Active interlocking metasurfaces enabled by shape memory alloys

• Published in: Materials & design Vol. 244; no. C; p. 113137
• Main Authors: Elsayed, Abdelrahman, Guleria, Taresh, Atli, Kadri C., Bolmin, Ophelia, Young, Benjamin, Noell, Philip J, Boyce, Brad L, Elwany, Alaa, Arroyave, Raymundo, Karaman, Ibrahim
• Format: Journal Article
• Language: English
• Published: United Kingdom Elsevier Ltd 01.08.2024; Elsevier
• Subjects: Additive manufacturing; Interlocking metasurfaces; Laser-powder bed fusion; NiTi; Shape memory alloys; Shape memory alloys; Interlocking metasurfaces; Additive manufacturing; Laser-powder bed fusion; NiTi
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2024.113137

[Display omitted] •Successfully manufactured two complex active NiTi Shape Memory Alloy (SMA) Interlocking Metasurfaces (ILMs) using laser powder bed fusion with a structured process optimization framework.•Finite element analysis and digital image correlation accurately predicted and validated strain behaviors during engage-disengage cycles.•ILMs exhibited high locking forces, complete shape recovery, and robust cyclic stability, demonstrating functional durability. Interlocking metasurfaces (ILMs) are a newly developed joining technology that relies on arrays of interlocking features that transmit force and constrain motion between adjoining bodies in one or more directions. This study explores harnessing the shape memory effect (SME) in Nickel-Titanium shape memory alloys (NiTi SMAs) in structures fabricated using additive manufacturing (AM) to advance the development of active ILMs by creating unit cells that open or close at specific temperatures. The study encompasses designing and fabricating two distinct interlocking array configurations using near-equiatomic NiTi powder and the laser powder bed fusion (L-PBF) AM technique, following a previously developed AM process optimization framework to manufacture defect-free parts. To guide the design process, finite element analysis (FEA) was employed to predict strain values during engage-disengage cycles. The martensitic transformation characteristics of the ILMs were characterized. Thermomechanical testing revealed that the ILMs demonstrate high locking force once engaged, coupled with complete shape recovery and good cyclic stability. Digital image correlation (DIC) was also employed to validate the FEA predictions during the engage-disengage cycles. The results indicate that NiTi SMA-based ILMs can be designed and fabricated into complex shapes using L-PBF. By leveraging the SME, the functionality of an ILM can be improved upon. The combination of computational modeling, additive manufacturing, and thermomechanical and physical property characterization provides a framework for designing future ILMs out of active materials.