Transactions of the Japan Society for Computational Engineering and Science
Online ISSN : 1347-8826
ISSN-L : 1344-9443
Volume 2014
Displaying 1-17 of 17 articles from this issue
  • Samuel Susanto SLAMET, Kyohei HATANO, Naoki TAKANO, Tomohisa NAGASAO
    2014 Volume 2014 Pages 20140001
    Published: February 07, 2014
    Released on J-STAGE: February 07, 2014
    JOURNAL FREE ACCESS
    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.
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  • Shinsuke Kondoh, Akira Tezuka, Hitoshi Komoto
    2014 Volume 2014 Pages 20140002
    Published: February 10, 2014
    Released on J-STAGE: February 10, 2014
    JOURNAL FREE ACCESS
    1DCAE concept aims to systematically apply CAE methods and tools in diverse domains in the early stage of product development, and collects attentions from industry in recent years. Following the 1DCAE concept, designers develop product models from various domains to support their decision making. It is essential for successful implementation of 1DCAE to clearly understand the roles of the employed models and their relations in context of a product development process. The objective of this study is to formulate practical guidelines for 1DCAE implementation and to architect its design support systems through case studies of the best 1DCAE practices. In particular, the paper proposes a design process model accompanied with the 1DCAE concept, which classifies the roles of the models and the underlying designers’ rationale behind a series of modeling operations, and advantages the systematic analysis of design cases. A simple case analysis is also provided to illustrate the proposed process model.
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  • Tetsuo YASUOKA, Yoshihiro MIZUTANI, Akira TODOROKI
    2014 Volume 2014 Pages 20140003
    Published: April 01, 2014
    Released on J-STAGE: April 01, 2014
    JOURNAL FREE ACCESS
    Stress intensity factor have been used as a parameter of crack growth evaluation such as fatigue or stress-corrosion cracking. Especially, welds and heat affected zones have two distributions: residual stress and yield strength. Those distributions might affect the crack growth evaluation. In other words, the potential exists to deviate from the applicable range of the stress intensity factor in those regions. In this study, the applicability of stress intensity factor was analytically investigated by comparing an elasticity solution with an elastoplastic solution of the stress state in front of a crack when the stress distribution and yield strength distribution were simultaneously present along the crack propagation path. As a result, the stress intensity factor tended to be inapplicable when the steep distributions were present in front of the crack. Additionally, the modified method of stress intensity factor for incorporating the influence of those distributions was proposed and the applicability of that was investigated.
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  • Seishiro MATSUBARA, Yusuke ARAKAWA, Junji KATO, Kenjiro TERADA, Takash ...
    2014 Volume 2014 Pages 20140004
    Published: April 15, 2014
    Released on J-STAGE: April 15, 2014
    JOURNAL FREE ACCESS
    The numerical study is made to illustrate the applicability of the method of decoupled multi-scale analysis to the micro-macro evaluation of the mechanical behavior of carbon-fiber-reinforced plastics (CFRP) that exhibit inelastic deformations and internal damage of the matrix material. During the course of this illustration, it is confirmed that the reliability of the decoupled method can be guaranteed if the macroscopic constitutive model is introduced so as to inherit the microscopic material behavior. To this end, with reference to the results of the numerical material testing on the periodic microstructures (unit cells) of CFRP, we propose an anisotropic elasto-plastic-creep-damage combined constitutive model to represent the macroscopic material behavior and demonstrate the characteristics of the inelastic deformations that resemble the material behavior assumed for plastics at micro-scale. With the identified macroscopic material parameters, the macroscopic structural analysis, which is followed by the localization analysis consistently, can be an actual proof of the utility value of the decoupled method in practice.
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  • Takashi SASAGAWA, Masato TANAKA, Mai GIMA, Masaki FUJIKAWA
    2014 Volume 2014 Pages 20140005
    Published: April 18, 2014
    Released on J-STAGE: April 18, 2014
    JOURNAL FREE ACCESS
    This paper presents a novel methodology for implementing an Ogden-type hyperelastic material model with numerically computed consistent tangent moduli using complex-step derivative approximation (CSDA). In this formulation, numerical calculations of exact eigenvalues and eigenvectors of complex symmetric matrices are required to obtain the accurate consistent tangent moduli . For the request, the numerical calculations have convergence criteria which are defined in each of real and imaginary part independently. Finite element analyses using Ogden material model implemented with the present methodology are presented to show that the consistent tangent moduli are in good agreement with the analytic ones.
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  • Shinya KAMINO, Mao KURUMATANI, Kenjiro TERADA, Takashi KYOYA, Kazuo KA ...
    2014 Volume 2014 Pages 20140006
    Published: April 24, 2014
    Released on J-STAGE: April 24, 2014
    JOURNAL FREE ACCESS
    This paper proposes a method for simulating compressive failure in quasi-brittle materials involving micro- or meso-scale contact on crack interfaces. The macroscopic compressive failure is assumed to be caused by tensile and shear fractures at micro-scale, both of whose traction-crack-opening behavior is represented by the cohesive crack model. The penalty method is employed to realize the frictional contact on cracked interfaces under compressive loading. First, the discrete micro-crack behavior is introduced to a finite element framework in consideration of material inhomogeneity of cement-based materials and by using penalty springs. Then, after verifying the basic performance for simulating fracture behavior involving tensile or shear cracks, we examine the role of the micro-scale frictional contact behavior on the compressive fracture behavior. Finally, a numerical example is presented to demonstrate the validity of the proposed method in comparison with the experimental result, reported in the literature, for the compressive fracture behavior in mortar and cement paste.
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  • Yohei FUKUZAWA, Hideki TOMIYAMA, Kazuya SHIBATA, Seiichi KOSHIZUKA
    2014 Volume 2014 Pages 20140007
    Published: May 23, 2014
    Released on J-STAGE: May 23, 2014
    JOURNAL FREE ACCESS
    Behavior of high viscous non-Newtonian fluid flow is analyzed using the MPS (moving particle semi-implicit) method. The power-law model is used as the constitutive equation of a non-Newtonian fluid in the MPS method. Furthermore, the gravity and the viscous terms in the momentum equation are implicitly solved. For a comparison with the theoretical distribution of the velocity in plane Poiseuille flow, the simulation results obtained are in good agreement.
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  • Mao KURUMATANI, Yuki NEMOTO, Shinichiro OKAZAKI, Soichi HIROSE
    2014 Volume 2014 Pages 20140008
    Published: June 04, 2014
    Released on J-STAGE: June 04, 2014
    JOURNAL FREE ACCESS
    3-D internal crack propagations formed in concrete around deformed tension bar, which is named as Goto Crack, are simulated in the finite element analysis with isotropic damage model in this paper. Goto Crack means that the internal cracks take the form of conical shape, and propagate toward the nearest lateral cracks which are initially formed. The isotropic damage model applied in this study is based on fracture mechanics for concrete, and is capable of simulating quasi-brittle fracture and crack propagation with the fracture energy. We first show the formulation of the isotropic damage model by means of modified von-Mises model and fracture mechanics for concrete. Then, several numerical experiments are presented to verify the basic performance of the 3-D fracture analysis method with damage model. Finally, we simulate the 3-D conical shaped internal cracks formed in concrete around deformed tension bar by applying the analysis method with damage model to an RC test specimen.
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  • Yoshihito IKEDA, Ryuji ENDO, Nobuyoshi TOSAKA
    2014 Volume 2014 Pages 20140009
    Published: August 19, 2014
    Released on J-STAGE: August 19, 2014
    JOURNAL FREE ACCESS
    Inverse analysis to identify every lateral stiffness of 3-story frame models was performed to study the characteristics of variable parametric projection filtering algorithm that is used as the inverse analysis procedure. Natural frequencies measured by the experimental modal analysis system were adopted as the observation data of the inverse problem. The variable parametric projection filter is including regularization parameter. As the regularization parameter is determined computationally by using natural frequency corresponding specific vibration mode, selection of vibration mode to determine the regularization parameter is important factor characterizing the variable parametric projection filter along with the initial value of iterative calculations. In this paper, characteristics of the variable parametric projection filter are made clear from viewpoint of the mode-dependent properties and initial value of iterative calculations through comparison with results of inverse analysis using Kalman filtering algorithm.
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  • Takahiro KIKUCHI, Yukihiro MICHIWAKI, Seiichi KOSHIZUKA, Tetsu KAMIYA, ...
    2014 Volume 2014 Pages 20140010
    Published: September 12, 2014
    Released on J-STAGE: September 12, 2014
    JOURNAL FREE ACCESS
    The uniaxial compression test of jelly food is simulated based on Hamiltonian MPS method with a wall boundary condition using the penalty method. The jelly is assumed to be a Mooney-Rivlin hyperelastic material. To improve the stability of calculation, viscous forces based on the MPS method and auxiliary potential forces are also employed. The contact forces which are pressing the jelly on the wall are calculated using a penalty function. The calculated stresses agree well with analytical solution.
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  • Shigenobu OKAZAWA, Koji NISHIGUCHI, Satoyuki TANAKA
    2014 Volume 2014 Pages 20140011
    Published: September 26, 2014
    Released on J-STAGE: September 26, 2014
    JOURNAL FREE ACCESS
    The final goal of this research is to develop a sophisticated computational method for solid-fluid interaction analysis method in fixed voxel mesh. The developed approach can treat large deformation object including free and moving boundary. This paper formulates interaction analysis with mixture theory. The present approach establishes single governing equation for multi-materials assuming incompressibility. Also free and moving boundary is captured computationally with PLIC (Piecewise Linear Interface Calculation) method. We test the validity of established formulation in solid-fluid infarction analyses including free and moving boundary.
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  • Junji KATO, Hiroya HOSHIBA, Shinsuke TAKASE, Kenjiro TERADA, Takashi K ...
    2014 Volume 2014 Pages 20140012
    Published: September 29, 2014
    Released on J-STAGE: September 29, 2014
    JOURNAL FREE ACCESS
    The present study proposes a topology optimization of composites considering elastoplastic deformation to maximize the ductility of a structure under a prescribed material volume. The concept of a so-called multiphase material optimization, which is originally defined for a continuous damage model, is extended to elastoplastic composites with appropriate regularization for material properties in order to regularize material parameters between two constituents. For optimization applying a gradient-based method, the accuracy of sensitivities is critical to obtain a reliable optimization result. In this study, we formulate the analytical sensitivity for topology optimization considering elastoplastic composites and observe its accuracy by comparing with that evaluated from the finite difference approach. It was verified that the proposed method can provide highly accurate sensitivity enough to obtain reliable optimization results.
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  • Chiaki ITOH, Kousuke IWASATO, Keiichi MURAKAMI, Seiji FUJINO
    2014 Volume 2014 Pages 20140013
    Published: October 07, 2014
    Released on J-STAGE: October 07, 2014
    JOURNAL FREE ACCESS
    Eisenstat SSOR preconditioning for Krylov subspace methods is known to be very efficient compared with other preconditionings. However, Eisenstat SSOR preconditioning is not suited to parallel computation because it includes sequential process of computations as L-1 and U-1. Moreover, we cannot avoid these substantial computations on parallel computers. In this paper, we propose a Cache-Cache Elements technique of Eisenstat SSOR preconditioning for parallelism, and demonstrate its effectiveness through numerical experiments.
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  • Yuichi SHINTAKU, Mayu MURAMATSU, Seiichiro TSUTSUMI, Kenjiro TERADA, T ...
    2014 Volume 2014 Pages 20140014
    Published: October 10, 2014
    Released on J-STAGE: October 10, 2014
    JOURNAL FREE ACCESS
    The objective of this study is to develop a new cohesive zone model to simulate transgranular fatigue crack propagation in polycrystalline meso-scale structures of metals. The proposed model is a combination of the interatomic potential-based cohesive crack model, which is derived from the universal binding energy relation, and the thermodynamics-based damage model, which realizes the stiffness reduction of the cohesive zone subjected to cyclic loading. To reflect the crystallographic slip behavior in cohesive cracking, we employ the standard crystal plasticity model. After the mesh-size dependency is examined, material parameters of the present model are determined with reference to a specific Paris law. Several representative numerical examples are presented to demonstrate the performance of the proposed model especially in reproducing the transgranular crack propagation with nucleation of micro-cracks under constant amplitude loading condition, and the delay of fatigue crack propagation caused by overloading.
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  • Naoki MORITA, Gaku HASHIMOTO, Hiroshi OKUDA
    2014 Volume 2014 Pages 20140015
    Published: October 17, 2014
    Released on J-STAGE: October 17, 2014
    JOURNAL FREE ACCESS
    Robust incomplete factorization (RIF) based on A-otrhogonalization process is an effective preconditioning technique for the conjugate gradient (CG) method to solve highly ill-conditioned linear systems. This research aims to apply the same sparsity pattern as that of coefficient matrix and parallelization of localized strategy to the process of RIF preconditioning for acceleration of convergence in finite element analysis of shell structures. As numerical results, the present RIF preconditioner leads to better convergence than the incomplete Cholesky preconditioner.
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  • Norimasa YAMASAKI
    2014 Volume 2014 Pages 20140016
    Published: October 24, 2014
    Released on J-STAGE: October 24, 2014
    JOURNAL FREE ACCESS
    In continuous casting process of steel, evenness of solidification is one of the most important issues of quality of the steel. Molten steel is solidified at water-cooled mold and followed by secondary cooling by water spray. To analyze the phenomenon of width direction’s unevenness of solidification, it is important to visualize the flow pattern of spray water. Computational fluid dynamics is useful but grid based methods for example FVM, FDM, and FEM are not appropriate because of complex free surfaces. So, particle based method called MPS was applied. One of the characteristic patterns of roll arrangement was modeled, and spray water flow was calculated. As a result, it has been found that there are dripping water between roller bearings and steel plate and overflowed water on rolls. The accuracy of the numerical model has been verified by water model experiment.
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  • Masao OGINO, Amane TAKEI, Hirofumi NOTSU, Shin-ichiro SUGIMOTO, Shinob ...
    2014 Volume 2014 Pages 20140017
    Published: December 26, 2014
    Released on J-STAGE: December 26, 2014
    JOURNAL FREE ACCESS
    This paper describes iterative methods for high frequency electromagnetic analysis using the finite element method of Maxwell equations including displacement current. For solving a complex symmetric system arising from the formulation of the E method, the conjugate orthogonal conjugate gradient method has been used. However, large-scale problems suffer from low convergence rate or no convergence. In this paper, to solve such a complex symmetric system, an iterative method like the minimal residual method is developed. The developed method shows a stable convergence behavior and a high convergence rate as compared to other iterative methods. Moreover, to treat a large-scale system on a parallel computer efficiently, an iterative substructuring method is also developed.
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