3 ms·
> Between 60 and 160 C, the coils contracted, pulling the > attached threads, and tightening the cuff. I have no background in material sciences, and I'm
by jonhohle 12y ago
> Between 60 and 160 C, the coils contracted, pulling the
> attached threads, and tightening the cuff.
I have no background in material sciences, and I'm sure the researches thought of this, but couldn't the model have been reversed to expand under exposure to heat and have trained the contracted state? This way, electricity would only be required to enter the suit, and the steady state would require no external power or mechanism. This seems like it would be safer in a situation like extreme low pressure where any failure would be fatal.
- theandrewbailey 12y agoAlternatively, the activation temperature could be lowered to body temperature, only requiring cooling to exit (or enter) the suit. As long as sufficient metabolism happens within, the suit would remain sufficiently pressurized. Standard HN disclaimer: IANAMS.
- saosebastiao 12y agoIts been more than a decade since I was an undergrad Materials Engineering student (I didn't even graduate in in that field), but I think the answer would be the same as for any coil. It is easy to elongate a compressed coil through deformation, but it is much harder to compress an elongated coil through deformation (while preserving the coil's properties...you can definitely smash one into a ball quite easily, but it no longer acts like a coil). With SMAs, there aren't two memories, there is a memory and a non-memory state. The non-memory state is like any other wire, deforming with physical force. In order for your proposal to work, you would have to take an elongated memory coil, and then physically deform it into a compressed coil to get the contracted state. That is a lot harder to do than to take an elongated coil and return it to a compressed memory state.