Ask A Scientist© Engineering Archive

Index Key:   ENG006
Author:      jdang
Subject:     Absorbing energy in a crash
Text:        What are the most efficient ways to absorb energy in a crash  
i.e. certain structures, foams, etc.?

Response #:  1 of 1
Author:      dipper
Text:        I am going to ask more questions of you before answering 
specifically. I assume that you are talking about a car crash.  If so, some 
parameters need to be defined.

1) Do you want to simply absorb energy and transfer (i.e. heat) or do you want 
to absorb and reflect (as in rubber or spring steel)?
2) Is this material space sensitive (in other words, do you care about its 
size)?
3) Is it weight sensitive?
4) How much force are you trying to stop, and at what acceleration?  An 
aircraft at 300,000 pound gross weight travelling at 400 mph is different than 
a bicycle and rider travelling at 10 mph with a gross weight of 100 pounds.  
If you are concerned about human survival, than an acceleration of about 5 - 7 
g's for a short time is about the limit of most human survival.  All of these 
things must be taken into consideration when considering an energy 
absorbing/converting material.  Write me with a few more specifics, and I will 
be glad to help as much as I can.