Mastering Meshing for Mechanical Analysis
Meshing plays a crucial role in mechanical simulations, impacting accuracy, efficiency, and overall computational performance. With new advancements in simulation software, engineers now have access to improved meshing techniques that enhance precision while optimizing processing time. Here we explore essential meshing techniques, including shell meshing, solid meshing, and adaptive meshing, with a focus on new features introduced in Ansys releases and provide our top six tips for generating high quality mesh.
The Fundamentals of Meshing
Meshing involves discretizing a geometric model into smaller elements, enabling numerical analysis. The choice of meshing technique depends on the geometry, analysis requirements, and computational constraints. The two primary types of meshes are:
- Shell Meshes: used for thin structures, where only surface representation is needed.
- Solid Meshes: used for volumetric structures requiring in-depth stress and deformation analysis.
Surface model mesh
Advancements in meshing techniques have made it easier to create structured, high-quality meshes with minimal manual intervention. The introduction of Prime Mesh, Multizone, and Geometry-Preserving Adaptivity (GPAD) tools has significantly improved meshing workflows.
Shell Meshing: The Power of Prime Mesh
One of the significant updates in recent Ansys releases is the Prime Mesh method. This tool is an excellent alternative to traditional batch meshing and provides a more structured and high-quality shell mesh. It simplifies meshing by automating key steps, ensuring a conformal and quad-dominant mesh.
Creating a Shell Mesh with Prime Mesh
When working with surface models, the goal is to create a connected mesh while maintaining the integrity of the geometry. The Prime Mesh method streamlines this process by:
- Automatically generating a quad-dominant mesh.
- Connecting all separate surfaces at the mesh level.
- Reducing manual adjustments required in SpaceClaim or Discovery.
Handling Topology with Prime Mesh Tools
Beyond creating a quality mesh, Prime Mesh introduces several auxiliary tools to refine meshing workflows:
- Repair Topology – this tool helps suppress unnecessary features such as holes that do not impact the structural integrity of the model. By using the ‘Fill Holes’ option, engineers can selectively remove elements that are irrelevant to the analysis.
- Connect Tool – when working with large surface assemblies, ensuring that all mesh elements are properly connected is crucial. Instead of relying on shared topology in SpaceClaim (which can be time-consuming), the Connect Tool within Prime Mesh efficiently merges surfaces at the mesh level, resulting in a conformal mesh.
- Quad Layer Tool – this tool helps create structured elements around holes or edge loops, improving element distribution and consistency.
Validating the Shell Mesh with Modal Analysis
A practical approach to verifying shell meshing quality is through a modal analysis. This process checks the dynamic characteristics of a model, helping engineers detect potential connection errors. If no rigid body modes appear at or near zero frequency, the mesh is likely well-connected and suitable for further analysis.
Solid Meshing: Achieving High-Quality Hexahedral Meshes
For solid components, hexahedral elements (hex meshes) are preferred over tetrahedral elements (tet meshes) due to their superior accuracy and convergence properties. However, generating a well-structured hex mesh can be challenging.
Multizone vs. Hex Dominant Method
Two commonly used methods for solid meshing are:
MultiZone Mesh example
- Hex Dominant Method – while tempting, this method often results in skewed elements and unstructured meshes. It also produces internal pyramid elements, reducing overall accuracy.
- MultiZone Method – this is the recommended approach when generating hex meshes, as it ensures structured, high-quality elements. However, it sometimes requires topology modifications to define source and target surfaces clearly.
Enhancing Hex Meshing with Virtual Topology
Virtual Topology is a powerful tool for modifying the geometry without altering the CAD model. By introducing split faces and refining edges, engineers can guide the mesher to produce a well-structured grid. This process is especially useful when working with complex geometries that require specific element distributions.
Another way to improve mesh control is through Edge Sizing with Bias, which refines elements near critical features like holes while maintaining efficiency in less critical regions.
Adaptive Meshing: Geometry-Preserving Adaptivity (GPAD)
Adaptive meshing techniques help improve simulation accuracy without unnecessarily increasing computational costs. One of the newest and most powerful tools in this domain is Geometry-Preserving Adaptivity (GPAD), introduced in recent Ansys versions.
Why Use GPAD?
Unlike standard meshing methods, GPAD refines the mesh dynamically during the simulation. It adjusts element sizes based on strain energy criteria, ensuring that areas experiencing high stress receive finer mesh refinement.
Setting Up GPAD for Mesh Convergence
Mesh convergence studies are essential for ensuring that simulation results are independent of mesh size. GPAD simplifies this process by automatically refining the mesh in critical regions. The setup involves:
- Scoping the Entire Model – Allowing mesh refinement across the full geometry.
- Using Strain Energy Criteria – Elements exceeding a threshold energy value are refined.
- Defining Refinement Steps – The number of refinement iterations ensures convergence is achieved efficiently.
GPAD vs. Nonlinear Adaptive Refinement (NLAD)
GPAD is designed for linear simulations, whereas NLAD is used for nonlinear cases. The primary difference is that GPAD refines the mesh while preserving geometric accuracy, making it ideal for capturing curved surfaces more accurately compared to NLAD, which simply refines existing elements.
Top Six Tips for High Quality Meshes: Key Takeaways and Best Practices
1. Use Prime Mesh for Shell Models – It provides a more efficient way to generate conformal meshes compared to traditional batch meshing.
2. Utilize Multizone for Solid Meshes – This method ensures structured, high-quality hexahedral elements, avoiding issues with the hex dominant approach.
3. Leverage Virtual Topology for Complex Parts – Small adjustments to
topology, such as face splitting, can significantly improve mesh quality.
4. Apply Edge Sizing and Biasing – Helps refine critical regions while maintaining efficiency in less important areas.
5. Use GPAD for Mesh Convergence Studies – Adaptive refinement ensures accuracy without unnecessary computational expense.
6. Validate Your Mesh Connections with Modal Analysis – This technique helps
verify that connections are properly established, reducing errors in subsequent simulations.
Conclusion
Efficient meshing is fundamental to accurate and reliable simulations. By leveraging the latest meshing tools like Prime Mesh, Multizone, and GPAD, engineers can significantly improve their meshing workflows while maintaining high-quality results. These innovations reduce manual effort, improve accuracy, and optimize computational resources, making them invaluable for modern simulation tasks.
If you want to explore more about meshing techniques and best practices, consider joining advanced mechanical simulation training or reaching out for expert consultancy.
Efficient meshing is not just about following a process; it’s about mastering the art of balancing accuracy and computational efficiency.
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Watch Coffee with an Expert: Meshing for Mechanical webinar on-demand
