SoylentNews is people
SoylentNews
from the forget-the-puncture-kit,-give-me-a-welding-torch dept.
Chainmail tires re-invent the wheel to get future NASA rovers rolling.
NASA has developed chainmail tires with a memory and thinks they'll do the trick for future rovers.
As readers of The Register's coverage of the Curiosity Rover may recall, the vehicle has experienced considerable wheel damage that has led to changes to its route in 2014 and a 2017 software update to preserve the wheels and provide better grip.
Throw in the fact that it's not yet possible to send a spare wheel to Mars and have it fitted, and NASA has a clear need for more robust tires.
Enter a technology called "spring tires" that use a tubular structure of steel mesh – think tire-shaped chainmail - to cushion rovers as they roll. Spring tires have many fine qualities as the mesh forms a pattern that provides good grip on many surfaces. Mesh is also light by nature and can survive some damage. But spring tires don't deform well: if one rolls over a sharp rock, it can acquire a dent - or "plastic deformation" as NASA boffins put it.
The tires use a nickel titanium alloy that can endure plastic deformation.
(Score: 3, Informative) by Anonymous Coward on Saturday November 25 2017, @01:01PM (3 children)
Compare this new "chainmail" tire to the original General Motors designed Lunar Rover tire,
https://en.wikipedia.org/wiki/Lunar_Roving_Vehicle#Wheels_and_power [wikipedia.org]
Very similar woven mesh design. The Lunar Rover tire has Titanium "tread" elements attached and there are various other detail differences.
Chainmail is a poor term, the new rover tire does not have little links looped together like actual chainmail (as used for the joints in medieval armor).
Why not acknowledge that this new wheel is a development of the older design?
(Score: 2) by mhajicek on Saturday November 25 2017, @05:56PM (2 children)
Indeed. Nothing to do with chainmail, these are just a material upgrade of the old lunar rover wheels. My question is how the nitinol will perform in the extreme temperature variations of extraterrestrial environments. My company makes nitinol medical implants, and liquid nitrogen is used to put the material into it's squishy state where it doesn't spring back until warmed. Then it's put on a forming mandrel and heated in molten salt to set the new shape. These critical temperatures can be controlled by the alloy mix, but I don't know how far. If the environment is too cold for the alloy the wheels would just squish and stay there
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek
(Score: 0) by Anonymous Coward on Saturday November 25 2017, @06:40PM (1 child)
A friend who had recently retired from Goodyear R&D, was asked to work on a volunteer project about 10 years ago -- re-create the Lunar Rover wheels/tires. While they had a sample to look at, the original tooling was gone, along with the know-how of the original makers. They had a devil of a time, but eventually worked out how to weave the wire and so on.
One possible reason for Nitinol would be to relatively easily form it to the correct curve(s), before weaving? Then it would hold its shape instead of trying to spring back to straight like the original galvanized music wire (spring wire). But I take your concern about extreme temps in space, one would hope that they have considered this!
How is Nitinol for abrasion resistance? Music wire is pretty darn hard, but if (as noted in Wiki) it was galvanized, that is not a hard surface. Maybe the Zinc was just to prevent rusting/oxidation while on Earth, before launch?
(Score: 2) by mhajicek on Saturday November 25 2017, @10:13PM
I think it's pretty good for wear resistance. I know it eats endmills like popcorn when you machine it unless you're running liquid nitrogen for coolant. It's also what's called "superelastic", look up the yield curves.
The spacelike surfaces of time foliations can have a cusp at the surface of discontinuity. - P. Hajicek