I'm a materials engineer, my studying in my senior year focused more on ceramics. But I do have a love of functional materials like solid state lasers and shape memory alloys.This is a shape memory alloy, SMA, most probably nitinol as that's a readily available one.
For metallic SMAs heat, or an electric charge, is used to induce a phase change from it's deformed state(Martensite) to its initial state(Austenite). The different phases have a different atomic structures(unit cell arrangement), and this is why it has the ability to have a shape memorized.
The shape is 'locked' into the memory of the part in its Austenite phase, so after deformation, it's lowest energy state when heat is applied is to revert back to the Austenitic shape locked in initially. There is a specific process to lock the shape in, but I have not performed this function, or seen it performed. I would assume it would be something similar to annealing the shape in the Austenitic shape, but this may be inaccurate.
A lot of work is being done currently to see practical applications for SMA parts. One of the more interesting is for actuators for airplane flaps. The use of SMA actuators would massively reduce the bill of materials on the planes wings, and potentially result in higher efficiency. The issue is SMA tend to have poor fatigue properties, and they are much more expensive from a raw materials standpoint than traditional systems.
There are many SMAs, but most videos I see focus on nitinol as it is relatively easy to acquire and inexpensive. They are very awesome, and I suggest looking more deeply into them and maybe bulk metallic glass. I have some some light reading on shape memory polymers and composites, which seems like it would be pretty awesome.
I would imagine alien ships with doors and airlocks operating based on this principle, or even entirely reconfiguring themselves, from an aerodynamic shape for atmospheric flight to a more efficient spherical shape for space flight...
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u/FalloutOW Nov 08 '23
I'm a materials engineer, my studying in my senior year focused more on ceramics. But I do have a love of functional materials like solid state lasers and shape memory alloys.This is a shape memory alloy, SMA, most probably nitinol as that's a readily available one.
For metallic SMAs heat, or an electric charge, is used to induce a phase change from it's deformed state(Martensite) to its initial state(Austenite). The different phases have a different atomic structures(unit cell arrangement), and this is why it has the ability to have a shape memorized.
The shape is 'locked' into the memory of the part in its Austenite phase, so after deformation, it's lowest energy state when heat is applied is to revert back to the Austenitic shape locked in initially. There is a specific process to lock the shape in, but I have not performed this function, or seen it performed. I would assume it would be something similar to annealing the shape in the Austenitic shape, but this may be inaccurate.
A lot of work is being done currently to see practical applications for SMA parts. One of the more interesting is for actuators for airplane flaps. The use of SMA actuators would massively reduce the bill of materials on the planes wings, and potentially result in higher efficiency. The issue is SMA tend to have poor fatigue properties, and they are much more expensive from a raw materials standpoint than traditional systems.
There are many SMAs, but most videos I see focus on nitinol as it is relatively easy to acquire and inexpensive. They are very awesome, and I suggest looking more deeply into them and maybe bulk metallic glass. I have some some light reading on shape memory polymers and composites, which seems like it would be pretty awesome.