Double-tubular origami metamaterials with independently programmable and tunable mechanical and acoustic properties

With the advance in mechanical metamaterials, recent research is emerging on the multifunctional ones, as they can provide versatile cross-domain properties for complicated engineering applications, such as energy and sound absorption, vibration isolation, and noise attenuation. However, in most cases, the multiple properties of existing metamaterials cannot be programmed independently, not to mention to be tuned post-fabrication. In this study, we propose a family of double-tubular origami metamaterials which exhibit unique rigid origami folding kinematics and geometric transposition in two orthogonal directions. By correlating the design parameters and initial folding states with the mechanical and acoustic responses, we show that these two properties can be independently programmed, i.e., varying one property in a large range while maintaining the other one nearly unchanged, thus decoupling traditionally interdependent behaviors. Specifically, the frequency range of the complete bandgap can change by up to 10.4 times while the stiffness remains constant; conversely, the stiffness can change by up to 16.9 times without altering the complete bandgap. Furthermore, prototypes fabricated from thermoplastic polymers demonstrate on-site tunability via thermomechanical reconfiguration, achieving directional performance swapping through geometric transposition. The integration of independent programmability and tunability positions these origami metamaterials as promising candidates for systems requiring both energy and sound absorption, or on-site reconfigurable systems for various application scenarios.