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DyMESH — Facts of Life

Practical guidance, caveats, and limitations for users of DyMESH, drawn from the EDC DyMESH — Important Notes presentation (2026 HVE Forum). These are the things to keep in mind before, during, and after a DyMESH run.

1. You are doing 3-D collision simulation

When using DyMESH, you're doing three-dimensional collision simulation. This is technically a very difficult task. Don't expect it to be simple. Setting up a credible DyMESH case takes care with geometry, stiffness, and impact configuration.

2. DyMESH will not work on every crash

DyMESH is a powerful general-purpose tool, but it is not going to work on every crash. Some impact configurations, geometries, or data quality problems will not yield a good simulation. Be prepared to fall back to other methods when a case is unsuitable.

3. Computer horsepower matters

Computer horsepower means everything to DyMESH. The contact search and force computation run every collision time step over the vehicle meshes, so CPU speed and memory directly determine how quickly (and how finely) a case can be run.

4. Be patient during a run

Be patient. HVE is resting in between integration time steps while DyMESH is executing, so quickly punching a bunch of buttons during a run may result in unexpected behavior. Let the run proceed rather than clicking through the interface while DyMESH is working.

5. No induced damage

Induced damage is not included. No damage will be displayed unless one or more vertices on one vehicle were actually in contact with the other vehicle. DyMESH represents only direct-contact (direct) damage — it does not model the secondary/induced structural deformation that propagates away from the contact region. (This is the same limitation noted in the technical overview: "local behavior of structure not captured in all cases; no induced damage.")

(updated: This is consistent with the code — a vertex only enters the damage profile once it has penetrated a master surface and been restored; see the IsDamaged / DamageThisTimeStep handling and MakeProfile() in Dymesh.cpp.)

6. Mesh quality is a factor

The quality of the vehicle mesh directly affects the result:

  • Poorly tessellated meshes do not work well. The contact algorithm relies on reasonably uniform, well-formed triangles.
  • Early EDC meshes do not meet all criteria, especially on the bottom of the vehicle.
  • Use the Tessellation option to improve a mesh before running DyMESH.

(updated: The Tessellation / "Vehicle Mesh Options" controls in the current code include a Tessellate toggle, a Vertex Weld Distance, and a Max Side Length — these are the levers referred to here for cleaning up a mesh.)

7. Generic vehicles must be tessellated

Generic Vehicles' meshes must be tessellated before use with DyMESH. Their as-delivered meshes are not suitable for the contact algorithm without tessellation.

Source: DyMESH Important Notes (2026 HVE Forum) — organized and verified against DYMESH.H / Dymesh.cpp, 2026-07-05.

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