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X. H. Liu - One of the best experts on this subject based on the ideXlab platform.
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A corotational interpolatory model for Fabric Drape simulation
International Journal for Numerical Methods in Engineering, 2009Co-Authors: X. H. Liu, Kam Yim SzeAbstract:Fabric Drapes are typical large displacement, large rotation but small strain problems. In particle models for Fabric Drape simulation, the Fabric deformation is characterized by the displacements of the particles distributed over the Fabric. In this paper, a new particle model based on the corotational concept is formulated. Under the small membrane strain assumption, the bending energy can be approximated as a quadratic function of the particle displacements that are finite. In other words, the tangential bending stiffness matrix is a constant and only the tangential membrane stiffness matrix needs to be updated after each iteration or step. On the other hand, the requirement on the particle alignment is relaxed by interpolating the particle displacement in a patch of nine particles. To account for the membrane energy, a simple and efficient method similar to the three-node membrane triangular element employing the Green strain measure is adopted. With the present model, the predicted Drapes appear to be natural and match our daily perception. In particular, circular clothes and circular pedestal that can only be treated laboriously by most particle models can be conveniently considered. Copyright © 2008 John Wiley & Sons, Ltd.
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Fabric Drape simulation by solid-shell finite element method
Finite Elements in Analysis and Design, 2007Co-Authors: Kam Yim Sze, X. H. LiuAbstract:In the last decade, considerable effort has been channeled into the development of solid-shell finite element models in which there are only translational but no rotational nodal dofs. Comparing with other shell elements, a distinctive advantage of solid-shell elements is that the complication on handling finite rotations does not exist. On the other hand, Fabric Drape is a typical geometric nonlinear problem in which the problem domain undergoes large displacement and rotation. To date, computational models for Drape simulation are mainly grid-based and fe-based. The former models are probably more successful and examples with extensive folds have seldom been reported by using the latter models. In this paper, a bilinear stress-resultant solid-shell element with assumed natural transverse shear and thickness strains is employed for Drape analyses. To reduce the computational burden of interpolating the assumed strain field, the solid-shell element is partitioned into a surface, four line and four point sub-elements. The partitioned element is compared with the original elements by popular geometric nonlinear benchmark problems of shells, no practical difference can be noted in both the converged solution and the convergent rate. However, when the elements are applied to Drape analyses with long free-hanging length, some nodal directors are often reversed and, thus, the converged solutions are non-physical. The cause has been traced and remedy is devised. Lastly, a number of Drape problems with large free-hanging lengths, extensive folds and Fabric-to-solid contact are successfully attempted. The predicted views appear to be natural and pleasant.
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Fabric Drape simulation by solid-shell finite element method
Finite Elements in Analysis and Design, 2007Co-Authors: Kam Yim Sze, X. H. LiuAbstract:In the last decade, considerable effort has been channeled into the development of solid-shell finite element models in which there are only translational but no rotational nodal dofs. Comparing with other shell elements, a distinctive advantage of solid-shell elements is that the complication on handling finite rotations does not exist. On the other hand, Fabric Drape is a typical geometric nonlinear problem in which the problem domain undergoes large displacement and rotation. To date, computational models for Drape simulation are mainly grid-based and fe-based. The former models are probably more successful and examples with extensive folds have seldom been reported by using the latter models. In this paper, a bilinear stress-resultant solid-shell element with assumed natural transverse shear and thickness strains is employed for Drape analyses. To reduce the computational burden of interpolating the assumed strain field, the solid-shell element is partitioned into a surface, four line and four point sub-elements. The partitioned element is compared with the original elements by popular geometric nonlinear benchmark problems of shells, no practical difference can be noted in both the converged solution and the convergent rate. However, when the elements are applied to Drape analyses with long free-hanging length, some nodal directors are often reversed and, thus, the converged solutions are non-physical. The cause has been traced and remedy is devised. Lastly, a number of Drape problems with large free-hanging lengths, extensive folds and Fabric-to-solid contact are successfully attempted. The predicted views appear to be natural and pleasant. © 2007 Elsevier B.V. All rights reserved.link_to_subscribed_fulltex
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A new skeletal model for Fabric Drapes
International Journal of Mechanics and Materials in Design, 2005Co-Authors: Kam Yim Sze, X. H. LiuAbstract:Fabric Drapes are typical large displacement, large rotation and small strain problems. Compared with continuum shell finite element methods, methods that skeletonize the Fabric sheet into a set of interconnected nodes appear to be more popular in Drape problems with extensive wrinkles. These skeletal methods may resort to particle mechanics and formulate the elastic energy or the equations of motion in terms of the node-to-node distance and the angles between the straight lines joining adjacent nodes. Alternatively, beam elements can be employed to skeletonize the Fabric sheet at the expense of using rotational in addition to translational nodal DOFs. In this paper, a new skeletal model based on the small strain and curvature assumptions is devised. In contrast to most, if not all, skeletal models for Fabric Drape simulation, all the stretching, shearing and bending energies in the model are simple polynomials of the grid-point␣displacement. Fabric Drape problems with extensive wrinkles are examined. The presence of sharp fold, seam and cut in the undeformed Fabric sheet as well as Fabric-to-solid contact are considered. The predicted appearances are pleasant and conform to real life observations.
Kam Yim Sze - One of the best experts on this subject based on the ideXlab platform.
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A geometric nonlinear rotation‐free triangle and its application to Drape simulation
International Journal for Numerical Methods in Engineering, 2011Co-Authors: Y. X. Zhou, Kam Yim SzeAbstract:SUMMARY In this paper, a rotation-free triangle is formulated. Unlike the thin and degenerated shell finite element models, rotation-free triangles employ translational displacements as the only nodal DOFs. Compared with the existing rotation-free triangles, the present triangle is simple and physical yet its accuracy remains competitive. Using a corotational approach and the small strain assumption, the tangential bending stiffness matrix of the present triangle can be approximated by a constant matrix that does not have to be updated regardless of the displacement magnitude. This unique feature suggests that the triangle is a good candidate for Fabric Drape simulation in which Fabric sheets are often flat initially and the displacement is much larger than those in conventional shell problems. Nonlinear shell and Fabric Drape examples are examined to demonstrate the efficacy of the formulation. Copyright © 2011 John Wiley & Sons, Ltd.
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A corotational interpolatory model for Fabric Drape simulation
International Journal for Numerical Methods in Engineering, 2009Co-Authors: X. H. Liu, Kam Yim SzeAbstract:Fabric Drapes are typical large displacement, large rotation but small strain problems. In particle models for Fabric Drape simulation, the Fabric deformation is characterized by the displacements of the particles distributed over the Fabric. In this paper, a new particle model based on the corotational concept is formulated. Under the small membrane strain assumption, the bending energy can be approximated as a quadratic function of the particle displacements that are finite. In other words, the tangential bending stiffness matrix is a constant and only the tangential membrane stiffness matrix needs to be updated after each iteration or step. On the other hand, the requirement on the particle alignment is relaxed by interpolating the particle displacement in a patch of nine particles. To account for the membrane energy, a simple and efficient method similar to the three-node membrane triangular element employing the Green strain measure is adopted. With the present model, the predicted Drapes appear to be natural and match our daily perception. In particular, circular clothes and circular pedestal that can only be treated laboriously by most particle models can be conveniently considered. Copyright © 2008 John Wiley & Sons, Ltd.
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Fabric Drape simulation by solid-shell finite element method
Finite Elements in Analysis and Design, 2007Co-Authors: Kam Yim Sze, X. H. LiuAbstract:In the last decade, considerable effort has been channeled into the development of solid-shell finite element models in which there are only translational but no rotational nodal dofs. Comparing with other shell elements, a distinctive advantage of solid-shell elements is that the complication on handling finite rotations does not exist. On the other hand, Fabric Drape is a typical geometric nonlinear problem in which the problem domain undergoes large displacement and rotation. To date, computational models for Drape simulation are mainly grid-based and fe-based. The former models are probably more successful and examples with extensive folds have seldom been reported by using the latter models. In this paper, a bilinear stress-resultant solid-shell element with assumed natural transverse shear and thickness strains is employed for Drape analyses. To reduce the computational burden of interpolating the assumed strain field, the solid-shell element is partitioned into a surface, four line and four point sub-elements. The partitioned element is compared with the original elements by popular geometric nonlinear benchmark problems of shells, no practical difference can be noted in both the converged solution and the convergent rate. However, when the elements are applied to Drape analyses with long free-hanging length, some nodal directors are often reversed and, thus, the converged solutions are non-physical. The cause has been traced and remedy is devised. Lastly, a number of Drape problems with large free-hanging lengths, extensive folds and Fabric-to-solid contact are successfully attempted. The predicted views appear to be natural and pleasant.
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Fabric Drape simulation by solid-shell finite element method
Finite Elements in Analysis and Design, 2007Co-Authors: Kam Yim Sze, X. H. LiuAbstract:In the last decade, considerable effort has been channeled into the development of solid-shell finite element models in which there are only translational but no rotational nodal dofs. Comparing with other shell elements, a distinctive advantage of solid-shell elements is that the complication on handling finite rotations does not exist. On the other hand, Fabric Drape is a typical geometric nonlinear problem in which the problem domain undergoes large displacement and rotation. To date, computational models for Drape simulation are mainly grid-based and fe-based. The former models are probably more successful and examples with extensive folds have seldom been reported by using the latter models. In this paper, a bilinear stress-resultant solid-shell element with assumed natural transverse shear and thickness strains is employed for Drape analyses. To reduce the computational burden of interpolating the assumed strain field, the solid-shell element is partitioned into a surface, four line and four point sub-elements. The partitioned element is compared with the original elements by popular geometric nonlinear benchmark problems of shells, no practical difference can be noted in both the converged solution and the convergent rate. However, when the elements are applied to Drape analyses with long free-hanging length, some nodal directors are often reversed and, thus, the converged solutions are non-physical. The cause has been traced and remedy is devised. Lastly, a number of Drape problems with large free-hanging lengths, extensive folds and Fabric-to-solid contact are successfully attempted. The predicted views appear to be natural and pleasant. © 2007 Elsevier B.V. All rights reserved.link_to_subscribed_fulltex
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A new skeletal model for Fabric Drapes
International Journal of Mechanics and Materials in Design, 2005Co-Authors: Kam Yim Sze, X. H. LiuAbstract:Fabric Drapes are typical large displacement, large rotation and small strain problems. Compared with continuum shell finite element methods, methods that skeletonize the Fabric sheet into a set of interconnected nodes appear to be more popular in Drape problems with extensive wrinkles. These skeletal methods may resort to particle mechanics and formulate the elastic energy or the equations of motion in terms of the node-to-node distance and the angles between the straight lines joining adjacent nodes. Alternatively, beam elements can be employed to skeletonize the Fabric sheet at the expense of using rotational in addition to translational nodal DOFs. In this paper, a new skeletal model based on the small strain and curvature assumptions is devised. In contrast to most, if not all, skeletal models for Fabric Drape simulation, all the stretching, shearing and bending energies in the model are simple polynomials of the grid-point␣displacement. Fabric Drape problems with extensive wrinkles are examined. The presence of sharp fold, seam and cut in the undeformed Fabric sheet as well as Fabric-to-solid contact are considered. The predicted appearances are pleasant and conform to real life observations.
Mohammad Latifi - One of the best experts on this subject based on the ideXlab platform.
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Shadow Moiré aided 3-D reconstruction of Fabric Drape
Fibers and Polymers, 2012Co-Authors: Syamak Farajikhah, K. Madanipour, Siamak Saharkhiz, Mohammad LatifiAbstract:The existing standard test method assesses Draped Fabrics two-dimensionally. In this study, a novel method is introduced to analyze and quantify Fabric Drapes in 3-D by using shadow moire method. Six different woven Fabrics with dissimilar Drape behaviors have been analyzed. A Drape index has been mathematically derived from the moire patterns employing the shadow moire topography technique. The results have been compared with the standard Drape coefficient. The 3-D profile of Fabrics has been graphically formed and displayed applying the moire fringes’ data.
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Shadow Moiré aided 3-D reconstruction of Fabric Drape
Fibers and Polymers, 2012Co-Authors: Syamak Farajikhah, K. Madanipour, Siamak Saharkhiz, Mohammad LatifiAbstract:The existing standard test method assesses Draped Fabrics two-dimensionally. In this study, a novel method is introduced to analyze and quantify Fabric Drapes in 3-D by using shadow moiré method. Six different woven Fabrics with dissimilar Drape behaviors have been analyzed. A Drape index has been mathematically derived from the moiré patterns employing the shadow moiré topography technique. The results have been compared with the standard Drape coefficient. The 3-D profile of Fabrics has been graphically formed and displayed applying the moiré fringes’ data.
Syamak Farajikhah - One of the best experts on this subject based on the ideXlab platform.
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Shadow Moiré aided 3-D reconstruction of Fabric Drape
Fibers and Polymers, 2012Co-Authors: Syamak Farajikhah, K. Madanipour, Siamak Saharkhiz, Mohammad LatifiAbstract:The existing standard test method assesses Draped Fabrics two-dimensionally. In this study, a novel method is introduced to analyze and quantify Fabric Drapes in 3-D by using shadow moire method. Six different woven Fabrics with dissimilar Drape behaviors have been analyzed. A Drape index has been mathematically derived from the moire patterns employing the shadow moire topography technique. The results have been compared with the standard Drape coefficient. The 3-D profile of Fabrics has been graphically formed and displayed applying the moire fringes’ data.
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Shadow Moiré aided 3-D reconstruction of Fabric Drape
Fibers and Polymers, 2012Co-Authors: Syamak Farajikhah, K. Madanipour, Siamak Saharkhiz, Mohammad LatifiAbstract:The existing standard test method assesses Draped Fabrics two-dimensionally. In this study, a novel method is introduced to analyze and quantify Fabric Drapes in 3-D by using shadow moiré method. Six different woven Fabrics with dissimilar Drape behaviors have been analyzed. A Drape index has been mathematically derived from the moiré patterns employing the shadow moiré topography technique. The results have been compared with the standard Drape coefficient. The 3-D profile of Fabrics has been graphically formed and displayed applying the moiré fringes’ data.
Qing Xie - One of the best experts on this subject based on the ideXlab platform.
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Application of solid-shell finite elements in Fabric Drape/cloth simulations
2015Co-Authors: Qing XieAbstract:The solid-shell elements which possess only translational but no rotational degrees of freedom have gained flourishing success in large deformation analyses in the last few decades. However, they have rarely been applied to Fabric Drape/cloth simulations. Probably the only attempt in the literature was employing solid-shell elements in static Fabric Drape analyses. Their results demonstrate the potential of solid-shell elements in static Fabric Drape analyses as well as the non-physical interpenetration of top and bottom element surfaces noticed in convergent solutions for Fabrics with large free-hanging length. In this thesis, possible remedies are developed to resolve the interpenetration deficiency and then the elements are applied to both static and dynamic Fabric Drape/cloth simulations. The linear and geometric nonlinear formulations of two-dimensional solid-shell elements are presented. The assumed natural strain methods(ANS)are employed to alleviate the transverse shear and trapezoidal lockings whilst the plane-stress enforcement is used to overcome thickness locking. Several remedies are attempted on avoiding interpenetration occurred in the nonlinear curved cantilever problem and the enhanced bending energy is most successful. The three-dimensional linear and geometric nonlinear triangular and quadrilateral solid-shell elements are evolved from the two-dimensional one. Due to the superior accuracy of the quadrilateral element over its triangular counterpart, the former is used to attempt the static Fabric Drape problems. In dynamic Fabric Drape/cloth simulations, techniques including the explicit time integration, cloth-to-object collision handling, local adaptive mesh generation, lower human body modeling and virtual sewing forces are employed and synergized with both quadrilateral and triangular solid-shell element models. In particular, the reversible local adaptive mesh generator based on the 1-4 splitting method is developed for circumventing the interpenetration deficiency by locally reducing the mesh size at low computational cost. The hybrid macro-transition elements formed by the quadrilateral and triangular element models are employed to ensure the mesh conformity. Meanwhile, the discrete Kirchhoff constraints derived by using a co-rotated framework are proposed to obtain the kinematic variables of the new-inserted nodes so that the oscillation appeared after each local subdivision is attenuated. The predicted steady-state shapes of Draped Fabrics look realistic and similar to the convergent static solutions. Those of the sewing garments also conform to our daily perception. Dynamic processes for cloth simulations including the sewed garments dressed on human body model with movement also appear realistic. This thesis focuses on avoiding the non-physical interpenetration of solid-shell elements and exploring the application of two solid-shell elements in dynamic Fabric Drape/cloth simulation which can shorten the fashion design cycle and enhance the visual reality of clothes on manikins in e-commerce of clothes and animated movies. Compared with the grid-based or particle-based computational method, the finite element method is less stringent in grid-point arrangement and more convenient in handling boundary, sewing and integration treatments. Compared with other shell elements, the solid-shell elements are more efficient in finite displacement analysis due to the absence of rotational freedoms.published_or_final_versionMechanical EngineeringDoctoralDoctor of Philosoph
