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DyMESH Reference Manual

DyMESH (Dynamic Mechanical Shell) is the three-dimensional dynamic-mesh collision and damage model used by HVE's simulation models. It computes inter-vehicle (and vehicle-environment) contact forces, moments, and damage directly from the polygon meshes that describe the exterior surfaces of the vehicles and objects in an event. The resulting collision forces are combined with the other external forces acting on each vehicle (tires, aerodynamic drag, etc.) and the six-degree-of-freedom equations of motion are integrated to produce the collision dynamics and the resulting damage (crush) profile.

DyMESH is invoked primarily by SIMON (and is also available to EDSMAC4). It replaces the idealized impulse-momentum treatment of impact with a true force-based, time-stepped collision simulation.

Provenance

This manual was organized from three 2026 HVE Forum presentations by Allen R. York and Terry D. Day of the Engineering Dynamics Company (EDC):

  • DyMESH Collision Simulation (York & Day, March 2026) — the core technical overview: history, mesh model, contact algorithm, force/damage computation, and coupling to the vehicle dynamics.
  • DyMESH Version 3 (EDC, 2026 HVE Forum) — the Version 3 additions, chiefly the DyMESH Wheels collision model (forces and moments from impact at the wheels).
  • DyMESH — Important Notes / Facts of Life (EDC, 2026 HVE Forum) — practical guidance, caveats, and limitations for users.

The technical content has been verified against the current HVE source code (Physics/Include/DYMESH.H, Physics/Source/LibHve/Dymesh.cpp, Physics/Source/Simon/PHYMODEL.CPP, and the CDyMeshOptionsDlg dialog in HVEINV-64). Where the current code differs from the slide decks, the discrepancy is called out with an italic (updated: ...) note.

Contents

  1. Overview — what DyMESH is and does; where it sits in HVE; which models use it; history.
  2. Collision Model — the technical model: mesh representation, contact (Location) and restoration detection, force and moment computation, 3-D force-deflection stiffness, vertex displacement (crush depth), restitution, and coupling to the equations of motion.
  3. Version 3 — the DyMESH Wheels collision model and other Version 3 capabilities.
  4. Facts of Life — practical notes, caveats, and limitations.

Source: DyMESH Collision Simulation, DyMESH Version 3, and DyMESH Important Notes (2026 HVE Forum) — organized and verified against DYMESH.H / Dymesh.cpp, 2026-07-05.

Next: DyMESH Overview →