"Crash tests with human dummies have confirmed the material efficiently absorbs energy and protects passengers from “secondary impacts”—i.e., slamming into the wall or a seat back when the train lurches unexpectedly. " http://www.wired.com/2014/12/aluminum-foam-trains/
I guess you'd have to be a dummy to volunteer for crash tests. Human dummies abound. Some animals are dummies, too.