6 ms·
Nitinol Engines (1992)
- eeZah7Ux 7y ago"Free Energy" wackos? facepalm
- 52-6F-62 7y agoThe attached CNN video is fascinating. It seems a shame that the research seemingly abated. Can anyone else speak to whether more work is being done into the metal or its applications?
- thecount122195 7y agoI recently went to a talk at my university on microcombusters but the professor (I cant remember his name off the top of my head) was also working on small insect like drones. There were videos of nitonol powered beetle crawling and a non flying prototype of a bee drone with nitinol wing flappers. Rather cool but he said they are incredibly inefficient compared to traditional electric motors.
- ncmncm 7y agoYou can make very tiny motors with nitinol, but it is a real waste of the capability of the material. 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.
- kybernetikos 7y agoWhat sort of orders of magnitude are we talking about here? Could you wind a watch with body heat?
- thecount122195 7y agoYea thats how it tied in with the over all microcombusters talk, they were using tiny swiss roll burners to power the nitinol motors. Due to liquid fuels having higher energy densities than batteries apparently they could go for much longer than their electrical counterparts even though they weren't as efficient.
- wigiv 7y agoI balked at first glance because "free energy," but here we have a unique method for turning thermal into kinetic energy. Slightly outside the bounding box of this energy system, of course, lies the expending of more energy than what's produced to keep the hot water hot and the cold water cold. 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?
- GuB-42 7y agoYes, I wonder why "free energy". It is not free energy, it is a respectable, thermodynamic law abiding machine. According to what I've seen here, it is good for making tiny engines but the efficiency is low.
- amluto 7y agoWikipedia claims that one of the problems of Stirling engines is that they depend on the rate at which heat can be transferred to a gas. A Nitinol engine has a metal as its working object (functionally like a working fluid, just not actually fluid), so the thermal conductivity could be considerably better. The result could plausibly be higher power for a given amount of metal in use.
- imode 7y agoWe already have this unique method via Nichrome wire. You can see a really neat application of this in a common toaster here: https://www.youtube.com/watch?v=1OfxlSG6q5Y https://www.youtube.com/watch?v=1OfxlSG6q5Y
- dirktheman 7y agoTechnology Connections is my favorite YouTube channel. He's just so good in explaining the technological intricacies of everyday things, and his humor is so wonderfully snarky. I highly recommend turning on the subtitles as well, he puts a lot of effort in them.
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- dmitrygr 7y agoNitinol is also used in the smallest & lightest servos you can buy: https://www.micronwings.com/Products/Servo%20Biometal/BioMetalIndex.shtml https://www.micronwings.com/Products/Servo%20Biometal/BioMet...
- mojomark 7y agoApplication of the subject aside, Nitinol is fun to play arround with. If you want to tinker, this book comes with a coil of Nitnol wire to use in the demos contained in the book: https://www.robotshop.com/en/muscle-wires-sample-kit.html https://www.robotshop.com/en/muscle-wires-sample-kit.html 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.
- Raphmedia 7y agoThere is also a deluxe kit that comes with more wire. 1 meter of each kinds instead of 20cm & 40cm wires. https://www.robotshop.com/en/muscle-wires-deluxe-kit.html https://www.robotshop.com/en/muscle-wires-deluxe-kit.html (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.)
- proee 7y agoOne problem with Nitinol is that it has a limited number of cycles before the material becomes weak and then breaks or no longer returns to its proper state. This is a major limitation on "muscle wires" when using them for products that require a high number of cycles of greater than 100k.
- ncmncm 7y agoWhere are you getting this? The credible sources I find say they improve with use.
- proee 7y agoHere is a good article showing thermal and mechanical fatigue. You can see under moderate mechanical stress, it fails between 1e5 and 1e7 cycles. While that sounds like a lot, consider that there are 3e7 seconds in a year. So if you had a mechanical device that operated at 1HZ, it would fail in less than a year. https://www.nitinol.com/wp-content/uploads/2011/05/Pelton-2011-NiTi-Fatigue-Microstructures-and-Mechanisms1.pdf https://www.nitinol.com/wp-content/uploads/2011/05/Pelton-20...
- blincoln 7y agoHow difficult/expensive is it to recycle the material? i.e. if one had some sort of wonder-generator based on it, would it make sense to use a model where once per year, the owner sends the nitinol pieces back to the manufacturer (who recycles them) in exchange for a discount on replacements? I assume since titanium is part of the alloy, just discarding it after use is probably not great from a cost perspective.
- Liquix 7y agoBanks reported no weakness nor degradation in his Nitinol engine after 20,000,000 revolutions. Any idea why there's such a big difference between the numbers reported in each paper?
- tshanmu 7y agoAny advice on where to get started on nitinol alloys/engines as a layman tinkerer?
- leptoniscool 7y agoThe "Earth Engine" is also similar?
- tke248 7y agoSeems like you could make a fan out of this stuff that could be used to vent the heat from air conditioning units instead of using electric fans.
- andbberger 7y agoI guess you could... but that would be complicated and expensive and electric fans are pretty efficient anyway.
- frogger101 7y agoThe omnipod insulin pump, by insulet, uses this in a clever way. https://journals.sagepub.com/doi/full/10.1177/1932296818798836 https://journals.sagepub.com/doi/full/10.1177/19322968187988...