This paper describes a stochastic homogenization analysis of a particle reinforced composite material using an approximation technique. In order to analyze the influence of a microscopic random variation of an elastic property of a component material on the homogenized elastic property of a particle reinforced composite material, the Monte-Carlo simulation is employed. Since the conventional Monte-Carlo simulation sometimes involves a higher computational cost, an approximate stochastic homogenization method using the Monte-Carlo simulation combined with a polynomial-based approximation technique is employed, and accuracy of the approximate Monte-Carlo simulation is investigated. In order to apply a lower order approximation to the approximate Monte-Carlo simulation effectively, the weighted least square method is proposed, and its effectiveness is discussed with the numerical results.
{"title":"Stochastic Homogenization Analysis of a Particle Reinforced Composite Material using an Approximate Monte-Carlo Simulation with the Weighted Least Square Method","authors":"S. Sakata, F. Ashida, Daiki Iwahashi","doi":"10.1299/JCST.7.1","DOIUrl":"https://doi.org/10.1299/JCST.7.1","url":null,"abstract":"This paper describes a stochastic homogenization analysis of a particle reinforced composite material using an approximation technique. In order to analyze the influence of a microscopic random variation of an elastic property of a component material on the homogenized elastic property of a particle reinforced composite material, the Monte-Carlo simulation is employed. Since the conventional Monte-Carlo simulation sometimes involves a higher computational cost, an approximate stochastic homogenization method using the Monte-Carlo simulation combined with a polynomial-based approximation technique is employed, and accuracy of the approximate Monte-Carlo simulation is investigated. In order to apply a lower order approximation to the approximate Monte-Carlo simulation effectively, the weighted least square method is proposed, and its effectiveness is discussed with the numerical results.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"239 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123872157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The general solutions for a penny-shaped crack in an infinite solid, subjected to arbitrary tractions on the crack surfaces were derived. The applicability was demonstrated deriving the closed-form solutions for a penny-shaped crack subjected to the lower-order loading such as constant tension, shear, bending, and torsion. Furthermore, we consider a circular crack subjected to cubic-order normal stresses. It is shown that the stress intensity factor distribution derived from the general solution exactly agree with the analytical solutions derived by Shah-Kobayashi.
{"title":"On the General Solutions for Mixed-Mode Penny-Shaped Crack and Their Applications","authors":"T. Nishioka, G. Zhou, T. Fujimoto","doi":"10.1299/JCST.2.34","DOIUrl":"https://doi.org/10.1299/JCST.2.34","url":null,"abstract":"The general solutions for a penny-shaped crack in an infinite solid, subjected to arbitrary tractions on the crack surfaces were derived. The applicability was demonstrated deriving the closed-form solutions for a penny-shaped crack subjected to the lower-order loading such as constant tension, shear, bending, and torsion. Furthermore, we consider a circular crack subjected to cubic-order normal stresses. It is shown that the stress intensity factor distribution derived from the general solution exactly agree with the analytical solutions derived by Shah-Kobayashi.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125258907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Slip deformation in Cu-9at.% Al symmetric type bicrystal models subjected to tensile loading is investigated by a finite element crystal plasticity analysis code. Accumulation of geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs) are studied in detail. Results of the analysis show asymmetric non-uniform deformation and accumulation of GNDs on the primary and secondary slip systems with activation of secondary slip system near the grain boundary. Mechanism of asymmetric non-uniform deformation with GNDs accumulated near the grain boundary in the Cu-9at.% Al symmetric type bicrystal models is discussed from the viewpoint of the effects of the elastic anisotropy of Cu-9at.% Al and the heterogeneity of initial statically stored dislocations density.
{"title":"Relationship between Micro-Incompatibility and Heterogeneity of Dislocation Density Distribution in Cu-9at.% Al Symmetric Type Bicrystal Models under Tensile Loading","authors":"Ryouji Kondou, T. Ohashi, S. Miura","doi":"10.1299/JCST.2.162","DOIUrl":"https://doi.org/10.1299/JCST.2.162","url":null,"abstract":"Slip deformation in Cu-9at.% Al symmetric type bicrystal models subjected to tensile loading is investigated by a finite element crystal plasticity analysis code. Accumulation of geometrically necessary dislocations (GNDs) and statistically stored dislocations (SSDs) are studied in detail. Results of the analysis show asymmetric non-uniform deformation and accumulation of GNDs on the primary and secondary slip systems with activation of secondary slip system near the grain boundary. Mechanism of asymmetric non-uniform deformation with GNDs accumulated near the grain boundary in the Cu-9at.% Al symmetric type bicrystal models is discussed from the viewpoint of the effects of the elastic anisotropy of Cu-9at.% Al and the heterogeneity of initial statically stored dislocations density.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"70 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131165702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We verified the generalization ability of the response surfaces of artificial neural networks (NNs), and that the surfaces could be applied to an engineering-design problem. A Bayesian framework to regularize NNs, which was proposed by Gull and Skilling, can be used to generate NN response surfaces with excellent generalization ability, i.e., to determine the regularizing constants in an objective function minimized during NN learning. This well-generalized NN might be useful to find an optimal solution in the process of response surface methodology (RSM). We, therefore, describe three rules based on the Bayesian framework to update the regularizing constants, utilizing these rules to generate NN response surfaces with noisy teacher data drawn from a typical unimodal or multimodal function. Good generalization ability was achieved with regularized NN response surfaces, even though an update rule including trace evaluation failed to determine the regularizing constants regardless of the response function. We, next, selected the most appropriate update rule, which included eigenvalue evaluation, and then the NN response surface regularized using the update rule was applied to finding the optimal solution to an illustrative engineering-design problem. The NN response surface did not fit the noise in the teacher data, and consequently, it could effectively be used to achieve a satisfactory solution. This may increase the opportunities for using NN in the process of RSM.
{"title":"Response Surfaces of Neural Networks Learned Using Bayesian Framework and Its Application to Optimization Problem","authors":"N. Takeda","doi":"10.1299/JCST.3.315","DOIUrl":"https://doi.org/10.1299/JCST.3.315","url":null,"abstract":"We verified the generalization ability of the response surfaces of artificial neural networks (NNs), and that the surfaces could be applied to an engineering-design problem. A Bayesian framework to regularize NNs, which was proposed by Gull and Skilling, can be used to generate NN response surfaces with excellent generalization ability, i.e., to determine the regularizing constants in an objective function minimized during NN learning. This well-generalized NN might be useful to find an optimal solution in the process of response surface methodology (RSM). We, therefore, describe three rules based on the Bayesian framework to update the regularizing constants, utilizing these rules to generate NN response surfaces with noisy teacher data drawn from a typical unimodal or multimodal function. Good generalization ability was achieved with regularized NN response surfaces, even though an update rule including trace evaluation failed to determine the regularizing constants regardless of the response function. We, next, selected the most appropriate update rule, which included eigenvalue evaluation, and then the NN response surface regularized using the update rule was applied to finding the optimal solution to an illustrative engineering-design problem. The NN response surface did not fit the noise in the teacher data, and consequently, it could effectively be used to achieve a satisfactory solution. This may increase the opportunities for using NN in the process of RSM.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127706137","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
An efficient homogenization method for nonlinear problems is introduced. We have already developed a homogenization technique using characteristic deformation mode superposition that avoids prohibitive computational cost. However, in the mode superposition technique, the approximation error created depends on the analysis case. In this paper a new method is proposed, in which the same accuracy as the exact method is preserved by solving the microscopic equilibrium equation, while approximating the tangential matrix of the multi-scale equilibrium equation using the mode superposition method. The performance of the proposed method is examined together with the block LU factorization algorithm, and satisfactory results are obtained.
{"title":"Nonlinear Homogenization Algorithms with Low Computational Cost","authors":"J. Okada, T. Washio, T. Hisada","doi":"10.1299/JCST.3.101","DOIUrl":"https://doi.org/10.1299/JCST.3.101","url":null,"abstract":"An efficient homogenization method for nonlinear problems is introduced. We have already developed a homogenization technique using characteristic deformation mode superposition that avoids prohibitive computational cost. However, in the mode superposition technique, the approximation error created depends on the analysis case. In this paper a new method is proposed, in which the same accuracy as the exact method is preserved by solving the microscopic equilibrium equation, while approximating the tangential matrix of the multi-scale equilibrium equation using the mode superposition method. The performance of the proposed method is examined together with the block LU factorization algorithm, and satisfactory results are obtained.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"474 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132588650","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Chen Jian Ken Lee, Wataru Furuya, Masato Tanaka, N. Takano
With smooth objective functions and constraint conditions, gradient-based methods can be used to solve multi-objective optimization problems efficiently. However, when applied to structural sizing optimization problems, using the Finite Element Method (FEM) and a finite difference scheme to calculate sensitivities can be computationally expensive. The adjoint variable method can be used to reduce computational cost. In order to solve multi-objective structural sizing and shape optimization problems efficiently, this paper proposes using the adjoint variable method. The adjoint variable method efficiently calculates multiple sensitivities for objectives that involve structural responses and cuts down computational cost by reducing the number of sensitivity calculations required per design variable.
{"title":"Adjoint Variable Method for Multi-Objective Sizing and Shape Optimization","authors":"Chen Jian Ken Lee, Wataru Furuya, Masato Tanaka, N. Takano","doi":"10.1299/JCST.3.275","DOIUrl":"https://doi.org/10.1299/JCST.3.275","url":null,"abstract":"With smooth objective functions and constraint conditions, gradient-based methods can be used to solve multi-objective optimization problems efficiently. However, when applied to structural sizing optimization problems, using the Finite Element Method (FEM) and a finite difference scheme to calculate sensitivities can be computationally expensive. The adjoint variable method can be used to reduce computational cost. In order to solve multi-objective structural sizing and shape optimization problems efficiently, this paper proposes using the adjoint variable method. The adjoint variable method efficiently calculates multiple sensitivities for objectives that involve structural responses and cuts down computational cost by reducing the number of sensitivity calculations required per design variable.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114241432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, a simple and efficient boundary element method using a modal transformation is presented to solve a transient acoustic problem in the open space around a structure caused by the vibration due to the impact force on it. After the transient vibration of the structure is obtained by the finite element analysis, the velocity response of the surface of the structure is transformed to frequency domain. Transient acoustic pressures at points of interest are calculated as a combination of steady-state acoustic boundary element solutions under the velocity boundary conditions at discrete frequencies. However, high frequency terms exceeding an allowable frequency, which is decided from the boundary element mesh, are automatically omitted to obtain a stable solution while saving the computation time considerably. To get the boundary element solution effectively, a modal transformation using vibration modes of the structure is made to the boundary element matrices at each frequency, since the acoustic behavior on the surface of the structure is considered to be related deeply to that of the vibration. However, extra modes are added to express the acoustic field around the surface where displacements are fixed.Based on the present method, a boundary element transient acoustic analysis program, ASA/ACOUSTICS has been developed. Numerical examples are demonstrated.
{"title":"An Efficient Boundary Element Method Using a Modal Transformation for Transient Acoustic Problem","authors":"M. Tanabe, T. Deura, H. Okuda","doi":"10.1299/JCST.2.222","DOIUrl":"https://doi.org/10.1299/JCST.2.222","url":null,"abstract":"In this paper, a simple and efficient boundary element method using a modal transformation is presented to solve a transient acoustic problem in the open space around a structure caused by the vibration due to the impact force on it. After the transient vibration of the structure is obtained by the finite element analysis, the velocity response of the surface of the structure is transformed to frequency domain. Transient acoustic pressures at points of interest are calculated as a combination of steady-state acoustic boundary element solutions under the velocity boundary conditions at discrete frequencies. However, high frequency terms exceeding an allowable frequency, which is decided from the boundary element mesh, are automatically omitted to obtain a stable solution while saving the computation time considerably. To get the boundary element solution effectively, a modal transformation using vibration modes of the structure is made to the boundary element matrices at each frequency, since the acoustic behavior on the surface of the structure is considered to be related deeply to that of the vibration. However, extra modes are added to express the acoustic field around the surface where displacements are fixed.Based on the present method, a boundary element transient acoustic analysis program, ASA/ACOUSTICS has been developed. Numerical examples are demonstrated.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114638235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Seungchol Choi, Yasuyuki Yamamoto, S. Matsumoto, Tomoko Yamamoto
A MEMS-viscosity sensor with dual spiral structure has been developed based on a novel measurement method unlike traditional method for viscosity measurement. This viscosity sensor, passing completely through a silicon wafer using MEMS (Micro Electro Mechanical Systems) fabrication processing, was made up the spiral structure with a vibrating body and a sensing body. When a large deflection was generated toward each direction of the vibration body of spiral structure due to the applied external load, it can be the cause of performance deterioration of the MEMS-viscosity sensor. And the analytical methods were proposed to fine the deflections by a computational analysis using FEM (Finite Element Method). A computational analysis was carried out by coupled analysis using modal analysis method and harmonic response analysis assuming air environment. In the spiral model of the MEMS-viscosity sensor on which normal loads of Fz=100 [μN] and Fz=1000 [μN] were applied, the maximum resonance points occurred at about 1400[Hz] of 1st mode along with vertical direction (Z-direction) respectively. When Fz=1000 [μN] was applied, the maximum value of deflection was obtained about 3.0x10 [m] in vertical direction, but the normal load of more than Fz=1000 [μN] should be avoided for safety and reliability of this MEMS-viscosity sensor because the deflections of horizontal directions (X and Y-direction) were near to limit of the design values. We found that the deflections of horizontal direction were small enough to be negligible compared to the vertical direction, and the spiral structure can be stably maintained against less than Fz=1000 [μN] of the external load. We also found out the waviness phenomenon in the deflections along the spiral beam. As a solution of the waviness phenomenon in the spiral structure with rectangular shape beam, it seems that the spiral beam must be given so that the spiral radius is continuously compensated by using other beam shapes. It was demonstrated that the approach using computational analysis allows us to deduce visually the deflection of the spiral structure for viscosity sensor.
{"title":"Computational Analysis of a Spiral Vibrating Beam for the MEMS-Viscosity Sensor","authors":"Seungchol Choi, Yasuyuki Yamamoto, S. Matsumoto, Tomoko Yamamoto","doi":"10.1299/JCST.7.89","DOIUrl":"https://doi.org/10.1299/JCST.7.89","url":null,"abstract":"A MEMS-viscosity sensor with dual spiral structure has been developed based on a novel measurement method unlike traditional method for viscosity measurement. This viscosity sensor, passing completely through a silicon wafer using MEMS (Micro Electro Mechanical Systems) fabrication processing, was made up the spiral structure with a vibrating body and a sensing body. When a large deflection was generated toward each direction of the vibration body of spiral structure due to the applied external load, it can be the cause of performance deterioration of the MEMS-viscosity sensor. And the analytical methods were proposed to fine the deflections by a computational analysis using FEM (Finite Element Method). A computational analysis was carried out by coupled analysis using modal analysis method and harmonic response analysis assuming air environment. In the spiral model of the MEMS-viscosity sensor on which normal loads of Fz=100 [μN] and Fz=1000 [μN] were applied, the maximum resonance points occurred at about 1400[Hz] of 1st mode along with vertical direction (Z-direction) respectively. When Fz=1000 [μN] was applied, the maximum value of deflection was obtained about 3.0x10 [m] in vertical direction, but the normal load of more than Fz=1000 [μN] should be avoided for safety and reliability of this MEMS-viscosity sensor because the deflections of horizontal directions (X and Y-direction) were near to limit of the design values. We found that the deflections of horizontal direction were small enough to be negligible compared to the vertical direction, and the spiral structure can be stably maintained against less than Fz=1000 [μN] of the external load. We also found out the waviness phenomenon in the deflections along the spiral beam. As a solution of the waviness phenomenon in the spiral structure with rectangular shape beam, it seems that the spiral beam must be given so that the spiral radius is continuously compensated by using other beam shapes. It was demonstrated that the approach using computational analysis allows us to deduce visually the deflection of the spiral structure for viscosity sensor.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116721017","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"FEM Simulation of Coupled Flow and Bed Morphodynamic Interactions due to Sediment Transport Phenomena","authors":"J. Camata, R. Elias, A. Coutinho","doi":"10.1299/JCST.7.306","DOIUrl":"https://doi.org/10.1299/JCST.7.306","url":null,"abstract":"","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116759627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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