Compression Spring Shear Spring Rate

[xr4titis]

Hola Forum,

Does anyone have a formula to derive the shear spring rate of a compression spring? In other words, the spring rate in the plane perpendicular to the axis of the spring.

I've seen this provided from a German spring manufacturer (that I can no longer get a hold of) as a function of in-axis deflection.

It doesn't need to be exact, just trying to determine feasability. Rough dimensions: O.D. = 8", Wire Dia. = 1" Free Length = 9", Travel = 3", Mat'l = Alloy Steel

Gracias,
Andrew

 

[desertfox]

Hi xr4titis

Kx = 10^6*d^4/(Cl*n*D*(0.204Hs^2 + 0.265*D^2)

Kx= lateral stiffness of spring

Cl= factor depending on vertical deflection due to load divided by the spring free length and the free length divided by the mean diameter of spring

n= number of active coils

Hs= compressed length of spring

D= mean dia of spring

d= wire dia of spring

Can you give me the rate of your spring and the number of active turns and I'll get the Cl factor for you.

regards

desertfox

 

[xr4titis]

thanks desertfox!

I'm still in the very early stages of design, but the spring rate will be around 5000 lb/in. Do you know the approx range of the Cl factor?

Andrew

 

[desertfox]

can't get to it now till friday sorry.

desertfox

 

[thought2007]

Hi xr4titis!

spring rate for compression spring derived formula is as
follows

Kx=G*d^4/8D^3n

Design follows iterative process intitally assuming wire dia & Spring index w.r.to space requirement & load requirement.

Hope it will help you

desertfox..Do u have derivation for the formula

John

 

[desertfox]

Hello thought2007

The op hasn't been in for over a week I assume he got the last part of the answer somewhere else.
In addition I think you misinterpreted the post he wanted the spring rate at 90 degrees to the normal axis of spring.

Regards

desertfox

 

[xr4titis]

Hey Guys,

Sorry I've been away from work for a while, but I would still very much appreciate the Cl factor for the lateral spring rate. I haven't correctly sized the springs yet as I am new to suspension design therefore I cannot provide exact parameters. However, the application is rail so the springs will be pretty beefy. Inner and Outer spring combined stiffness of 10,000 to 15,000 lb/in. Can you please provide an approximate range for Cl? Possibly as a function of Vertical deflection?

 

[israelkk]

Spring Design and Application editrd by Nicholas P. Chironis 1961, printed by McGraw Hill. Pages 61-62.

 

[israelkk]

Mechanical springs, by A. M. Wahl 1963 pages 70-72 Chap. 5-13 Lateral loading of compression springs.

Mechanical Springs, by A. M. Wahl 1963 pages 282-284 Chap. 24-4 Combined axial and lateral loading.