Stiff outer piece with flex element? Model T bumper did that, hard flat face mounted on a leaf spring across the frame. Plenty of old timey B&W film with the Keystone cops demonstrating it.
Like aerodynamics, tho, over 55 and it gets spicy. As said, more metal = more damage. One exciting video of a cruiser doing over 100mph shows a slow motion collision with a deer going up, tearing off the hood, thru the windshield, and out the back glass. Pretty much processed it and all that was left might fit a cooler. IIRC trooper was unharmed, cruiser totaled, tag filled.
I did that with a 90 Cherokee late one night at 35mph, punctured the radiator, destroyed the cheap plastic grille, etc. and the deer skidded down the asphalt, got up and walked away. Thought it could get around the front of my Jeep after leaping over a ten foot fence. And did. I drove it a few blocks home steaming. Pinched off the core tubes and drove with that radiator for another 18 months. Brand new all brass three core lasted about 90 days, then crunch.
It ran too cold anyway.