How NASA Reinvented The Wheel

If you're a long-time blog follower, you might be wondering if this isn't a repeat posting, but it's not.

I did previously post a video titled How NASA Reinvented The Wheel - Shape Memory Alloys, but that one was by Brian at Real Engineering.

The topic are largely the same, though this one goes more deeply into how NiTiNOL works on the stress-strain curve and how the deformation of NiTiNOL is an autenite to twinned martensitic crystal transformation - complete with some nice animations.

It does also mention that the crystal transformation are exo- and endothermic (17:05), something that I don't think I've seen mentioned in other videos. I admit that if hot water is necessary for the martensite to austenite transition, it must be endothermic, but I haven't seen anything demonstrating that transition being both noticeable with bare hands - and a large enough NiTiNOL sample - or via thermal imaging camera. Neat detail there, doctor Derek.

Nitinol: The Shape Memory Effect and Superelasticity

The initial part of this video from The Engineering Guy isn't anything new to most of us teaching material science: NiTiNOL changes shape as its temperature is raised. From there, though, this video does a great job showing animations and graphics explaining what's happening within NiTiNOL when its temperature changes. 

I haven't heard the explanation of the mirrored or non-mirrored rhombic crystals. That's really interesting, and I'd admittedly like to get some confirmation from an expert that it's not an over simplification. 

Bike tires that last a lifetime without any puncture or degradation are inspired by NASA's rover technology

 

I've posted about the NASA rover's memory metal ties on the blog before, and we certainly know that technology developed for the space program often makes its way into our everyday life. So it's not a total shock that those tires would be finding their way into use here on the Earth.

But I wouldn't have bet that the first Earthly use for this tire technology would be on bicycles.

Who knew?

As this article writes, "The airless METL bike tires are crafted out of the Shape Memory Alloy Radial Technology (SMART) – made from strong (like titanium), lightweight yet ultra-elastic material (like rubber) known as NiTinol+."

The METL tires come from The Smart Tire Technology Company and aren't available just yet, though they are taking names for the waitlist. I'm really curious how much those tires would cost and whether they would adaptable from one bike to the next one that a cyclist would purchase. Otherwise, it might not necessarily be a great investment.

Shape-Morphing Smart Materials; The Future of Assistive Technology | Mark C Ransley | TEDxUCL

That's a fascinating idea - wearing a suit of materials that could stiffen, expand, and contract with the application of electricity. Memory metal does seems fairly well a natural for that. Interestingly, the talk never mentions them.

I appreciate the speaker's sense of humor as he goes through each of the other options

• dielectric polymers - perfect except for needing "tens of thousands of volts to operate...enough to give you a pretty nasty electric shock" (4:46)
• carbon nanotube aerogel - perfect except for also needing tens of thousands of volts to operate
• nylon fishing line muscles - relies on heat, much faster to heat up (and contract) than to cool down (and release)
• solid state actuators - either fast or strong but not currently both
• architectured materials - the current choice of the speaker's research group

The use of computer simulations to design materials - 3d printable structures - to predict the flexibility and changing shape of the material is really interesting.

And I'm amazed that the research group is looking at 3d printed materials - assumedly polymer materials - was the outcome. 

I'd very much like to see larger version of the materials that the speaker demonstrates (much too far from the camera) at 11:45. It's made from laser sintered nylon. 

How NASA Reinvented The Wheel - Shape Memory Alloys

Was the Mars Rover really lowered down by flying platform and hooks and winches?

That's kind of awesome!

We get to see the reveal of the memory metal 'tire' at 4:10 in the above video, a mesh tire made of what looks like a chain mail of nitinol. Then there's a great explanation of why nitinol is a super-elastic material (using our old friend, the stress-strain curve) and some nice atomic-level diagrams.

Then we get a bunch of close-up video of the wheel deforming and returning to its original shape.

It's a brilliant idea.

Shape Memory Alloy demonstration

Let's start the year off with a little art.

Because the video is so short, I'll simply copy the description from YouTube,

Shape memory alloys are materials that are able to 'remember' their shape under different conditions. Here we show an example where the petals of the flower are made from a shape memory alloy that have been conditioned to a shape representing closed petals at room temperature and an open petal shape at higher temperatures, achieved using a hot air blower. The flower can then be made to open and close by heating and cooling. Whilst this is an interesting example of how shape memory alloys can be used in art, they can also be used in a range of engineering applications from medical devices to automotive valves.

For more information on studying metallurgy and materials science at the University of Birmingham, please go to: https://www.birmingham.ac.uk/schools/metallurgy-materials/index.aspx

Smart Materials of the Future - with Anna Ploszajski

"Rock-paper-scissors is a game that you use to compare materials' properties. The rock blunts the scissors because rock is harder than stainless steel."

C'mon, nerd, rock-paper-scissors is just a game like mumbledepeg or roshambo.

The simplicity of showing a smart material via pine cones is brilliant.

Oh, I found a definition of smart materials that I very much like (via BBC): "[s]mart materials have properties that react to changes in their environment. This means that one of their properties can be changed by an external condition, such as temperature, light, pressure or electricity. This change is reversible and can be repeated many times."

Other smart materials mentioned in the video are lime mortar from the Egyptian pyramids, piezoelectric quartz crystals, thermochromic pigments (on a mug), NiTiNOL, and ferrofluids. Most of the latter materials are applied to the future of airplane design.

Watch NASA Plane Fold Its Wings Mid-Flight

We've been hearing for a few years that plane designers are trying to use NiTiNOL to change the angle of the wings or of the fins (my terms, probably not the term of the designers) behind the jet engines.

Now, it looks like NASA might've been successful in adjusting the wing angle using a memory alloy.

And, if you were curious about the size of the plan we see above, here's a longer video with a little more context and without the voice-over.

Mitch Anthamatten Explains a Shape-Memory Cycle Involving Strain Induced Crystallization

Wait, a shape memory polymer?

There's a bunch of good connections here to what we teach in our material science course.

• The polymer switches from being largely amorphous to largely crystalline on addition of strain.
• The addition of heat energy then causes the polymer to shift back to amorphism.
• The phase change happens around body temperature, like the stints we talk about.
• We have a solid-state phase change.
• At 0:55, the professor says the energy is 'enough to melt those crystals.' I'm way less knowledgeable and more a neophyte about all this than he is, but that sounds wrong to me. I don't think of a crystalline solid changing to an amorphous solid as 'melting.'

All that in less than two minutes time...

That's better than watching the Kentucky Derby.

Memory alloy that bounces back into shape 10 million times

Admittedly, I'm a bit far from testing any of my samples of NiTiNOL ten million times, so I can't guarantee that my metal samples don't survive ten million cycles.

Professor Manfred Wuttig, however, seems able to make an actual claim that his new memory alloy (NiTiNOL doped with some copper), can survive ten million cycles.

And that's certainly something. In fact, it's the kind of something that makes a memory alloy far more useful. See, most memory alloys return to their shape above their transition temperature, but every transition sees the sample adding dislocations to the original shape during the transition leading to eventual functional fatigue and a change in the transition temperatures. After only a few transitions, the sample is less and less back to its original shape. A sample that can return to its original shape for ten million cycles, though, is a significant breakthrough.

Check out one of the these articles covering the original research...

• Popular Mechanics
• BBC
• Born2Invest

Nitinol Teaspoon That Bends!

Someone fetch me the Great Randi...or at least Uri Geller.

C'mon, those references aren't that old, are they?

Whatever...some people just don't appreciate culture. Everyone, though, can appreciate this wonderful demonstration of a fun application of nitinol, a shape memory alloy of NIckel-TItanium (from the Naval Ordinance Lab).

For a scant $50 or so, I'd actually be pretty tempted to order one myself if they weren't currently out of stock.

Material Marvels with Ainissa Ramirez - Shape Memory Alloys

Those Lego figures stuck to the boards are ones I'm trying to collect. I have the wolfman, but I need all the rest. Wonder is Ainissa would send them my way.
Ainissa actually does a great job explaining why the memory alloy switches back and forth as temperature is raised - at least at a low level of explanation - at 2:20, explaining that the material switches from monoclinic to cubic crystal structures.

What is ANGIOPLASTY and STENTING?

I'm guessing percutaneous coronary intervention is a phrase that is just casually thrown around in some medical fields, but it seems a pretty daunting introduction to me. The animation shows how balloons and stents - assumedly made of memory metal - are used to open a clogged artery.

It's a great explanation and illustration of a fairly complex process that would be nigh impossible to actually film from this same perspective.

Now I just need to get my hands on a stent to show in class.

Metals with a Memory

Memory metals - nitinol being the one with which I am most familiar - are a fascinating material with their solid state transition radically changing the material's macroscopic shape. The old chestnut of turning a straight piece into a coil in hot water is nice, but the creativity of using metals with different transition temperatures to make a little sculpture here with uncurling biceps, straightening spine and neck, able to 'stand' straight up as the temperature rises is very well done.

Nitinol Experiments

Scientific Tuesday's presents a bunch of easy trick to do with Nitinol.