In my experience, challenges of Nitinol (a.k.a. 'muscle wire') for use as a electoactive linear actuator is that if you're not careful you can over heat (or apply too much tensile load to) the wire and it will permanently deform (lose it's memory). Still, and interesting material to toy around with.
(Disclaimer: I work at RobotShop in their Web & IT team -- I have nothing to do with marketing though and I'm just a fan of Hacker News.)
This is a major limitation on "muscle wires" when using them for products that require a high number of cycles of greater than 100k.
So if you had a mechanical device that operated at 1HZ, it would fail in less than a year.
I assume since titanium is part of the alloy, just discarding it after use is probably not great from a cost perspective.
But using natural low-grade temperature differentials as the author suggests, what might this arrangement achieve that a Stirling engine doesn't? More torque? Advantage of fewer moving parts? Novelty only?
excellent writing and delivery, and yes, usually an easter egg or two in the CC ;)
According to what I've seen here, it is good for making tiny engines but the efficiency is low.
Can anyone else speak to whether more work is being done into the metal or its applications?
Those work by using electrical resistance to heat a sample, which moves, and then cools off and can be moved back again, such as by a spring. Turning high-grade electrical energy to low-grade heat, thence to motion, wastes most of it (probably ~70%) vs. a magnetic motor that wastes normally less than 10%.
But nitinol can extract high-grade mechanical energy (kinetic energy of motion, or potential spring tension) from existing low-grade heat by conducting the heat from a higher temperature source to a lower temperature sink. I don't know why the other commenter claimed they wear out; the reported experience from labs was that after 20M cycles they were (a little) stronger than they began.