Technical Paper
Calculating A and B Stiffness Coefficients from NCAP Barrier Crash Test Utilizing Load Cell and Accelerometer Data
2024-04-09
2024-01-2473
The use of A and B stiffness coefficients to model the frontal stiffness of vehicles is a commonly used and accepted technique within the field of collision reconstruction. Methods for calculating stiffness coefficients rely upon the examination of the residual crush of a vehicle that was involved in a crash test. When vehicles are involved in a collision, portions of the crushed vehicle structures rebound from their maximum dynamic crush position. Once the vehicle structures have fully rebounded, the remaining damage is called the residual crush. A problem can arise when the plastic bumper cover rebounds more than the structural components of the vehicle, resulting in an air gap between the structural components and the plastic bumper cover. Most modern NCAP tests quantify crush based on the deformed location of the plastic bumper cover and not the structural components underneath the plastic bumper cover. This results in an underreporting of the actual residual crush.