Moment Developed by Restrained Spring

[BigAL]

I am using a heavy (1500#/in.) compression spring already designed by the spring supplier using SMI Spring Designer.
The spring is precompressed about halway to solid. A plate is used at that point to compress the spring further. The plate must not rotate as the spring is further compressed.
Is there an equation to determine the moment that must be resisted to prevent rotation of this plate as it strokes?

 

[peglor]

Correct me if I'm wrong, but I thought coiled springs bulged outwards as they compressed rather than twisting. A very quick experiment with the spring from a pen seems to confirm this.

The mechanism a coil spring is using to compress is to convert the linear load on an end of the spring into a torque through the cross section of the spring material.

If you look at a coil spring from the side you can see that it is basically a stack of torsion springs. Unless you twist the spring, there should be no torque reaction from the spring as it is compressed.

 

[desertfox]

Hi BigAL

Yes there are formula for compression and tension springs
unwinding under large deflections, refer to a book called
"Mechanical Springs" by A.M.Wahl this would exert a moment on the plate that it would have to resist.Over here in the UK we call this spring wind up "ratcheting"

Hope this is of help