Error Types

When models are imported there are two types of errors – geometry errors and topology errors. Geometry errors are errors in definition of the underlying geometry while topology errors are errors in how the underlying components like faces, edges and vertices are connected. These have to be fixed before mesh analysis can be performed.

When models pass the initial validity checks, mesh generation could still fail. If bodies in the model overlap, mesh will not be invoked. If bodies are very close to each other, mesh might fail. Small features (small edges, small edges, sliver edges) might be present in the bodies which might cause mesh to fail.

The following are common errors present in models:

  1. api_check_entity() errors. These are errors detected by the kernel and are geometry and topology errors.
  2. non-manifold topology. These are non-manifold edges and vertices that are present in the model.
    3. Note: One of the requirements for valid mesh generation is that the surface mesh must be manifold, that is, a plot of all the surface triangles of a 3D solid object should not have any “holes.” Such a mesh is often referred to as a watertight mesh. If there is a hole and you were to fill the object with water, the water would leak out of that hole – the mesh would not be watertight. Zero-area holes (often called cracks) will also “leak.” Having multiple triangles cover the same patch also results in a mesh that is not manifold. Refer to Detecting Errors for information on detecting and correcting such errors.
  3. Body pair intersection. This detects if pairs of bodies intersect.
  4. Small feature detection – small edge length, small face area and sliver face detection.
  5. Misaligned entities detection – detects pairs of faces from bodies that can be aligned to remove interbody intersections. This improves the odds of mesh success.
  6. Mesh failure error display. This is available for single body, body pairs and last simulation run (all bodies in model). Errors reported by the meshing module are reported to the user.

Errors of type 1, 2, and 3 must be resolved before the mesh can be applied to the model.