Every meshing decision is a trade-off between accuracy, run time and how much manual cleanup you’re willing to do. Shell, tetra and hexa elements each solve that trade-off differently, and picking the wrong one doesn’t usually fail loudly, it just quietly costs you solver time, mesh quality warnings, or results you can’t fully trust. Here’s how we think about the choice.
Shell Meshing: For Anything Thin
If a part’s thickness is small relative to its other dimensions, sheet metal panels, brackets, thin-walled housings, shell elements are almost always the right call. They represent the mid-surface of the part with 2D elements carrying a thickness property, which keeps element counts (and solve times) far lower than trying to fill a thin volume with 3D elements. The catch is upstream: shell meshing depends on clean mid-surface extraction, and geometry with variable thickness, fillets or messy CAD history can turn that step into the most time-consuming part of the job.
Tetra Meshing: For Anything Complex
Tetrahedral elements are the default answer for geometrically complex, chunky, or irregular parts, castings, cast housings, organic shapes, anything where a clean hexahedral grid isn’t realistic without heavy simplification. Modern tetra meshers handle complex geometry with far less manual intervention than hexa meshing, which makes them the practical choice when turnaround matters more than squeezing out the last bit of solver efficiency. The trade-off is element count and, for some solvers, a stiffer response unless second-order (mid-side node) elements are used.
Hexa Meshing: For Anything That Needs to Be Trusted
Hexahedral elements give the best accuracy-per-element of any mesh type, and they’re what we reach for on high-fidelity structural and crash models where result quality can’t be compromised: crash boxes, chassis members, anything with a load path that needs to be captured precisely. The cost is time. Building a clean hex mesh usually takes longer and more manual effort than tetra, which is exactly why it’s reserved for the parts of a model where that investment actually pays off, not applied uniformly across an entire assembly.
So Which One Do You Pick?
In practice, most real assemblies use all three: shells for the sheet-metal body, tetra for the cast or complex brackets, hexa for the handful of components where the load path is the whole point of the analysis. The mesh strategy should follow the question the simulation is trying to answer, not the other way around. Whatever the mix, every mesh we build gets checked against solver-specific quality criteria, Jacobian, warpage, skewness, before it’s handed off, because a mesh that looks fine visually can still quietly fail those checks.
Want a second opinion on a meshing strategy for an upcoming project? Get in touch, or see the full detail on our FE Meshing service.