応用力学論文集
Online ISSN : 1884-832X
Print ISSN : 1345-9139
ISSN-L : 1345-9139
10 巻
選択された号の論文の117件中1~50を表示しています
  • 西村 直志
    2007 年 10 巻 p. 3-14
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Fundamentals of Fast Multipole Method (FMM) and FMM accelerated Boundary Integral Equation Method (BIEM) are presented. Some developments of FMM in computational mechanics related to elasticity, Helmholtz' equation, periodicity, parallelisation, etc. are discussed.
  • 東平 光生, 岩崎 健太郎, 小林 遼, 木内 拓
    2007 年 10 巻 p. 17-26
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    A method by means of the volume integral equation for forward and inverse scattering analysis of elastic waves is presented in this paper. The volume integral equation is directly solved by FFT and Krylov subspace iteration technique. The shift operator is also introduced to the inverse scattering analysis to regularize the equation. It is found from the numerical results that the present technique for the volume integral equation is successful for both the forward and inverse scattering problem.
  • 帯屋 洋之, 井嶋 克志, 村上 卓志, 川崎 徳明, 西村 裕次
    2007 年 10 巻 p. 27-36
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Purposeo f the shape analysis is to find the mechanically rational form for many kind of structures, for example, membrane structures, suspended cables, and so on. The perfect equilibrium solutions with isotonic tensile can be obtained by shape analysis using tangent stiffness method.The solutions constitute the polyhedrons which can be similar in curved surfaces of soap film. When we evaluate the polyhedron equilibrium solutions, the approximation performance is depending on their mesh density and mesh distribution. This study proposes a new technique to obtain the polyhedron solutions which can express smooth surfaces by parallel calculation of soap film analysis only to normal direction and axial line analysis in tangent plane of the surface. By using this technique, node distribution becomes more rational and larger compulsoiy displacement can be adopted when the simultaneous control is used as the incremental method.
  • 阿部 孝弘, 矢富 盟祥, 鰭 洋一, 高橋 圭太
    2007 年 10 巻 p. 37-46
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In this paper, we examine the crack extension behavior in the brittle material under the compression mixed mode loadings based on the energy release rate criterion. Two initial parallel cracks were inserted in the center of a disc-type test-piece made of a cement paste. The compressive loads were obliquely applied to the parallel cracks. We study the influencesto the crack extension behavior by changing, the loading angle, the friction of the crack surface, the difference of length between two cracks, the distance of two parallel cracks. The energy release rate is computed for the extending crack tips at the onset of crack kinking by using the E-integral which is path independent even for a path containing a kinking crack tip.
  • 末武 義崇
    2007 年 10 巻 p. 47-57
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In order to refine plate analyses, many high-order theories have been presented, in which the transverse shear deformation is included. Especially, we have to introduce high-order displacement fields for the analysis of in-plane deformation. However, governing equations of those high-order theories are usually quite complicated. In this paper, we establisha low-order theory for thick plate analyses, in which in-plane deformation can be evaluated. In order to do that, we pay attention to constitution of lateral loads and introduce a transverse normal stress into a two-dimensional constitutive law. It follows form the present numerical examples that the new theory presented here gives us excellent results for in-plane deformation and stress analyses of thickp lates.
  • 中畑 和之, 上甲 智史, 廣瀬 壮一
    2007 年 10 巻 p. 61-68
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Phased array transducer has an advantage of transmitting ultrasonic beams to various directions from a fixed position. In this study, we propose a new flaw imaging technique based on linearized inverse scattering methods. Here incident waves of strong intensity are generated in specified directions by a beam steering technique of the phased array transducer, and scattered waves are received simultaneously at each array element on a flat surface of a specimen. Since the data processing in our methods is performed by means of 2-D FFT, high-speed imaging of flaw shapes is possible with a portable computer. From numerical simulations by BEM, these imaging methods show reasonable resolution to evaluate flaw shapes if ultrasonic beams are transmitted in several directions.
  • 吉田 郁政, 我妻 克明, 天野 由華, 金 哲佑, 川谷 充郎
    2007 年 10 巻 p. 69-76
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In order to overcome the ill-posedness, two methods are studied One is to add prior information term to objective function, the other is to narrow solution space. In the first method, we compare Gauss and Laplace distribution to express uncertainties of prior information. It is indicated that Laplace type prior information is useful when the number of damaged points is small. The estimation performance, however, is bad when observation noise is considered or the number of the damaged point increases. In the second method, parameters which indicate location and level of damage are optimized. The performance of the damaged etectioni s much improved in the caset hat noise is considered and the number of damaged point is increased.
  • 三上 修一, シェリフ ベスキロウン, 山崎 智之, 大島 俊之
    2007 年 10 巻 p. 77-88
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In this study, the state of the art of modal parameters-shift-basedd amage identification isadvanced by incorporating a tunable piezoelectric actuator into the structure to enrich themodal parameters measurements, meanwhile implementing an identification algorithm tosufficientlyu tilizet he enriched information.B y integratingt unablep iezoelectrica ctuatorsi ntothe structure, we can introduce additional resonant peaks into the system dynamic response inthe frequency domain, and these additional peaks can be adjusted over the frequency band bytuning the actuator. Clearly, a significantly increased amount of modal parameters shiftinformation can be expected to reflect the damage effect. A series of analyses using areinforced concrete (RC) wall and a RC column integrated with a tunable piezoelectricactuator is carried out to demonstrate this proposed methodology and verify the performance.The results indicate that piezoelectric actuator has high potential applicability to damageassessment of concrete structures.
  • 車谷 麻緒, 寺田 賢二郎
    2007 年 10 巻 p. 91-100
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    We propose an integrated procedure for image-based non-linear analysis of composite materials with the nodal-integration finite element method (NI-FEM), which is named the “image-based NI-FEM”. First, we introduce the NI-FEM based on node-based approximation in place of conventional element-based FEM, and explain the method of imposing the compatibility conditions at material interface. Secondly, the computational implementations of image-based NI-FEM are presented for realizing seamless modeling and analysis for composite materials by means of the level-set function and Delaunay triangulation. Finally, after carrying out several peformance assessment of NI-FEM for the analysis of elastic-plastic composite materials, we demonstrate the capabilities of the proposed method to characterize the non-linear material behavior of composite materials in conjunction with the homogenization analysis.
  • グナワン アリーフ, 天間 祐輔, 廣瀬 壮一
    2007 年 10 巻 p. 101-108
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper introduces a method to perform the scattering analysis of guided waves in a 3-D plate by using the mode-exciting method. This method has computational advantage that numerical methods such as FEM and BEM can be used uncoupled with other technique which make the analysis simpler than other methods. We first explain about the theory of guided wave in a 3-D plate and show the scattering-analysis method based on the mode-exciting method. Some numerical examples are shown and verified by experiments. The analysis and experiment results show good agreement.
  • 水澤 富作, 和田 裕明, 名木野 晴暢
    2007 年 10 巻 p. 109-119
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper presents a numerical method, the BF-spline Ritz method, for free vibration analysis of skew Mindlin plates with arbitrary boundary conditions. The proposed method utilizes admissible functions comprising the B-spline functions multiplied by a boundary function to define the trial function for the transverse displacement and rotations of the Mindlin plates. The geometric boundary conditions of the plate at edges are automatically satisfied using boundary functions. To demonstrate the validity and accuracy of the BF-spline Ritz method, several examples are solved, and results are compared with those obtained by other numerical methods. Excellent convergence and high accuracy are obtained by the present method regardless of boundary conditions. The effects of skew angles, thickness to width ratio, and aspect ratio on frequency parameters of skew Mindlin plates with clamped and free edges are shown in tabular forms to serve as benchmark data for future development of new numerical methods.
  • 陸田 秀実
    2007 年 10 巻 p. 121-130
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    We developed a new numerical scheme, Particle CIP method, for computing water entry of rigid body and elastic structure. Fluid-structure interaction is simulated using coupling algorithm; two fluids are treated on a fixed eulerian grid with massless maker particles to rebuild density function for capturing interface. On the other hand, structure is solved by lagrangian meshless method using SPH method. The present method was applied to water entry problems of V-shaped wedge, circular cylinder, cylindrical shell. The free surface deformation was first compared with numerical and experimental results. Both the impact pressure and the strain were also compared with some results obtained by other researchers.
  • 竹内 則雄, 見原 理一
    2007 年 10 巻 p. 131-138
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In the existing HPM (Hybrid-type Penalty Method), independent rigid-body displacement, rotation, and the strain are set as the unknown parameter of the displacement field for each sub-domain. In this paper, we proposes the new displacement field which sets the stress as the unknown parameter instead of the strain as a displacement field of HPM. The simple numerical examples show that the accuracy of the solution obtained by this technique is the same as the displacement field which assumes the strain in the unknown parameter. The collapsing load calculated by this method is equivalent to RBSM in the material nonlinear analysis which used surface force using load incremental method.
  • 牛島 省, 福谷 彰, 牧野 統師, 禰津 家久
    2007 年 10 巻 p. 139-146
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper presents a computational method to predict the movements of the arbitrarily-shaped solid objects transported in 3D free-surface flows. This method can deal with the collisions among the objects and their deformations as well as the fluid-solid interactions. A T-type model is employed, in which an object is represented by multiple tetrahedron elements and contact spheres are set up near the boundaries of the object. The T-type model allows us to evaluate the inertial tensors and fluid forces exactly, while it makes the evaluation of the contact forces much easy. Both T-type rigid and mass-spring models were implemented in the MICS, which is a solver for incompressible multiphase fluids, and their validity was discussed through the comparisons with experimental results.
  • 須賀 伸介
    2007 年 10 巻 p. 147-156
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    We investigate stability and accuracy of the numerical scheme obtained from the lattice Boltzmann method (LBM) for numerical solutions of two-dimensional advection-diffusion equations. A system of explicit finite difference equations derived from the the lttice Boltzmann equation (LBE) based on the Bhatnagar, Gross and Krook (BGK) model for a 9-velocity model gives the numerical scheme. The stability regions of the scheme in various cases of the relaxation parameter ω in the LBE are found by numerically solving the eigenvalue problems of the amplification matrix of the scheme corresponding to each cases. In order to investigate the accuracy of the scheme, a benchmark problem is solved, and the explicit scheme based on the LBM is compared with traditional explicit and implicit schemes. The results of the numerical experiments show that the explicit schemes based on the LBM demonstrate comparable accuracy to the bilinear finite element scheme if the parameters appeared in the scheme are set as values in the stability reagion.
  • 西藤 潤, 小林 俊一
    2007 年 10 巻 p. 157-166
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    When an elasto-plastic body is subjected to repeated excitations or moving loads, its safety can be simply but directly evaluated by means of shakedown analysis. The advantage of shakedown analysis in comparison with ordinary elasto-plastic finite element analysis is its time and cost effectiveness. In this paper, a new algorithm of shakedown analysis based on Quasi-Newton method is investigated. With this newly proposed algorithm, a size of linear equations can be reduced to be as same as monotonic loading cases. In addition to this, modification of feasible directions in the iterative calculations is proposed to improve the convergence of numerical calculations. Two numerical examples are presented to illustrate the validity of the proposed algorithm.
  • Eduardo Alberto de Souza Neto, Djordje PERIC, 渡邊 育夢, 寺田 賢二郎
    2007 年 10 巻 p. 167-174
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    We examine the finite element performance at micro scale for the evaluation of the macroscopic material behavior and strength with two-scale finite element analysis method incorporating the elastic-plasticdamage constitutive model for crystal grain. In the two-scale analysis, the intragranular deformations are non-homogeneous as a result of intergranular deformation even if the macroscopic deformation is simply homogeneous. Hence it is vital that the effect of finite element mesh discretizing each grain is examined in order to characterize the macroscopic material behavior. And then the two-scale analyses are conducted to assess the convergence of solutions with mesh refinement of each grain. Besides numerical simulations obtained with the F-bar element and the standard enhanced assumed strain element are compared against the standard displacement-based isoparametric element so as to assess the importance of finite element formulation on computational results.
  • 中島 修治, 川原 睦人
    2007 年 10 巻 p. 175-186
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    The main purpose of this paper is to obtain the optimal shape of a body, which minimizes the fluid forces in an incompressible viscous flow. The main idea of the present paper is to add a process of partial control to formulation of the shape optimization and based on the hexahedral bubble element by the stabilized bubble function. The formulation of the shape optimization is based on the optimal control theory. An optimal state is defined by reduction of the fluid forces subjected to the body. the space discretization of the basic equations, the incompressible Navier-Stokes equations by the finite element approximations using the MINI element, in which hexahedral bubble element and bilinear element is employed, the temporal discretization by the fractional step method, calculation of the performance function gradient by the adjoint equation, and the minimization algorithm of the performance function by the weighted gradient method with the partial control algorithm. As a numerical example, a drag force minimization problem of a body in incompressible viscous flows in two and three dimension is carried out. As a result, each optimal shape at Re = 1, Re = 40, Re = 80 and Re = 100 is derived by the partial control algorithm. The present algorithm is shown to be useful for the optimal shape design of the incompressible viscous flow.
  • Santosh Shrestha, Mitao Ohga
    2007 年 10 巻 p. 187-192
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    A coupling of the traditional finite element method (FEM) with the recently developed scaled boundary finite element method (SBFEM) is applied for analyzing two-dimensional (2D) linear elastic fracture mechanics problems. Since shape functions of SBFEM are compatible with finite element shape functions and no discontinuity occurs across the interface, the FEM can be coupled with SBFEM without any special treatment that require for the coupling with others methods. The SBFEM has an ability to analytically compute stress and displacement field of singularities region at the crack-tip more accurately without any a priori assumptions. The SBFEM was employed for the modelling of near cracks region, where their capabilities can be exploited to the greatest benefit, and the FEM for areas away from cracks, where no singularities in the stress fields are expected to arise. The effectiveness of the proposed coupled method was examined by computing the mixed mode SIFs and T-stress in 2D cracked structures. The computed results are in excellent agreement with those obtained from existing numerical methods.
  • 高瀬 慎介, 田中 聖三, 樫山 和男
    2007 年 10 巻 p. 193-200
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper presents a mesh re-generation technique based on background mesh for shallow water flows with moving boundaries. The stabilized space-time finite element method based on GLS (Galerkin Least Square) method is introduced for both space and time discretization to compute the moving boundary problems in shallow water flows, accurately. In order to improve the robustness of computation and the consideration of accurate landform the re-generation technique using a back-ground mesh is introduced. The present method is applied to several wave run-up problems. The efficiency of the present method is shown by numerical results.
  • 松原 仁, 矢川 元基
    2007 年 10 巻 p. 201-209
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    The present paper discusses the accuracy of patch-by-patch approximation of mixed-type finite element scheme. In the approximation, not only a displacement field for each element but also stress and strain fields for each patch are defined. In order to determine unknown parameters of stress/strain fields of a patch, the Hu-Washizu principle is employed. In this paper, the accuracy of the generalized finite element functions implemented in the proposed approximation is shown. Furthermore, to show the effectiveness of the approximation in the fracture mechanics that have singular stress fields, the approximation is applied to linear fracture problem.
  • 吉川 仁, 西村 直志
    2007 年 10 巻 p. 211-216
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper discusses a three dimensional implementation of boundary integral equation method (BIEM) for large scale time domain elastodynamic problems and its application to ultrasonic quantitative nondestructive evaluation (QNDE). We use a regular mesh in order to reduce the computational time and memory requirements for solving the large scale problem. We show the efficiency of the proposed method by applying it to a simple wave propagation problem and to a realistic laser-ultrasonic QNDE problem.
  • 斎藤 隆泰, 廣瀬 壮一, 福井 卓雄, 石田 貴之
    2007 年 10 巻 p. 217-224
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper presents a Operational Quadrature time-domain Boundary Element Method (OQBEM) in 3-D scalar and elastic wave problems. Time-domain Boundary Element Method (BEM) is known as a suitable numerical approach for transient analysis of scalar and elastic waves in an infinite or half space domain, since BEM can deal with an infinite region without any modification. However, the use of direct time-domain BEM sometimes causes the instability of time-stepping solutions. To overcome this difficulty, a new time-domain BEM (OQ-BEM) for 3-D scalar and elastic wave problems is developed in conjunction with Operational Quadrature Method (OQM), which was proposed by Lubich to obtain stable solutions in a time-stepping scheme. In OQ-BEM, the convolution integrals in boundary integral equations are numerically approximated by quadrature formulas, whose weights are computed by using the Laplace transform of the fundamental solutions of a linear multistep method. As numerical examples, wave scattering solutions obtained by the OQ-BEM are shown and the accuracy of the method is confirmed to validate the proposed method.
  • 若井 淳, 堀 宗朗, 小国 健二
    2007 年 10 巻 p. 225-230
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In order to analyze failure phenomena, it is important to use heterogeneous models instead of an ideally homogeneous one since crack path is strongly influenced by the presence of local heterogeneities. Numerical Monte-Carlo simulation is not feasible for such heterogeneous models if each simulation is computationally expensive. The authors are proposing FEM-β to solve this problem. The present paper provides one example of Monte-Carlo simulation of analyzing crack path in heterogeneous models. The probability density functions of the crack paths are obtained, and they are compared with the path of the ideally homogeneous model. The usefulness of the Monte-Carlo simulation of heterogeneous models for failure analysis is discussed.
  • 松本 純一
    2007 年 10 巻 p. 231-242
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    An explicit finite element method with orthogonal basis bubble function element is proposed in this paper. As the numerical approach, the spacial discretization is applied the mixed interpolation for velocity and pressure fields by the bubble element and linear element, respectively. The two-level three-level formulation with bubble function that is bubble function element stabilization method is proposed for the incompressible viscous flow. The special bubble function with two-level partition is extended as orthogonal basis bubble function element. Three-level bubble function is applied the induction of stabilized operator control term. To verify applicability of presented method, standing vortex problem and cavity flow are performed for the numerical examples.
  • 大谷 佳広, 西村 直志
    2007 年 10 巻 p. 243-254
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper presents an FMM for periodic boundary value problems for Maxwell's equations in 3D. The periodic Green function and its derivatives, which are essential to the present method, are derived with Fourier analysis. We verify the proposed method by comparing the obtained numerical results with analytic solutions for models of the multi-layered dielectric slab. We then apply the proposed method to scattering problems for periodic two dimensional arrays of dielectric spheres and compare the obtained energy transmittances with those in the previous studies. We observe good agreements.
  • 田中 聖三, 樫山 和男
    2007 年 10 巻 p. 255-262
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper presents an ALE finite element method for free surface flow problems based on background mesh. The mesh re-generation method based on background mesh is introduced to improve the applicability and the robustness of the method. And the decision method of free surface position is investigated to the complicated free surface shapes. The stabilization methods based on SUPG and PSPG methods are employed to improve numerical stabilities. As numerical examples, the present method is applied to the hydraulic jump problem and wave problem around a submerged breakwater. The efficiency and applicability of the present method are shown by numerical results.
  • バティ アブドールカディール, 岸 徳光, 今野 久志, 岡田 慎哉
    2007 年 10 巻 p. 265-272
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In order to establish a proper finite element model of prototype RC girder with sand element for impact response analysis, dynamic response analysis of RC girders with sand cushion subjected to impact force due to weight falling from the height of H = 2.5, 5, 7.5 and 10m was performed to improve the state of the art of protective design for real scale rock-sheds by using LS-DYNA code. An applicability of proposed model was discussed comparing with experimental results (e. g. impact force, reaction force and displacement waves). From this study, dynamic characteristics of impact response can be better simulated by using the proposed model. As a result, when the sand cushion was set up, the impact force, reaction force, mid span displacement waves, distribution of reaction force-displacement loops, and crack patterns obtained from the numerical analysis are in good agreement with those from the experimental results.
  • 園田 佳巨, 深澤 仁, 曽我部 正道
    2007 年 10 巻 p. 273-280
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Recently, the risk of derailment accident caused by over-speed, earthquake and other reasons is concerned. For a bullet train, if derailment occurs, it brings about the unimaginable catastrophic accident. Thus, to prevent derailment accident of the bullet train is regarded as an important issue for the railway technology. As one of the effective measure, derailment stopper made of reinforced concrete is proposed. As it is difficult to evaluate the impact load under the collision between train and protective device, there are no design concepts for them against derailment accident. Therefore, this study aims at evaluating impact load by 3-dimensional non-linear FE analysis under the assumption of dynamic contact condition. From these calculations, impact load could be predicted, and failure possibility is estimated by analytical results.
  • 山川 優樹, 森田 耕平, 池田 清宏, Jacques Desrues
    2007 年 10 巻 p. 281-292
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Deformation behaviors of soil specimens, such as strain localization and formation of shear band with some geometric patterns, are very complex and quite diversified. Recently, experimental failure behaviors of soil deformation have been extensivelystudied with the aid of image processing techniques such as stereophotogrammetry. This research aims to capture these failure behaviors of soils from a viewpoint of diffuse bifurcation, which engenders non-homogeneous or localized deformation from a homogeneous state. FE-basednumerical bifurcation analysis and plane-strain biaxial experiments on sand by ALERT-Geomaterials are compared to provide a clear insight into the complex phenomena in soil deformation. Fully nonlinear finite deformation FE-analysis with Cam-clay or Drucker-Prager plasticity models formulated in the framework of the multiplicative finite strain theory is utilized to simulate the soil deformation. Analysis results reveal that such complex failure modes of soils are arguably caused by clustered bifurcation points and repeated occurrences of the diffuse mode bifurcations. Moreover, these analyses quantitatively well estimate the location of the bifurcation points and the degradation and oscillation of stress in the post-bifurcation regimes.
  • 下薗 征史, 園田 佳巨, 西本 安志
    2007 年 10 巻 p. 293-300
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    To protect vessel's body from the colliding accident, rubber fenders are usually installed on the quay berth. There are various shapes and degrees of stiffness of rubber fenders and they are selected by specified static energy absorbing capacity. However their design method is going to be revised by the concept of performance based design in the near future. According to new design concept, energy absorbing capacity of rubber fender should be estimated by considering impact velocity of colliding vessel. Therefore, main objectives of this study are to investigate strain rate effect of rubber material, and to simulate dynamic behavior of rubber fender with strain rate effect. To achieve these objectives, dynamic constitutive law of rubber material is considered by experimental results, and dynamic response ofrubber fenders are conducted by 3-dimensional nonlinear finite element method.
  • 沖中 知雄, カリモフ パベル, 江藤 剛治
    2007 年 10 巻 p. 301-309
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    The stress field around the propagating crack tip under the static loading is visualized. An ultra high speed camera of 1Mfps (Million frames per second) is applied to visualize the stress field around the crack tip by means of conventional photo-elastic imaging technique. A new video trigger system is also developed to detect the initiation of the crack propagation. As a result, it is revealed that the elastic wave, propagating in the specimen, has a significant effect on the crack propagation behavior.
  • 吉田 秀典, 乗金 悠里, 森本 亮司, 井上 純哉
    2007 年 10 巻 p. 311-322
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In Japan, it is planned to dispose high-level radioactive waste and TRU waste in a stable rock mass. As for the HLW problems, it is necessary to ensure that residual radioactive substances are kept from reaching the biosphere after many thousands of years. Thus the mathematical model by which not only mechanical but also hydraulic behaviors can be predicted for a long-term is of prime importance. The mechanical and hydraulic properties of discontinuous rock mass have strong correlations respectively. In this study, a creep test with associated to the coupled behaviors is conducted with the use of an artificial specimen so as to seize the mechanism of the mechanical and hydraulic behaviors. Moreover, the numerical analysis by which the coupled behavior in the creep test is reproduced is carried on, and the numerical result has modestly good accordance with the measured data. From the comparison of the experiment and the analysis, the mechanism of coupled behavior is discussed.
  • 岡安 崇史, 大山 将史, 古野 裕子, 光岡 宗司, 井上 英二, 橋口 公一
    2007 年 10 巻 p. 323-330
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Unconventional elastoplastic constitutive models such as the subloading surface model proposed by Hashiguchi can describe mechanical behavior of soils including cyclic loading behavior, realistically. Among them, the superloading yield surface model, which was proposed by Asaoka et al. is possible to predict the defamation behavior for various structured soils or densities of soils using a unique set of material parameters. In this article, the finite element analysis program in which the superloading yield surface model was incorporated is adopted for an analysis of wheel-soft ground interaction phenomena Soil compaction behavior for the various kinds of structured grounds due to the repetition of the rigid wheel travels is simulated by using the unique set of the material parameters for the structured ground. Moreover the influence upon soil compaction due to difference of layer thickness of ground is also examined here by the present analysis program
  • 鱸 洋一, 大熊 俊明, 矢富 盟祥
    2007 年 10 巻 p. 331-342
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In this paper, we propose maximum frictional shear fracture criterion, which explains mode II type crack extension in geomaterials under the compressive loads. It is important to elucidate the fracture criterions under compressive loads such as the explanation of the existence and the creation of long faults, landslide in slope ground and so on. We examine an implicit soil/water coupling elastic-plastic calculation algorithm with contact conditions on the crack surfaces in order to obtain stress fields near a crack tip under the biaxial compressive loads. We find that the maximum frictional shear stress causes a crack extension with the same direction of an initial crack in any condition and the tensile cracks never extend from the upper side of a crack near the tip.
  • 石井 建樹, 京谷 孝史, 寺田 賢二郎
    2007 年 10 巻 p. 343-350
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Failure processes of quasi-brittle solids like a rock mass generally involve not only cracking within constituents but also slippage between crack interfaces, especially when they are subjected to compressive loading. In this paper, these processes under uni-axial compressive loading are simulated in terms of the numerical analysis method based on the finite cover method (FCM). The results of several numerical tests demonstrate the effects of slippage between the crack interfaces to crack propagation.
  • Liang LU, Katsuhiko ARAI, Zongjian WANG
    2007 年 10 巻 p. 351-362
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper reports the results of laboratory model tests subjected to bearing capacity of rigid strip footing. Based on the results, this paper proposes a numerical procedure for estimating the bearing capacity of rigid strip footing under some complex conditions. The procedure uses a smeared shear band approach and a modified initial stress method to provide an explicit collapse mechanism represented by the stress yield condition, assuming the Mohr-Coulomb yield criterion with a simple non-associated flow rule. The procedure employs a simple constitutive model which requires a small number of soil parameters, so that it may be applied to practical design work rather than the simulation of actual failure behavior. Comparison is made between the results calculated by the numerical procedures and those of the laboratory model tests.
  • 王 宗建, 荒井 克彦, 竜田 尚希, 山内 章喜, 古川 晋
    2007 年 10 巻 p. 363-374
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper performs laboratory model tests for simulating the slope failure due to vibration, and indicates that a slope failure during earthquake tends to occur when a cumulative plastic deformation exceeds a certain critical value. Based on the result, this paper proposes a numerical procedure to evaluate the slope stability during earthquake, in which the cumulative plastic deformation is calculated by a dynamic analysis using seismic wave, and in which the critical value of deformation is estimated by a static analysis considering seismic intensity.
  • 河井 克之, 飯塚 敦, 霜永 勝之, 橘 伸也
    2007 年 10 巻 p. 375-381
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    It is known that the vegetation is effective in preventing slope failure. In this study, we focus on the vegetation uptake from ground and show the way to estimate its effects on the ground quantitatively. The effect of uptake can be regarded as reduction of water content within soil. The ‘root element’, where the reduction of water content occurs, is applied to the existing code of soil/water coupled finite element analysis with unsaturated soil mechanics. To estimate the effects of uptake, three kinds of conditions, such as the amount of uptake water, the initial degree of saturation of the ground, and groundwater level are provided. Consequently, it was found that the uptake increased suction and encouraged non-uniform settlement of ground surface. Its effects appeared prominently in a dry ground having low groundwater level and much uptake. This method is effective to understand the effects of vegetation.
  • K. Hashiguchi, S. Ozaki
    2007 年 10 巻 p. 383-389
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    The constitutive equation of friction has been developed by the authors so as to describe the smooth transition from the elastic to plastic sliding state and the transition from the static to the kinetic friction and its vice versa, which is called the time-dependent subloading-friction model. In this article this model is further extended so as to describe the anisotropic hardening by incorporating the concept of the rotation of yield surface, i. e. the rotational hardening that has been adopted in the elastoplasticonstitutive equation of soils.
  • 伊藤 誠, 水野 英二, 畑中 重光
    2007 年 10 巻 p. 391-402
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    3-D FEM analysis of confined concrete subjected to the axial compressive load has been carried out to investigate the confining effect and damage condition insideconcrete. In the present analysis, therefore, the influence of the transverse reinforcement ratio, the yield strength of reinforcement and concrete strength on the confining effect inside concrete has been evaluated in tarms of the confining efficiency that is related to the rate of “equivalent confining pressure”. The followings have turned out from the present analysis.(1) The confining efficiency depends on the mechanical reinforcement ratio, which is the ratio of confining pressure to concrete strength.(2) In the case of low mechanical reinforcement ratio, the confining effect extends the inner part of the concrete. Otherwise, the confining effect becomes predominant only near the comers.
  • 荒井 克彦, 辻 慎一朗, 藤田 貴準, 町原 秀夫
    2007 年 10 巻 p. 403-414
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper discusses active earth pressure acting on concrete block retaining wall considering deformation and stiffness of wall and backfill material. Many laboratory model tests are performed, subjected to block retaining walls which have reinforced or unreinforced backfill, and which have different inclination. Earth pressure distribution and active thrust, etc. are monitored according to the displacement of retaining wall. The monitored results are simulated fairly well by proposed FE analysis which employs Mohr-Coulomb yield criterion, a simple non-associated flow rule, and initial stress method for nonlinear analysis. By applying the proposed procedure to the result of full-scale model test, it is shown that the procedure duplicates fairly well the results observed in the test.
  • シン グエンデュイ, 斉木 功, 岩熊 哲夫
    2007 年 10 巻 p. 415-423
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Application of composites in civil engineering, such as repair of bridges and piers by graphite-epoxy composites, is growing rapidly. One of the problems in strength of composite materials is interfacial debonding between the fiber and matrix. We here employ an analytical model considering partial debonding along fiber's interface, and construct a finite element, in which an approximate scheme to calculate the stress re-distribution due to partial debonding is included. Several numerical examples and comparisons with experimental data show the characteristics and feasibility of this model.
  • 陳 玳行, 尾崎 伸吾
    2007 年 10 巻 p. 425-436
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    In this paper, the effect of height of the hexagonal honeycomb core on the equivalent elastic moduli is studied by using numerical results of the finite element method. For honeycomb core subjected to in-plane loading, there exist deformations in the height direction for cell walls due to the effect of Poisson's ratio. Since these deformations are different for adjacent walls if they are not joined together along the common edge, the in-plane stiffnesses should be analyzed as a three-dimensional problem, in which the deformations in the height direction are considered. Based on this fact, an equation to calculate elastic moduli from their values under the plane strain condition is proposed. Then, the validity of the present formula for elastic moduli is verified comparing with the numerical results by the finite element method.
  • 巨視的弾性条件下における疲労き裂発生
    堤 成一郎, 矢嶋 泰基, 村上 幸治, 後藤 浩二, 豊貞 雅宏
    2007 年 10 巻 p. 437-444
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Plastic stretching within a yield surface has to be considered to describe cyclic plasticity phenomena. An elastoplastic constitutive model incorporating subloading surface concept has been proposed for materials exhibiting not only a purely elastic response under a particular lower state of stress but also a damage evolution. In this study, the model is extended to describe cyclic plasticity phenomena, such as ratcheting and fatigue crack nucleation triggered by the accumulated plastic strain/work, under macroscopically elastic condition. The applicability of the model is verified through the comparison with the experimental data for SN490B. It is also discussed about S-N curve obtained by the proposed model and the fatigue crack nucleation.
  • 尾崎 伸吾, 橋口 公一, 陳 玳行
    2007 年 10 巻 p. 445-455
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    It is important to clarify the frictional sliding characteristics of unstable vibration, such as stickslip motion, for the design of machine elements and constructions. Especially, wear of machine elements is accelerated, and acoustic emission system and machine life are also highly affected by stick-slip motion. In this study, the time-dependent subloading-friction model, which can rationally describe the reciprocal transition of static-kinematic frictions, is applied to the analysis of stick-slip motion. Concretely, one-dimensional model of spring-mass system is implemented by incorporating the present friction model. The model is then applied to simulations of stick-slip motion under various conditions. It is shown by the present simulations that an unstable region of stick-slip motion in the (K-μ) plane, and effect of time-and state-dependent parameters on the stick-slip amplitude.
  • 亀田 好洋, 伊藤 睦, 梅原 秀哲, 水野 英二
    2007 年 10 巻 p. 457-466
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    The present paper deals with the experimental and analytical study on the mechanical properties of reinforced concrete (RC) columns subjected to flexural deformation under axial compression. The pushover loading test has been performed on 8 types of RC column specimens with the different lateral hoop ratios under constant axial compression force. The experimental results have been compared with the analytical results from the finite element program FEAP, then and the mechanical properties, such as the toughness and the plastic hinge moment in the post-peak region of RC columns, have been examined for 8 types of RC column specimens. Furthermore, the effect of axial loading and the lateral hoop ratio on the material property (i. e., softening behavior) of the core concrete has been discussed It turns out that the lateral hoop ratio almost has no influence on the post-peak behavior of RC columns at structural level and the softening behavior of the coe concrete at material level.
  • 金田 一広, ハザリカ ヘマンタ, 山崎 浩之
    2007 年 10 巻 p. 467-476
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    It is known that the use of compressible material (e. g tire chips) on the backfill can significantly reduce the load against retaining wall. This reduction of earth pressure is achieved through a mechanism of simulating the quasi-active or the intermediate active state. If there exists a highly compressible material between soils and retaining wall, the backfill soils approaches to active state. In this paper, this mechanism has been numerically evaluated. In the numerical simulation, the modified Cam clay model with super-subloading yield auface and rotational hardening concept (SYS Cam Clay model) was used. The SYS Cam Claymodel (Asaoka et al 2002) is the elasto-plastic model that takes into the account the soil structure as well as overconsolidation and anisotropy, which was introduced by Hashiguchi. Using this model, the typical responses of dense and loose sand can be described.
  • 張 広鋒, 岸 徳光, 三上 浩, 高玉 郁子
    2007 年 10 巻 p. 477-484
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    This paper aims to establish a nonlinear numerical analysis method based on three-dimensional elasto-plastic FEM for simulating punching shear failure behavior of two-way RC slabs. In this method, rebars were modeled as a piece of plate to enhance the applicability in case of complicated arrangement of rebar. Geometrical discontinuity of punching shear failure surface, bond slipping of main rebar and splitting of concrete cover were considered applying with discrete crack approach. Two slabs that tested using a circular loading-plate were analyzed, in which, diameter of loading-plate is different with each other. The validity of the proposed method was inspected by comparing the analytical load-displacement curves and distribution of cracks with those of the experimental ones. As a result, load-carrying capacity and punching shear failure behavior of two way RC slabs can be simulated with a good agreement of the proposed method.
  • 高橋 弘, 丸橋 史和, 橋本 久儀
    2007 年 10 巻 p. 487-496
    発行日: 2007/08/29
    公開日: 2010/06/04
    ジャーナル フリー
    Recently, a soil mixing machine has been receiving considerable attention in order to restore the contaminated soils. In the remediation sites, contaminated soils are fed into the machine and they are mixed with the liquid agent. As the liquid agent is expensive, it is necessary to obtain the mixing behavior of contaminated soils and agent, and to know the optimum operating condition in order to perform the effective remediation. However, many parameters affect the mixing behavior and experimental investigation is uneconomical and ineffective.
    In this study, the mixing of contaminated soils and liquid agent was simulated by using distinct element method (DEM). In the DEM simulation, the increase of water content due to the addition of liquid agent was simulated and this result was compared with the experimental one. It was confirmed through the comparison that the model proposed here was almost reasonable.
feedback
Top