Radial Expansion of a Helical Rectangular Cross Section Spring 1

[Shockdesigner331]

Hello all. I've been looking around for a formula for the radial expansion of a helical rectiangular cross section spring for quite some time now without success. I have an application where knowing the expansion is critical as I need to use as much OD as possible for stress reasons. I've searched on-line and come up with very little. If anyone would share what knowledge they have it would be much appreciated. Thanks.

 

[israelkk]

Mechanical springs 1963 2nd edition by Wahl pages 249-250. If you will read it carefully how he developed it you can easily adapt it to square or rectangular wire by using the polar moment of inertia of a square or rectangular wire instead of the round wire. I think that relying on this to keep safe distance from the walls in a tight place is a risky and undesirable approach. I am sure that a spring that will fit your need your requirements can be found without this approach.

http://israelkk.googlepages.com/home

 

[GregLocock]

A crude approach that is at least is a step in the right direction is to assume that the length along the centreline of the wire of 1 turn of the spring is unchanged. The length of a helix is pretty obvious.

That agrees very well with the chanhge in rate seen in practice.



Cheers

Greg Locock

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