The Experts below are selected from a list of 264 Experts worldwide ranked by ideXlab platform
Seongwhan Park - One of the best experts on this subject based on the ideXlab platform.
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graph based Midsurface extraction for finite element analysis
Computer Supported Cooperative Work in Design, 2007Co-Authors: Seongwhan ParkAbstract:The geometry of CAD model needs to be idealized in order to reduce the complexity of the finite element model. A thin solid model should be abstracted to Midsurface model. This paper describes a graph-based method that extracts Midsurface patches from solid model and joins them automatically. Face-pairs are first found by ray-casting process, and Midsurface patches are generated by geometric interpolation of them. During this process, a graph which contains mapping information of face-pairs and Midsurface patches is generated. Using this graph, Midsurface patches are extended, trimmed and joined to generate a complete Midsurface model. In this paper, a concrete method of Midsurface patch connection which is not handled in the previous researches is proposed.
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CSCWD - Graph-based Midsurface extraction for finite element analysis
2007 11th International Conference on Computer Supported Cooperative Work in Design, 2007Co-Authors: Seongwhan ParkAbstract:The geometry of CAD model needs to be idealized in order to reduce the complexity of the finite element model. A thin solid model should be abstracted to Midsurface model. This paper describes a graph-based method that extracts Midsurface patches from solid model and joins them automatically. Face-pairs are first found by ray-casting process, and Midsurface patches are generated by geometric interpolation of them. During this process, a graph which contains mapping information of face-pairs and Midsurface patches is generated. Using this graph, Midsurface patches are extended, trimmed and joined to generate a complete Midsurface model. In this paper, a concrete method of Midsurface patch connection which is not handled in the previous researches is proposed.
M L Szwabowicz - One of the best experts on this subject based on the ideXlab platform.
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determination of the Midsurface of a deformed shell from prescribed surface strains and bendings via the polar decomposition
International Journal of Non-linear Mechanics, 2008Co-Authors: W Pietraszkiewicz, M L Szwabowicz, C ValleeAbstract:Abstract We show how to determine the Midsurface of a deformed thin shell from known geometry of the undeformed Midsurface as well as the surface strains and bendings. The latter two fields are assumed to have been found independently and beforehand by solving the so-called intrinsic field equations of the non-linear theory of thin shells. By the polar decomposition theorem the Midsurface deformation gradient is represented as composition of the surface stretch and 3D finite rotation fields. Right and left polar decomposition theorems are discussed. For each decomposition the problem is solved in three steps: (a) the stretch field is found by pure algebra, (b) the rotation field is obtained by solving a system of first-order PDEs, and (c) position of the deformed Midsurface follows then by quadratures. The integrability conditions for the rotation field are proved to be equivalent to the compatibility conditions of the non-linear theory of thin shells. Along any path on the undeformed shell Midsurface the system of PDEs for the rotation field reduces to the system of linear tensor ODEs identical to the one that describes spherical motion of a rigid body about a fixed point. This allows one to use analytical and numerical methods developed in analytical mechanics that in special cases may lead to closed-form solutions.
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determination of the Midsurface of a deformed shell from prescribed fields of surface strains and bendings
International Journal of Solids and Structures, 2007Co-Authors: W Pietraszkiewicz, M L SzwabowiczAbstract:Abstract We show how to determine the Midsurface of a deformed thin shell from the following set of data: known geometry of the undeformed Midsurface, the surface strains and the surface bendings. It is assumed that the two latter fields had been obtained beforehand by solving a problem posed for the so-called intrinsic field equations of the non-linear theory of thin shells. Two different methods of determining the deformed Midsurface in space are worked out: (a) directly from its first and second fundamental form using some results from mathematical analysis; (b) integrating the system of first-order PDEs for the surface deformation gradient. In both cases the corresponding integrability conditions are discussed; it is shown that they are equivalent to the compatibility conditions of the non-linear theory of thin shells.
W Pietraszkiewicz - One of the best experts on this subject based on the ideXlab platform.
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determination of the Midsurface of a deformed shell from prescribed surface strains and bendings via the polar decomposition
International Journal of Non-linear Mechanics, 2008Co-Authors: W Pietraszkiewicz, M L Szwabowicz, C ValleeAbstract:Abstract We show how to determine the Midsurface of a deformed thin shell from known geometry of the undeformed Midsurface as well as the surface strains and bendings. The latter two fields are assumed to have been found independently and beforehand by solving the so-called intrinsic field equations of the non-linear theory of thin shells. By the polar decomposition theorem the Midsurface deformation gradient is represented as composition of the surface stretch and 3D finite rotation fields. Right and left polar decomposition theorems are discussed. For each decomposition the problem is solved in three steps: (a) the stretch field is found by pure algebra, (b) the rotation field is obtained by solving a system of first-order PDEs, and (c) position of the deformed Midsurface follows then by quadratures. The integrability conditions for the rotation field are proved to be equivalent to the compatibility conditions of the non-linear theory of thin shells. Along any path on the undeformed shell Midsurface the system of PDEs for the rotation field reduces to the system of linear tensor ODEs identical to the one that describes spherical motion of a rigid body about a fixed point. This allows one to use analytical and numerical methods developed in analytical mechanics that in special cases may lead to closed-form solutions.
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determination of the Midsurface of a deformed shell from prescribed fields of surface strains and bendings
International Journal of Solids and Structures, 2007Co-Authors: W Pietraszkiewicz, M L SzwabowiczAbstract:Abstract We show how to determine the Midsurface of a deformed thin shell from the following set of data: known geometry of the undeformed Midsurface, the surface strains and the surface bendings. It is assumed that the two latter fields had been obtained beforehand by solving a problem posed for the so-called intrinsic field equations of the non-linear theory of thin shells. Two different methods of determining the deformed Midsurface in space are worked out: (a) directly from its first and second fundamental form using some results from mathematical analysis; (b) integrating the system of first-order PDEs for the surface deformation gradient. In both cases the corresponding integrability conditions are discussed; it is shown that they are equivalent to the compatibility conditions of the non-linear theory of thin shells.
Kazumi Matsui - One of the best experts on this subject based on the ideXlab platform.
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A quadrilateral shell element with degree of freedom to represent thickness–stretch
Computational Mechanics, 2017Co-Authors: Takeki Yamamoto, Takahiro Yamada, Kazumi MatsuiAbstract:This paper presents a quadrilateral shell element incorporating thickness–stretch, and demonstrates its performance in small and large deformation analyses for hyperelastic material and elastoplastic models. In terms of geometry, the proposed shell element is based on the formulation of the MITC4 shell element, with additional degrees of freedom to represent thickness–stretch. To consider the change in thickness, we introduce a displacement variation to the MITC4 shell element, in the thickness direction. After the thickness direction is expressed in terms of the director vectors that are defined at each Midsurface node, additional nodes are placed along the thickness direction from the bottom surface to the top surface. The thickness–stretch is described by the movement of these additional nodes. The additional degrees of freedom are used to compute the transverse normal strain without assuming the plane stress condition. Hence, the three dimensional constitutive equation can be employed in the proposed formulation without any modification. By virtue of not imposing the plane stress condition, the surface traction is evaluated at the surface where the traction is applied, whereas it is assessed at the Midsurface for conventional shell elements. Several numerical examples are presented to examine the fundamental performance of the proposed shell element. In particular, the proposed approach is capable of evaluating the change in thickness and the stress distribution when the effect of the surface traction is included. The behavior of the proposed shell element is compared with that of solid elements.
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A quadrilateral shell element with degree of freedom to represent thickness---stretch
Computational Mechanics, 2016Co-Authors: Takeki Yamamoto, Takahiro Yamada, Kazumi MatsuiAbstract:This paper presents a quadrilateral shell element incorporating thickness---stretch, and demonstrates its performance in small and large deformation analyses for hyperelastic material and elastoplastic models. In terms of geometry, the proposed shell element is based on the formulation of the MITC4 shell element, with additional degrees of freedom to represent thickness---stretch. To consider the change in thickness, we introduce a displacement variation to the MITC4 shell element, in the thickness direction. After the thickness direction is expressed in terms of the director vectors that are defined at each Midsurface node, additional nodes are placed along the thickness direction from the bottom surface to the top surface. The thickness---stretch is described by the movement of these additional nodes. The additional degrees of freedom are used to compute the transverse normal strain without assuming the plane stress condition. Hence, the three dimensional constitutive equation can be employed in the proposed formulation without any modification. By virtue of not imposing the plane stress condition, the surface traction is evaluated at the surface where the traction is applied, whereas it is assessed at the Midsurface for conventional shell elements. Several numerical examples are presented to examine the fundamental performance of the proposed shell element. In particular, the proposed approach is capable of evaluating the change in thickness and the stress distribution when the effect of the surface traction is included. The behavior of the proposed shell element is compared with that of solid elements.
Manicka Dhanasekar - One of the best experts on this subject based on the ideXlab platform.
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plane hybrid stress elements for 3d analysis of moderately thick solids subjected to loading symmetric to Midsurface
International Journal of Solids and Structures, 2007Co-Authors: Q Z Xiao, Manicka DhanasekarAbstract:Abstract Plane semi-analytical hybrid stress elements are formulated from the 3D Hellinger–Reissner principle for modelling moderately thick structural components with and without hollows subjected to loadings symmetric to the Midsurface. These components possess symmetry in the thickness direction but could not be idealised as either plane stress or plane strain problems. 3D displacement and stress fields conforming to the exact plane stress solution are assumed and normal stresses on the surfaces parallel to the thickness direction are nullified. These 2D elements possess good convergence characteristics and simulate the 3D behaviour of solids whose stress free surfaces exhibit negligible out-of-plane distortion with good level of accuracy comparable to 3D analyses by ABAQUS.