Front crash with crumple zone: relative velocity calculation

[marellasunny]

EURONCAP front crash test involves crashing a car moving at 64 kph onto a deformable barrier at 40% of the total vehicle width. According to the EURONCAP website, this is equivalent to two vehicles crashing into each other at 55 kph. How did they arrive at this figure?

I presumed that the above mentioned crash-test would be equivalent to two cars moving at 32kph into each other. But, I am starting to get the idea that these relative velocity figures are better calculated by taking absorbed kinetic energy into account. Please provide me with some simple equations.

Citation from the EURONCAP website: ''By carrying out frontal impact tests at 64km/h (about 40 mph) we are simulating a car impacting a similar sized car where both cars are traveling the same speed of 55 km/h.''

 

[mfb]

If two identical cars collide head-on with the same speed x, this is equivalent to a car crashing into an ideal wall with the same speed - the "collision front" won't move due to symmetry in the crash. With their deformable barrier, they simulate lower speeds because the car can move into the barrier a bit. I guess the numbers they use are based on experience.