A plane wing that changes shape in flight to better handle the airflow crossing it could be on the horizon thanks to a materials science advance from researchers in Stockholm. The trick involves the melting and hole-punching power of lasers.
Researchers out of the KTH Royal Institute of Technology in Stockholm, Sweden, experimented with paraffin. Working with a 2D version of the material, they were able to use lasers to poke tiny holes through the wax and then melt it very gradually to direct the liquid paraffin where they wanted it thanks to a tilting stage. The effect was a laser-induced shape change that took place over several cycles of laser pulses and stage tilting.
“Everything is just shifted a few tens of micrometers during each cycle,” said study co-author Wouter van der Wijngaart. “It can reshape objects to pass through narrow gaps and reconstitute them into any target shape. This could enable limitless on-the-fly creation of tools and other objects, without introducing additional materials.”
Even though the breakthrough came using a 2D material, the researchers say that the findings will translate to 3D materials. Such a breakthrough, they say, could lead to airplane wings that could self-modify to optimize drag, cars that become more aerodynamic on the fly, or even office spaces where seats are created on demand.
The process by which the material was reshaped in this study is known as phase change pumping.
"By melting part of an object with a hot spot, such as a laser spot, a liquid zone is created within the material," explained the researchers in a report on the findings published in the journal Advanced Functional Materials.
"The movement of the hot spot inside the object generates a melting front, where the laser heats the material above its melting point, and a freezing front, where heat loss to the surroundings cools the material below its freezing point," they added. "Most materials decrease in density during melting and increase during freezing, resulting in material flow through the liquid zone from the melting front to the freezing front."
While the experiments involved in this particular study introduced laser heat externally, the researchers say that embedding a heat source in the material could lead to more automated shape shifting in practical applications.
You can see the technique at work in the following video, where the research team morphed the paraffin into the three letters of their institute.
Source: KTH
