Research Themes

• Investigation on the deformation and strength characteristics of structural members made of bio-inspired helicoidally laminated CFRPs
  Grants-in-Aid for Scientific Research
  01 Apr. 2021 - 31 Mar. 2024
  松本 高志
  本研究の目的は，生体を模倣したらせん積層CFRPによる構造部材の脆性挙動の改善と粘り強い特性の獲得という視点から，部材の挙動と特性を明らかにし，損傷と破壊の形態と機構を検討することとする．これまでに小規模の試験体で，「構造部材」に対しては「部位」に相当する規模を検討した．本研究では次の段階に進み，生体模倣らせん積層CFRP構造部材を作製して，その挙動と特性を明らかにし，損傷と破壊の形態と機構を検討する．
  生体の外骨格に相当する部材として閉断面の箱形断面梁を製作して曲げ試験を実施する．初年度は断面外寸を数cmとした箱形断面梁をプロトタイプとして，製作技術と試験計測の課題解消と実施可能条件の特定を経て，らせん積層CFRP箱形断面梁の挙動と特性を明らかにし，損傷と破壊の形態と機構を検討する．
  製作技術においては，プリプレグを積層する芯材を割り型とし，真空加圧・加熱成形により試験体を自主製造する手順を確立する．既往の製作は板材であったが今回は閉断面部材であり製作と品質管理の難易度が上がる．試験計測は，荷重，変位，ひずみの計測を行う．ひずみは，曲げ支間断面内線形分布，曲げ支間上下フランジひずみ挙動，せん断支間ウェブのせん断ひずみ挙動を確認するように計測する．加えて，これまでに開発した面的に変位を計測できる画像解析を用いる．画像解析は異方性の変位場をも捉えることができる．これによりらせん積層複合材料の複雑な変形挙動を確認する．
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 21H01411
• Investigation on the deformation and strength characteristics of helicoidally laminated CFRPs towards the achievement of ductility and toughness
  Grants-in-Aid for Scientific Research
  01 Apr. 2018 - 31 Mar. 2021
  Matsumoto Takashi
  Inspired by the strong and tough exoskeleton of bio-structures, helicoidally laminated CFRP composite material and structural member have been investigated to see whether those helicoidally laminated CFRP shows the mitigation of brittleness and further strengthening and toughening. CFRP has the advantage of low density and high strength for structural usage. However, the material and structural member behavior of commonly used cross ply and quasi-isotropic CFRP laminate are very brittle, and they show a localized fracture, immediately after the peak load. If CFRP acquires strengthening and toughening with the mitigation of brittleness, the possibility as a structural material can be further expanded. The current research examined the various helicoidal laminate structures experimentally, and the damage and fracture mechanisms of material and structural member are observed and analyzed in order to improve the load and deformation capacity of CFRP structural members.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 18H01515
• Improvement of deformation and load bearing performance of CFRP members through integrated approach of material and structure
  Grants-in-Aid for Scientific Research
  01 Apr. 2015 - 31 Mar. 2018
  Matsumoto Takashi
  Freedom of CFRP material design as a laminate composite is wide, and deformation and strength characteristics of structural members change widely according to its laminate structure. Therefore, in order to establish the design method of a CFRP structural member, it is necessary to understand loading effects and damage states of a structural member. Through the integrated approach of material and structure with material element experiment, structural member experiment, image analysis, composite theory, and finite element analysis, this research clarified the mechanisms of deformation and load bearing behavior and improved the deformation and load bearing performance of a CFRP structural member.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), Hokkaido University, 15H04028
• Integrated approach to understanding the deformation and load bearing mechanisms of CFRP material and structure
  Grants-in-Aid for Scientific Research
  01 Apr. 2012 - 31 Mar. 2015
  MATSUMOTO Takashi
  Freedom of CFRP material design as a laminate composite is wide, and deformation and strength characteristics of structural members change widely according to its laminate structure. Therefore, in order to establish the design method of a CFRP structural member, it is necessary to understand loading effects and damage states of a structural member. Under the integrated approach of material and structure, this research includes the following five topics: (1) applicable range of material test values, (2) material characteristic values for structural analysis, (3) deformation and strength mechanisms of a structural member, (4) analysis method on the deformation and strength of a structural member, (5) optimal laminate structure for structural performance. Throughout these topics, deformation and strength mechanisms of CFRP structural members is examined and clarified.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 24560575
• Prescriptive Innovation Strategy for Sustainable InfrastructureDevelopment: Filling the Gap between Urban Needs and Innovation
  Grants-in-Aid for Scientific Research
  2010 - 2012
  HORITA Masahide, TODO Yasuyuki, MATSUMOTO Takashi, ISHIDA Tetsuya, KUNISHIMA Masahiko
  This study has explored an alternative model for innovation strategy in infrastructure development. There has been a historical debate as to whether innovation in the infrastructure sector has responded to the contemporary societal needs. This study takes a constructivist turn in analyzing the process of technological innovation and diffusion. Attempts have been made to apply such a qualitative approach to prescriptive examination of the current issues on infrastructure such as public-private partnership and urban sanitation in developing countries.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), The University of Tokyo, 22360171
• Analysis and experiment on the durability of HPFRCC structures under severe loading conditions
  Grants-in-Aid for Scientific Research
  2009 - 2011
  MATSUMOTO Takashi
  Severe loading conditions such as tension-compression fatigue and fatigue with the presence of water are encountered in some structural applications of HPFRCC (High Performance Fiber Reinforced Cement Composite). First, the material properties of HPFRCC under such conditions are clarified experimentally, and a micromechanics based model is developed. Next, procedures for structural analysis under those conditions are developed with the micromechanics model utilized. Stress and damage states of HPFRCC structures are analyzed, and finally the durability of those structures is evaluated.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (C), Hokkaido University, 21560493
• A Model for Infrastructure Management System in Local Government
  Grants-in-Aid for Scientific Research
  2005 - 2006
  OZAWA Kazumasa, HORITA Masahide, MATSUMOTO Takashi, KISHI Toshiharu, WATANABE Tsunemi
  The objective of this study is to establish an infrastructure management system in local government in Japan. The following issues were carried out.
  (1) Problems of the infrastructure management system in local government are analyzed.
  (2) A model for infrastructure management system is proposed to solve the problems in local government.
  (3) The infrastructure management systems in foreign countries are investigated to understand the advanced maintenance system.
  (4) The strategy for introducing the proposed system is made and sub-system and tools in the system are designed.
  (5) The concept of new sub-system, such as a data base, an accounting system, a life cycle cost evaluation, and a human resource development, are developed to apply the proposed system.
  (6) The proposed system is evaluated for the practical application of the prototype of the system.
  The further study is needed to promote the proposed system together with a study on project delivery method for public services and financing scheme for it. It is also important to develop the capacity building for engineers considering the tacit knowledge of veterans.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (A), The University of Tokyo, 17206047
• 疲労荷重下構造物の力学的劣化に関する実験と解析手法の構築
  科学研究費助成事業
  2001 - 2002
  松本 高志
  本研究の目的は,疲労荷重下構造物の力学的劣化(疲労と剥離)に関する解析手法を構築することである.まず,.疲労荷重下におけるひび割れ伝達応力の劣化挙動を実験計測した.伝達応力の劣化は疲労ひび割れ進展の支配的機構であり,実験計測の後モデル化し有限要素法に組み込むことを念頭においた.実験計測の結果,ひび割れ伝達応力は疲労繰り返し荷重下において減少していくことが確認された.次に,二材料間界面の混合荷重下における破壊靭性値,特に疲労荷重後の破壊靭性値について実験計測を行った.疲労荷重下の構造物において界面破壊が観測されることが多く,この実験によって支配的機構を解明することを目指した.剥離についてもモデル化を行い有限要素法に組み込む一つの方法を提示した.ひび割れ伝達応力の減少と疲労載荷後の界面破壊靭性値の低減の確認により,疲労荷重下のひび割れ進展が説明できることが解析的にも示され,構造物の高精度寿命予測について欠くことのできない機構であることが新たな知見として得られた.最終的にはコンクリート構造物,特に道路橋鉄筋コンクリート床版,における疲労ひび割れ進展による床版崩壊を再現するべく,三次元での床版疲労解析手法を開発した.定点繰り返し荷重による疲労破壊の解析的再現が確認された.こうした疲労損傷を受けた床版に断面増厚補強工法を施した際の延命効果を疲労と剥離の影響を考慮した上で算定し得る解析手法の提案を行った.
  日本学術振興会, 若手研究(B), 東京大学, 13750453
• Mechanics of Discontinuous Solids for the Safety Evaluation of Nuclear Waste Disposal- Development of Coupled Flow Analysis Method
  Grants-in-Aid for Scientific Research
  2001 - 2002
  HORII Hideyuki, INOUE Junya, MATSUMOTO Takashi
  Due to the defomiation of sliding opening of joints in fractured rock mass, consequent changes in the flow characteristics of jointed rock mass would be anticipated. The effect of deformation of joints are clarified by newly developed FE analysis method, which enable us to investigate both mechanical and hydraulic property of a joint whose surface geometry is obtained from existing rock joints. In the present study, a number of numerical techniques are employed in order to evaluate the excavation-induced changes in hydraulic properties of jointed rock mass. These are represent by the Micromechanics-Based Continuum (MBC) model analysis (FE excavation analysis in jointed rock mass), FE flow and transport analysis in the dscrete network of joints, and a separate computational module connecting these two techniques which is incorporated to modify initially imposed transmissivity into the excavation-induced ones. The effect of excavation on the hydraulic properties is evaluated by including this excavation-induced transmissivity of individual joints in the FE flow analysis in jointed rock mass. The excavation induced transmissivity of individual joint is calculated by the numerical and analytical techniques developed for flow through a single rock joint. The calculation of the excavation-induced transmissivity involves the distribution of shear displacement and normal stress around the excavation, and implicitly takes into account the effect of surface geometric roughness. Using the proposed model, test simulation for a deep underground repository is performed to illustrate the typical trends predicted in the pesent method.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), The University of Tokyo, 13555127
• Development of an Analysis Methods for the Progressive Failure of Discontinuous Solids
  Grants-in-Aid for Scientific Research
  2000 - 2002
  HORII Hideyuki, INOUE Junya, MATSUMOTO Takashi
  Deformation in excavation disturbed zone is investigated by a model tunnel of high level nuclear waste repository. The experiment is conducted using artificial soft rock under a plane strain condition. The deformation is measured by a newly developed measurement system which consists of a microscope and a high precision X-Y stage. From the experiment, it is clarified that a wedge shaped damaged zone is formed during the course of stress redistribution. Taking into account the result of the experiment new tunnel design concept is proposed, in which the formation of the wedge shaped damaged zone is considered to be the final stage of tunnel breakage. A numerical analysis method is developed by introducing an interface element which enables us to analyze propagation of rupture zone and the formation of the wedge shaped damaged zone. From the analysis, it is shown that the design depth is deepened by adopting a formation of rapture zone in the excavation disturbed zone. In the present study, creep experiment is also conducted using artificial soft rock, in order to clarify the mechanism of creep rapture. In the experiment, displacement field is measured by the measurement system developed in the present study. From the experiment, the deformation field is heterogeneous from the very first stage of stress state, in the case of high state, in the case of high stress level which is comparable with the capacity of the material. On the contrary, in the cased of low stress level, the deformation field is almost homogeneous and the shear band which is observed almost from the beginning of a test in the case of high stress level is not formed until the creep rapture takes place. From the experiment, it is clarified that the development of a model based on the mechanism of creep rapture and localization mode is indispensable in order to evaluate long term safety of underground structures, in which the creep rupture becomes a dominant problem to be clarified.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), The University of Tokyo, 12450175
• Development of a numerical method and proposal of design method for structures in discontinuous rock
  Grants-in-Aid for Scientific Research
  1998 - 1999
  HORII Hideyuki, MATSUMOTO Takashi, YOSHIDA Hidenori
  In order to realize safe and economic design and construction of rock structures, it is necessary to develop an analysis method that can accurately predict the behavior of rock mass during excavation. In the present study, MBC (Micromechanics Based Continuum) model is developed. In MBC model jointed rock mass is replaced with an equivalent continuum body whose constitutive equation is obtained from the relationship of the average stress and average strain over a representative volume element. To derive the average strain, the displacement jump along a joint is evaluated. The derived constitutive relationship directly reflects the orientation and spacing of the dominant joints and presents strong induced anisotropy.
  First, analysis of the cavern excavation for Shiobara power station is carried out and the results of the analysis are compared with real data. It is shown that the developed method captures the complicated behaviors of the rock mass during large-scale cavern excavation.
  For the present numerical method to be adopted in the design, its input data must be determined from geological survey and in-situ test. A method to determine the input parameters for the MBC model from measured convergence during tunnel excavation is proposed.
  A design method of deep tunnel for nuclear waste disposal is proposed based on the proposed MBC model. It is demonstrated that the thickness of tunnel lining is determined rationally for given joint orientation and density according to the proposed design method.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), UNIVERSITY OF TOKYO, 10555151
• Development of theory and analysis method for localization and progressive failure
  Grants-in-Aid for Scientific Research
  1998 - 1999
  HORII Hideyuki, MATSUMOTO Takashi, YOSHIDA Hidenori
  A theory and an analysis method for cracking localization are presented. The method to judge the initiation of localization and to find the localized is solution is presented through consideration of spring-crack element models. It is shown that the problem is reduced to a minimization problem under constraint conditions. The theory is generalized and applied to problems of cracking localization in concrete. The proposed method can reproduce the localization of initially distributed cracks into a single crack in a four-point bending test. It is shown that to capture the ultimate strength of structures treatment of the localization of cracks or shear failure planes is necessary in many cases, and minimization problems under constraint conditions are the problems to be solved.
  A finite element with displacement discontinuities is developed and finite element analysis for cracking localization is carried out using the proposed theory of cracking localization. It is demonstrated that crack growth and localization in concrete dam under large earthquake excitation is captured by the present method.
  The progressive failure in soft rock is also considered, and an analysis method for progressive failure in soft rock is presented. Plane strain biaxial compression tests on artificial soft rock are carried out and the pre-peak constitutive relationship, the failure condition and the behavior of failure plane are modeled. Analysis of progressive failure in soft rock are carried out and results are compared with that of model tests with soft rock.
  Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (B), THE UNIVERSITY OF TOKYO, 10450166