In this paper, the elastoplastic deformation behaviors of cylindrical tubes subjected to statically axial compression are studied by using finite element method (FEM). Specifically, the effects of tube geometries and strain hardening are investigated. Although it is generally recognized that the deformation in the circumferential direction is dependent on the ratio of the radius to thickness (R/t), the deformation is also greatly dependent on the edge constraint. In this study, we used flanges as an edge constraint. The deformation mode in the circumferential direction also affects the deformation in the axial direction. A method to control the deformation mode, such as adding a disk in the tube center, is proposed to maintain the deformation in the axisymmetric mode.
{"title":"Deformation Modes for Axial Crushing of Cylindrical Tubes Considering the Edge Effect","authors":"Dai-heng Chen, K. Masuda, K. Ushijima, S. Ozaki","doi":"10.1299/JCST.3.339","DOIUrl":"https://doi.org/10.1299/JCST.3.339","url":null,"abstract":"In this paper, the elastoplastic deformation behaviors of cylindrical tubes subjected to statically axial compression are studied by using finite element method (FEM). Specifically, the effects of tube geometries and strain hardening are investigated. Although it is generally recognized that the deformation in the circumferential direction is dependent on the ratio of the radius to thickness (R/t), the deformation is also greatly dependent on the edge constraint. In this study, we used flanges as an edge constraint. The deformation mode in the circumferential direction also affects the deformation in the axial direction. A method to control the deformation mode, such as adding a disk in the tube center, is proposed to maintain the deformation in the axisymmetric mode.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"5 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":"124163741","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}
When analyzing the strength of large structures, the stiffness of the foundation, on which the structure is placed, might significantly affect the numerical results. In this paper, a finite element approach to estimate the foundation stiffness as an inverse problem is proposed, where the target large structure is placed on the elastic foundation that are modeled as groups of one-dimensional spring elements in parallel. The magnitude of the spring constant that represents the foundation stiffness can exactly be calculated algebraically by use of the same number of measured surface deflections. In the numerical analyses, unknowns are the diagonal components in the global stiffness matrix that include the aforementioned spring constants. The validity and the accuracy of the proposed numerical method are verified by comparing the numerical results to the exact solutions for bending problems of a cantilever supported by a single spring element.
{"title":"Identification of the Foundation Stiffness of Large Structure as an Inverse Problem","authors":"T. Fukuoka, M. Nomura, Yuyong Zhao","doi":"10.1299/JCST.2.578","DOIUrl":"https://doi.org/10.1299/JCST.2.578","url":null,"abstract":"When analyzing the strength of large structures, the stiffness of the foundation, on which the structure is placed, might significantly affect the numerical results. In this paper, a finite element approach to estimate the foundation stiffness as an inverse problem is proposed, where the target large structure is placed on the elastic foundation that are modeled as groups of one-dimensional spring elements in parallel. The magnitude of the spring constant that represents the foundation stiffness can exactly be calculated algebraically by use of the same number of measured surface deflections. In the numerical analyses, unknowns are the diagonal components in the global stiffness matrix that include the aforementioned spring constants. The validity and the accuracy of the proposed numerical method are verified by comparing the numerical results to the exact solutions for bending problems of a cantilever supported by a single spring element.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"40 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":"132762804","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}
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}
To investigate the effect of liquid water saturation on the efficiency of polymer electrolyte fuel cells, it is important to determine the exact relationship between the liquid water saturation profile and other parameters. In this paper, the pore size distribution (PSD) is used to calculate the liquid water saturation in a fuel cell. Using the PSD, liquid water saturation is calculated from experimental data for the capillary pressure on a porous media. Numerical analysis is used to analyze and evaluate the liquid water pressure and temperature profiles in a fuel cell. This paper uses two-phase, three-dimensional analysis to determine the effects of using the PSD.
{"title":"Numerical Analysis of a Three-Dimensional Sandwich Model for Investigating the Effect of Using the Pore Size Distribution","authors":"Y. Tachikawa, Yuya Matsuda, H. Kanayama","doi":"10.1299/JCST.4.89","DOIUrl":"https://doi.org/10.1299/JCST.4.89","url":null,"abstract":"To investigate the effect of liquid water saturation on the efficiency of polymer electrolyte fuel cells, it is important to determine the exact relationship between the liquid water saturation profile and other parameters. In this paper, the pore size distribution (PSD) is used to calculate the liquid water saturation in a fuel cell. Using the PSD, liquid water saturation is calculated from experimental data for the capillary pressure on a porous media. Numerical analysis is used to analyze and evaluate the liquid water pressure and temperature profiles in a fuel cell. This paper uses two-phase, three-dimensional analysis to determine the effects of using the PSD.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"6 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":"131513946","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}
Recently, tightly coupled partitioned iterative methods have drawn a great deal of attentions due to easy implementation and encapsulation features, and several nonlinear algorithms have been proposed so far. However, their practical performances have not been well understood yet. This paper describes the intensive parametric study on convergence and stability performances of four nonlinear algorithms and their relaxed variations for partitioned iterative methods of steady / unsteady fluid-structure interaction (FSI) problems. Here we choose three typical FSI problems as test problems, i.e. (1) Collapsible channel as a steady problem, (2) Cavity with flexible bottom membrane and (3) Channel with flexible wall as unsteady problems. Efficiency and robustness dependency of those nonlinear algorithms on physical parameters such as degree of nonlinearity, added mass effect, time step, and on control parameters peculiar to each algorithm are clarified. Through those tests, we demonstrate that Broyden method is the fastest algorithm for easy FSI problems such as weakly coupling and Line Search method has robustness even for difficult FSI problems such as strongly coupling.
{"title":"Practical Performances of Non-linear Algorithms for Partitioned Iterative Method of Fluid-Structure Interaction Problems","authors":"S. Minami, S. Yoshimura","doi":"10.1299/JCST.3.396","DOIUrl":"https://doi.org/10.1299/JCST.3.396","url":null,"abstract":"Recently, tightly coupled partitioned iterative methods have drawn a great deal of attentions due to easy implementation and encapsulation features, and several nonlinear algorithms have been proposed so far. However, their practical performances have not been well understood yet. This paper describes the intensive parametric study on convergence and stability performances of four nonlinear algorithms and their relaxed variations for partitioned iterative methods of steady / unsteady fluid-structure interaction (FSI) problems. Here we choose three typical FSI problems as test problems, i.e. (1) Collapsible channel as a steady problem, (2) Cavity with flexible bottom membrane and (3) Channel with flexible wall as unsteady problems. Efficiency and robustness dependency of those nonlinear algorithms on physical parameters such as degree of nonlinearity, added mass effect, time step, and on control parameters peculiar to each algorithm are clarified. Through those tests, we demonstrate that Broyden method is the fastest algorithm for easy FSI problems such as weakly coupling and Line Search method has robustness even for difficult FSI problems such as strongly coupling.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"164 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":"132538211","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}
{"title":"Evaluation of Intensity of Singularity for Three-Materials Joints with Power-Logarithmic Singularities using an Enriched Finite Element Method","authors":"Chonlada Luangarpa, H. Koguchi","doi":"10.1299/JCST.7.239","DOIUrl":"https://doi.org/10.1299/JCST.7.239","url":null,"abstract":"","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"59 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":"128282478","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 three-dimensional incremental finite element formulation for the multiaxial behavior of shape memory alloy devices is proposed in the present study by considering the coupling effect of the axial and torsional behaviors of shape memory alloys. The previously proposed one-dimensional constitutive model for shape memory alloy devices is extended to take account of the multiaxial stress state introducing some new material constants. The calculated results are compared with the uniaxial, purely torsional and multiaxial test results for NiTi tubes to illustrate the validity of the proposed computational modeling.
{"title":"Computational Modeling of Superelastic Behaviors of Shape Memory Alloy Devices Under Combined Stresses","authors":"Y. Toi, Daegon Choi","doi":"10.1299/JCST.2.535","DOIUrl":"https://doi.org/10.1299/JCST.2.535","url":null,"abstract":"The three-dimensional incremental finite element formulation for the multiaxial behavior of shape memory alloy devices is proposed in the present study by considering the coupling effect of the axial and torsional behaviors of shape memory alloys. The previously proposed one-dimensional constitutive model for shape memory alloy devices is extended to take account of the multiaxial stress state introducing some new material constants. The calculated results are compared with the uniaxial, purely torsional and multiaxial test results for NiTi tubes to illustrate the validity of the proposed computational modeling.","PeriodicalId":196913,"journal":{"name":"Journal of Computational Science and Technology","volume":"87 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":"134244682","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}
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