5 ms·
Terfenol-D
- amelius 5y agoIs this the magnetic complement of the piezo-electric sensor/actuator?
- yetihehe 5y agoYes. > The alloy has the highest magnetostriction of any alloy, up to 0.002 m/m at saturation; it expands and contracts in a magnetic field.
- formerly_proven 5y agoI think that would be electrostriction <=> magnetostriction. The ...striction effects are non-linear, while piezo... is linear.
- yetihehe 5y ago...striction effects are linear. Piezo elements are electrostriction. This material is used instead of piezo in deep sea sonars because it can work at higher pressures.
- Munksgaard 5y agoWhy is this (almost) at the top of HN? Nothing really stood out for me after a quick skim of the wiki page. Is there some additional context that I'm not aware of, or is this just a case of "huh, cool"?
- stinos 5y agoWhy is this (almost) at the top of HN? .... is this just a case of "huh, cool"? That's why I upvoted indeed and it's one of the reasons HN is what it is. It's one of the welcome additions to the software- and hardware-related posts which, let's be honest, often go on and on about the same subject. Moreover if we're lucky someone here actually works in a field which uses this materail and can bring up interesting stories.
- space_ghost 5y agoFully agree. The best HN posts are the ones where a few experts in an esoteric field can totally geek out about their art. I may not understand half of what they say but it's always fully interesting.
- ganzuul 5y agoPerhaps something that could be used in the MEGA drive.
- hnbad 5y agoHad to look up what you meant but I think it's this: https://medium.com/predict/mega-drive-the-tech-that-promises-near-light-speed-travel-d9d9ded1ca44 https://medium.com/predict/mega-drive-the-tech-that-promises... To clarify: to people outside North America "Mega Drive" normally refers to the Sega Genesis gaming console.
- kragen 5y agoIt's a violation of the conservation of momentum; it's extremely unlikely to be real.
- ganzuul 5y agoGeneral relativity does not conserve energy.
- thechao 5y agoOk, I’ll bite: how do we manipulate local nonrelativistic spacetime curvature near a spaceship to take advantage of the magnetorestrictive properties of this material? I’ve just finished my last undergrad-equivalent course GR, so voice this in the appropriate math.
- michael-ax 5y agothrow when heavy, pull when light. its crazy. https://www.scientificamerican.com/article/the-good-kind-of-crazy-the-quest-for-exotic-propulsion/ https://www.scientificamerican.com/article/the-good-kind-of-... https://owlcation.com/stem/What-is-the-Mass-Effect-Gravity-Assist-or-MEGA-Drive https://owlcation.com/stem/What-is-the-Mass-Effect-Gravity-A...
- zafka 5y agoI have a box with samples of this somewhere behind me on my shelf. :) Been meaning to find some time to play with it.The samples came from: Extrema Products Inc. - Subsidiary of Edge technologies. I received a kit with a variety of little rods and a 1.5" or so disk.
- Zenst 5y agoDoes this material also produce a magnetic field when stressed?
- michael-ax 5y agoI'm proud of everyone else that picked up on the piezo analogy! so cool! Here's a deeper look on the idea and the mass-change experiments: https://owlcation.com/stem/What-is-the-Mass-Effect-Gravity-Assist-or-MEGA-Drive https://owlcation.com/stem/What-is-the-Mass-Effect-Gravity-A... edited to add video and sciAm paywall links: https://www.youtube.com/watch?v=_INqXPFdJM8 https://www.youtube.com/watch?v=_INqXPFdJM8 https://www.scientificamerican.com/article/the-good-kind-of-crazy-the-quest-for-exotic-propulsion/ https://www.scientificamerican.com/article/the-good-kind-of-...
- dr_dshiv 5y agoHow does it generate low frequencies? And what are the properties of low frequency sonar? I've been working with voice coil tactile speakers and it is HARD to make powerful low frequencies.
- trasz 5y agoI wonder, how strong, physically, is it? I mean, what’s the formula for computing the mechanical force it can actuate with, compared to eg an electromagnet?
- anonu 5y agoStuff like is what adds up to make USA submarine technology probably the most superior tech in the world.
- captainmuon 5y ago0.002 m/m doesn't sound very much. I was imagining something that visibly changes shape in a magnetic field, like some kind of magnetic magic goo...