"A perfect system will collapse with increased resistance to the stop point to keep g load below about 40g."
You really know your stuff! This almost perfectly describes design for the latest auto NCAP tests...
"Steel work hardens as it bends and that is why all cars use it I think."
Plus it's cheap. Not dirt cheap like it used to be though, which gives other technologies a good look in - expect composite skinned ally spaceframes to make more of an appearance.
"I am not familiar with steel reinforced composite but it makes sense to me. How is it done?"
I've not seen it, but i suggest bonding a carbon fiber skin to a tubular (high tensile) steel spaceframe. This would be ideal for helis, and i have even suggested it for DJs Unicopter.
"Try that (drop hammer) with a sheet of carbon fiber and the drop hammer will not survive."
F1 carbon nosecones seem to crush pretty well. I can see your point though: Carbon composite does not inherently want to absorb impact energy, and bounce back would be the worst thing possible. Any composites experts care to comment?
Mart