Details of a Researcher - Takano, Naoki

Papers - Takano, Naoki

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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

TAKANO Naoki

材料 47 ( 11 ) 1183-1187 1998

Research paper (scientific journal), Joint Work, Accepted

耐久限度を考慮した疲労設計基準決定システムの構築

TAKANO Naoki

材料 47 ( 1 ) 90-94 1998

Research paper (scientific journal), Joint Work, Accepted

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

TAKANO Naoki

材料 47 ( 5 ) 446-451 1998

Research paper (scientific journal), Joint Work, Accepted

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－

TAKANO Naoki

材料 47 ( 6 ) 593-598 1998

Research paper (scientific journal), Joint Work, Accepted

Design of Microstructures for the Emergence of Macroscopic Function by Homogenization Method and Genetic Algorithms

Naoki Takano, Masaru Zako, Masaya Nakagawa and Norio Takeda

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

Research paper (scientific journal), Joint Work, Accepted, 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.

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

TAKANO Naoki

材料 47 ( 11 ) 1178-1182 1998

Research paper (scientific journal), Joint Work, Accepted

Computational analysis of deep-drawing for composite materials considering the microstructure -proposition of analytical method

Takano N., Zako M., Ohnishi Y.

Zairyo/Journal of the Society of Materials Science, Japan (Zairyo/Journal of the Society of Materials Science, Japan) 47 ( 6 ) 593 - 598 1998

ISSN 05145163

In order to simulate the deep-draw forming process for composite materials with complex microstructure, a novel computational method that takes the microscopic large deformation into consideration is proposed. The microstructure of composite materials affects the deep-draw forming process. The proposed method decouples this complicated problem into macro- and microscopic problems by means of homogenized nonlinear material properties, which contributes much to the computational cost effectiveness. First, using the large deformation analysis and homogenization, the homogenized nonlinear properties considering the microstructural geometrical nonlinearity are obtained by microscopic analyses. Secondly, the deep-draw forming analysis is carried out macroscopically with precalculated material database. This material database consists of 21 independent parameters given by microscopic analyses, and is referred with respect to three macroscopic strain parameters. An example of deep-draw forming simulation for a formed core is shown.

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I : Numerical analysis and design - Development of new methods like homogenization method to composite materials

Takano N., Zako M.

Zairyo/Journal of the Society of Materials Science, Japan (Zairyo/Journal of the Society of Materials Science, Japan) 46 ( 1 ) 97 - 102 1997.12

ISSN 05145163

Design method for three-dimensional reinforcement partially considering the correlation between layout and cross-sectional shape

Zako M., Takano N., Sakata S.

Nippon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A (Nippon Kikai Gakkai Ronbunshu, A Hen/Transactions of the Japan Society of Mechanical Engineers, Part A) 63 ( 613 ) 2070 - 2076 1997.09

ISSN 03875008

In this paper, we describe a methodology for three-dimensional structural design for reinforcement that determines both layout and cross-sectional shape. Considering the difference in scale between the design variables for the layout design and those for the design of a cross-sectional shape, we separate the design problem into two sub-problems. One can be called a macroscopic design problem, and the other a microscopic one. The proposed design method takes the correlation between the sub-problems partially into account by using a new parameter to construct a feedback loop. The effectiveness of this method has been proved through simple numerical examples.

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Mesoscopic strength evaluation of woven fabric composite materials by homogenization method and anisotropic damage mechanics

Takano N., Zako M., Uetsuji Y., Kashiwagi Y.

ISSN 03875008

In this paper, a woven structure consisting of fiber bundles is defined as a mesostructure and we evaluate the strength of woven fabric composite materials mesoscopically by the homogenization method and anisotropic damage mechanics. A numerical simulation system for virtual strength test has been developed to predict the initial mesoscopic fracture, the fractured location in both macro-and mesostructure and the fracture mode. The mesoscopic fracture mode is shown schematically, which greatly aids in the understanding of the mesomechanics of woven fabric composite materials. This system is effective for material and structure design and proves the necessity of considering the interaction between macro-and mesostructures. Furthermore, the formulation and a numerical example for mesoscopic fracture propagation considering the fracture mode are shown.

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複合材料の設計と評価の最前線　１．数値解析・設計－均質化法等新しい手法の複合材料への展開

TAKANO Naoki

材料 46 ( 1 ) 97-102 1997

Research paper (scientific journal), Joint Work, Accepted

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

TAKANO Naoki

日本機械学会論文集A編 63 ( 608 ) 808-814 1997

Research paper (scientific journal), Joint Work, Accepted

Cost Effective Design Procedure for Laminated Composite Structure Based on GA

Masaru Zako, Naoki Takano, Norio Takeda and Tetsuya Tsujikami

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

Research paper (scientific journal), Joint Work, Accepted, 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.

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

TAKANO Naoki

日本機械学会論文集A編 63 ( 613 ) 2070-2076 1997

Research paper (scientific journal), Joint Work, Accepted

Efficient application of GA to design of fiber reinforced composites

Zako M., Takano N., Tsujikami T., Takeda N.

Zairyo/Journal of the Society of Materials Science, Japan (Zairyo/Journal of the Society of Materials Science, Japan) 45 ( 12 ) 1316 - 1321 1996.12

ISSN 05145163

In this paper, a cost effective design procedure for laminated composite structure using GA (Genetic Algorithms) is proposed. Design variables considered to enhance the rigidity of the laminated composite structure are the number of laminae, the fiber orientation and the stacking sequence. The fiber orientations are chosen among some prepared angles. In the proposed design procedure, a rigidity function is defined to determine which angle to reinforce by means of weighing coefficients and transformed elastic constants in the prepared angles. The weighing coefficients are defined to represent the distribution of principal stress in the structure. Then, the orientation of reinforcements can be found according to the weighing coefficients such that the defined rigidity function takes maximum. Futhermore, to find a global optimum solution, the weighing coefficients are adjusted. In this paper, the detail of our developed procedure and some applications are shown.

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Development of expert system for three-dimensional analysis of composites

Zako M., Tsujikami T., Takano N., Uemura M., Ichikawa M., Hirata T.

ISSN 03875008

There are, at present, too many design parameters for composite structures such as reinforcing fiber architecture, fiber orientation, and volume fraction, among others. Therefore, the material data base system, which can calculate three-dimensional mechanical properties of lamina and laminate using the classical stacking theory, has been developed. The advantage of this system is that it is able to calculate mechanical properties easily and visually by using graphical user interface. As an application of the developed system, a wastewater treatment tank made of GFRP under internal water pressure has been analyzed. The computational results show good agreement with the experimental ones. It is revealed that the proposed system is very useful for three-dimensional structural analysis of composite materials.

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

Zako M., Takano N., Tsumura T.

Materials Science Research International (Materials Science Research International) 2 ( 2 ) 117 - 122 1996.06

ISSN 13411683

To predict the strength of notched unidirectional (UD) fiber reinforced laminates, computational modeling method is shown as well as its verification. Both intra-laminar damage such as fiber breaking, matrix cracking and fiber-matrix interface debonding and inter-laminar damage such as delamination occur and propagate up to the final breaking. In the proposed numerical method, the occurrence of the intra-laminar damage is judged by Hoffman's failure criterion and its propagating behavior is theoretically formulated by anisotropic damage mechanics. The delamination is numerically treated by introducing inter-laminar element (IE) in the finite element analysis. Applying the proposed method to CFRP laminates with a hole under tensile load, the damage mode in each lamina and the notched strength have been predicted. By comparison with the experimental results, the validity and the reliability of our simulation have been recognized.

Development of virtual production system for tape winding structures (1st Report, tape winding simulation and strength evaluation)

Zako M., Takano N., Tujikami T., Hirata T.

ISSN 03875008

The strength of tape-wound structures depends on many factors such as winding angle and path. Because winding path cannot be obtained explicitly before production, it is very difficult to evaluate the strength. Therefore, a computer system for the design and analysis of wound structures has been developed. This system consists of calculating the winding path and generating a finite-element model to predict the strength. This paper focuses on the algorithm of winding simulation and the modeling method of complicatedly wound tape layers. As an example, design and FEM analysis are carried out for CFRP-tape-wound pipe. It is found that the developed system is very useful for design and safety evaluations of winding structures.

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Homogenization analysis method for composites considering geometrical nonlinearity and fracture of microstructure

Takano N., Zako M., Heguri H., Kikuchi N.

ISSN 03875008

For the design and production of new advanced composite materials and structures, the need for numerical simulations of their mechanical behaviors is increasing. There are two requirements for the simulation. First, microstructural architectures must be considered. The homogenization analysis method, which is an applied mathematical method developed from late 1970's to early 1980's, seems to be the most appropriate method for modelling microstructures in current literature. The second requirement is the solution of nonlinear problems. Therefore, we have developed a nonlinear homogenization method where both geometrical nonlinearity due to large deformation of microstructures and material nonlinearity due to microscopic fractures are considered. The new formulation of the nonlinear homogenization method is based on a stepwise linear algorithm with initial stresses. Two examples, i.e., biomechanical problem and fracture behavior of woven fabric composite material, were solved.

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Three-dimensional microstructural design of woven fabric composite materials by homogenization method (2nd report, detailed analysis of microscopic behavior under bending load)

Takano N., Zako M., Sakata S.

ISSN 03875008

For design and development of advanced textile composite materials, evaluation of their bending strength is essential. However, as far as we know, there has been no literature on the numerical simulation predicting the bending strength of textile composites. In this paper, we show a methodology for calculation of the bending strength for woven fabric composite materials by the homogenization method. Both the location and the cause of microscopic fracture in a fiber bundle and resin are discussed in detail. The effect of the pitch of woven fabrics on the bending characteristics is also noted.

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