Using CAD Geometry in Structural Simulation – Change or Accept?

I will be speaking at the ASSESS conference this week on disruptive technologies in simulation. In that vein, many people have asked me how Altair SimSolid is different than traditional finite element analysis.  Their question usually goes something like, “You just hide the mesh right? Don’t you solve the problem the same way?”

My answer is no, we solve the problem in a significantly different way. I won’t go in to the technical details here but the fundamental difference is in the philosophy of how design geometry is processed to create the analysis model.

Traditional FEA vendors spend considerable time and effort to modify the geometry to make it suitable for the meshing process. In effect, they require geometry changes to support their analysis processes.

These required changes apply to both parts and assemblies. For parts, small geometric features are removed, thin solids are converted to mid-surfaces and small gaps and overlaps are cleaned up. For assemblies, gaps and overlaps between mating surfaces must be identified and fixed – never an easy task in complex multi-part assemblies. The bottom line is, make the geometry pristine and everything is OK. That said, the reality is that this is a laborious process and subtle geometry problems are often difficult to find and correct.

The geometry philosophy with Altair SimSolid is disruptively different.  We accept the design geometry as is. A basic assumption of Altair SimSolid is to try to use the full geometry representation and be tolerant to part assemblies with ill-defined boundaries.  Why? Because this is the reality of geometry that CAD systems create today. Nobody wants to take the time to refine geometry at the early stages of design to remove these details or inconsistencies.  This ability to handle fuzzy, non-exact geometry is key to expanding the use of simulation in the product design process.

Using Altair SimSolid, we accept:

  • full part geometry detail – all fillets, rounds, holes, imprints and other small features,
  • surface construction complexity – such as odd face transitions and small splinter surfaces,
  • a broad range of part sizes – such as small bolts, washers and nuts along with their larger structural components,
  • and gaps and overlaps between parts in an assembly – some may be unintentional, as in small mistakes in mating and alignment, or intentional, as in geometry overlap between bolt with threads placed in a smaller hole.

Altair SimSolid’s new meshless methods are capable of analyzing CAD geometry of large assemblies directly without modification.  Our connections between parts are easy to apply and robust. In many cases this is done automatically. Our bottom line – Altair SimSolid allows rapid structural performance evaluation of evolving designs.  With Altair SimSolid, analysis is capable of working with the design process, not against it.

Altair SimSolid is new. For those looking for more information, Desktop Engineering and have a couple of good overview articles.  Of course, if you are in the Washington D.C. area this week, come to ASSESS 2016.  I would love to talk to you in more detail about what we are up to.

Ken Welch
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Ken Welch

About Ken Welch

Ken was the cofounder and CEO at SIMSOLID corporation. He has over 30 years experience in the CAE industry in a variety of technical, sales and executive roles at companies including PDA Engineering, Rasna, Moldflow and MSC Software. Ken holds a B.S. and M.S. in civil engineering from the University of California, Davis.