I posted this in someone's FS thread where they had a set of springs they knew nothing about. I thought it might come in handy for someone else so I figure'd I'd throw it where it'd get more exposure as well.
Anyway, say you have some springs you don't know anything about kicking around and you want to figure out the spring rate. Here's some maths you can do to figure it out. Use callipers when working this out.
We'll need all of these things:
G=Torsional modules for steel (11.25 x 10^6 or 11,250.000)
d=Wire diameter in inches
8=A constant for all coil springs
N=Number of active coils
D=Mean coil diameter in inches
x=Inside diameter of the spring
G and 8 are already figured out above. Figuring out the number of active coils should just be a matter of counting the coils on your spring. d and x can be determined with your calipers. The only thing left on that list to figure out is D.
To determine D you need to do this:
(x+(x+(2*d)))/2
Now we have everything we need to figure out the spring rate. Work it like this:
(G*d^4)/(8*N*D^3)=spring rate
Hopefully this helps someone.
One thing to note, this won't work with progressive springs or springs made of exotic materials (to the best of my knowledge).
Anyway, say you have some springs you don't know anything about kicking around and you want to figure out the spring rate. Here's some maths you can do to figure it out. Use callipers when working this out.
We'll need all of these things:
G=Torsional modules for steel (11.25 x 10^6 or 11,250.000)
d=Wire diameter in inches
8=A constant for all coil springs
N=Number of active coils
D=Mean coil diameter in inches
x=Inside diameter of the spring
G and 8 are already figured out above. Figuring out the number of active coils should just be a matter of counting the coils on your spring. d and x can be determined with your calipers. The only thing left on that list to figure out is D.
To determine D you need to do this:
(x+(x+(2*d)))/2
Now we have everything we need to figure out the spring rate. Work it like this:
(G*d^4)/(8*N*D^3)=spring rate
Hopefully this helps someone.
One thing to note, this won't work with progressive springs or springs made of exotic materials (to the best of my knowledge).
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