Today we will talk about the Mesh tool in ANSYS Workbench, which can divide structural meshes and fluid domain meshes. Here we systematically review the 7 core techniques of the ANSYS Workbench Mesh tool to help you move from “computable” to “accurate”.
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Background Overall Division, Local Refinement
In Workbench Mesh, the global size (Global Sizing) sets the basic mesh density, usually taken as 1/5 to 1/10 of the model’s minimum feature size. Local refinement (Local Sizing) performs detailed processing for stress concentration areas, geometric discontinuities, and contact regions.
You can use local control types such as Sphere of Influence in mesh control to limit the method and range of mesh refinement, avoiding excessive density in the full model that leads to excessive computation. The mesh size in key areas is recommended to be 1/3 to 1/5 of the main mesh. For features such as holes and chamfers, enable Capture Curvature to automatically capture curvature changes. During local refinement, it is recommended to set 2-3 transition layers to allow smooth changes in mesh size, avoiding convergence difficulties caused by sudden changes in element quality.
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Hexahedral Mesh Control
Hexahedral mesh is superior to tetrahedral mesh in calculation accuracy and computational efficiency, but the division difficulty is relatively high. ANSYS Mesh provides several implementation methods.
Sweep is suitable for regular extruded bodies, such as pipes and shaft parts. The MultiZone method can decompose the model into mapped block geometry, and relevant partitioning strategies can be set. Hex Dominant can divide complex geometry into hexahedral-dominated mesh while allowing local tetrahedral mesh transition.
None of these methods is the best; rather, you should choose the one that best suits your model.
For pipe structures, the Sweep + inflation layer combination can obtain high-quality boundary layer mesh. When automatic division fails, try Virtual Topology to simplify geometric features.
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Application of Second-Order Elements in Hexahedral Mesh Control
Second-order elements (Quadratic) have higher displacement solution accuracy compared to first-order elements, especially in areas with large bending deformation and stress gradients.
In structural analysis, second-order elements are preferred for bending-dominated problems,
for solid elements, you can use second-order hexahedra (SOLID186), second-order tetrahedra
(SOLID187)
, second-order prisms
(SOLID186)
, second-order pyramids
(SOLID186)
.
In contact analysis, second-order elements can better capture contact pressure distribution, but attention should be paid to contact penetration control. However, it should be noted that second-order elements have many more nodes compared to first-order elements, and the computational cost increases significantly.
04
Curvature and Proximity Capture Functions
Curvature Capture (C
apture Curvature) and Proximity Capture (Capture Proximity) are two commonly used methods for overall mesh control.
Curvature capture can automatically identify geometric high-curvature areas
, such as fillets and surface transitions. It can help us dynamically refine the mesh in these areas, accurately capture the local geometric features of the model, and improve the mesh accuracy in surface areas. A key parameter is the Curvature Normal Angle. By reducing this value, you can increase the curvature sensitivity and make the mesh in local areas denser. This parameter needs to be adjusted appropriately according to your model.
Proximity capture can automatically detect narrow gaps, thin-wall flow channels, and other areas that exist in the model
. If you are dividing CFD fluid domain mesh in Mesh, this function is quite useful. It can refine the mesh in local areas and improve the calculation accuracy of flow gradients and boundary layer effects.
05
Nonlinear Adaptive Region
When materials enter plasticity, rubber compression, or metal forming, mesh distortion is the main cause of convergence failure.
Inserting a Nonlinear Adaptive Region function in the model
can solve such problems to a certain extent.
Three trigger criteria:
- Energy: based on element strain energy change.
- Box: triggered when nodes enter a specified region.
- Mesh: based on Maximum Corner Angle judgment.
Typical application scenarios include large geometric deformation of rubber materials, metal extrusion forming, and other problems.
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Contact Surface Local Refinement
Contact nonlinearity is a commonly encountered convergence problem in CAE calculations, and the mesh quality of the contact surface is also critical for calculation convergence. For contact surface mesh refinement,
use the Contact Sizing tool to directly control the contact area mesh.
It is recommended that the contact surface mesh be 1-2 times finer than the target surface. In the depth direction of the contact pair, at least 3-5 layers of elements should penetrate the depth to ensure smooth transition of contact pressure. In edge contact areas, Sizing can be set separately for chamfer and fillet areas for local control to avoid sharp angle contact.
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Hexahedral Mesh Control Inflation Layer Mesh (Inflation)
Inflation layers are commonly used in CFD fluid domain mesh to capture boundary layer flow characteristics. They can also play an important role in structural analysis.
In structural analysis,
at stress concentration areas such as notches and steps
, generate inflation layers to capture stress gradients.
Refine the mesh in hole edge areas to focus on the calculation results of that area
. At contact interfaces, generate inflation layers to simulate the attenuation of contact pressure along the depth direction. In thermal analysis, surface thermal boundary layers can be processed.
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