mesh 178.docx

1、mesh 17817.1Understanding the role of the Mesh moduleThe Mesh module allows you to generate meshes on parts and assemblies created within Abaqus/CAE. Various levels of automation and control are available so that you can create a mesh that meets the needs of your analysis. As with creating parts and

2、 assemblies, the process of assigning mesh attributes to the modelsuch as seeds, mesh techniques, and element typesis feature based. As a result you can modify the parameters that define a part or an assembly, and the mesh attributes that you specified within the Mesh module are regenerated automati

3、cally.The Mesh module provides the following features: Tools for prescribing mesh density at local and global levels. Model coloring that indicates the meshing technique assigned to each region in the model. A variety of mesh controls, such as: Element shape Meshing technique Meshing algorithm Adapt

4、ive remeshing rule A tool for assigning Abaqus/Standard and Abaqus/Explicit element types to mesh elements. The elements can belong either to a model that you created or to an orphan mesh. A tool for verifying mesh quality. Tools for refining the mesh and for improving the mesh quality. A tool for s

5、aving the meshed assembly or selected part instances as an orphan mesh part17.2Entering and exiting the Mesh moduleYou can enter the Mesh module at any time during an Abaqus/CAE session by clicking Mesh in the Module list located in the context bar. Upon entering the Mesh module, the Abaqus/CAE inte

6、rface changes in the following ways: The Seed, Mesh, Feature, and Tools menus appear on the main menu bar. The Object field that appears in the context bar allows you to display either a part or the assembly. 17.3.1The meshing processTo create an acceptable mesh, you use the following process: Assig

7、n mesh attributes and set mesh controls The Mesh module provides a variety of tools that allow you to specify different mesh characteristics, such as mesh density, element shape, and element type.Generate the mesh The Mesh module uses a variety of techniques to generate meshes. The different mesh te

8、chniques provide you with different levels of control over the mesh.Refine the mesh The Mesh module provides a variety of tools that allow you to refine the mesh: The seeding tools allow you to adjust the mesh density in selected regions. The Partition toolset allows you to partition complex models

9、into simpler subregions. The Virtual Topology toolset allows you to simplify your model by combining small faces and edges with adjacent faces and edges. The Edit Mesh toolset allows you to make minor adjustments to your mesh.Optimize the mesh You can assign remeshing rules to regions of your model.

10、 Remeshing rules enable successive refinement of your mesh where each refinement is based on the results of an analysis.Verify the mesh The verification tools provide you with information concerning the quality of the elements used in a mesh.17.3.2Mesh attributes and controlsAbaqus/CAE provides you

11、with a variety of tools for controlling mesh characteristics: You can specify the density of a mesh by creating seeds along the edges of the model to indicate where the corner nodes of the elements should be located. For example, Figure 171 displays a model with biased seeding along the top and left

12、 edges. Figure 171 A model with biased seeding.For more information, see “Understanding seeding,” Section 17.4. You can select the shape of the mesh elements. For example, Figure 172 shows a model that has been meshed first with quadrilateral elements and then with triangular elements. Figure 172 Tw

13、o meshes with different element shapes.For more information, see “Assigning Abaqus element types,” Section 17.5. You can choose the meshing techniquefree, structured, or sweptand, where applicable, you can choose the meshing algorithmmedial axis or advancing front. For more information, see “Mesh ge

14、neration,” Section 17.3.3. You can select the element type that is assigned to the mesh by choosing the element family, geometric order, and shape along with specific element controls, such as hourglassing. For more information, see “Understanding mesh generation,” Section 17.7.For information on re

15、lated topics, click any of the following items: “Understanding seeding,” Section 17.4 “Assigning Abaqus element types,” Section 17.5 “Verifying and improving meshes,” Section 17.617.3.3Mesh generationAbaqus/CAE can use a variety of meshing techniques to mesh models of different topologies. In some c

16、ases you can choose the technique used to mesh a model or model region. In other cases only one technique is valid. The different meshing techniques provide varying levels of automation and user control. There are two meshing methodologies available in Abaqus/CAE: top-down and bottom-up.Top-down mes

17、hing generates a mesh by working down from the geometry of a part or region to the individual mesh nodes and elements. You can use top-down meshing techniques to mesh one-, two-, or three-dimensional geometry using any available element type. The resulting mesh exactly conforms to the original geome

18、try. The rigid conformance to geometry makes top-down meshing predominantly an automated process but may make it difficult to produce a high-quality mesh on regions with complex shapes.Bottom-up meshing generates a mesh by working up from two-dimensional entities (geometric faces, element faces, or

19、two-dimensional elements) to create a three-dimensional mesh. You can use bottom-up meshing techniques to mesh only solid three-dimensional geometry using allor nearly allhexahedral elements. Generating a mesh using the bottom-up meshing technique is a manual process, and the resulting mesh may vary

20、 significantly from the original geometry. However, allowing the mesh to vary from geometry may allow you to produce a high quality hexahedral mesh on regions with complex shapes.For information on related topics, click any of the following items: “Top-down meshing,” Section 17.3.4 “Bottom-up meshin

21、g,” Section 17.3.5 Abaqus/CAE may change the color of the part instances in the assembly displayed in the viewport. These color cues describe the meshability and dependence of each instance. Independent instances appear in a color that describes their meshability, while dependent intances appear blu

22、e in the Assembly context and white in the Part context. See “Meshing independent and dependent part instances,” Section 17.3.10. Note: Part instances are color coded according to their meshability and dependence only when the Mesh defaults color mapping is selected. If you displayed the default col

23、or mapping in a different module, Abaqus/CAE applies the Mesh defaults color mapping automatically upon your entry to the Mesh module. If you selected a non-default color mapping such as Materials in a different module, Abaqus/CAE continues color coding according to that color mapping (in this case,

24、 by material type) when you enter the Mesh module.To exit the Mesh module, select any other module from the Module list. You need not save your mesh before exiting the module; it will be saved automatically when you save the entire model by selecting FileSave or FileSave As from the main menu bar.17

25、.3.4Top-down meshingTop-down meshing relies on the geometry of a part to define the outer bounds of the mesh. The top-down mesh matches the geometry; you may need to simplify and/or partition complex geometry so that Abaqus/CAE recognizes basic shapes that it can use to generate a high-quality mesh.

26、 In some cases top-down methods may not allow you to mesh portions of a complex part with the desired type of elements. The top-down techniquesstructured, swept, and free meshingand their geometry requirements are well-defined, and loads and boundary conditions applied to a part are associated autom

27、atically with the resulting mesh.Structured meshing Structured meshing is the top-down technique that gives you the most control over your mesh because it applies preestablished mesh patterns to particular model topologies. Most unpartitioned solid models are too complex to be meshed using preestabl

28、ished mesh patterns. However, you can often partition complex models into simple regions with topologies for which structured meshing patterns exist. Figure 173 shows an example of a structured mesh. For more information, see “Structured meshing and mapped meshing,” Section 17.8. Figure 173 A struct

29、ured mesh.Swept meshing Abaqus/CAE creates swept meshes by internally generating the mesh on an edge or face and then sweeping that mesh along a sweep path. The result can be either a two-dimensional mesh created from an edge or a three-dimensional mesh created from a face. Like structured meshing,

30、swept meshing is a top-down technique limited to models with specific topologies and geometries. Figure 174 shows an example of a swept mesh. For more information, see “Swept meshing,” Section 17.9. Figure 174 A swept mesh.Free meshing The free meshing technique is the most flexible top-down meshing

31、 technique. It uses no preestablished mesh patterns and can be applied to almost any model shape. However, free meshing provides you with the least control over the mesh since there is no way to predict the mesh pattern. Figure 175 shows an example of a free mesh. For more information, see “Free mes

32、hing,” Section 17.10. Figure 175 A free mesh generated with tetrahedral elements.For information on related topics, click any of the following items: “Bottom-up meshing,” Section 17.3.5 “Understanding mesh generation,” Section 17.7 “Assigning Abaqus element types,” Section 17.5 “Verifying and improving meshes,” Section 17.617.3.5Bottom-up meshingBottom-up meshing uses the part geometry as a guideline for the outer bounds of the mesh, but