Phononic crystals, capable of tailoring mechanical wave propagation and displaying omnidirectional bandgaps, are vital for numerous potential applications such as wave filtering, waveguiding, acoustic cloaking, and energy harvesting. In natural materials, vibration mitigation depending on the intrinsic damping feature usually cannot be readily adjusted and broad attenuation frequency ranges are still rare in these materials. Here, we propose an approach to design metamaterials with tunable vibration mitigation in multiple frequency ranges, which can be dynamically tuned by an external thermal field. The proposed method utilizes reversible Young's Modulus-temperature relationship of glassy polymers and nonuniformity of the steady temperature field in solid structures. Through numerical simulations and low amplitude transmission testing, we demonstrate that the proposed method and metamaterials can exhibit broad and multiple omnidirectional bandgaps. The finding reported here provides a routine to design phononic metamaterial systems with tunable bandgaps, offering a wide range of potential applications in harsh environmental conditions and being extended to baseline lattices with other topologies.

Composites with both lightweight and high strength have tremendous demands in aerospace, rail transit, and military, etc., especially for ones with strong high-strain-rate dynamic impact resistance. Among them, bioinspired helicoidal composites is one type of them. Currently, due to the limitation of fabrication, only 0, 45, and 90° helicoidal composites have been investigated to enhance impact resistance. Other angle helicoidal composites have not been completely explored yet. Here, we have fabricated a series of helicoidal composite specimens with 0°–90° helicoidal angles by Fused Deposition Modeling (FDM), tested their high strain rate impact resistance using Split Hopkinson Pressure Bar (SHPB), high-speed camera images and Digital Image Correlation (DIC), and analyzed the relationship of the strain rate and dynamic stress–strain. In order to verify the experimental results, the numerical simulations have been carried out. The results indicate that dynamic experiments have revealed remarkable strain rate sensitivity, the maximum stress for 60° helicoidal composite is higher than others at the strain rates are 700 s⁻¹ and 1000 s⁻¹. The underlying mechanism of the enhancements lies in that helicoidal angles remedy effective the weakness of adhesion between adjacent filaments. Helicoidal modes effectively improve the anisotropy. Our findings here provide a method to enhance the high strain rate impact performance and broaden the application of 3D printing.