{"title":"Numerical modeling of carbon‐based material systems and related topics","authors":"I. Tsukrov","doi":"10.1002/CNM.1077","DOIUrl":"https://doi.org/10.1002/CNM.1077","url":null,"abstract":"","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":"24 1","pages":"2137-2138"},"PeriodicalIF":0.0,"publicationDate":"2007-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1077","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533682","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 work presents a computational strategy for identification of planar defects (cracks) in homogenous isotropic linear elastic solids. The underlying strategy is a regularizing variational approach based on the diffuse interface model proposed by Ambrosio and Tortorelli. With the help of this model, the sharp interface problem of crack identification is split into two coupled elliptic boundary value problems solved using the finite element method. Numerical examples illustrate the application of the proposed approach for effective reconstruction of the position and the shape of a single crack using only the information collected on the surface of the analyzed body.
{"title":"Variational approach to the free-discontinuity problem of inverse crack identification","authors":"R. Tsotsova","doi":"10.1002/CNM.1078","DOIUrl":"https://doi.org/10.1002/CNM.1078","url":null,"abstract":"This work presents a computational strategy for identification of planar defects (cracks) in homogenous isotropic linear elastic solids. The underlying strategy is a regularizing variational approach based on the diffuse interface model proposed by Ambrosio and Tortorelli. With the help of this model, the sharp interface problem of crack identification is split into two coupled elliptic boundary value problems solved using the finite element method. Numerical examples illustrate the application of the proposed approach for effective reconstruction of the position and the shape of a single crack using only the information collected on the surface of the analyzed body.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":"24 1","pages":"2216-2228"},"PeriodicalIF":0.0,"publicationDate":"2007-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1078","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51534081","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 class of methods and algorithms for the solution of two-dimensional quasi-static problems of stress distribution near holes is considered for finite strains. It is assumed that the holes have originated successively in a previously loaded body made of incompressible viscoelastic material. The problem is formulated on the basis of the theory of repeated superposition of large deformations. The mechanical properties of the material are described by convolution integral relations with the kernel of weak singularity. The solution is obtained using the approximate analytical methods (Signorini's technique, Laplace transform, and Muskhelishvili's technique). A special-purpose software for analytical calculations is used for the solution. Some numerical results are presented.
{"title":"A class of methods and algorithms for the analysis of successive origination of holes in a pre-stressed viscoelastic body. Finite strains","authors":"V. Levin, K. M. Zingerman","doi":"10.1002/CNM.1080","DOIUrl":"https://doi.org/10.1002/CNM.1080","url":null,"abstract":"A class of methods and algorithms for the solution of two-dimensional quasi-static problems of stress distribution near holes is considered for finite strains. It is assumed that the holes have originated successively in a previously loaded body made of incompressible viscoelastic material. The problem is formulated on the basis of the theory of repeated superposition of large deformations. The mechanical properties of the material are described by convolution integral relations with the kernel of weak singularity. The solution is obtained using the approximate analytical methods (Signorini's technique, Laplace transform, and Muskhelishvili's technique). A special-purpose software for analytical calculations is used for the solution. Some numerical results are presented.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":"24 1","pages":"2240-2251"},"PeriodicalIF":0.0,"publicationDate":"2007-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1080","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51534167","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}
Claudio Esperança, Antonio A. F. Oliveira, P. R. Cavalcanti
SUMMARYThis work describes several improvements over the technique known as Atomic Meshes introducedby Hale[8], which aims at producing numerical meshes from image data “directly”, i.e., bypassingany image segmentation step. We propose two modifications to Hale’s original idea: (1) a procedurewhereby atoms are initially projected onto perceived features, and (2) the introduction of a Laplaciancomponent to the formulation of the energy field governing atom movement. These aim at improvingthe adaptation of the mesh to the image while producing better shaped triangles. True to Hale’sidea, no image segmentation is ever tried, but since the atom placement and movement criteria aremore sensitive to image borders, experiments indicate that the resulting meshes tend to conform moreclosely to the image features. Copyright °c 2000 John Wiley & Sons, Ltd.key words: Numerical meshes; seismic data; image processing 1. IntroductionCreating meshes which approximate or are in some way conformal to the features of a givenimage has captured the attention of many researchers over the last years. The idea is thatthe resulting mesh contains much of the information of the underlying image which makes itideal for applications such as image compression, image modeling, medical image analysis andothers [13].A particularly interesting application is the creation of meshes from seismic images.Traditionally,thegeologicalinterpretationofseismicdataresultsinasetofcurvesandsurfaces,which are used to construct a consistent earth model. This model can then be used to generatediscrete meshes for several kinds of numerical simulations, such as a reservoir simulation,the propagation of acoustic waves, or large-scale fluid and heat flow within saturated poroussediments.The geological model must contain all of the geological features, such as horizons (separatingsurfaces between geological layers) and faults (discontinuities caused by the brittle behavior
{"title":"Improved atomic meshes","authors":"Claudio Esperança, Antonio A. F. Oliveira, P. R. Cavalcanti","doi":"10.1002/CNM.1074","DOIUrl":"https://doi.org/10.1002/CNM.1074","url":null,"abstract":"SUMMARYThis work describes several improvements over the technique known as Atomic Meshes introducedby Hale[8], which aims at producing numerical meshes from image data “directly”, i.e., bypassingany image segmentation step. We propose two modifications to Hale’s original idea: (1) a procedurewhereby atoms are initially projected onto perceived features, and (2) the introduction of a Laplaciancomponent to the formulation of the energy field governing atom movement. These aim at improvingthe adaptation of the mesh to the image while producing better shaped triangles. True to Hale’sidea, no image segmentation is ever tried, but since the atom placement and movement criteria aremore sensitive to image borders, experiments indicate that the resulting meshes tend to conform moreclosely to the image features. Copyright °c 2000 John Wiley & Sons, Ltd.key words: Numerical meshes; seismic data; image processing 1. IntroductionCreating meshes which approximate or are in some way conformal to the features of a givenimage has captured the attention of many researchers over the last years. The idea is thatthe resulting mesh contains much of the information of the underlying image which makes itideal for applications such as image compression, image modeling, medical image analysis andothers [13].A particularly interesting application is the creation of meshes from seismic images.Traditionally,thegeologicalinterpretationofseismicdataresultsinasetofcurvesandsurfaces,which are used to construct a consistent earth model. This model can then be used to generatediscrete meshes for several kinds of numerical simulations, such as a reservoir simulation,the propagation of acoustic waves, or large-scale fluid and heat flow within saturated poroussediments.The geological model must contain all of the geological features, such as horizons (separatingsurfaces between geological layers) and faults (discontinuities caused by the brittle behavior","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":"35 1","pages":"1873-1886"},"PeriodicalIF":0.0,"publicationDate":"2007-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1074","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533477","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 three-dimensional finite element model is proposed for the fiber interaction effects during fiber microbuckling in fiber-reinforced composites. The model considers an elastic matrix reinforced by a periodic fiber series subjected to compression in axial direction. It accounts for the distinct difference in mechanical properties of the reinforcement and the matrix, as well as for the spatial problem character at the fiber-matrix scale. Perfect bonding at the fiber-matrix interfaces and the periodicity of the buckled system in the plane of fibers (in-plane microbuckling) are assumed. For comparison purposes, a dilute approximation model dealing with a single fiber in a matrix is presented as well. An eigenvalue analysis of the considered systems fiber-matrix is performed. Calculations are carried out for the cases of both isotropic and transversal isotropic fibers in elastic isotropic matrices. Results show that the fiber interaction results in a significant increase in the buckling wavelength and in an important decrease in the critical shortening.
{"title":"Three‐dimensional FE model for fiber interaction effects during microbuckling in composites with isotropic and anisotropic fibers","authors":"Y. Lapusta, J. Harich, W. Wagner","doi":"10.1002/CNM.1084","DOIUrl":"https://doi.org/10.1002/CNM.1084","url":null,"abstract":"A three-dimensional finite element model is proposed for the fiber interaction effects during fiber microbuckling in fiber-reinforced composites. The model considers an elastic matrix reinforced by a periodic fiber series subjected to compression in axial direction. It accounts for the distinct difference in mechanical properties of the reinforcement and the matrix, as well as for the spatial problem character at the fiber-matrix scale. Perfect bonding at the fiber-matrix interfaces and the periodicity of the buckled system in the plane of fibers (in-plane microbuckling) are assumed. For comparison purposes, a dilute approximation model dealing with a single fiber in a matrix is presented as well. An eigenvalue analysis of the considered systems fiber-matrix is performed. Calculations are carried out for the cases of both isotropic and transversal isotropic fibers in elastic isotropic matrices. Results show that the fiber interaction results in a significant increase in the buckling wavelength and in an important decrease in the critical shortening.","PeriodicalId":51245,"journal":{"name":"Communications in Numerical Methods in Engineering","volume":"24 1","pages":"2206-2215"},"PeriodicalIF":0.0,"publicationDate":"2007-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1002/CNM.1084","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"51533914","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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