共查询到19条相似文献,搜索用时 664 毫秒
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介绍了金属体积塑性成形过程数值模拟方法、关键应用技术及其仿真系统的构成和国内外相关软件系统,对二维、三维有限元网格自动生成技术进行了较为详细的论述,综述了金属塑性成形过程优化设计方法、有限体积法以及无网格方法的国内外现状.最后给出了目前存在的问题及其将来应努力的方向. 相似文献
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介绍了金属体积塑性成形过程数值模拟方法、关键应用技术及其仿真系统的构成和国内外相关软件系统,对二维、三维有限元网格自动生成技术进行了较为详细的论述,综述了金属塑性成形过程优化设计方法、有限体积法以及无网格方法的国内外现状.最后给出了目前存在的问题及其将来应努力的方向. 相似文献
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面向叶片精锻过程的三维有限元模拟 总被引:3,自引:0,他引:3
对刚粘塑性有限元用于模拟分析叶片精锻过程的基本原理进行了论述 ;对模拟中需解决的关键问题提出了相应的算法和处理技术 ;开发了考虑工模具间的摩擦的三维刚粘塑性有限元模拟分析系统 .采用该系统 ,对航空发动机压气机简单叶片和带阻尼台叶片精锻过程进行了三维有限元模拟分析 .模拟过程中对榫头和叶身过渡处采用圆角连接 ,改善了金属的流动性和充填性 ,使叶片锻造三维有限元模拟的建模与分析更接近于实际过程 .结果表明 :采用作者所提出的基于边界构形的网格重划方法 -内缩法 ,进行畸变网格的重划是可行的 ;采用作者所提出的动态边界条件的处理方法以避免模具死锁问题是有效的 ;所开发的软件系统是可靠的 . 相似文献
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《中国新技术新产品》2020,(18)
利用柔性可弯辊轧制成形三维曲面件是一种新的板料成形方法,该文介绍了柔性轧制成形原理,基于离散化思想建立了刚性短辊按一定曲线排列的工作辊模型,解决了整体工作辊绕自身弯曲轴线无法转动的问题。给出了单元类型、网格划分技术、接触条件设置等关键问题的选择方法,利用建立的有限元模型模拟了凸曲面件的成形,模拟结果与理论分析和成形实验结果一致。 相似文献
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Z. C. He G. Y. Li Z. H. Zhong A. G. Cheng G. Y. Zhang G. R. Liu Eric Li Z. Zhou 《Computational Mechanics》2013,52(1):221-236
Strain smoothing operation has been recently adopted to soften the stiffness of the model created using tetrahedron mesh, such as the Face-based Smoothed Finite Element Method (FS-FEM), with the aim to improve solution accuracy and the applicability of low order tetrahedral elements. In this paper, a new method with strain smoothing operation based on the edge of four-node tetrahedron mesh is proposed, and the edge-based smoothing domain of tetrahedron mesh is serving as the assembly unit for computing the 3D stiffness matrix. Numerical results demonstrate that the proposed method possesses a close-to-exact stiffness of the continuous system and gives better results than both the FEM and FS-FEM using tetrahedron mesh or even the FEM using hexahedral mesh in the static and dynamic analysis. In addition, a novel domain-based selective scheme is proposed leading to a combined ES-T-/NS-FEM model that is immune from volumetric locking and hence works well for nearly incompressible materials. The proposed method is an innovative and unique numerical method with its distinct features, which possesses strong potentials in the successful applications for static and dynamics problems. 相似文献
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Adaptive generation of hexahedral element meshes for finite element analysis of metal plastic forming process 总被引:1,自引:0,他引:1
A method for the adaptive generation of hexahedral element mesh based on the geometric features of solid model is proposed. The first step is to construct the refinement information fields of source points and the corresponding ones of elements according to the surface curvature of the analyzed solid model. A thickness refinement criterion is then used to construct the thickness-based refinement information field of elements from digital topology. The second step is to generate a core mesh through removing all the undesired elements using even and odd parity rules. Then the core mesh is magnified in an inside–out manner method through a surface node projection process using the closest position approach. Finally, in order to match the mesh to the characteristic boundary of the solid model, a threading method is proposed and applied. The present method was applied in the mesh construction of different engineering problems. The resulting meshes are well-shaped and capture all the geometric features of the original solid models. 相似文献
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Guido Dhondt 《International journal for numerical methods in engineering》2001,50(9):2109-2126
A new method is presented leading to a 20‐node brick element mesh for an arbitrary structure based on a triangulation of the structure's surface. Starting from a hexahedral master mesh encompassing the structure, the elements which are intersected by the triangulation are determined, cut and remeshed. The resulting hexahedral mesh can be tied to the underlying elements by multiple point constraints or can be continued throughout the complete structure leading to a pure 20‐node brick mesh. Several examples show the effectiveness of the method. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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Soji Yamakawa Kenji Shimada 《International journal for numerical methods in engineering》2003,57(15):2099-2129
A new fully automatic hex‐dominant mesh generation technique of an arbitrary 3D geometric domain is presented herein. The proposed method generates a high‐quality hex‐dominant mesh by: (1) controlling the directionality of the output hex‐dominant mesh; and (2) avoiding ill‐shaped elements induced by nodes located too closely to each other. The proposed method takes a 3D geometric domain as input and creates a hex‐dominant mesh consisting mostly of hexahedral elements, with additional prism and tetrahedral elements. Rectangular solid cells are packed on the boundary of and inside the input domain to obtain ideal node locations for a hex‐dominant mesh. Each cell has a potential energy field that mimics a body‐centred cubic (BCC) structure (seen in natural substances such as NaCl) and the cells are moved to stable positions by a physically based simulation. The simulation mimics the formation of a crystal pattern so that the centres of the cells provide ideal node locations for a hex‐dominant mesh. Via the advancing front method, the centres of the packed cells are then connected to form a tetrahedral mesh, and this is converted to a hex‐dominant mesh by merging some of the tetrahedrons. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
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Matthew L. Staten Kenji Shimada 《International journal for numerical methods in engineering》2010,83(7):899-914
This paper discusses using valences in objective functions for topological modification of 3D hexahedral meshes. For topological optimization of 2D quadrilateral meshes, node valence (i.e. number of element edges attached to each node) is used to maximize the number of regular nodes (i.e. nodes with four attached edges). Difficulties in developing 3D hexahedral local topology modifications have limited the success of hexahedral topology optimization, although published literature suggests using an object function based on node valence. However, in this paper, we show that node valence is not a consistent measure of good hexahedral element topology, and objective functions based on node valence can lead to element topology, which will only admit concave element shapes. Instead, we propose that objective functions based on edge valence (i.e. number of quadrilateral faces attached to each element edge) will provide a consistent measure of element topology. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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R. Boman J.‐P. Ponthot 《International journal for numerical methods in engineering》2012,92(10):857-890
In computational solid mechanics, the ALE formalism can be very useful to reduce the size of finite element models of continuous forming operations such as roll forming. The mesh of these ALE models is said to be quasi‐Eulerian because the nodes remain almost fixed—or almost Eulerian—in the main process direction, although they are required to move in the orthogonal plane in order to follow the lateral displacements of the solid. This paper extensively presents a complete node relocation procedure dedicated to such ALE models. The discussion focusses on quadrangular and hexahedral meshes with local refinements. The main concern of this work is the preservation of the geometrical features and the shape of the free boundaries of the mesh. With this aim in view, each type of nodes (corner, edge, surface and volume) is treated sequentially with dedicated algorithms. A special care is given to highly curved 3D surfaces for which a CPU‐efficient smoothing technique is proposed. This new method relies on a spline surface reconstruction, on a very fast weighted Laplacian smoother with original weights and on a robust reprojection algorithm. The overall consistency of this mesh management procedure is finally demonstrated in two numerical applications. The first one is a 2D ALE simulation of a drawbead, which provides similar results to an equivalent Lagrangian model yet is much faster. The second application is a 3D industrial ALE model of a 16‐stand roll forming line. In this case, all attempts to perform the same simulation by using the Lagrangian formalism have been unsuccessful. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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Dae‐Young Kwak Yong‐Taek Im 《International journal for numerical methods in engineering》2002,53(11):2501-2528
In the present study, a hexahedral mesh generator was developed for remeshing in three‐dimensional metal forming simulations. It is based on the master grid approach and octree‐based refinement scheme to generate uniformly sized or locally refined hexahedral mesh system. In particular, for refined hexahedral mesh generation, the modified Laplacian mesh smoothing scheme mentioned in the two‐dimensional study (Part I) was used to improve the mesh quality while also minimizing the loss of element size conditions. In order to investigate the applicability and effectiveness of the developed hexahedral mesh generator, several three‐dimensional metal forming simulations were carried out using uniformly sized hexahedral mesh systems. Also, a comparative study of indentation analyses was conducted to check the computational efficiency of locally refined hexahedral mesh systems. In particular, for specification of refinement conditions, distributions of effective strain‐rate gradient and posteriori error values based on a Z2 error estimator were used. From this study, it is construed that the developed hexahedral mesh generator can be effectively used for three‐dimensional metal forming simulations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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In the numerical simulation of bulk metal forming process by the finite element method (FEM) extremely degenerated meshes result due to high local deformation. The finite elements distort so much that they lose their regular shape. Remeshing and rezoning techniques are necessary to avoid the resulting numerical problems. For remeshing it is important to create a new mesh with regular elements, and to refine the generated grid in dependency of geometric features. An automatic remeshing-module independent of the FE-code is developed at the Institute of Metal forming and Metal forming Machine tools (IFUM). This program creates a mesh that meets all requirements of the object by combination of adaptive meshing and optimisation of the correct grid distortion. In this paper an algorithm to mesh complex 3D geometries with tetrahedron elements is introduced, by taking into account the specific of metal forming processes and their implication in FE-Analysis. 相似文献
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Lu Sun Guoqun Zhao Xinwu Ma 《International journal for numerical methods in engineering》2012,89(6):726-761
The quality of finite element meshes is one of the key factors that affects the accuracy and reliability of numerical simulation results of many science and engineering problems. In order to solve the problem wherein the surface elements of the mesh generated by the grid‐based method have poor quality, this paper studied mesh quality improvement methods, including node position smoothing and topological optimization. A curvature‐based Laplacian scheme was used for smoothing of nodes on the C‐edges, which combined the normal component with the tangential component of the Laplacian operator at the curved boundary. A projection‐based Laplacian algorithm for smoothing the remaining boundary nodes was established. The deviation of the newly smoothed node from the practical surface of the solid model was solved. A node‐ and area‐weighted combination method was proposed for smoothing of interior nodes. Five element‐inserting modes, three element‐collapsing modes and three mixed modes for topological optimization were newly established. The rules for harmonious application and conformity problem of each mode, especially the mixed mode, were provided. Finally, several examples were given to demonstrate the practicability and validity of the mesh quality improvement methods presented in this paper. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献