Importance of Conducting Convergence Study in FEM Simulations

Designing a bracket in #SolidWorks I thought was easy until #FiniteElementMethod entered the conversation ??. One bracket design, five simulation cases and five different von Mises stress results. One of these results stood out and became the suitable design for a bracket at a given load – Thanks to convergence study! I realised the importance of conducting a convergence study to find that close-to-perfect solution. Initially, I underestimated the impact of mesh size and element quality on the accuracy of my simulation results, but through convergence study, I discovered that smaller mesh sizes and higher element quality significantly improved the accuracy of stress and displacement predictions. The process taught me that neglecting convergence studies could lead to misleading results and potentially flawed designs, not only in this bracket but with any elements subject to FEM. I methodically refined the mesh and observed the stabilisation of results until it reached the point where further mesh refinement no longer significantly affected the results, indicating that the solution had converged.

I put a short guide below for the convergence study and hope it helps:

1. Create or import your CAD model in SolidWorks.
2. Define material properties, apply loads, and boundary conditions.
3. Generate an initial mesh using the default settings or a coarse mesh.
4. Run the simulation and record key results (e.g., stress, displacement).
5. Gradually refine the mesh by reducing the element size. You can do this manually or use SolidWorks’ adaptive meshing feature.
6. Run the simulation for each refined mesh and record the same key results.
7. Plot the key results (e.g., maximum stress, displacement) against the mesh size or number of elements.
8. Look for convergence, where the results stabilise and do not significantly change with further mesh refinement.
9. Identify the mesh size where the results converge. This mesh size ensures that the results are accurate and not dependent on the mesh.
10. If results do not converge, further refine the mesh or check for model setup issues, such as improper boundary conditions or load applications.
11. Compare the converged results with theoretical values or experimental data, if available, to ensure validity.
12. Document the convergence study process, including plots and observations, to justify the chosen mesh size.

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