Crash & Impact Simulation
Explicit dynamics for crash simulation: material failure, contact algorithms, airbag deployment, and occupant safety.
Definition & Context
Crash simulation uses explicit dynamics finite-element solvers (LS-DYNA, Abaqus/Explicit, Radioss, PAM-CRASH) to model high-speed, highly nonlinear events — vehicle impact, drop test, blast — in milliseconds of physical time. Explicit time integration marches forward with tiny stable time steps governed by the Courant condition (element size / wave speed).
These models combine large deformation, material plasticity and failure, self-contact, and strain-rate-dependent material laws (e.g. Johnson–Cook). Occupant safety adds dummy models, airbags (control-volume or ALE), and seatbelt elements, validated against physical crash tests and rated by protocols such as Euro NCAP.
In contemporary engineering practice, Crash & Impact Simulation represents a critical interdisciplinary methodology. By replacing manual heuristics with rigorous digital simulation and parametric constraints, engineering teams establish an unbroken digital thread from initial concept through detailed physical realization.
Achieving high-quality results in Crash & Impact Simulation requires a thorough understanding of geometric tolerances, material behavior, and coordinate governance. Digital models serve not merely as graphical representations, but as authoritative engineering databases driving downstream analysis, procurement, and robotic fabrication.
Why It Matters
Virtual crash testing slashes the number of destroyed physical prototypes and lets safety engineers iterate structures and restraint systems quickly to meet regulatory and NCAP star ratings.
Best Practices
- Respect the Courant stable time step; mass scaling can help but distorts inertia if overused.
- Use strain-rate-dependent material models — metals are stronger at crash strain rates.
- Define robust contact (self-contact for buckling folds) to prevent element penetration.
- Check energy balance: hourglass and sliding energy should stay a small fraction of total.
- Correlate against physical test pulses and deformation before trusting design studies.
Common Pitfalls
- Excessive mass scaling that adds non-physical inertia and hides real behaviour.
- Reduced-integration elements without hourglass control, producing zero-energy modes.
- Missing self-contact so folding structure passes through itself.
- Rate-independent material data giving unrealistically weak response.
Core Commands & Practical System Operations
Executing Crash & Impact Simulation effectively relies on specialized CAD/BIM command workflows and system variable configurations: BIM & CAD tools: WALL, FLOOR, ROOF, FAMILY, XREF, IFCEXPORT. Setup: Coordinate shared project base points, configure Level/Grid datum.
Standard Engineering Workflow for Crash & Impact Simulation
1. Spatial Programming & Shared Georeferencing
Establish project base points, survey coordinates, building storeys, and column grid systems coordinated across architectural, structural, and MEP consultants.
2. LOD 200 - 300 Parametric Component Assembly
Model multi-layer architectural assemblies (curtain walls, structural framing, floor slabs, MEP risers) using intelligent parametric family components.
3. Interdisciplinary Clash Detection & Coordination
Federate discipline models in Navisworks or Solibri. Run automated hard/soft clash tests and track issues using BCF (BIM Collaboration Format) workflows.
4. 2D Construction Documentation & Quantity Schedules
Extract live plans, building sections, elevations, and automated component schedules (doors, windows, concrete volume) linked directly to the central model.
Common Failure Scenarios & Troubleshooting
| Failure / Geometric Issue | Root Cause & Mitigation Strategy |
|---|---|
| Architectural and Structural models do not align when linked | Shared coordinates were not acquired. Ensure both teams use 'Acquire Coordinates' from a designated master site model. |
| Wall joints and multi-layer materials do not clean up cleanly | Layer core priorities are misconfigured. Ensure structural cores have Priority 1, substrate Priority 2, insulation Priority 3, and finishes Priority 4/5. |
| IFC export drops custom attributes and scheduling properties | Map property sets using custom IFC export translation tables before exporting to external coordination software. |
Industry Standards & Compliance Codes
- ISO 19650-1/-2 (Organization of information about construction works - BIM)
- buildingSMART openBIM & IFC 4x3
- AIA Document E202 (Building Information Modeling Protocol)
- National CAD Standard (NCS)