3 diameter coil spring

[dgallup]

I've got this coil spring with 3 different outside diameters (see the attachment). The wire size is constant. I know all the dimensions and have a load at one length. The transition between the two smaller diameters is pretty small, the bigger transition bothers me. Can I assume the rate will be constant at fairly small deflections? Will I get a reasonable approximation if I calculate the rate of each straight section and add them the way I would add serial capacitance?

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[MikeHalloran]

I don't think the rates are going to add like capacitances.
Any tapered spring is nonlinear.
You treat it as one-turn springs in series, i.e., the forces are equal,
until the largest diameter spring reaches coil-bind, at which point it ceases to be effective, so the rate of the overall spring goes up, and you recurse as next largest coil binds and is removed from the length summation, etc.




Mike Halloran
Pembroke Pines, FL, USA

 

[dgallup]

It will never reach coil bind in this application but I agree that upper transition will probably be non-linear. The best thing would be to get them measured I suppose. We used to have a spring tester but management was too cheap to repair or replace it.

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.