I am not too sure that there has been too much design in aircraft that
utilizes the crumple capabilities of metal. Even in the metal planes. At
least the GA planes.

The likely accidents are much different than in cars, and I am not sure that
you have the weight available to really play with crumple zones. Sure, you
would want to ensure that the wings will shear off at a certain amount of
force, and that the engine will not go straight back into the cockpit.
Other than that, where would you go for a crumple rather than a solid
resistance?

Also, the likely bounce is much different in a plane than a car.

This would make a neat new thread.