Originally Posted by
bmclaughlin807
Helmets do NOT absorb energy by breaking up.... that is the failure mode when the energy is too high for the helmet to absorb. Helmets are designed to absorb energy by crushing the foam... if the foam is crushed the helmet did it's job and absorbed energy, if it's not crushed the helmet didn't perform properly. Helmet foam does not crush and then re-expand to it's former size/shape/strength.... once crushed it stays crushed and the amount of crush gives a pretty good indication of how much energy the foam absorbed.
I wasn't sure of the exact process. Thanks for the clarification.
Originally Posted by
lechatmort
vehicles aren't supposed to break up either, rather they crumple
Yes, I meant they crumple. I didn't think that needed explaining, but thanks for pointing it out.