Helical Spring Lateral stiffness Value

[cnv]

I'm tyring to find the lateral spring stiffness constant k. Does anyone know what the equation is? Axial is everywhere, but I can't find the lateral one anywhere.

 

[handleman]

Probably because (unless I misunderstood your post) this is non-standard, non-designed-for use of helical springs.

 

[wes616]

k = 32 x (di^4 x E)/ (pi) x do x Nac

where Nac is the number of active coils

di - inner diameter

do - outer diameter

E - Elasticity

Wes C.
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Light travels faster than sound. That's why some people appear bright until you hear them speak.

 

[cnv]

Just to make sure. I'm looking at the stiffness of a helical compression sping laying horizontal and defelecting down in the z axis. Is that the picture you had Wes?

 

[EnglishMuffin]

Since the lateral deflection of a coil spring involves both bending and torsion, wes616's formula must be incorrect, or at least incomplete, since it would have to involve both E & G. See the following - although it may be a little overcomplicated for what you need :

http://scholar.lib.vt.edu/theses/available/etd-05062002-004428/unrestricted/Etd.pdf

 

[cnv]

Yeah I have that paper and it gets me the axial I need. Basicly i'm trying to maximze the axial to lateral stiffness. Thanks

 

[israelkk]

See thread693-148558

 

[wes616]

CNV, What I gave was for torsional springs(which by the way, is independent of rigidity constnat). However, upon re-reading your OP, I assume you are looking for what israelkk has suggested.

Good luck

Wes C.
------------------------------
Light travels faster than sound. That's why some people appear bright until you hear them speak.

 

[cnv]

thanks to all. I will try that book...

 

[btrueblood]

The simple equations are prefaced by the "book" (in my case, Wahl's Mechanical Springs, 2nd ed.) as being only generally accurate (+/- 30%). The real transverse stiffness will vary with the direction of the applied load relative to the windings (ends) of the coil, in my experience. Also, I noted in testing that if the spring is compressed, then deflected laterally, you will see the wires near the ends "slipping" across one another instead of laying down neatly atop one another, adding friction & hysteresis into the mix...