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The novelty of this research lies in the successful fabrication of a 3D-printed honeycomb structure filled with nanofillers for acoustic properties, utilizing an impedance tube setup in accordance with ASTM standard E 1050-12. The Creality Ender-3, a 3D printer, was used for printing the honeycomb structures, and polylactic acid (PLA) material was employed for their construction. The organic, inorganic, and polymeric compounds within the composites were identified using fourier transformation infrared (FTIR) spectroscopy. The structure and homogeneity of the samples were examined using a field emission scanning electron microscope (FESEM). To determine the sound absorption coefficient of the 3D printed honeycomb structure, numerous samples were systematically developed using central composite design (CCD) and analysed using response surface methodology (RSM). The RSM mathematical model was established to predict the optimum values of each factor and noise reduction coefficient (NRC). The optimum values for an NRC of 0.377 were found to be 1.116 wt% carbon black, 1.025 wt% aluminium powder, and 3.151 mm distance between parallel edges. Overall, the results demonstrate that a 3Dprinted honeycomb structure filled with nanofillers is an excellent material that can be utilized in various fields, including defence and aviation, where lightweight and acoustic properties are of great importance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Spinal interbody cages adapted for an auxetic, and honeycomb using standard CAD software operations and manufactured with SLM. • Auxetic-based cages exhibit higher strength properties than honeycomb-based cages. • The stiffness of the auxetic cages is comparable to stiffness of human cortical bone. • The honeycomb cages exhibit lower value of Young's modulus closer to that for vertebrae. This paper presents a method for modeling a biomedical device by adaptation a commercially available interbody cage for an auxetic metamaterial and honeycomb structure using standard operations in Computer-Aided design software. The mechanical properties of experimental prototypes of Ti-6Al-4 V cages made by selective laser melting using computer modeling (finite element analysis), static and low-cycle fatigue compression tests (up to 3500 cycles) are characterized. 3D printed cells with structures with an angle of inclination between cell edges of less than 90˚ (auxetic metamaterial) are shown to exhibit higher static compressive strength and fatigue resistance than cells based on structures with an angle of inclination greater than 90˚ (honeycomb structure). The changes in the inclination angle differently affect to the porosity and consequently to mechanical behavior of auxetic metamaterial and honeycomb structure. The Young modulus of the auxetic-based interbody cage is 6.68 ± 0.28 GPa and comparable to the elastic modulus of human cortical bone. The honeycomb-based cage exhibits lower values of Young modulus (1.19 ± 0.03 GPa) close to that of trabecular bone and vertebrae. Importantly, the auxetic-based cage is not destroyed after 3500 cycles under 14 kN load with residual deformations ≤ 1 % (0.21 ± 0.10 mm displacements). [ABSTRACT FROM AUTHOR]

With booming development of 5G communications and electronic devices, electromagnetic waves (EMWs) radiation pollution has aroused much concern on public, and great efforts are being made to develop the high-performance electromagnetic interference shielding (EMI SE) materials. However, inherent deficiencies of traditionally processing technology restrain the current materials to fabricate desirable architectures for SE applications. Herein, taking full advantages of 3D printing in free-construction, architected honeycombs featuring lightweight and high-efficient EMI SE are designed with polylactic acid (PLA) as matrix, and graphene nanosheets and carbon nanotubes hybrids (GNs/CNTs) as functional fillers. The optimal printed material shows a high electrical conductivity up to 110.8 S/m and outstanding EMI SE property of 53.5 dB, far exceeding the standard of commercially shielding materials (20 dB). More encouragingly, this work makes a deep insight into the intrinsic connection of porous structure of 3D-printed components on shielding mechanism, which reveals that as the pore size is far less than a certain proportion of incident wavelength (λ/5), the components exhibit a good reconcilability on the lightweight (0.4–1.0 g/cm3) and high-performance EMI SE (35–45 dB). From fundamental materials to desirable components, this breakthrough lays a solid foundation for the free-construction of diversified architectures in EMI SE applications. [Display omitted] • The strong conductive networks are constructed by the hybridization of graphene nanosheets and carbon nanotubes. • The hybrid networks endow the 3D-printed components with superior electromagnetic interference shielding (∼53.5 dB). • The diameter of porous structures should be less than the 1/5 of incident wavelength (λ) to shield electromagnetic waves. • The 3D-printed honeycombs exhibit a good reconcilability on lightweight and electromagnetic interference shielding. [ABSTRACT FROM AUTHOR]