Masaki Hamamoto, Yoshiji Ohta, Keita Hara, T. Hisada
{"title":"Three-Dimensional Free-Flight Analysis of the Rapid Turning of a Dragonfly Using Fluid-Structure Interaction Analysis","authors":"Masaki Hamamoto, Yoshiji Ohta, Keita Hara, T. Hisada","doi":"10.1299/JCST.7.75","DOIUrl":"https://doi.org/10.1299/JCST.7.75","url":null,"abstract":"","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"63 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":"130485039","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}
A. Tani, Kenji Tanaka, Yuichiro Yamabe, H. Kawamura
The authors have already proposed an intelligent fuzzy optimal and active control system (IFOACS) and the effectiveness of IFOACS was proved using digital simulations and shaking table tests. However, the results show that the control effect of IFOACS becomes small in case of near-source region earthquakes. To improve control effects in case of near-source region earthquakes, a combinatorial control system (CCS), in which IFOACS is combined with a fuzzy active control system (FACS), is also proposed. In this paper, control rules in CCS are optimized using parameter-free genetic algorithms (PfGAs) considering limitations of an actuator such as maximal strokes and control forces. Effectiveness of proposed combinatorial control system (CCS) is verified and discussed based on results of digital simulations.
{"title":"Intelligent Fuzzy Optimal Active and Combinatorial Control System of Building Structures","authors":"A. Tani, Kenji Tanaka, Yuichiro Yamabe, H. Kawamura","doi":"10.1299/JCST.2.381","DOIUrl":"https://doi.org/10.1299/JCST.2.381","url":null,"abstract":"The authors have already proposed an intelligent fuzzy optimal and active control system (IFOACS) and the effectiveness of IFOACS was proved using digital simulations and shaking table tests. However, the results show that the control effect of IFOACS becomes small in case of near-source region earthquakes. To improve control effects in case of near-source region earthquakes, a combinatorial control system (CCS), in which IFOACS is combined with a fuzzy active control system (FACS), is also proposed. In this paper, control rules in CCS are optimized using parameter-free genetic algorithms (PfGAs) considering limitations of an actuator such as maximal strokes and control forces. Effectiveness of proposed combinatorial control system (CCS) is verified and discussed based on results of digital simulations.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"2 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":"128663247","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 the previous paper, the geometrically necessary (GN) incompatibility is newly defined and a new annihilation term of dislocation pairs due to the dynamic recovery is introduced into an expression of dislocation density. Furthermore, a multiscale model of crystal plasticity is proposed by considering the GN dislocation density and incompatibility. However, details of dislocation-crystal plasticity calculation are not given. In this paper, we explain a method of dislocation-crystal plasticity analysis. A finite element simulation is carried out for an f.c.c. single crystal under plane strain tension. It is numerically predicted that micro shear bands are formed at large strain, and sub-GNBs: small angle tilt boundaries are induced along these bands. Furthermore, the annihilation of dislocation pairs and the increase of dislocation mean free path characterizing stage III of work-hardening are computationally predicted.
{"title":"A Dislocation-Crystal Plasticity Simulation on FCC Single Crystal Considering Geometrically Necessary Dislocation Density and Incompatibility","authors":"Y. Aoyagi, K. Shizawa","doi":"10.1299/JCST.2.197","DOIUrl":"https://doi.org/10.1299/JCST.2.197","url":null,"abstract":"In the previous paper, the geometrically necessary (GN) incompatibility is newly defined and a new annihilation term of dislocation pairs due to the dynamic recovery is introduced into an expression of dislocation density. Furthermore, a multiscale model of crystal plasticity is proposed by considering the GN dislocation density and incompatibility. However, details of dislocation-crystal plasticity calculation are not given. In this paper, we explain a method of dislocation-crystal plasticity analysis. A finite element simulation is carried out for an f.c.c. single crystal under plane strain tension. It is numerically predicted that micro shear bands are formed at large strain, and sub-GNBs: small angle tilt boundaries are induced along these bands. Furthermore, the annihilation of dislocation pairs and the increase of dislocation mean free path characterizing stage III of work-hardening are computationally predicted.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"44 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":"128431325","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 the United States and Japan, baseball is a very popular sport played by many people. However, the ball used is hard and moves fast. A professional baseball pitcher in good form can throw a ball at speeds upwards of 41.7m/s (150km/hr). If a ball at this speed hits the batter, serious injury can occur. In this paper we will describe our investigations on the impact of a baseball with living tissues by finite element analysis. Baseballs were projected at a load cell plate using a specialized pitching machine. The dynamic properties of the baseball were determined by comparing the wall-ball collision experimentally measuring the time history of the force and the displacement using dynamic finite element analysis software (ANSYS/ LS-DYNA). The finite element model representing a human humerus and its surrounding tissue was simulated for balls pitched at variable speeds and pitch types (knuckle and fastball). In so doing, the stress distribution and stress wave in the bone and soft tissue were obtained. From the results, the peak stress of the bone nearly yielded to the stress caused by a high fast ball. If the collision position or direction is moved from the center of the upper arm, it is assumed that the stress exuded on the humerus will be reduced. Some methods to reduce the severity of the injury which can be applied in actual baseball games are also discussed.
{"title":"Study on Impact Loading and Humerus Injury for Baseball","authors":"Shinobu Sakai, J. Oda, S. Yonemura, J. Sakamoto","doi":"10.1299/JCST.2.609","DOIUrl":"https://doi.org/10.1299/JCST.2.609","url":null,"abstract":"In the United States and Japan, baseball is a very popular sport played by many people. However, the ball used is hard and moves fast. A professional baseball pitcher in good form can throw a ball at speeds upwards of 41.7m/s (150km/hr). If a ball at this speed hits the batter, serious injury can occur. In this paper we will describe our investigations on the impact of a baseball with living tissues by finite element analysis. Baseballs were projected at a load cell plate using a specialized pitching machine. The dynamic properties of the baseball were determined by comparing the wall-ball collision experimentally measuring the time history of the force and the displacement using dynamic finite element analysis software (ANSYS/ LS-DYNA). The finite element model representing a human humerus and its surrounding tissue was simulated for balls pitched at variable speeds and pitch types (knuckle and fastball). In so doing, the stress distribution and stress wave in the bone and soft tissue were obtained. From the results, the peak stress of the bone nearly yielded to the stress caused by a high fast ball. If the collision position or direction is moved from the center of the upper arm, it is assumed that the stress exuded on the humerus will be reduced. Some methods to reduce the severity of the injury which can be applied in actual baseball games are also discussed.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"93 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":"126372532","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}
This paper proposes a systematic scheme of removing void elements to achieve fast and efficient level set based topology optimization. When performing optimization, unless special treatment is applied to the stiffness matrix, the density of these void elements are usually represented numerically by a small positive value. In level set based topology optimization, since the amount of computational resources required for FEM dwarfs those required for level set evolution, the removal of these elements from the global stiffness matrix can drastically reduce total computation time. The proposed scheme removes the void elements, determined by their nodes' level set values, from the optimization process by use of mapping procedures. The results presented here show time reductions of at least 70%. An additional advantage of the presented scheme is that it can be easily used with any black box FEM routine.
{"title":"Removing Void Elements for Structural Level Set Topology Optimizaiton","authors":"Chen Jian Ken Lee, Zhiqiang Zhang, N. Takano","doi":"10.1299/JCST.3.385","DOIUrl":"https://doi.org/10.1299/JCST.3.385","url":null,"abstract":"This paper proposes a systematic scheme of removing void elements to achieve fast and efficient level set based topology optimization. When performing optimization, unless special treatment is applied to the stiffness matrix, the density of these void elements are usually represented numerically by a small positive value. In level set based topology optimization, since the amount of computational resources required for FEM dwarfs those required for level set evolution, the removal of these elements from the global stiffness matrix can drastically reduce total computation time. The proposed scheme removes the void elements, determined by their nodes' level set values, from the optimization process by use of mapping procedures. The results presented here show time reductions of at least 70%. An additional advantage of the presented scheme is that it can be easily used with any black box FEM routine.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"7 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":"125933747","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, nonlinear boundary value problems are analyzed by using the over-range collocation method (ORCM). By introducing some collocation points, which are located at outside of domain of the analyzed body, unsatisfactory issue of the positivity conditions of boundary points in collocation methods can be avoided. Quite accurate numerical results of the nonlinear partial differential equations have been obtained. Because the ORCM does not demand any specific type of partial differential equations, it shows promise of wide engineering applications of the ORCM.
{"title":"Nonlinear Analyses by Using the ORCM","authors":"Yong-Ming Guo, Hirotaka Osako, S. Kamitani","doi":"10.1299/JCST.7.114","DOIUrl":"https://doi.org/10.1299/JCST.7.114","url":null,"abstract":"In this paper, nonlinear boundary value problems are analyzed by using the over-range collocation method (ORCM). By introducing some collocation points, which are located at outside of domain of the analyzed body, unsatisfactory issue of the positivity conditions of boundary points in collocation methods can be avoided. Quite accurate numerical results of the nonlinear partial differential equations have been obtained. Because the ORCM does not demand any specific type of partial differential equations, it shows promise of wide engineering applications of the ORCM.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"101 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":"126897119","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}
It is well known that the compressibility or incompressibility of biological tissue stems from its microscopic structure, which is generally composed of material with varied compressibility, including incompressibility. This paper proposes a framework for a homogenization method in which the compressibility/incompressibility of the macrostructure properly reflects that of the microstructure. The formulation is based on the mixed variational principle with a perturbed Lagrange-multiplier. It is shown that the rate of volumetric change of the macrostructure can be controlled through the homogenization procedure by introducing the constraint on the microstructure only. A couple of numerical examples are given to demonstrate the validity of the proposed method. By comparing the numerical results with theoretical solutions, the method is also confirmed to be free from locking.
{"title":"Study on Compressibility Control of Hyperelastic Material for Homogenization Method Using Mixed Finite Element Analysis","authors":"J. Okada, T. Hisada","doi":"10.1299/JCST.3.89","DOIUrl":"https://doi.org/10.1299/JCST.3.89","url":null,"abstract":"It is well known that the compressibility or incompressibility of biological tissue stems from its microscopic structure, which is generally composed of material with varied compressibility, including incompressibility. This paper proposes a framework for a homogenization method in which the compressibility/incompressibility of the macrostructure properly reflects that of the microstructure. The formulation is based on the mixed variational principle with a perturbed Lagrange-multiplier. It is shown that the rate of volumetric change of the macrostructure can be controlled through the homogenization procedure by introducing the constraint on the microstructure only. A couple of numerical examples are given to demonstrate the validity of the proposed method. By comparing the numerical results with theoretical solutions, the method is also confirmed to be free from locking.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"37 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":"132695972","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}
By means of reaction pathway analysis, we have investigated the nucleation of 90° and 30° partial dislocation from a sharp corner in an f.c.c. crystal copper. The anisotropy aspects of dislocation nucleation revealed by the results have shown that the stress-dependent activation energy of 30° partial dislocation is approximately twice over the counterpart of 90° partial dislocation, and that the maximum inelastic displacement for the former is also higher. Moreover, the shape of the saddle-point configuration of 30° partial dislocation is similar to a half-ellipse whereas in the case of 90° partial dislocation it is more like a semi-circle, reflecting the different Peierls barriers influenced by the Burgers vectors. Further study of the surface reconstruction demonstrates that although the nucleation of 30° partial dislocation has been enhanced by surface reduction, it is still more energy-unfavorable than the 90° partial dislocation. These results suggest that the higher Peierls barrier is responsible for the larger activation energy of 30° partial dislocation nucleation.
{"title":"Anisotropy Behavior of Dislocation Nucleation from a Sharp Corner in Copper","authors":"Yu Sun, S. Izumi, S. Hara, S. Sakai","doi":"10.1299/JCST.5.54","DOIUrl":"https://doi.org/10.1299/JCST.5.54","url":null,"abstract":"By means of reaction pathway analysis, we have investigated the nucleation of 90° and 30° partial dislocation from a sharp corner in an f.c.c. crystal copper. The anisotropy aspects of dislocation nucleation revealed by the results have shown that the stress-dependent activation energy of 30° partial dislocation is approximately twice over the counterpart of 90° partial dislocation, and that the maximum inelastic displacement for the former is also higher. Moreover, the shape of the saddle-point configuration of 30° partial dislocation is similar to a half-ellipse whereas in the case of 90° partial dislocation it is more like a semi-circle, reflecting the different Peierls barriers influenced by the Burgers vectors. Further study of the surface reconstruction demonstrates that although the nucleation of 30° partial dislocation has been enhanced by surface reduction, it is still more energy-unfavorable than the 90° partial dislocation. These results suggest that the higher Peierls barrier is responsible for the larger activation energy of 30° partial dislocation nucleation.","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":"127946282","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 residual stress fields, the so-called partial elastic contact of crack surfaces sometimes occurs, where a fatigue crack is closed at the crack mouth while it is open at the crack tip. The partial elastic contact has a significant effect on the lives of fatigue cracks. However, there are few studies on the partial elastic contact of crack surfaces for three-dimensional cracks. In this paper, the propagation paths and lives of semi-elliptical slant surface fatigue cracks are predicted. The finite element method was employed for these simulations. The residual stress was introduced by applying an equivalent nodal force in correspondence with initial strains. The results of the propagation paths and lives considering the partial elastic contact of crack surfaces differed from those without consideration of the elastic contact. In particular the estimated results of the crack propagation rate sometimes brought one-order difference. These results demonstrate the necessity of simulation considering the partial elastic contact of crack surfaces.
{"title":"Predictions of Propagation Behavior of Semi-Elliptical Slant Surface Cracks in Residual Stress Fields Based on Simulations of the Partial Elastic Contact of Crack Surfaces","authors":"M. Tsuji, H. Tokumasu, S. Kubo","doi":"10.1299/JCST.3.476","DOIUrl":"https://doi.org/10.1299/JCST.3.476","url":null,"abstract":"In residual stress fields, the so-called partial elastic contact of crack surfaces sometimes occurs, where a fatigue crack is closed at the crack mouth while it is open at the crack tip. The partial elastic contact has a significant effect on the lives of fatigue cracks. However, there are few studies on the partial elastic contact of crack surfaces for three-dimensional cracks. In this paper, the propagation paths and lives of semi-elliptical slant surface fatigue cracks are predicted. The finite element method was employed for these simulations. The residual stress was introduced by applying an equivalent nodal force in correspondence with initial strains. The results of the propagation paths and lives considering the partial elastic contact of crack surfaces differed from those without consideration of the elastic contact. In particular the estimated results of the crack propagation rate sometimes brought one-order difference. These results demonstrate the necessity of simulation considering the partial elastic contact of crack surfaces.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"2017 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":"116851620","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：