I am trying to develop my own spring steel version of a carbon fiber running blade that you might see in the paralympics. Except mine is for someone who still has their foot/leg. Nothing like that exists and out of necessity I am trying to develop one that is similar and I think i might be able to do it using a less expensive material too. I really need help calculating what steel to use, thickness, width, angles, etc. Carbon fiber is ideal but very expensive. Would spring steel work? Any concerns with that choice other than a bit heavier? It would have to be formed in the shape of a "J"This would need to support a 215 pound person walking, running etc. Any help is greatly appreciated!
Have a look at the spring steel used in cultivator tines for the agricultural industry - lighter than leaf springs and already designed in the vertical orientation you are looking for.
Link to some examples here