CRASH3
Definition
Calspan Reconstruction of Accident Speeds on the Highway version 3: a mathematical model that relates permanent crush depth to absorbed energy through vehicle-specific stiffness coefficients, allowing calculation of the change in velocity (delta-V) a vehicle experienced.
- Full name
- Calspan Reconstruction of Accident Speeds on the Highway v3
- Input
- Permanent crush depth measurements
- Output
- Absorbed energy and delta-V
- Requires
- Vehicle-specific stiffness coefficients
Common questions
Why does CRASH3 need vehicle-specific stiffness coefficients?+
Crush stiffness varies by make, model, and structural design, so a generic coefficient set would misestimate energy absorption. Coefficients are derived from crash test data for the specific vehicle or a close structural match.
What is delta-V used for once it is calculated?+
Delta-V is the change in velocity the vehicle experienced during impact, and it correlates with occupant injury risk, so reconstructionists use it to assess crash severity and to cross-check speed estimates from other physical evidence.
Related terms
- Dynamic Crush
- The maximum deformation depth at the moment of peak force during impact, before any elastic recovery. Dynamic crush is larger than residual...
- Energy Equivalent Speed (EES)
- The speed at which a vehicle would strike a rigid fixed barrier to absorb the same amount of energy as observed from...
- Residual Crush
- The permanent, non-recoverable deformation depth remaining after the elastic springback of the vehicle structure. This is what is measured at the scene...
- SMAC
- Simulation Model of Automobile Collisions: a trajectory and damage simulation that uses CRASH3-type stiffness data to model full collision kinematics, including vehicle...
- Stiffness Coefficients a and B
- Vehicle-specific constants derived from staged barrier crash tests. A is the force threshold below which no permanent crush occurs (N/m width). B...