Direct Midmesh

Use the midmesh functionality in HyperMesh to automatically generate a mesh at the midplane location, directly from the input geometry (components, elements, solids or surfaces), without first creating a midsurface. This saves significant time over the traditional midsurface-based approach.

The resulting output consists of 2D shell elements created with the user-provided target size, as well as 1D elements defining the topology of the mesh (vertices/edges/faces). Midmesh generation is also multithreaded to take advantage of multi-core environments.

Midmesh Generation Workflow

There are several steps involved in generating a good quality midmesh. Following the workflow shown in Figure 3 helps guarantee the best result with minimal manual effort.

Nominal Run
Extract the base midmesh.

Cleanup Resulting Topology
Use the semi-automated midmesh edit edge and edit face tools to correct the 1D topology and fix any bad/missing faces. The goal is to prepare the model for final remeshing.

Rebuild Mesh
Remesh to the final size and quality using the rebuild mesh functionality, and correct any remaining mesh quality issues.

Apply Thickness
Map the thickness from the original solid to the midmesh via the Map Thickness tool.

Create Midmesh

Midmesh generation is possible on dirty geometry, but a cleaner output can be obtained by removing duplicate or overlapping surfaces, stitching free edges, removing logos and other small features that are not of interest, and merging any solids that should be topologically connected.
It is recommended to use a smaller element size (for example, 2 or 4mm depending on model scale) in order to get a good sampling of the input geometry. The final rebuild mesh step takes care of remeshing to the desired size and quality. Using an element size smaller than the representative feature size will not necessarily give better results and will take significantly more run time. Several options are available to control the resulting midmesh output.

Edit Midmesh

Once the midmesh is generated, there may be problem areas that need to be corrected. The 1D topology is important for the rebuild mesh operation, and care must be taken to prepare it accordingly. In addition, making sure the faces do not have intersected, overlapped, or missing elements, and that they have proper alignment, is also essential. Specialized midmesh edit tools streamline the process of repairing the 1D topology edges, and correcting issues with the midmesh faces.

Direct Midmesh Workflow Demonstration

In this demonstration you will see an overview of the Direct Midmesh Tool.