# Force & Torque Equations for a Twist Tie

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1. Sep 21, 2016

### pduves

Hello! I'm posting this because I cannot find this type of question and analysis anywhere!

What are the force and torque equations describing the following?
1. A thin metal wire is bent around the OD of a cylindrical tube (wall thickness, t) perpendicular to the axis.
2. The cylindrical tube is "sliced" along its wall thickness in the radial direction (creating a disconnection of the wall thickness along the "spine" of the cylinder). Because of the shape of the cylinder, the "spine" portion opens wider as the cylindrical walls come apart.
3. The wire is bent around the OD so the ends of the wire come together above the "sliced" area.
4. The wires begin to "twist" together (like a twist-tie) forming a double-helix.
5. A force/torque is applied to twist the wire ends around each other (double-helix). The force/torque pulls the wire tighter around the cylinder and slowly brings the "sliced" portion of the tube closer together.
6. Along with the force/torque on the double-helix wire, an upward "pull force" is also applied to pull the wire to a snug fit around the cylinder.
7. The separated, "sliced" portion of the wire slowly comes together. The separated walls are connected again.

How much force/torque is required to bring the "sliced" portion of the cylindrical tube back together using the "twist-tied" wire?

Hope this makes sense! I think its a great physics problem! Thanks!

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2. Sep 21, 2016

### Nidum

Applied torque to tension in cable analysis + Deformation of split cylinder under distributed radial load analysis + Tension in cable wound on drum with friction analysis .

Last edited: Sep 21, 2016