FEM: Six steps to achieve a proper mesh to the static structural analysis

Six steps to achieve a proper mesh to the static structural analysis

Have ever you asked: How to achieve a proper mesh to the static structural analysis?

There are a couple of strategies to do it. However, I will show one that I always successfully have used.

1.    Check the possibility to apply symmetry.

2.    Perform a CAD pre-treatment, removing gaps, redundant or excessive edges, unnecessary details, surface smoothing, and everything out of analysis interest region (Caution: Do never remove details, like chamfer in regions wherein there are maximum stress – see step 6 Convergence).

3.     Run the first analysis with coarse mesh to identify regions of maximum stress. After this identification, perform local refinement on these regions (if the geometry is simple, go to step 5).

4.    Evaluate elements quality, in particular on regions of maximum stress. All them must have good quality, even the big ones. In general, the acceptable average quality should be above grade 0,8 and the standard derivation lower than 0,09. 

     To understand more about elements and mesh quality, I suggest the reading of these three articles:

      MESH QUALITY AND BODY SIMPLIFICATION (PART 1) - TYPES OF ELEMENTS
      MESH QUALITY AND BODY SIMPLIFICATION (PART 3) - ELEMENTS QUALITY
      MESH QUALITY AND BODY SIMPLIFICATION (PART 4) - MESH QUALITY

5.    Choose which solver to use: Direct or Iterative:

        •    Direct: Indicated to linear structural analysis due to better accuracy. Can be applied to non-linearity, however, requires more processing power.

        •    Iterative: Indicated to non-linear structural analysis. To linearity, there is the risk to do not the convergence happens.

6.    Perform the convergence test. There are software that do it automatically, do it directly if you have a simple geometry. If the geometry is complex, it is better to do local increment manually, after then, perform the automatic convergence. This care will avoid that the software creates too many small elements in regions without necessity.