Discrete Modeling

Overview

Discrete geometry representations (also called polygonal models, facet models, mesh models, etc.) utilize a mesh to describe geometry rather than analytic surfaces. They are often used in applications where the definition of the geometry comes from measurements or the results of a simulation (design optimization, additive manufacturing, etc.), or in cases where the only available representation of a CAD model is an STL file or similar.

Simmetrix' Discrete Model technology allows a user to define and modify models using discrete geometry. These models can then be used like any other model for mesh generation and adaptivity. Discrete geometry can also be deformed to change shape during mesh adaptivity, allowing for simulations with evolving geometry. 

Capabilities:

• Import various discrete data (STL, existing meshes, etc.) to define a discrete model
• Boolean operations on discrete assembly models
• Smoothing of Discrete models to eliminate artifacts (e.g., if discrete data was 3D image data)
• Support model queries from GeomSim (except calls requiring parametric information)
• Support most meshing capabilities in MeshSim and MeshSim Advanced

 

Boolean Operations

In the example shown, a CAD-based STL assembly model has overlapping faces between two of the parts.  After performing a union between the parts, the overlapping faces are resolved and a non-manifold face is created between the parts.

In addition to unioning, subtraction, intersection and imprinting are also supported.

   

Boolean Subtraction

For this example, the desire is to add pins to the assembly by subtracting them from the main bracket part. 

      

The subtraction intersects the faces of the pin with the solid of the bracket, while not changing the tessellation of the pin. 

  

After the subtraction, the interior region is removed, and the assembly is meshed.

  

 

Discrete Shape Smoothing

Shape smoothing is most often used when the imported data is 3D Imaging data, however it can be applied to any Discrete model.  This example shows the model before/after smoothing is applied.

Heart modeling at University of Michigan

Discrete modeling tools are used to import patient-specific data.  The resultant model is then meshed using MeshSim tools and evaluated for blood flow studies.

Geometry Cleanup

One benefit of Discrete modeling is the ability to manipulate model faces. 

The model below was imported from CAD, and shows some tangencies where fillet faces come together.

By defining new model edges in the Discrete model and merging model faces together, the tangencies are removed.