You’ve likely heard of Nitinol wire before, but we suspect the common base knowledge doesn’t go much beyond repeating that it’s a shape-memory alloy. [Bill Hammack], the Engineer Guy, takes us on a quick journey of all the cool stuff there is to know about Nitinol and shape-memory alloys.
The name itself is like saying Kleenex when you mean tissue, or using the V-word when you mean hook and loop fasteners. The first few letters of Nickel Titanium Naval Ordnance Laboratories combine to form the name of what is essentially a nickel-titanium alloy developed in 1962: Nitinol. It’s called shape-memory because you can stretch or bend it at room temperature and it will return to the original shape when heated at around 75 C (167 F). This particular metal can do that because its bonds form a “twinned structure” of rhombus shapes — bending or stretching moves those rhombuses (or rhombi, take your pick) but doesn’t change which atoms are bonded to one another.
Has this material science excursion bored you to tears yet? That’s why we love [Bill’s] work. He has always done a fantastic job of demystifying common mysticism and this is no different. The video below does a much better job of illustrating what we’ve described above, but also pull out a Nitinol engine for added wow-factor. A straight piece of Nitinol is bent into a loop around two pulleys. The lower pulley is submerged in hot water, causing the Nitinol to want to straighten out, but it loops back to the top pulley, bending and cooling in the air and creating a lever effect that drives the engine. We saw a more complex version of this concept last year.
You know those eyeglass frames you can bend in any way and they’ll pop back to the original shape? They’re taking advantage of the super-elasticity of Nitinol. [Bill] also recounts uses as stents for medical applications, and oddball engineering tricks in the automotive industry.
It’s great to see the Engineer Guy back. Favorites of ours have been the science behind disposable diapers and the aluminum beverage can. More recently he released Faraday’s lecture series, wrote a book on airships, appeared on Outlaw Tech on the Science Channel, and started a family. Thanks for fitting these illustrative videos in when you can [Bill]!
Continue reading “The Metal That Never Forgets: Nitinol And Shape-Memory”
We’re beginning to think the “S” in [Jeremy S Cook] stands for strandbeest. He’ll be the talk of the 4th of July picnic once he brings out his latest build—a weaponized, remote-controlled strandbeest that shoots bottle rockets. There are a bank of money shots up on Imgur.
This ‘beest is the natural next step after his remote-controlled walker, which we featured a month or so ago. Like that one, the locomotion comes from a pair of micro gear motors that are controlled by an Arduino Nano over Bluetooth. The pyrotechnics begin when nitinol wire cleverly strung across two lever nuts is triggered. All the electronics are housed inside a 3D-printed box that [Jeremy] designed to sit in the middle of the legs. We love the face plate he added later in the build, because those gumdrop LED eyes are sweet.
Can you believe that this vehicle of destruction began as a pile of innocent, pasta-colored pieces of kit? We dig the camouflaged battleship paint job, ’cause it really toughens up the whole aesthetic. And really, that’s probably what you want if you’re driving around a spindly beast that can just shoot rockets whenever. Let’s light this candle after the break, shall we?
Continue reading “R/C Rocket-Beest Burns Up Fuses Out There Alone”
Most of what we see on the wearable tech front is built around traditional textiles, like adding turn signals to a jacket for safer bike riding, or wiring up a scarf with RGB LEDs and a color sensor to make it match any outfit. Although we’ve seen the odd light-up hair accessory here and there, we’ve never seen anything quite like these Bluetooth-enabled, shape-shifting, touch-sensing hair extensions created by UC Berkeley students [Sarah], [Molly], and [Christine].
HairIO is based on the idea that hair is an important part of self-expression, and that it can be a natural platform for sandboxing wearable interactivity. Each hair extension is braided up with nitinol wire, which holds one shape at room temperature and changes to a different shape when heated. The idea is that you could walk around with a straight braid that curls up when you get a text, or lifts up to guide the way when a friend sends directions. You could even use the braid to wrap up your hair in a bun for work, and then literally let it down at 5:00 by sending a signal to straighten out the braid. There’s a slick video after the break that demonstrates the possibilities.
HairIO is controlled with an Arduino Nano and a custom PCB that combines the Nano, a Bluetooth module, and BJTs that drive the braid. Each braid circuit also has a thermistor to keep the heat under control. The team also adapted the swept-frequency capacitive sensing of Disney’s Touché project to make HairIO extensions respond to complex touches. Our favorite part has to be that they chalked some of the artificial tresses with thermochromic pigment powder so they change color with heat. Makes us wish we still had our Hypercolor t-shirt.
Nitinol wire is nifty stuff. You can use it to retract the landing gear on an RC plane, or make a marker dance to Duke Nukem.
Continue reading “HairIO: An Interactive Extension Of The Self”
There are individuals who push tools, materials, and craftsmanship to the limit in the world of micro RC aircraft, and [Martin Newell] gives some insight into the kind of work that goes into making something like a 1:96 scale P-51 Mustang from scratch. The tiny plane is 100% flyable. It even includes working navigation lights and flashing cannons (both done with 0402 LEDs) and functional, retractable landing gear. It weighs an incredible 2.9 grams. Apart from the battery, everything in the plane was built or assembled from scratch. A video is embedded below.
Continue reading “A Micro RC Plane Builder Shares His Tricks”
Nitinol is a kind of wire that has a memory. If you heat it, it tries to return to the shape it remembers. [Latheman666] recently posted a video (see below) of a Nitinol engine that uses a temperature differential to generate motion.
[Dr. Alfred Johnson] holds a patent on this kind of motor. The concept sounds simple enough. A Nitnol spring shrinks in hot water and expands in cold. The spring is looped over two pulleys. One pulley is geared so it has mechanical advantage over the other one so that there’s a net torque which moves the hot part of the spring towards the cold side, and feeds more cold spring into the hot water. The cold spring then contracts and the entire process starts again.
We haven’t entirely gotten our heads around the gearing, but it seems plausible. On the other hand, this video was posted on April 1. What say you, Hackaday Commenteers?
Continue reading “Doc Johnson’s Shape Memory Motor”
[serdef] is clearly just having a little bit of fun here. One never needs a whiteboard pen that’s syncronized by MIDI to dance along with the theme from Duke Nukem.
But if you had all of the parts on hand (a highly liquid MIDI-driven relay board that connects straight up to a soundcard, some muscle wire, tape, and a whiteboard pen, naturally) we’re pretty sure that you would. You can watch the dancing pen in a video below the break.
The project is really about documenting the properties of [serdef]’s muscle wire, and he found that it doesn’t really contract enough with a short piece to get the desired effect. So he added more wire. We’ve always meant to get around to playing with muscle wire, and we were surprised by how quickly it reacted to changing the voltage in [serdef]’s second video.
Now the dancing pen isn’t the most sophisticated muscle wire project we’ve ever seen. And that award also doesn’t go to this Nitinol-powered inchworm. Did you know that there’s muscle wire inside Microsoft’s Surface?
Continue reading “Muscle Wire Pen Dances To Duke Nukem”
[Steven’s] at it again with another cool science experiment that isn’t too difficult to do. This time he’s made himself a Nitinol wire inchworm, which actually moves across the table when you apply a switching electrical current to it!
Nitinol is a shape memory alloy which has a cool property that causes it to retain (and return to) a preset shape when heat (or electricity!) is applied. It’s actually quite simple — he’s wrapped the Nitinol wire tightly around a nail, and then heated it to set it to a coiled shape. Now the Nitinol spring can be stretched out flat, but as soon as it is heated, it will attempt to return to its coiled state!
Using some balsa wood and a few other odds and ends he’s taken advantage of this memory effect to make an electric inchworm — check it out after the break!
Continue reading “Making A Nitinol Wire Inchworm”