Meshing Irregular 3D Shape with Hexahedral Elements Only

Barry_jfri

Hello everyone,

I am using HyperMesh 2024 to mesh a biological tissue with an irregular 3D shape. I know it’s fairly easy to generate a voxel mesh from medical images, but the boundary ends up with a step-like, unsmooth appearance. To solve this, I used a custom code employing the marching cubes algorithm, which provided me with a closed surface with a smooth boundary. Then, I needed to create a solid mesh inside this surface using only hexahedral elements.

The only method that has somewhat worked for me so far is the Tight Wrap option in the "Design Space" tool with the "Generate Solid Mesh" option checked on. But this approach results in essential holes and gaps being closed, and I lose anatomical accuracy, unless I use a very small element size.

So, I have the following questions and would greatly appreciate your help:

1. Is there a way in HyperMesh to smooth the step-like boundary of a voxel mesh? My model is 3D.
2. Are there any alternative methods (direct or indirect) to create a solid mesh by only of hexahedral elements within a closed surface? I have also tried the "Hex-core" option from the "Optimize" tab, but it always fails to generate a mesh.
3. On another note, I need to subtract one solid mesh from another in my model. I noticed that the Boolean tools in the "3D" tab work only with solids, but my components are basically mesh (FE solids.) Is there a way to perform this subtraction with FE solids?
   
   Thank you,
   Barry

Jason_Craanen

Hello,

YOu could decrease the Jacobian on the Wrap tool. This will give you a smoother boundary at the loss of element quality. I believe you can also adjust the gap and hole option to leave them. Or go an delete elements after.

There is no real way to fill a volume with hex mesh. You more need to think about it as dragging elements to creates hexas. You could then morph them as needed after.

You can do boolean with solid mesh for tetra mesh only.

Over all there is not easy method for what you are trying to do. I often recommend using tetra mesh for these complex volumes if you can.