COLLEGE STATION, TX—Engineers at Texas A&M University have developed functional interlocking metasurfaces (ILMs) that provide more structural strength and stability than nuts, bolts or adhesives. The new type of mechanical joints rely on shape memory alloys.

Similar to Legos or Velcro, ILMs enable the joining of two bodies by transmitting force and constraining movement. Until now, this joining method has been passive, requiring force for engagement.

“ILMs are poised to redefine joining technologies across a range of applications, much like Velcro did decades ago,” claims Ibrahim Karaman, Ph.D., head of the Department of Materials Science and Engineering at Texas A&M. According to Karaman, active ILMs “have the potential to revolutionize mechanical joint design in industries requiring precise, repeatable assembly and disassembly.”

Practical applications include designing reconfigurable aerospace engineering components where parts must be assembled and disassembled multiple times. Active ILMs could also provide flexible and adaptable joints for robotics-enhancing functionality.

“In collaboration with Sandia National Laboratories, the original developers of ILMs, we have engineered and fabricated ILMs from shape memory alloys (SMAs),” explains Karaman. “Our research demonstrates that these ILMs can be selectively disengaged and re-engaged on demand while maintaining consistent joint strength and structural integrity.”

Using additive manufacturing technology, Karaman and his colleagues designed and fabricated active ILMs by integrating SMAs, such as nickel-titanium, which can recover their original shape after deformation by changing temperatures.

“Control of joining technology through temperature changes opens new possibilities for smart, adaptive structures without loss in strength or stability, and with increased options for flexibility and functionality,” says Karaman.

“We anticipate that incorporating SMAs into ILMs will unlock numerous future applications, though several challenges remain,” adds Karaman. “Achieving superelasticity in complex 3D-printed ILMs will enable localized control of structural stiffness and facilitate reattachment with high locking forces. Additionally, we expect this technology to address longstanding challenges associated with joining techniques in extreme environments.”