants undergo remodeling. © 2009 Springer-Verlag.

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Creative design with multi-objective topology optimization

Chen Jian Ken Lee, Naoki Takano

Transactions of Japan Society for Computational Engineering and Science, Vol.2009 2009 Paper No.20090011 2009年07月

研究論文（学術雑誌）, 共著, 最終著者, 査読有り

Reduction of finite element mesh and model order for fast dynamic analysis of global/Local problem

Atsushi Sando, Naoki Takano, Mitsuteru Asai, Toshiyuki Toriyama, Shoji Kido, Jan.G.Korvonk

Jurnal of Solid Mechanics and Materials Engineering （日本機械学会） 3 （ 3 ） 572 - 583 2009年03月

研究論文（学術雑誌）, 共著, 査読有り

Insertion testing of polyethylene glycol microneedle array into cultured human skin with biaxial tension

Naoki Takano, Hiroto Tachiawa, Takaya Miyano, Kazuaki Nishiyabu

Journal of Solid Mechanics and Materials Engineering （日本機械学会） 3 （ 3 ） 604-612 2009年03月

研究論文（学術雑誌）, 共著, 査読有り

Removing void elements for structural level set topology optimizaiton

Chen Jian Ken Lee, Zhiqian Zhang, Naoki Takano

Journal of Computational Science and Technology （JSME） 3 （ 1 ） 385 - 395 2009年01月

研究論文（学術雑誌）, 共著, 査読有り

Adjoint variable method for multi-objective sizing and shape optimization

Chen Jian Ken Lee, Wataru Furuya, Masato Tanaka, Naoki Takano

Journal of Computational Science and Technology （JSME） 3 （ 1 ） 275 - 286 2009年01月

研究論文（学術雑誌）, 共著, 最終著者, 査読有り

透過型光学系を有する微小領域X線回折法によるヒト海綿骨内生体アパタイト結晶配向性の2次元定量解析

宮部さやか, 中野貴由, 石本卓也, 高野直樹, 安達泰治, 岩城啓好, 高岡邦夫, 馬越佑吉

日本金属学会誌 72 （ 1 ） 57 - 62 2008年

研究論文（学術雑誌）, 共著, 査読有り

ナノ粒子分散材の3次元モルフォロジー分析と有限要素モデリング

高野直樹, 浅井光輝, 黄田尚宏, 橋本和信

材料 57 （ 5 ） 423 - 429 2008年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

骨質を考慮した椎体海綿骨の高分解能ミクロ応力解析

田原大輔, 安達泰治, 高野直樹, 中野貴由

日本臨床バイオメカニクス学会誌 20 7 - 14 2008年

研究論文（学術雑誌）, 共著, 査読有り

HMS採血ポンプ用新型バイモルフ圧電アクチュエータの提案

上辻靖智, 長倉秀幸, 川原慎太郎, 黄輝心, 槌谷和義, 山本英毅, 高野直樹, 仲町英治

材料 56 （ 5 ） 477 - 482 2007年05月

研究論文（学術雑誌）, 共著, 査読有り

Two-dimensional quantitative analysis of preferential alignment of BAp c-axis for isolated human trabecular bone using microbeam X-ray diffractometer with a transmission optical system

Sayaka Miyabe, Takayoshi Nakano, Takuya Ishimoto, Naoki Takano, Taiji Adachi, Hiroyoshi Iwaki, Akio Kobayashi, Kuio Takaoka, Yukichi Umakoshi

Materials Transactions （Materials Transactions） 48 （ 3 ） 343 - 347 2007年03月

研究論文（学術雑誌）, 査読有り, ISSN 13459678

Two-dimensional quantitative analysis of microbeam X-ray diffraction (XRD) was performed using a transmission optical system to examine biological apatite (BAp) orientation in an isolated trabecula of a human fourth lumber vertebral body. The incident X-ray beam is 20 μm in diameter, which is small enough for the isolated trabecula despite a slight beam divergence of 0.2°. Integrated intensities of (002) and (310) are obtained separately by different incident angles and detector positions. Distribution of the preferential orientation of the BAp c-axis is finally calculated quantitatively as an integrated intensity ratio of (002)/(310) in a plane containing the trabecular direction. Preferential alignment of the BAp c-axis was finally determined to be perfectly parallel to the fiber direction in a rod-shaped trabecula, since accurate one-dimensional alignment is different from the alignment in the femoral cortical bone as a long bone that shows the local maximum of preferential alignment perpendicular to the longitudinal bone axis. For example, the integrated intensity ratio of (002)/(310) has a maximum value of 16 along the trabecular fiber and a minimum value of 0.09 in the perpendicular direction. Using this method, the anisotropy of BAp orientation in the trabecular bone can be quantitatively evaluated in the plane including the trabecular fiber. Thus, we successfully obtained a methodology that two-dimensionally analyzes the distribution of the BAp c-axis along all axes within a plane in a bone specimen. © 2007 The Japan Institute of Metals.

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An iterative solver applied to strongly coupled piezoelectric problems of porous Pb(Zr,Ti)O3 with nondestructive modelling of microstructure

Mitsuteru Asai, Naoki Takano, Yasutomo Uetsuji, Kunihiko Taki

Modelling and Simulation in Materials Science and Engineering 15 （ 6 ） 597 - 617 2007年

研究論文（学術雑誌）, 共著, 査読有り

均質化法による多孔質圧電材料のイメージベース・マルチスケール解析

浅井光輝, 高野直樹, 滝邦彦, 足森崇志, 日下貴之, 上辻靖智

材料 55 （ 12 ） 1111 - 1116 2006年12月

研究論文（学術雑誌）, 共著, 査読有り

海綿骨の骨梁モルフォロジーと生体アパタイト結晶配向性を考慮したマルチスケール応力解析

河貝光寛, 高野直樹, 中野貴由, 浅井光輝

材料 55 （ 9 ） 874 - 880 2006年08月

研究論文（学術雑誌）, 共著, 査読有り

Image-based multi-scale modelling strategy for complex and heterogeneous porous microstructures by mesh superposition method

Mitsuhiro Kawagai, Atsushi Sando, Naoki Takano

Modelling and Simulation in Materials Science and Engineering （Modelling and Simulation in Materials Science and Engineering） 14 （ 1 ） 53 - 69 2006年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 09650393

This study is focused on the multi-scale modelling strategy for complex and heterogeneous microstructures of real materials by automatic image-based modelling and finite element mesh superposition method. The synergetic application of the conventional asymptotic homogenization method and the authors' mesh superposition method has been proposed to obtain the microscopic responses under high gradient of macroscopic fields at the macroscopic crack tip and/or interface, for instance. For complex and random microstructures, automatic image-based voxel meshing by means of x-ray CT is commonly required; however, it cannot always adapt to the mathematical theory of microscopic modelling in the mesh superposition method. Therefore, a modelling technique for mesh refinement is proposed in this paper using additional elements for insulation in consideration of the theoretical background of the mesh superposition method. In this paper, we provide the modelling procedure and its theoretical consideration of mesh refinement for flexible modelling of real materials. To demonstrate the technique, a numerical example of a porous ceramic component with random microstructure and macroscopic crack is illustrated. © 2006 IOP Publishing Ltd.

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生体硬組織の高分解能イメージベース・マルチスケールモデリング

山東篤, 櫛田慶幸, 高野直樹, 安達泰治, 中野貴由, 馬越佑吉, 石本卓也, 榎元孝俊, 河井まりこ, 山本敏男

日本計算工学会論文集 Paper No.20060017 2006年

研究論文（学術雑誌）, 共著, 査読有り

Stress analysis of endodontically treated anterior teeth restored with different types of post material

Takashi Nakamura, Tatsuo Ohyama, Tomonori Waki, Soichiro Kinuta, Kazumichi Wakabayashik Yoshihiko Mutobe, Naoki Takano, Hirofumi Yatani

Dental Materials Journal （Dental Materials Journal） 25 （ 1 ） 145 - 150 2005年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 02874547

Finite element analysis was performed to evaluate stress distribution in maxillary central incisors treated endodontically and restored with a post and an all-ceramic crown. Tensile stress at tooth root was analyzed using two-dimensional finite element models with different post diameters and lengths. One post length was 1/3 of the root (short), while the other was 2/3 of the root (long); one post diameter was 1/3 of the root (narrow), while the other was 2/3 of the root (wide). The following combinations were used for posts and cores: gold alloy cast post and core, commercial stainless steel post and resin core, and fiber post and resin core. Results showed that the fiber post produced less stress on the root dentin around the post tip than did the metal posts. This finding thus suggested that to reduce the stresses that cause root fracture, a long, thin fiber post should be used.

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Finite element analysis of fiber-reinforced fixed partial dentures

Takashi Nakamura, Tatsuo Ohyama, Tomonori Waki, Soichiro Kinuta, Kazumichi Wakabayashi, Naoki Takano, Hirofumi Yatani

Dental Materials Journal （Dental Materials Journal） 24 （ 2 ） 275 - 279 2005年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 02874547

Two-dimensional finite element models were created for a three-unit posterior fixed partial denture. An experimental resin-impregnated glass fiber was used as the fiber-reinforced composite (FRC) for the framework. The FRC was evaluated using varying combinations of position and thickness, alongside with two types of veneering composite. A load of 50 N simulating bite force was applied at the pontic in a vertical direction. Tensile stress was examined using a finite element analysis program. Model without FRC showed tensile stress concentrations within the veneering composite on the cervical side of the pontic - from the connector area to the bottom of the pontic. Model with FRC at the top of the pontic had almost the same stress distribution as the model without FRC. Models with 0.4-0.8 mm thick FRC positioned at the bottom of the pontic showed maximum tensile stresses reduced by 4-19% within the veneering composite.

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多孔体モルフォロジーのディジタルイメージベース・アナリシス

高野直樹, 辻村幸治

日本機械学会論文集(A編) 70 （ 694 ） 787 - 793 2004年06月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

マルチスケール法による不均質体中のき裂先端におけるミクロ応力解析

高野直樹, 奥野義紘

日本機械学会論文集(A編) 70 （ 692 ） 525 - 531 2004年04月

研究論文（学術雑誌）, 共著, 査読有り

Study on large deformation characteristics of knitted fabric reinforced thermoplastic composites at forming temperature by digital image-based strain measurement technique

Naoki Takano, Masaru Zako, Reiko Fujitsu and Kazuaki Nishiyabu

Composites Science and Technology （Composites Science and Technology） 64 （ 13-14 ） 2153 - 2163 2004年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 02663538

The continuous fiber reinforced thermoplastic composites, such as textile composites, have many attractive properties and functions and they are used widely nowadays in industrial applications. The important point in the design and manufacturing is that the composites as well as the reinforcing textiles undergo large deformation during thermoforming, which is much influential on the overall properties. Hence, the large deformation characteristics must be investigated at thermoforming temperature. For this sake, the digital image-based measurement technique of large strain distribution is developed. It is applicable to arbitrary complex shaped components with the help of 3D-CAD. As the large strain definition, Biot's strain is adopted that is calculated by the polar decomposition of the deformation gradient tensor based on continuum mechanics. The developed strain measurement technique is applied to the deep-drawing of aramid rib-knitted fabric reinforced polypropylene composites. The comparison between rib and plain-knitted fabrics reinforced composites is studied and many differences are found. The large deformation characteristics are also investigated from microscopic point of view under uniaxial tension at thermoforming temperature. © 2004 Elsevier Ltd. All rights reserved.

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Three-scale finite element analysis of heterogeneous media by asymptotic homogenization and mesh superposition methods

Naoki Takano, Yoshihiro Okuno

International Journal of Solids and Structures （International Journal of Solids and Structures） 41 （ 15 ） 4121 - 4135 2004年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 00207683

This paper studies a three-scale computational method that simultaneously considers the microstructure of heterogeneous materials, the macroscopic component, and the fracture origin such as interface or crack. The synergetic application of the asymptotic homogenization and mesh superposition methods to problems with strong scale mixing is emphasized. The scale gap between the microstructure and the component is very large, but the fracture origin is at the middle scale between them. The overall behavior is analyzed by means of the homogenization of the heterogeneity expressed by the unit cell model, while the fracture origin is modeled directly with the microscopic heterogeneity by another microscopic mesh. The microscopic mesh is superposed onto the macroscopic mesh. This mesh superposition method can analyze the non-periodic microscopic stress at the crack tip under a non-uniform macroscopic strain field with high gradient. Hence, the present three-scale method can accurately focus on the behaviors at arbitrary scale differently from the conventional hierarchical model. A demonstrative example of porous thin film on a substrate with an interface crack was solved and the microscopic stress was analyzed at the crack tip considering the random dispersion of pores and the high gradient of macroscopic strain field. To solve the large-scale 3D problem with approximately 80,000 solid elements, a renumbering technique and the out-of-core skyline solver was employed. © 2004 Elsevier Ltd. All rights reserved.

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界面き裂を有する不均質接合体のマルチスケール有限要素解析

高野直樹, 座古勝, 奥野義紘

材料 52 （ 8 ） 952 - 957 2003年08月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

テキスタイル複合材料成形品における大ひずみ分布のデジタルイメージベース計測

高野直樹, 座古勝, 藤津麗子, 西藪和明

日本複合材料学会誌 29 （ 1 ） 17 - 23 2003年01月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Multi-scale finite element analysis of porous materials and components by asymptotic homogenization theory and enhanced mesh superposition method

Naoki Takano, Masaru Zako, Yoshihiro Okuno

Modelling and Simulation in Materials Science and Engineering （Modelling and Simulation in Materials Science and Engineering） 11 （ 2 ） 137 - 156 2003年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 09650393

To analyse the macroscopic and microscopic behaviours of heterogeneous materials and components, a multi-scale computational method is studied. Although asymptotic homogenization theory has been the main tool during the last decade to solve various multi-scale problems, the assumption of the periodicity of the microscopic unit cell and the incapability of considering the scale effect have resulted in the limitations to this theory's applications. These problems should be overcome because advanced materials are often used as joint or laminated components and the interface crack problem must be analysed. For this sake, a novel multi-scale finite element method is proposed that uses the enhanced mesh superposition method together with the asymptotic homogenization theory. The finite element mesh superposition method uses the global mesh and the local mesh that is superimposed arbitrarily onto the global mesh. The enhanced method allows the adoption of different constitutive laws for the two meshes. The advantage of the homogenization theory to predict the homogenized material model accurately based on the complex microstructure is still utilized. The homogenized material model is used for the global mesh, whilst the microscopic heterogeneity and the crack are considered in the local mesh with the material properties of the constituents. The formulation, modeling strategy, implementation and numerical accuracy of the proposed method is described. A porous ceramic is studied in the numerical example.

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Microstructure-based stress analysis and evaluation for porous ceramics by homogenization method with digital image-based modeling

Naoki Takano, Masaru Zako, Futoshi Kubo, Keiichi Kimura

International Journal of Solids and Structures （International Journal of Solids and Structures） 40 （ 5 ） 1225 - 1242 2003年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 00207683

Multi-scale analysis using the asymptotic homogenization method is becoming a matter of concern for microstructural design and analysis of advanced heterogeneous materials. One of the problems is the lack of the experimental verification of the multi-scale analysis. Hence, it is applied to the porous alumina with needle-like pores to compare the predicted homogenized properties with the experimental result. The complex and random microstructure was modeled three-dimensionally with the help of the digital image-based modeling technique. An appropriate size of the unit microstructure model was investigated. The predicted elastic properties agreed quite well with the measured values. Next, a four-point bending test was simulated and finally the microscopic stress distribution was predicted. However, it was very hard to evaluate the calculated microscopic stress quantitatively. Therefore, a numerical algorithm to help understanding the three-dimensional and complex stress distribution in the random porous microstructure is proposed. An original histogram display of the stress distribution is shown to be effective to evaluate the stress concentration in the porous materials. © 2002 Elsevier Science Ltd. All rights reserved.

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針状気孔を有するアルミナ多孔体の３次元ミクロ構造モデリングと均質化

高野直樹, 木村圭一, 座古勝, 久保太

日本機械学会論文集(A編) 68 （ 672 ） 1163 - 1169 2002年08月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

セラミックスのランダムなミクロ構造を考慮したマルチスケール解析とミクロ応力評価

高野直樹, 木村圭一, 座古勝, 久保太

日本機械学会論文集(A編) 68 （ 671 ） 1046 - 1053 2002年07月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

せん断変形した織布の樹脂透過テンソルの数値解析

高野直樹, 座古勝, 岡崎亨

日本機械学会論文集(A編) 68 （ 668 ） 529 - 536 2002年04月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Microstructure-based evaluation of the influence of woven architecture on permeability by asymptotic homogenization theory

Naoki Takano, Masaru Zako, Toru Okazaki, Kenjiro Terada

Composites Science and Technology （Composites Science and Technology） 62 （ 10-11 ） 1347 - 1356 2002年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 02663538

A microstructure-based computational approach is taken to predict the permeability tensor of woven fabric composites, which is a key parameter in resin transfer moulding (RTM) simulation of polymer-matrix composites. An asymptotic homogenization theory is employed to evaluate the permeability from both macro- and microscopic standpoints with the help of the finite-element method (FEM). This theory allows us to study the relation between microscopic woven architecture and macroscopic permeability based on the method of two-scale asymptotic expansions. While the fluid velocity is introduced for Stokes flow microscopically, the macroscopic one is for seepage flow with the Darcy's law. The latter can be characterized for arbitrary configurations of unit microstructures that are analyzed for the former under the assumption of the periodicity. After discussing the validity of this approach, we present a typical numerical example to discuss the permeability characteristics of plain weave fabrics undergoing shear deformation in the preforming in comparison with the underformed one. Another notable feature of the proposed method is that the correlation between the macroscopic behaviors and the microscopic ones can be analyzed, which is important to analyze and/or design the RTM process. Hence, it is also demonstrated that the microscopic velocity field evaluated with macroscopic pressure gradient provides important information about the flow in RTM processes. © 2002 Elsevier Science Ltd. All rights reserved.

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セラミックス多孔体のイメージベースモデリングと均質化法による弾性解析

木村圭一, 高野直樹, 久保太, 小川秋水, 河本洋, 座古勝

日本セラミックス協会学術論文誌 110 （ 1282 ） 567 - 575 2002年

研究論文（学術雑誌）, 共著, 査読有り

Microstructure-based deep-drawing simulation of knitted fabric reinforced thermoplastic by homogenization theory

Naoki Takano, Yoshihiko Onishi, Masaru Zako, Kazuaki Nishiyabu

International Journal of Solids and Structures 38 （ 36-37 ） 6333 - 6356 2001年08月

筆頭著者, 査読有り, ISSN 00207683

Process simulation of fiber reinforced composite materials is an important research theme for the development of low-cost and advanced functional composite materials. This paper aims at the simulation of deep-drawing process of knitted fiber reinforced thermoplastics and its verification. The feature of the simulation is that the large deformation of the knitted microstructures can be traced everywhere in the deep-drawn product. The homogenization theory is applied to analyze the micro-macro coupled behaviors of the knitted fabric composite material. By employing a simplified nonlinear computational algorithm, the deep-drawing simulation was carried out on a personal computer. The predicted largely deformed microstructures were compared with the experimental results. The numerical results and experimental ones agreed quite well. This deep-drawing simulation requires us to prepare only the mechanical properties of the constituents, while it provides us all the necessary quantities such as the deformation, strain, stress and stiffness from both microscopic and macroscopic standpoints. © 2001 Elsevier Science Ltd. All rights reserved.

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Finite element mesh superposition method applied to local stress analysis of interphase of composite joints

Naoki Takano, Masaru Zako, Toru Okazaki, Futoshi Kubo

Materials Science Research International 2 219 - 224 2001年05月

研究論文（学術雑誌）, 共著, 査読有り

均質化法による編物強化熱可塑性プラスチックの深絞り成形解析とその検証

高野直樹, 大西慶弘, 西藪和明, 座古勝

材料 50 （ 5 ） 461 - 467 2001年05月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

繊維強化複合材料のミクロ構造に基づく樹脂透過性の３次元評価

高野直樹, 寺田賢二郎, 座古勝

材料 50 （ 5 ） 488 - 494 2001年05月

研究論文（学術雑誌）, 共著, 査読有り

Computational method for homogenization of heterogeneous materials with voxel element modeling of their microstructures

Naoki Takano, Masaru Zako, Futoshi Kubo, Keiichi Kimura

Materials Science Research International 2 66 - 71 2001年05月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

重合メッシュ法による不均質体のミクロ応力解析

高野直樹, 座古勝

日本機械学会論文集(A編) 67 （ 656 ） 603 - 610 2001年04月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Efficient modeling of microscopic heterogeneity and local crack in composite materials by finite element mesh superposition method

Naoki Takano, Masaru Zako, Toru Okazaki

JSME International Journal, Series A 44 （ 4 ） 602 - 609 2001年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 13447912

The finite element mesh superposition method is applied to the two-dimensional crack problem of composite materials. The microscopic heterogeneity involved in the composite materials is modeled by the fixed grid model. On this global mesh, a local mesh that considers the local crack is superimposed without taking care of the matching of nodes and elements of both meshes. The use of the fixed grid model for the global mesh can reduce the time and efforts for the mesh generation to express the complex heterogeneous microstructures. Also it makes the computation and the implementation of the finite element mesh superposition method very easy. The accuracy was verified by comparing with the theory and the calculation by the conventional fine mesh.

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均質化法によるテキスタイル複合材料の樹脂浸透係数の評価

高野直樹, 寺田賢二郎, 座古勝, 吉岡智美

日本複合材料学会誌 26 （ 5 ） 171 - 178 2000年05月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

局所的不均質部を有する構造体のグローバル／ローカルモデリング

高野直樹, 座古勝, 石園学

日本機械学会論文集(A編) 66 （ 642 ） 220 - 227 2000年02月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Integrated design of graded microstructures of heterogeneous materials

Naoki Takano, Masaru Zako

Archive of Applied Mechanics 70 （ 8-9 ） 585 - 596 2000年01月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 09391533

This paper proposes a novel, integrated, computational design methodology of graded microstructures of heterogeneous materials for the emergence of macroscopic function. In the first step of the design procedure, some discrete microstructures among a large number of graded microstructures are determined by the genetic algorithm as the optimization method. In this determination procedure, the homogenized modeling is adopted considering the micro-macro coupling by the homogenization method. This method enables us to study complex microstructures. Homogenized properties such as elastic properties, coefficient of thermal expansion and thermal conductivity can be calculated rigorously based on continuum mechanics. Calculated homogenized properties are stored in the micro-macro correlative database. The genetic algorithm can select the best geometrical arrangement of multiple microstructures from the pre-calculated database to construct the graded microstructure architecture. By using the database, the microscopic and macroscopic analyses are separated from each other, which reduces considerably the computational cost for the micro-macro coupled design. In the second step, continuously graded microstructures are designed using a feature-based 3D-CAD system by interpolating the discretized graded microstructures. In addition, a solid model is produced by the stereolithography technique to help in understanding the computationally designed complex microstructures. Brief descriptions of the formulation of the homogenization method for heat conduction and thermal stress problems are shown. A design problem for a plate with graded microstructures in its thickness direction is shown. The objective function for this example is the control of the wrap of the plate under the condition of temperature distribution. © Springer-Verlag 2000.

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Multi-scale computational method for elastic bodies with global and local heterogeneity

Naoki Takano, Masaru Zako, Manabu Ishizono

Journal of Computer-Aided Materials Design （Journal of Computer-Aided Materials Design） 7 （ 2 ） 111 - 132 2000年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 09281045

A multi-scale computational method using the homogenization theory and the finite element mesh superposition technique is presented for the stress analysis of composite materials and structures from both micro- and macroscopic standpoints. The proposed method is based on the continuum mechanics, and the micro-macro coupling effects are considered for a variety of composites with very complex microstructures. To bridge the gap of the length scale between the microscale and the macroscale, the homogenized material model is basically used. The classical homogenized model can be applied to be case that the microstructures are periodically arrayed in the structure and that the macroscopic strain field is uniform within the microscopic unit cell domain. When these two conditions are satisfied, the homogenization theory provides the most reliable homogenized properties rigorously to the continuum mechanics. This theory can also calculate the microscopic stresses as well as the macroscopic stresses, which is the most attractive advantage of this theory over other homogenizing techniques such as the rule of mixture. The most notable feature of this paper is utilize the finite element mesh superposition technique along with the homogenization theory in order to analyze cases where non-periodic local heterogeneity exists and the macroscopic field is non-uniform. The accuracy of the analysis using the finite element mesh superposition technique is verified through a simple example. Then, two numerical examples of knitted fabric composite materials and particulate reinforced composite material are shown. In the latter example, a shell-solid connection is also adopted for the cost-effective multi-scale modeling and analysis.

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傾斜ミクロ構造設計による材料機能化

高野直樹, 座古勝, 中川雅也

日本複合材料学会誌 26 （ 1 ） 9 - 16 2000年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

The formulation of homogenization method applied to large deformation problem for composite materials

Naoki Takano, Yoshihiro Ohnishi, Masaru Zako, Kazuaki Nishiyabu

International Journal of Solids and Structures 37 （ 44 ） 6517 - 6535 2000年

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

複合材料構造物の階層モデリングと局所的応力解析手法

高野直樹, 柏木有希雄, 大西慶弘, 座古勝

日本機械学会論文集(A編) 65 （ 631 ） 498 - 505 1999年03月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Hierarchical modelling of textile composite materials and structures by the homogenization method

Naoki Takano, Yasutomo Uetsuji, Yukio Kashiwagi, Masaru Zako

Modelling and Simulation in Materials Science and Engineering （Modelling and Simulation in Materials Science and Engineering） 7 （ 2 ） 207-231 - 231 1999年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 09650393

For the simulation of mechanical behaviours of textile composite materials and structures, a novel hierarchical modelling technique is proposed. Not only the global deformation but also the stresses at multiscales are analyzed precisely. Four-level hierarchy is defined for the textile composites such as woven and knitted fabric composites. The stresses at the mesostructure, which is a periodic unit cell of textile composite materials consisting of fibre bundles and matrix, can be evaluated accurately by the homogenization method and finite-element mesh superposition technique. The latter technique makes it possible to overlay arbitrary local fine mesh on the global rough mesh. Anisotropic damage mechanics is also utilized for strength evaluation at the mesoscale. Three-dimensional modelling of the mesostructure of woven and knitted fabric composite materials is shown. Localization analysis has been carried out within practical computational time and cost by the proposed hierarchical modelling.

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Intelligent material systems using epoxy particles to repair microcracks and delamination damage in GFRP

Masaru Zako, Naoki Takano

Journal of Intelligent Material Systems and Structures （Journal of Intelligent Material Systems and Structures） 10 （ 10 ） 836 - 841 1999年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 1045389X

The objective of this study is to propose an intelligent material system that can perform a self-repairing operation against initial damage that might occur in GFRP laminates. Specifically, we highlight the development of a novel actuator to be used in such self-repairing operations. There has been much research on sensor systems to detect damage and some actuators to control the shape of the structure or to control the vibration. However, no literature can be found on the actuator aiming at the self-repair of damage. For this purpose, a small grain particle-type adhesive is embedded in a glass/epoxy composite (GFRP) laminate. The diameter of the particle is approximately 50 μm. Hence, in the developed intelligent material system, coldsetting epoxy resin is used as the matrix, uni-directionally arranged glass fiber is used as the reinforcement, and a thermosetting epoxy particle is used as a repairing actuator. The volume fraction of the particles in the matrix was approximately 40%. The embedded particles can repair the damage, when melted by heat. Basic characteristics of the particles were investigated first, and we confirmed that the embedded particles in the matrix can melt by heat and flow to repair the crack. We also confirmed that the embedded particles do not deteriorate the stiffness of the GFRP laminate. Then we investigated the efficiency of the repairing operation against initial damage such as microscopic matrix cracks and delamination, by conducting two typical tests, i.e., static three-point bending of [0/90] laminate and tensile fatigue of [0/90]slaminate. Damage was observed by CCD camera. As a result, the decrease in the stiffness due to initial damage has been recovered and consequently increased, the residual fatigue life.

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CFRP貼付補強によるコンクリートのインテリジェント化

座古勝, 高野直樹, 藤岡英典

材料 47 （ 11 ） 1183 - 1187 1998年11月

研究論文（学術雑誌）, 共著, 査読有り

CFRP貼付補強コンクリートのインテリジェント化のためのセンサ・アクチュエータに関する研究

座古勝, 高野直樹, 藤岡英典

材料 47 （ 11 ） 1178 - 1182 1998年11月

研究論文（学術雑誌）, 共著, 査読有り

Design of microstructures for the emergence of macroscopic function by homogenization method and genetic algorithms

Naoki Takano, Masaru Zako, Masaya Nakagawa, Norio Takeda

Materials Science Research International 4 （ 3 ） 153 - 158 1998年09月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 13411683

In this paper, a design procedure of the microstructure of composite materials is proposed for the emergence of desired macroscopic function. The homogenization method is used for the expression of the correlativity between micro- and macroscopic properties, and genetic algorithms (GA) is used to solve the optimization problem. Using the micro-macro correlative database of material properties constructed by the homogenization method, the design problem is separated into micro- and macroscopic sub-problems. Thus, the proposed procedure is quite efficient and extendable to various design problems of new advanced materials such as functionally gradient materials. As an example, a plate of graded micro-porous materials, that is free of warp and/or twist under the environment with temperature gradient from the upper to lower surfaces, is shown.

ミクロ構造を考慮した複合材料の深絞り成形解析－解析手法の提案－

高野直樹, 座古勝, 大西慶弘

材料 47 （ 6 ） 593 - 598 1998年06月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

関数近似法を用いた遺伝的アルゴリズムによる積層複合材料の設計手法

座古勝, 高野直樹, 竹田憲生

材料 47 （ 5 ） 446 - 451 1998年05月

研究論文（学術雑誌）, 共著, 査読有り

耐久限度を考慮した疲労設計基準決定システムの構築

座古勝, 高野直樹, 花木聡

材料 47 （ 1 ） 90 - 94 1998年01月

研究論文（学術雑誌）, 共著, 査読有り

部材のレイアウトと断面形状の相関を部分的に考慮した三次元補強設計法

座古勝, 高野直樹, 坂田誠一郎

日本機械学会論文集(A編) 63 （ 613 ） 2070 - 2076 1997年09月

研究論文（学術雑誌）, 共著, 査読有り

均質化法と異方損傷力学を用いた織物複合材料のメゾ強度評価

高野直樹, 座古勝, 上辻靖智, 柏木有希雄

日本機械学会論文集(A編) 63 （ 608 ） 808 - 814 1997年04月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Cost effective design procedure for laminated composite structure based on GA

Masaru Zako, Naoki Takano, Norio Takeda, Tetsuya Tsujikami

Science and Engineering of Composite Materials 6 （ 2 ） 131 - 140 1997年

研究論文（学術雑誌）, 共著, 査読有り, ISSN 0334181X

We present a design procedure for symmetrically laminated composite structure with GA (Genetic Algorithm) and finite element analysis. Design variables to enhance the rigidity of the laminated composite structure are the number of laminae, the fiber orientation and the stacking sequence. Here, the fiber orientation is selected among some prepared angles from a manufacturing viewpoint. In a conventional design procedure based on GA, an objective function is calculated by costly finite element analysis. Consequently, it is quite time consuming and unpractical. In this paper, to minimize the displacement at a point in the structure, we define an approximated rigidity function of the laminated composites by means of weighing coefficients and transformed elastic moduli in the prepared angles. The weighing coefficients are initially determined using the distribution of principal stress in the structure under an applied load. Then, we can guess that reinforcements should be oriented according to the weighing coefficients with which the rigidity function takes maximum. To find the global optimum solution, the weighing coefficients are adjusted with as small a number of finite element analyses as possible. As a conclusion, the proposed procedure can reduce the computational cost remarkably compared to the conventional one, and can be applied practically to arbitrary shaped structures.

繊維強化複合材料の剛性設計のためのGAの効率的適用

座古勝, 高野直樹, 辻上哲也, 竹田憲生

材料 45 （ 12 ） 1316 - 1321 1996年12月

研究論文（学術雑誌）, 共著, 査読有り

複合材料用三次元構造解析支援システムの構築

座古勝, 辻上哲也, 高野直樹, 植村益次, 市川昌弘, 平田俊治

日本機械学会論文集(A編) 62 （ 598 ） 1501 - 1505 1996年06月

研究論文（学術雑誌）, 共著, 査読有り

ワインディング構造物の仮想試作システム構築（第１報，テープワインディングならびにその強度）

座古勝, 高野直樹, 辻上哲也, 平田俊治

日本機械学会論文集(A編) 62 （ 598 ） 1450 - 1455 1996年06月

研究論文（学術雑誌）, 共著, 査読有り

Macro-micro uncoupled analysis procedure for nonlinear structural mechanics of composites - RVE approach to microstructural geometrically nonlinear problem

Naoki Takano, Masaru Zako, Yoshihiro Ohnishi

Materials Science Research International 45 （ 2 ） 163 - 168 1996年06月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り, ISSN 05145163

Numerical prediction of strength of notched UD laminates by analyzing the propagation of intra- and inter-laminar damage

Masaru Zako, Naoki Takano, Takuya Tsumura

Materials Science Research International 45 （ 2 ） 117 - 122 1996年06月

研究論文（学術雑誌）, 共著, 査読有り, ISSN 13411683

均質化法による織物複合材料の三次元マイクロ構造設計（第２報，曲げ負荷時のマイクロスコピックな挙動の詳細解析

高野直樹, 座古勝, 坂田誠一郎

日本機械学会論文集(A編) 62 （ 595 ） 884 - 889 1996年03月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

複合材料のマイクロ構造における幾何学的非線形性と破壊を考慮した均質化解析手法

高野直樹, 座古勝, 平郡久司, 菊池昇

日本機械学会論文集(A編) 62 （ 595 ） 859 - 864 1996年03月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

複合材料の非線形構造力学解析のためのマクロ－マイクロ非連成化手法－マイクロ構造における幾何学的非線形問題へのRVEアプローチ－

高野直樹, 座古勝, 大西慶弘

材料 45 （ 2 ） 163 - 168 1996年02月

研究論文（学術雑誌）, 共著, 査読有り

微視破壊を考慮した均質化法による織物複合材料の非線形解析

高野直樹, 座古勝

材料 44 （ 505 ） 1231 - 1237 1995年10月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

信頼性に基づく先端材料用設計寿命評価システム

座古勝, 高野直樹, 市川昌弘, 花木聡

日本機械学会論文集(A編) 61 （ 589 ） 1909 - 1913 1995年09月

研究論文（学術雑誌）, 共著, 査読有り

損傷力学に基づく複合材料用3次元有限要素法の開発

座古勝, 辻上哲也, 高野直樹, 津村卓也

材料 44 （ 502 ） 921 - 926 1995年07月

研究論文（学術雑誌）, 共著, 査読有り

均質化法による単層波状コアサンドイッチ板の解析－面内のみ周期性を有する複合構造への均質化法の適用について－

高野直樹, 座古勝, 菊池昇

材料 44 （ 502 ） 905 - 910 1995年07月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Stress analysis of sandwich plate by the homogenization method

Naoki Takano, Masaru Zako, Noboru Kikuchi

Materials Science Research International 1 （ 2 ） 82 - 88 1995年06月

研究論文（学術雑誌）, 単著, 筆頭著者, 査読有り, ISSN 05145163

The effectiveness of the homogenization method for analysis of composite materials has been shown since it was firstly introduced in 1970's. As this method is applicable to periodic problems only, however, some engineering problems remain unsolved. For instance, we could not apply it to honey-comb sandwich plates and panels with reinforcing ribs because these structures are not periodic in the thickness direction. In this paper, the application of the homogenization method to those composite structures is discussed. As a practical example, stress analysis of single-layered corrugated core sandwich plate is presented. A method to homogenize the complicated geometry to a simple solid model, to get the homogenized material constants, and to calculate the microscopic stress is proposed. © 1995, The Society of Materials Science, Japan. All rights reserved.

Access to Document (DOI)

均質化法による織物複合材料の三次元マイクロ構造設計（第１報，強度に及ぼす織物積層方向位置ずれの影響）

高野直樹, 座古勝, 坂田誠一郎

日本機械学会論文集(A編) 61 （ 585 ） 1038 - 1043 1995年05月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

Fixed Grid に基づく均質化法による複合材料のマイクロスコピック・シミュレーション技法の提案

高野直樹, 座古勝

日本機械学会論文集(A編) 61 （ 583 ） 589 - 594 1995年03月

研究論文（学術雑誌）, 共著, 筆頭著者, 査読有り

スーパコンピュータによる大規模構造解析（ICCG法による有限要素解析）

三好俊郎, 高野直樹, 吉田有一郎

日本機械学会論文集(A編) 53 （ 492 ） 1607 - 1613 1987年08月

研究論文（学術雑誌）, 共著, 査読有り

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