Design of 3D-printed magneto-responsive metamaterials for programmable stiffness and energy absorption

Mechanical metamaterials enable control of macroscopic properties, such as stiffness, through the careful design of their internal architecture. The primary objective of this research is to develop a unit cell consisting of a polymeric metamaterial with embedded pins that provides tunable mechanical behavior through a non-contact interaction mechanism. The unit cells are arranged within a housing, allowing the overall stiffness of the structure to be adjusted under external loads. Tunability is governed by the orientation of the embedded pins, which is controlled using an external neodymium magnet, enabling real-time reconfiguration and adjustment of the effective stiffness. The use of a magnetic field to manipulate the internal components without disassembling the structure represents a key advantage of the proposed approach. Numerical results from finite element simulations are compared with experimental results from 3D-printed specimens fabricated with K + polymer to validate the system's performance. The results show that shaft rotation can increase stiffness by more than 30.91% and improve energy absorption by approximately 16%, while the simulations demonstrate good agreement with the experimental observations. The structure is also examined under alternative loading conditions to evaluate its adaptability and to confirm that the tunable stiffness behavior is consistently maintained. Overall, the proposed design exhibits a stable and predictable tunable response, indicating its potential for adaptive mechanical systems.