A good mesh is key to any successful Finite Element Analysis and extracting accurate, valid results. So, what happens when all we get from the mesher in SOLIDWORKS Simulation is this?
There are many reasons this message can appear, and my goal for this article is to provide some useful steps in identifying the source of mesh failure, provide insights into the operations of the mesh algorithm, and ultimately resolve the mesh failure.
The first step is to check to see if there are multiple bodies in the study. If so, apply a finer mesh control on each of the bodies that are failing. A finer mesh can often resolve mesh failures by decreasing the size of elements on small features or thin model geometry. If there are any noticeable small or thin features, then it would be best to apply a finer mesh on these faces as well.
Red mesh icons in the ‘Parts’ list of the Simulation study tree indicates a mesh failure while green icons indicate a successful mesh, as shown below.
On the next attempt, if you haven’t done so already, try meshing with the ‘Curvature-based mesh’ under ‘Mesh Parameters’ and turn on the option for ‘Remesh failed parts with incompatible mesh’ under ‘Advanced’ after all mesh controls have been applied.
The Standard mesh is going to yield a mesh with elements that are more uniform in size and orientation, and thus, can be restrictive. The Curvature-based mesh is not restricted in this way, which allows more freedom for the mesh algorithm to complete. However, also consider that the Standard mesh can reduce run-time for the solver, especially for Frequency studies, so there are benefits for each mesh type. Similarly, turning on the option for ‘Remesh failed parts with incompatible mesh’ gives the SOLIDWORKS Simulation mesher additional freedom to mesh the interfaces of components independently so the sizes of the elements can be dissimilar.
If one or more components are still failing to mesh it is likely the model geometry that is the culprit. The next logical step is to create a new study so that only the body that is failing to mesh is included. Define a shell for this solid body by right clicking on the body in the Simulation tree and select ‘Define Shell by Selected Faces…’ and select all of the faces on the body (you can click on a face before defining the shell, use the ‘invert selection’ tool, and save it as a new selection set to save some time here).
For a solid body mesh it is generally not possible to see which geometry fails to mesh. The benefit of applying a shell mesh to each of the solid’s faces is going to provide a visualization for any faces that might not be meshing. After defining the shell and creating the shell mesh we can see the results. As shown below, any holes or missing faces in the shell body indicate problem areas for SOLIDWORKS Simulation.
The meshing algorithm works by first placing nodes along every edge of the model, attempting to space them apart using the size parameters defined during mesh creation. It then uses 2D elements to connect each node and fill every face of the geometry and, again, attempts to size the elements based on the parameters. For solid elements, it goes on to fill in the internal volume of the part with tetrahedral elements using the 2D elements as an outline. Therefore, if the shell mesh is successful at capturing all the faces of the geometry then there is most likely a thin feature that the 3D tetrahedral elements are unable to fill. On the other hand, if there are holes in the shell mesh, as previously depicted, then the meshing algorithm is unable to fill the holes and either the model geometry should be adjusted accordingly, or a finer mesh will be needed near these areas.
Other useful tools for checking geometry are ‘Check…’ (Tools -> Evaluate -> Check…)
and ‘Geometry Analysis’ under and Tools -> Geometry Analysis.
These tools can help in identifying short edges, sliver faces, knife edges, and invalid geometry, all of which can cause the mesh to fail. For this model, there are 5 short edges where the holes of the shell mesh were located, which indicates this feature is the reason for the mesh failure.
After cleaning up the model geometry, the check geometry tool no longer shows short edges and the body is ready to mesh the part as a solid again.
Support Engineer – Simulation
Computer Aided Technology, LLC