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I am working on art project, which is a living statue made from plastic pipes and fabric, and it folds, unfolds, dances pretty violently. I want to attach some LED strips to the pipes, but I am worried that my wiring may break down due to mechanical stress.

What are the best wires in terms of mechanical flexibility and fatigue resistance?

Atilla Filiz
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    Don't worry about the wires, they will handle it, worry about the points where it is attached. Useful google keyword: strain relief – PlasmaHH Apr 24 '17 at 11:15
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    @PlasmaHH "Don't worry about the wires" is particularly bad advice if the cable is expected to frequently and repeatedly bend back 180 degree on itself in a few millimeters of space. My guess is it might last about an hour if the speeds are anything like the OP has eluded to. – Trevor_G Apr 24 '17 at 14:38
  • @Trevor: I was not assuming the OP looks for ways to make cables survive obvious abuse. In that case my advice is: don't worry to use cables, there is nothing you can do. – PlasmaHH Apr 24 '17 at 14:53
  • @PlasmaHH :) True enough. – Trevor_G Apr 24 '17 at 14:56
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    Google the NASA worksmanship standards - they show ways to route/retain wires & other components against high stress, might be helpful. – John U Apr 24 '17 at 15:11

2 Answers2

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First you need to choose the right kind of cable. There are some really flexible cables out there including instrument wires which are extremely flexible.

Generally the more strands the better for flexibility, however too much flexibility is also hard to control. It is often better to go with a stiffer cable that can carry the current and is flexible, but also rigid enough to form into loops and coils. Something like heavy speaker wire.

When crossing hinges and joints DO NOT go straight across. Instead detour the wire through an S-Bend so it twists rather than bends as shown in the upper image below. (Note you are looking down on the hinge, hinging action here is in and out the page.)

enter image description here

If it is a really extreme bend, or you need the cable to stretch a little through the motion then you may also want to consider coiling the cable through that S-Bended.

Coils and loops should also be employed wherever the mechanical motion ends up stretching the cable, for example, going round the outside of a hinge.

Control the stress. All cables should be firmly anchored using tie-wraps or other features so they have limited motion where they are not supposed to move, and controlled stress where they are expected to move.

Also, take great care to avoid chafing on other moving parts. Especially when travelling round a sharp metal edge. The wire may survive but the insulation may fail resulting in a short. Where necessary add plastic material to the metal on those edges to provide a softer, insulated edge.

Any and all connectors or soldered connections need to have their own stress relief.

ADDITION:

Before you start, figure out your longest length and test the setup up on the floor with that much cable. Finding out you have too much voltage drop along the cable after you tie it all down is rather annoying and embarrassing.

Trevor_G
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You want "test lead wire" — this is wire made with very many fine strands and covered with a very flexible silicone insulation.

Some examples from Digi-Key

Dave Tweed
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  • In general, "Stranded" wire will tolerate many more bending-actions than "Solid" wire. However, avoid having the flex-regions near the termination of the wire (where the wire ends, and connects to something else). This is especially true for when using Stranded wired that has been soldered to a connector. The transition from the soldered region of the stranded wire to the un-soldered region is a zone of stress-concentrations where the wire can become fatigued. – Chris Knudsen Apr 24 '17 at 12:22
  • Use strain relief methods where you can (like cable grips: https://www.digikey.com/products/en/cables-wires-management/cable-and-cord-grips/492?k=cable%20grip ). – Chris Knudsen Apr 24 '17 at 12:22
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    I'd say "automation wire" (wire designed specifically to flex millions of times in high-speed industrial robots) is a better fit. – Bryan Boettcher Apr 24 '17 at 15:06