Problem description

My mesh fails with a certain error code, but what does it mean? How can I fix it?

When the PLAXIS 3D mesher cannot successfully generate the 3D mesh, it will return an error code. Usually this error code refers to the location in the internal process of the PLAXIS 3D Mesher where the iterative process could not succeed in creating a 3D mesh.

Solution

Whenever possible, the PLAXIS 3D program tries to offer a hint where you might be able to optimize the geometry or the local mesh coarseness in order to successfully generate the 3D mesh.

Sometimes some simple optimization can do the trick:

• Try to refine parts of the geometry where you expect smaller elements.
• When objects should be connected, make sure that they are really connected. Anchors that are nearly placed on a plate are actually not connected and will cause severe difficulties in the mesher or in the calculation.
• There are other cases in which geometry objects are close to each other that the automatic mesh generator cannot fit (good-quality) elements around. Such issues can be found in the geometry by using this command in Structures/Mesh mode:

  checkgeometry

  This command checks if objects overlap or are adjacent, and gives a list of items with their distance. In some cases, this command does not give any feedback. This command, by default, takes a distance tolerance related to the model's size. If the command does not give this info, then a parameter can be added to this command, e.g. 0.1 to check all geometry that is located within 0.1 m:

  checkgeometry 0.1

• Sometimes the model contains very small elements. These small elements usually make the mesh generation process slower and it may even not find a good mesh. To find small surfaces  in the mesh mode, go to the mesh mode and type, for instance:

  tabulate Surfaces "Area" "Area<1"

  This will list all areas with a calculated surface area smaller than 0.1 m² (when the meter is set to be the unit of length). Sometimes these small areas are leftovers from the used commands in the Structures mode (especially when importing geometries and when using the intersect and combine tools), or some very inconvenient intersection results by combining the soil and the defined structures (e.g. when a part of a plate sticks 0.01 m into the next soil layer). Reducing the number of small elements will usually improve the mesh generation process. This is available since PLAXIS 3D 2011.01.

• In order to find small volumes, this command could help you find these:

  tabulate Volumes "volume" "volume<1"

• In order to find small lines, use this command:

  tabulate Lines "Length" "Length<0.1"

• As a good practice, partitioning of the geometry can be performed. This can be done by using a volume to partition the created geometry or a closed box of surfaces. This will allow the mesher to isolate each partition and assist in the generation of the mesh. Typically this can be done using a top surface, then extrude that surface to the elevation covering the main part of the geometry (e.g. piles, tunnels).
• Using PLAXIS 3D 2013 or earlier that still contains triangulated geometry? In that case, you might want to try meshing with both angle tolerances of 1 in the expert settings. This usually helps for circular objects.

We encourage the users who still encounter a failing 3D mesh generation to send the project to our support department so the Plaxis development team can improve the stability and quality of the PLAXIS 3D Mesher.