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!
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$\begingroup$ Determine the load and desired deflection then use Euler beam theory applied to a cantilever (tons of examples on the internet) to give you the cross-sectional shape and size that satisfies that while keeping the stress low enough. $\endgroup$– user1318499Commented Feb 22, 2019 at 4:55
2 Answers
What steel to use? What thickness and width? What angles to use?
An inexpensive source of spring steel for experimenting with are leaf springs.
You have serious competition, named Keahi Seymour and his 25 mph 'bionic boots'.
There are also fictional designs to draw from.
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