The model already contains a consistent geometry, element, and material. Now we must decide how much discretization you need. We will not choose a mesh for its appearance: we will build a comparable family, we will audit it and let a Physical magnitude determines when refining stops substantially changing the response.
Your mission
You will generate three structured hexahedral meshes, you will check their topology and quality, you will measure the tip displacement with the same test case and select the first mesh whose variation compared to the next is less than 2%.
Central rule: an attractive mesh does not demonstrate convergence; a small difference is also meaningless if the cases represent different problems.
Objectives
By completing M04 you will be able to demonstrate that:
- You distinguish refinement, quality and convergence.
- You build a hexahedral mesh using parametric divisions.
- You explain the difference between a global control and one applied to specific lines.
- You audit topology, attributes, and shape warnings before solving.
- You keep geometry, material, load and measurement point constant.
- You calculate the change relative to the next finer mesh.
- You select a mesh by a stated criterion or conclude that the study is insufficient.
Prerequisites and downloads
- Have completed M03 and recognize
SOLID185,TYPEandMAT. - Remember from M02 that a selection is a temporary state and must be recovered with
ALLSEL,ALL. - Having run the first simulation of M00. Your solution block is reused as an instrument, not new content.
04_start.mac— starting point.04_mesh_convergence.mac— complete study.04_bug_hunt.mac— five deliberate contaminations.04_challenge.mac— challenge with non-divisible sizes.04_expected_results.csv— acceptance contract.
How to use this lesson
| Track | Duration | Scope |
|---|---|---|
| Quick win | 35–40 min | Prediction, first mesh, and mesh audit record. |
| Complete | 70–75 min | Also, 40/320/2560 family, convergence and challenge with mesh_h limit. |
Recommendation: a beautiful mesh does not demonstrate convergence. You need a comparable family and a monitored magnitude with explicit tolerance.
Session map
- Mission: targets, downloads and refinement prediction.
- Mental model: quality, convergence, and a defensible decision.
- Demo: meshing, quality, family and convergence.
- Bug hunting: incomparable meshes and invented convergence.
- Challenge: mesh_h which does not cleanly split the part.
- Mastery: final test that records demonstrated mastery and recommends M05.