Interlocking metasurfaces get a grip with shape memory alloys

ILMs are said to offer the potential to transform mechanical joint design in manufacturing for aerospace, robotics and biomedical devices.   

“ILMs are poised to redefine joining technologies across a range of applications, much like Velcro did decades ago,” said Dr Ibrahim Karaman, professor and head of the Department of Materials Science and Engineering Department at Texas A&M. “In collaboration with Sandia National Laboratories, the original developers of ILMs, we have engineered and fabricated ILMs from shape memory alloys. Our research demonstrates that these ILMs can be selectively disengaged and re-engaged on demand while maintaining consistent joint strength and structural integrity.” 

The team’s findings are detailed in Materials & Design.   

ILMs enable the joining of two bodies by transmitting force and constraining movement, but until now this joining method has been passive, requiring force for engagement.

Using 3D printing, the teams designed and fabricated active ILMs by integrating SMAs, specifically nickel-titanium, which can recover their original shape after deformation by changing temperatures.

According to Texas A&M, 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.   

“Active ILMs have the potential to revolutionise mechanical joint design in industries requiring precise, repeatable assembly and disassembly,” said Abdelrahman Elsayed, graduate research assistant in the materials science and engineering department at Texas A&M.   

Practical applications of ILMs include designing reconfigurable aerospace engineering components where parts are assembled and disassembled multiple times. Active ILMs could also provide flexible and adaptable joints for robotics-enhancing functionality. In biomedical devices, the ability to adjust implants and prosthetics to body movements and temperatures could offer a better option for patients.   

The current findings utilised the shape memory effect of SMAs to recover the ILMs’ shape by adding heat. The researchers hope to build on these findings by using the superelasticity effect of SMAs to create ILMs that can withstand large deformation and instantaneously recover under very high stress levels.  

“We anticipate that incorporating SMAs into ILMs will unlock numerous future applications, though several challenges remain,” Karaman said in a statement. “Achieving superelasticity in complex 3D-printed ILMs will enable localised 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. We are highly enthusiastic about the transformative potential of ILM technology.”