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Article type: Cover
Pages
Cover1-
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Article type: Appendix
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App1-
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Article type: Index
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Toc1-
Published: August 05, 2003
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Jing HAN, Ryouiti ITOH
Article type: Article
Pages
1-2
Published: August 05, 2003
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The design variable progressive optimization method based on RSA was proposed and applied to optimize the shape of 2-piece aluminum beverage bottle bottoms. On the basis of sensitivity analyses, the most effective dimensions are selected as design variables in the first stage design optimization, while the dimensions with relatively small influences are optimized in the secondary stage. In the design optimization of the bottom, the column strength was maximized, the bulge strength was restricted to fall into a range, and the maximum bottom growth and the axial displacement of sidewall constrained.
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Kouetsu YAMAZAKI, Soichi TAKAHASHI, Shigeru YONEMURA
Article type: Article
Pages
3-4
Published: August 05, 2003
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This paper has tried to develop crushable beverage cans for recycling. Trapezoidally planed cylinders based on origami model are studied by the experiment of PP-sheet and by the numerical simulation of implicit finite element analysis. It is found that the axial crushing load can be reduced by adjusting the trapezoidal parameters such as the number and sizes of trapezoid and the spiral angle.
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Naoki Takahashi, Srinivas Kodiyalam, Kazuhiro Iijima
Article type: Article
Pages
5-6
Published: August 05, 2003
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In the process of a car body design, it is very important not only to satisfy various performance but also to consider cost and weight reduction. We have been solving these trade-off issues with conventional way, but it is not still efficient because the analysis models on the simulation environment are much more sophisticated. The designers are now exploring more efficient optimization method. This time we show the framework for solving the Crash-NVH trade-off problem on a large simulation environment.
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Koetsu YAMAZAKI, Makoto FURUTOCHI, Yuki KASHIWANO
Article type: Article
Pages
7-8
Published: August 05, 2003
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In this paper, experimental formula of energy absorption prediction for crack initiation and penetration of conical projectile into ductile metal sheet are derived in order to apply to evaluate the crash worthiness of honeycomb structures. Moreover, the projectile penetration phenomena are simulated by implementing dynamic analysis using LS-DYNA, and the numerical results are compared with experimental ones.
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[in Japanese], [in Japanese]
Article type: Article
Pages
9-10
Published: August 05, 2003
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Tomoki USHIRO, Noriyasu HIROKAWA, Kikuo FUJITA
Article type: Article
Pages
11-12
Published: August 05, 2003
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This paper discusses the role of cumulative function approximation in computational cost improvement of robust design, which is typical of complicated design optimization problems. Robust optimal design is often expensive in computational cost for considering the distribution under the deviation of design variables by means of substitutional models. The proposed method uses the cumulative function approximation, which has been configured based on Voronoi diagram by the authors, to efficiently construct such models instead of whenever referring exact values. Its effectiveness is demonstrated in comparison between nominal optimal design and robust optimal design and between direct optimization and cumulative approximation based optimization through numerical examples.
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Ryohei Yokoyama, Koichi Ito
Article type: Article
Pages
13-14
Published: August 05, 2003
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A method for improving local optimal solutions of nonlinear programming problems by treating constraints directly, named "Modal Trimming Method, " has been proposed, and it has turned out that the method has a high possibility of deriving the global optimal solutions by the suboptimal ones for a wide range of problems. It has also been shown that the aforementioned feature, i.e., the capability of the global search for deriving the global optimal solutions, is because the renewal of solutions based on the extended Newton-Raphson method creates a chaos behavior of the solutions. In this paper, the mechanism and conditions for the chaos behavior are clarified, and a strategy for improving the capability of global search is proposed.
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Juhachi ODA, Ryo KANAI, Yosuke KAWATO
Article type: Article
Pages
15-16
Published: August 05, 2003
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The Genetic Algorithm (GA), which is optimum method based schema theorem, is applicable on a wide scale problem. So, various optimum methods derived from the GA are studied. In this study, one of them, that is the Special Feature Extracting GA (SFE-GA), is proposed. The SFE-GA is based on the idea that genes possessing suitable environment extend to all over the mass, and is GA with an operation of stepping up the function. This method is applied to a problem that searches of the maximum value in a simple function, and the validity is checked. The behavior in search is clarified and it is confirmed to extract the effective schema sequentially.
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Koetsu YAMAZAKI, ALI KHAN Md. Shawkut
Article type: Article
Pages
17-18
Published: August 05, 2003
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This paper proposes a modeling method of stress concentrated members for the first order analysis(FOA). When a complicated solid structure is simplified as an assemblage of simple beam elements applied to element forces such as axial force, shear force, bending moment and twisting moment, the total stiffness equation or FOA of the solid structure is constructed and solved for the given boundary and loading conditions by the usual manner. Then, the total deformation of simplified model is estimated and the element forces are calculated in the element level. The stress concentration of simplified of simplified each member with holes, notches and variable cross section is also predicted by the suggested approximate formulation. A V-notch model is picked up and how the suggested formulas can predict the stress concentration precisely will be shown. These formulas can be used to show the influence of the design parameter changes to the designer and how the load transmission path will change by the design changes.
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Hiroshi FURUYA, Hiromichi Ohira
Article type: Article
Pages
19-20
Published: August 05, 2003
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Shape optimization of displacement magnification mechanisms for piezo-ceramic actuator was examined to realize a realize a requested actuation stroke and output force simultaneously. The basic formulation to determine the shape optimization was derived using the concept of compliance for the thermal expansion. Numerical examples for simple cantilever with PZT actuator were demonstrated to design optimum configuration. The numerical results show that the properties of optimum design of displacement magnification mechanisms depended on the objective function on the optimization.
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Yayoi Murase, Masataka Yoshimura, Shinji Nishiwaki, Kazuhiro Izui
Article type: Article
Pages
21-22
Published: August 05, 2003
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As products become progressively more complex, the design of their mechanical systems requires knowledge of an increasingly large number of design disciplines. The design and manufacture of such high performance and high quality products has made it necessary to partition the mechanical design problem into multiple components and distribute design tasks across multiple disciplines that also support concurrent optimization. To provide a globally optimal design requires effective information exchange between the design section that are responsible for each component. Therefore this paper proposes a collaborative design optimization method for distributed environments, where each section's optimization process maintains its autonomy while enabling the constructive exchange of design solutions between sections that ultimately leads to an optimal design. Several information exchange schemes are proposed and applied to the design optimization problem for a platform type of Space Station. A comparison of information exchange schemes is followed by discussion of the effectiveness of various design environments.
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XiaoHong DING, Koetsu YAMAZAKI
Article type: Article
Pages
23-24
Published: August 05, 2003
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This paper proposes a new engineering design idea of heat transfer system by utilizing the optimality of branch systems in nature, such as botanical tree and root systems, animal vascular systems, and so on. The growth mechanism of branch systems in nature is studied and the generation process is simulated. By applying the generation method, a heat transfer system with branch-like cooling pipe is generated. Finite element analysis of temperature distribution is implemented to confirm the validity of the generation method.
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Yukio TADA, Hiroshi KITAMURA
Article type: Article
Pages
25-26
Published: August 05, 2003
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This paper proposes an optimum design problem of structural and control systems, taking a 2-link flexible arm modeled by finite element method as an example. An output feedback H_∞controller is designed using H_∞control theory with the use of frequency weighting functions. Structual weight and H_∞norm of transfer function from disturbance input to controlled output are adopted as objective functions of structural system and control one, respectively. Design variables are cross sectional heights of flexible arm with rectangular cross section. As this design problem is a multipurpose objective one, it is transformed into a single-purpose problem for obtaining Parato optima. Through the numerical examination we show the validity of the present optimum design and discuss the effect of frequency weighting functions.
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Osamu OKUDA
Article type: Article
Pages
27-28
Published: August 05, 2003
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In this research, we describe parallel numerical simulation method to compute the stress distribution of two-dimensional composite materials with fiber-reinforcements. The fibers are completely surrounded by matrix, and distributed in a squared arrangement. This multi-phase polymer is modeled using quadrilateral finite element discretization. The effects of parallel computation based on unstructured domain decomposition method by initial value setting and the arrangement of reinforcements are discussed.
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Yoshiyasu HIRANO, Akira TODOROKI
Article type: Article
Pages
29-30
Published: August 05, 2003
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In the present study, a mechanism of fractal image of laminates on lamination parameters is discussed in detail, and a stacking sequence optimization method using the mechanism is proposed for complicated structures that include both of in-plane and out-of-plane lamination parameters. The new method employs branch and bound method for the optimizations of stacking sequences. For the estimation of the fractal branch of stacking sequences, the new method requires approximation of the objective function of the optimizations with quadratic polynomials using both in-plane and out-of-plane lamination parameters. The new method is applied to a stacking sequence optimization problem of a maximization of bucking load of a composite cylindrical shell structure. The method gives successfully optimal stacking sequences and validity was confirmed of this new method.
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Shiro Yoshida, Shigeru Oshiba
Article type: Article
Pages
31-32
Published: August 05, 2003
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Automatic parking system of this subject is designed to accommodate palettes with cars of different types onboard with utmost density. Meanwhile, when a palette with a car onboard is moving. the dynamic characteristics of the car affect the control system of its drive mechanism. As a result, in the case of an off-road vehicle of some types, the palette cannot be reached to the intended position with pre-determined accuracy. In this paper, the interaction between the car and the palette is presented through the experimentation and the simulation.
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Yuji ODAKA, Hiroshi FURUYA
Article type: Article
Pages
33-34
Published: August 05, 2003
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This paper investigates the structural optimization of plate wing for supersonic flutter. The analytical sensitivity of the critical dynamic pressure on supersonic flutter is formulated by the theoretical sensitivity analysis. The sensitivity is implemented in the steepest descent method to investigated the performance of the optimization. A delta wing model is considered for a numerical example. The numerical results indicate that the computational cost is reduced and the critical dynamic pressure is improved with respect to the results with the evolutionary structural optimization.
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Shigenobu OGATA, Ju LI, Yoji SHIBUTANI, Sidney YIP
Article type: Article
Pages
35-36
Published: August 05, 2003
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Ideal pure and simple shear strength of fcc metals (Al, Cu, Ni, Ag) are estimated by first principle density functional calculations. For Al and Cu, even though Al has smaller modulus than Cu in 111<112^^-> shear, its ideal pure and simple shear strength is higher, By a comparative analysis of stacking fault energy, ion relaxation, and valence charge redistribution, we find directional bonding a Ai induces such high ideal shear strength. On the other hand, Su, Ni, and Ag do not have basically directional bonding.
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Yoshitaka UMENO, Akihiro KUSHIMA, Takayuki KITAMURA
Article type: Article
Pages
37-38
Published: August 05, 2003
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The carbon nanotube (CNT), which was discovered by Iijima in 1991,is attracting attention because of its characteristic mechanical and electronic properties, and its application to novel minute devices is expected. It is interesting to investigate change in its electronic property under deformation. However, the electronic property under high strain has not been clarified. In this study, tight-binding semi-empirical band calculations are conducted to elucidate the change in the electronic property of CNTs under deformation. Transition from metallic to semiconducting electrical conductivity is observed under deformation and vice versa.
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Tomotsugu SHIMOKAWA, Jakob SCHIOTZ, Karsten W. JACOBSEN
Article type: Article
Pages
39-40
Published: August 05, 2003
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In the quasicontinuum method, one of the big problem that unphysical force appears near the interface of atomic (non-local)/continuum (local) regions is solved by introduing a buffer layer of a new kind of atoms (quasi-non-local atom) between that regions. This quasi-non-local atom can feel its first neighbor atoms and non-local atoms within the cut-off distance. Vacancy formation energy of Al is calculated to confirm its availability.
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Yoshihiko HANGAI, Nobuhiro YOSHIKAWA
Article type: Article
Pages
41-42
Published: August 05, 2003
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An atomistic calculation makes it possible to evaluate the strength of coating, which feature is affected by nano structure such as nanopore. However, because of the restriction of the computational resources, the atomistic calculation has the limitation of analytical region to nano meter order. To compensate this situation, a multiscale analysis from atomistic to continuum is introduced. The quasicontinuum model has been developed for the multiscale modeling to enable as seamless description of solid mechanical behavior from the atomistic to the continuum scale. In the quasicontinuum method, system under interest is modeled by the distributed atoms, and discretized by finite element meshes, and their positions are prescribed by means of the nodal displacements related to the conventional shape functions. Sum of the interatomic potential, which is determined by the positions of the atoms, is equivalent to the total energy of the system. The total energy of the system is determined by the nodal displacements and minimized through the variational method of the conventional finite element formulation. In this method, the total degrees of freedom are largely reduced in comparison to the molecular dynamics. In this paper, a fundamental research to utilize the quasicontinuum model in two dimensional atomistic fracture problems is carried out. We find out the adequate discretization manner around a crack tip, and we conclude that the finest elements should be extended to at least 15 atoms distance from the crack tip.
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Tomohiro SATO, Kenichi SAITOH, Noboru SHINKE
Article type: Article
Pages
43-44
Published: August 05, 2003
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Thin film Ni-Ti alloy is known as micro actuator that has unique structural property and behavior. To investigate these properties by computational atomistic simulation, at first, we evaluate interactions in Ni-Ti alloy by using EAM potential function. We calculate potential energy of B2,L1_0 and strained B2 (as B19) structures at Ok. Among these structures, B2 is the most stable. Secondly, we evaluate behavior of nano-scale Ni-Ti alloy by molecular dynamics simulation. In uniaxial tensile simulation of B2-structured-Ni-Ti monocrystal composed of 11774 atoms, it is observed that sudden stress relaxation occurs. After detecting 0 stress situation, we simulate heating process. Then increase of stress and recovery of lattice structure which are of almost B2 structures are observed. These behaviors show possibility of shape memory effect in nano-size Ni-Ti alloy.
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Kazuhiro MATSUBARA, Yutaka KURODA, Takeshi SUNAGA, Tomoyasu AIHARA
Article type: Article
Pages
45-46
Published: August 05, 2003
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In present study, mechanical behaviors of single phase amorphous solid and nano-crystal dispersed amorphous solid were simulated by using molecular dynamics (MD) method. Plastic deformation of single phase amorphous solid was analyzed by statistical mechanics, solid mechanics and fluid dynamics from MD time series data. The simulated amorphous solids are a-Ar and a-Ar-Xe. Tensile and shearing plastic deformation were simulated for the former. Tensile deformation and hydrostatic compression, in elastic region, were done for the latter and the nano-crystal Xe dispersed binary amorphous Ar-Xe solid. The plastic deformation shows vicouse character. The nano-crystal modifies the elastic properties of a-Ar-Xe solid drastically.
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Ryosuke MATSUMOTO, Akihiro NAKATANI, Hiroshi KITAGAWA
Article type: Article
Pages
47-48
Published: August 05, 2003
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This paper shows the deformation effects on the mechanical property and crystallization behavior in amorphous metal by molecular dynamics (MD) simulations. The Finnis-Sinclair potential for Fe is assumed as interatomic potential. At first, MD simulations of cyclic loading for the model amorphous are performed to obtain severely deformed materials. Then reloading and crystallization simulations are performed. The maximum stress and strain-stress relation within the elastic range are much influenced by deformation history, but the crystallization behavior does not depend on it so far.
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Kisaragi YASHIRO, Yoshihiro TOMITA
Article type: Article
Pages
49-50
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Glassy polymers show complex deformation behavior due to the internal inhomogeneous structure composed of the random-coil chains and the locally crystallized chains. In the present study, several molecular dynamics simulations are conducted on an amorphous polyehylene containing eight folded chain crystals. It is suggested from the simulations that the composite does not show anisotropy in the stress-strain behavior while the internal chain structure differently deforms.
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Tadao FUKUTA, Yasuhiro AKAHOSHI, Shoji HARADA
Article type: Article
Pages
51-52
Published: August 05, 2003
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It is well known that nuclear pressure vessel steel shows embrittlement under thermal aging and strong neutron irradiation. To examine this attention has been paid to copper-rich precipitates how they work to embrittle reactor pressure vessel steels. Our final goal is to evaluate such embrittlement from microscopic viewpoint based on atomistic simulation. In this study, we simulate nanoscale copper precipitation process based on the vacancy jump model using Multi Vacancy Lattice Monte Carlo (MVLMC) method, where an activation energy is calculated from the first neighboring interaction model.
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K. Shintani, S. Kameoka, T. Nakajima
Article type: Article
Pages
53-54
Published: August 05, 2003
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Nanomaterials such as carbon nanotubes, semiconductor nanowires, and metallic nanowires have the electronic and mechanical properties peculiar to and useful to nanotechnological applications. Metallic nanowires have drawn much attention of researchers since a single-atom chain of gold atoms at a nanocontact between a STM probe tip and a metal surface was observed. They are promisingly applicable to wiring in nanocircuits. Understanding their deformation mechanism is essential to realization of such an application. In this molecular-dynamics study, deformation of gold nanowires under enforced elongation is addressed. Two kinds of model nanowires are prepared. The modified embedded-atom method potential is employed for calculating the interations between gold atoms. Before elongation, a model nanowire is equilibrated at a specified temperature. Then, the atoms at one end of the nanowire and moved translationally in the direction along the nanowire axis.
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Kenichi SAITOH, Noboru SHINKE, Noriyuki TSUJIMURA
Article type: Article
Pages
55-56
Published: August 05, 2003
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Atomic structure and mechanical properties of metal nanowire is investigated by molecular dynamics simulation using FS potential for gold atoms. The model of wire is composed of a shell (tube) structure determined by chiral vector (m, n), which is covering up along another single straight string of atoms. Radius of wire structurally stable is limited to that near the nearest neighbor distance of f.c.c. crystal. (6,0) or (7,3) wire is nominated as probable structure, because either is preserving initial straight shape regardless of chirality. In tensile loading testing with analysis of principal atomic stresses calculated from atomic stress tensors, twisting structure, i.e. (7,3) wire shows continuous region of tension standing in one spiral row of atoms and it also presents smooth stress-strain curve with large breaking strain.
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Kazuya MAKITA, Katsuhiko YOSHIDA, Kazuto SETO, Toru WATANABE
Article type: Article
Pages
57-58
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper deals with active vibration control of parallel flexible structures supported with a rigid-body rotor like a space station. One of the authors had presented a vibration control mechanism, so that it is two or more structures are connected with actuators. In this case, one structure is utilized as a reaction wall to control another structure. However, in such a mechanism, the control performance reduces as the natural frequencies of structures become closer. In this report, authors present a modified mechanism that actuators are connected to the structures with long arms so that the direction of vibration in a mode differs on each structure. In this way, it is possible to control both structures effectively, even if dynamic properties of structures are identical. Computer simulation and and control experiment are carried out and the effectiveness of presented mechanism is confirmed.
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Takashi TAKAHSI, Yuichi IWASAKI, Toru WATANABE, Kazuto SETO
Article type: Article
Pages
59-60
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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At present there are no control devices that can be matched for both small and large earthquake of a high-rise building. In order to control vibration of such a building, the connected building control method and variable damping device for realizing the semi-active control system is used. The semi-active device is defined as a kind of passive device with variable properties changed by external maneuvers. A magnetorheological fluid damper as a variable damping device is used. This paper presents two methods for designing the semi active controller with Genetic Algorithm and LQ control theory. The simulation and experimental results demonstrate the availability and possibility of semi-active control.
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Toshi KATO, Toru WATANABE, Kazuto SETO
Article type: Article
Pages
61-62
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The paper proposes a hybrid connected building control method for high-rise buildings corresponding to large earthquake. The conventional vibration control method for high rise buildings is not effective to the large earthquake because of using the control force as the inertia force of the additional mass. In this hybrid control, lower modes are controlled using passive way, while higher modes are controlled by active controllers. The effective of this method is examined through simulations and experiments.
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Masakazu HARAGUCHI, Makoto YOSHIDA, Jinhao QIU, Junji TANI
Article type: Article
Pages
63-64
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes the vibration control of a plate using a piezoelectric element as a self-sensing actuator. By using self-sensing actuator techniques, one piezoelectric element, which is bonded on the face of the plate, gets the information of the vibration of the plate, and produces control input simultaneously. The control input signal is generated by the adaptive control system with the filtered-X LMS algorithm. Experimental investigations are performed and the results show that the vibration level is successfully reduced at a broad frequency band.
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Masahiko NARUKE, Masahiro NISHI, Takashi SYONO, Toru WATANABE, Kazuto ...
Article type: Article
Pages
65-66
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper proposes a new modeling method for controlling and active isolation system with an elastic table and multi modes of vibration. In the lightweight isolation system, the multi modes vibrations appear on elastic table in lower frequency region. In order to control the first to fifth modes of the elastic table, a reduced-order model with 5DOF system is constructed in the vertical direction. And, the flexible table is thought as a rigid body in horizontal direction. So, each model is compiled. For designing the controller, LQ control theory and double-active control method with feed forward control are used. Finally, the discrete model and the controller design are verified through numerical simulations.
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Kanichi KOYAMA, Hiroshi OKUBO
Article type: Article
Pages
67-68
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes a method of vibration control for a flexible cantilever beam with peizoelectric actuator. Sliding mode control is applied to the vibration control of the smart structure in the presence of model parameter errors. In this paper, it is shown by a numerical simulation and an experiment that the sliding mode control has high performance of robustness over parameter errors.
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Daisuke HOSHI, Naoki YAMADA, Jinhao QIU, Junji TANI, Hirofumi TAKAHASH ...
Article type: Article
Pages
69-70
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Piezoelectric materials are the most widely used functional materials for sensor and actuator applications in smart structural systems. Piezoelectric fibers developed a few years ago have been used for vibration suppression and noise reduction of smart structures. However piezoelectric fibers without a core must use inter-digital electrodes so that it is difficult to use a single fiber. This paper introduces the development of piezoelectric fibers with a metal core, which can be used as an electrode. When the other electrode is coated on the outer surface of the fiber by sputtering or using conductive paste, a single fiber can be used as a sensor or an actuator. The fabricated fibers were bonded on the surface of a composite beam and the sensor functions of the fibers was confirmed by measuring the output of the fibers during the vibration of the beam and the actuator function was confirmed by applying an external voltage to the fibers to excite the vibration of the beam.
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Hisao Tamaue, Junichiro Kuwahara, Yoji Okabe, Nobuo Takeda
Article type: Article
Pages
71-72
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In order to monitor damages in Carbon Fiber Reinforced Plastic (CFRP) laminates, it is attempted to detect transmitted waves in laminates using embedded small-diameter fiber Bragg Grating (FBG) sensors. In this research, velocities of elastic waves in CFRP unidirectional laminates and quasi-isotopic laminates were calculated theoretically. Then the relationship between the grating length and the wavelength of the elastic wave was simulated. From these results, the optimum grating length to detect elastic waves was determined.
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Kazuro kageyama, Isamu Ohsawa, Makoto Kanai, Tomokazu Motegi, Keiichi ...
Article type: Article
Pages
73-74
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new fiber-optic vibration sensor has been developed and applied to structural health monitoring. The sensor is based on a new finding that frequency of light wave transmitted through a bended optical fiber is shifted by vibration at the bended region. Because this sensing principle is independent of the temperature, this sensor is available in hot condition in theoretical sense. The sensor can detect AE signals and elastic wave propagation in the material located in high-temperature condition without any characteristic changes. The durable, low-cost and high-sensitive sensor can show a new scope to structural health monitoring in the very variety of applications, especially in high-temperature conditions.
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Takeshi YAMAHIRA, Yasubumi FURUYA, Yoshiaki SHINYA, Shizuka TAMOTO, Mi ...
Article type: Article
Pages
75-76
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Material Characteristics of thermoelastic shape memory alloy(SMA) have to be improved toward two times higher level so that SMAs can be applied to smart material/structure systems. For this purpose, the novel material processing technique, "Rapid-solidification, melt-spinning method" was used to control the crystal microstructures with fine columnar grains with strong texture. We succeeded in producing the rapid-solidified various kinds of SMA (TiNiCu, TiNiPd, NiAlMn, RuNb, RuTa systems) foils and fine fibers with sharper hysteresis and more ductility than those of bulk-materials. The thermo-mechanical properties of these SMAs were investigated systematically. Next, SMA bulk actuator material to get large recover force could be produced by adopting short time spark plasma sintering (SPS) method for rapid-solidified SMAs ribbons/fibers. Lastly, new concept for complex thermo-magneto actuator with capability of more rapid response speed was proposed. That was designed by combination super-elastic character of SMA with bias-magnetic force. These results are useful for develop the smarter materials and structure systems based on SMA technology.
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Akira TODOROKI, Miho Tanaka, [in Japanese]
Article type: Article
Pages
77-78
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The present study employs an electric resistance change method for delamination detection. Authors have found that the electric resistance change method with response surfaces is very effective to identify delaminations in CFRP laminates experimentally and analytically. In the present study, effect of spacing between electrodes on the method is investigated with FEM analyses. Five types of spacing are analyzed here, and the two types of fiber volume fractions are also calculated. Cross-ply beam type specimens are adopted for the analyses. As a result, it was revealed that effect of the spacing depends on the fiber volume fraction. For laminates of high fiber volume fraction, short spacing is required to obtain high estimation performance of delamination location and length.
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Kazuro KAGEYAMA, Isamu OHSAWA, Makoto KANAI, Keiichi NAGATA, Tsuyoshi ...
Article type: Article
Pages
79-80
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A new fiber-optic vibration sensor has been developed and applied to structural health monitoring. The sensor is based on a new finding that frequency of light wave transmitted through a bended part of an optical fiber is shifted by vibration at the bended region. A very high sensitivity has been achieved in the extremely wide frequency band. The sensor is applied to detection of AE location based on frequency distribution of elastic wave traveling through the material. AE location can be estimated by analyzing time-lag when two of elastic waves distributed with propagation go through the sensor. The system of the analysis needs a method of Short-Time Fourier Transform called STFT, which makes it possible to analyze spectrum alteration of signals as time passing. The performance of the system is examined experimentally. And the system is useful to structural health monitoring in the very variety of applications.
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Kotoji ANDO, Koji TAKAHASHI, Masahiro YOKOUCHI, Sang Kee LEE, Hiroyosh ...
Article type: Article
Pages
81-82
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Al_2O_3 reinforced by SiC whiskers (Al_2O_3/SiC-W) was sintered in order to investigate the fatigue strength of crack-healed specimens at high temperature. A semi-elliptical surface crack of 100μm in surface length was introduced on each specimen surface. These specimens were crack-healed at 1300℃ for 1 h in air, and static and cyclic fatigue strengths were systematically investigated at room temperature, 900℃, and 1100℃ by three-point bending. The static and cyclic fatigue limits of the crack-healed specimens were more than 70% of the average bending strength at each testing temperature. Crack-healed specimens of Al_2O_3/SiC-W were not sensitive to static and cyclic fatigues at room temperature and high temperatures. Therefore, the combination of crack-healing and whisker reinforcement can play an important role in increasing static fatigue strengths at high temperature.
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Koji TAKAHASHI, Kotoji ANDO, Shoko YOSHIDA, Shinji SAITO
Article type: Article
Pages
83-84
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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Si_3N_4/SiC composite ceramics were sintered and subjected to three-point bending. A semi-elliptical surface crack of 100μm in surface length was made on each specimen. The pre-cracked specimens were subjected to crack-healing under a cyclic bending stress of 5 Hz and the resultant bending strength and fatigue strength were investigated. The threshold stress for crack-healing, below which the pre-cracked specimens recovered their bending strength, was 300MPa at 1000℃ and 1200℃, which was 75% of the bending strength of the pre-cracked specimens. The crack-healed specimens exhibited quite high cyclic fatigue strength at crack-healing temperatures of 1000℃ and 1200℃.
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Hiroshi ASANUMA
Article type: Article
Pages
85-86
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes development of a new fiber-reinforced metal (FRM) which have a self-repairing function as well as high mechanical properties. The author proposed a FRM having fiber/matrix interfacial layer which can be locally melted and then solidified to enable debonding and bonding reversibly between the fiber and matrix. As an example in this study, a stainless steel fiber/aluminum composite with Zn-Al interfacial layer was made by the interphase forming/bonding method developed by the author. The fiber pull-out force was examined as a function of temperature and the result shows that it drastically decreases beyond the eutectic temperature of the interfacial layer due to its local melting. At this temperature, the reduced force can be increased only by holding because of the mutual diffusion between the interfacial layer and matrix. These behaviors can be used for repair or prevention of fracture of the composite.
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T. Yamamoto, S. Takeda, Y. Okabe, N. Takeda
Article type: Article
Pages
87-88
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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A small-diameter fiber Bragg Grating (FBG) sensor is easily embedded in adhesive layer between a repair patch and a structure, since the diameter of this sensor is very small. Thus, the FBG sensor was embedded into the adhesive layer to detect the debonding between the patch and the substrate. First, it was confirmed that debonding progress of the patch was not affected by embedment of the FBG sensor. Secondly, it was experimentally and theoretically revealed that the delamination length could be evaluated quantitatively by the comparison of intensity ratio of the two peaks in the reflection spectrum from the sensor.
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Masayuki OKUGAWA, Koichi EGAWA
Article type: Article
Pages
89-90
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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The objective was to apply a structural health monitoring concept to detect loosening of a bolt without human involvement. This paper proposes a new method of a bolt loosening detection by adopting a smart washer which uses a piezoelectric material. The proposed washer is a cantilevered plate type patched piezoelectric material. A self-sensing and actuation function featuring this material is applied to the washer. An explanation that natural frequency decreases with decrease of the bolt tightening axial tension by using the system identification, the concept of the proposed method and experiments verifying its effectiveness are described. The natural frequency of the smart washer was identified with sub-space state space identification method. There was good correlation between the change of the natural frequency of the smart washer system and the decrement of bolt tightening axial tension.
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Yusuke Hirata, Dong Yeul Song, Nobuo Takeda
Article type: Article
Pages
91-92
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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In this study, the electrical resistance change behavior of CFRP laminate [±25/±25/90]s under re/unload loading condition was investigated. Especially, the effect of the delamination on the electrical characteristics was evaluated using the internal and the surface electrical voltage distribution. From the experimental results, we identified that the internal voltage distribution in thickness direction does not change despite of the delamination, because the voltage distribution of the bottom and the top surface indicates that the electrical current can flow through the region that has no delamination. And for further theoretical investigation, DC network circuit of CFRP using discrete Kirchhoff-Monte Carlo model was examined in section3.
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Masataka IMORI, Hiroshi ASANUMA
Article type: Article
Pages
93-94
Published: August 05, 2003
Released on J-STAGE: August 01, 2017
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This paper describes fabrication and evaluation of the active laminate proposed by Asanuma. It was made by hot-pressing of high strength aluminum alloy plates as a high CTE material, a unidirectional CFRP prepreg as a low CTE material and an electric resistance heater, a unidirectional KFRP prepreg as a low CTE material and an insulator between them, and copper foils as electrodes. In this study, curvature change and output force of them were examined and compared with those of the active laminate using a pure aluminum plate. The curvatures of all of the active laminates were linearly changed as a function of temperature up to the temperature of 413K, but above this temperature, a hysteresis loop of curvature appeared during a thermal cycle only in the case of using the pure aluminum plate. The active laminates using the aluminum alloys generated higher forces than that of using the pure aluminum plate above the temperature of about 380K. According to the results, advantages of using the high strength aluminum alloys instead of using pure aluminum were clarified.
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