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The gradient honeycomb structures absorb a wide range of energy, but a systematic study on anisotropic design is lagged. The same justify the novelty of the current work, wherein the honeycomb design of anisotropic gradient honeycomb structure comprises its originality. The gradient 3D-printed honeycomb structures fabricated samples were subjected to a static and cyclic compression test in the in-plane direction, and the energy absorption capabilities were analyzed. The cyclic compression and free vibration test confirmed the highest damping ability attributed to hybrid gradient structure. A high damping ability demonstrates application possibilities as an efficient and effective energy absorption element and other technical curiosity. [ABSTRACT FROM AUTHOR]

• SiCN honeycomb ceramic is prepared from 3D printed photocurable polysilazane. • The optimal composition of acrylate and polysilazane affords high-strength ceramic. • Combination of acrylate and polysilazane results in high-content free carbon. • SiCN honeycomb ceramic has excellent intrinsic microwave-absorbing property. The combination of 3D printing technology and polymer-derived ceramic route provides an attractive strategy to construct microwave-absorbing honeycomb with fine structure through flexible process. However, preparation of honeycomb ceramics with both excellent mechanical and microwave-absorbing properties is still challenging. Herein, SiCN honeycomb ceramic was fabricated by stereolithography from UV curable polymeric precursor consisting of polysilazane and multifunctional acrylates. By optimizing the multifunctional acrylates and its ratio, the decomposition of organic moiety and the ceramization process of precursor are matched, rendering the achieved ceramic with high compactness. The hardness and specific compressive strength of SiCN honeycomb ceramic reach as high as 14.3 GPa and 333.3 MPa/(g·cm3), respectively. Meanwhile, at low pyrolysis temperature, the copolymerized acrylate and polysilazane that formed during curing process was converted to free-carbon nanodamins in-situ, which endows SiCN honeycomb ceramic with the minimum reflection loss of –49.0 dB, namely microwave absorption rate over 99.99%. [ABSTRACT FROM AUTHOR]

The mechanical performance of honeycomb sandwich structures fabricated with thermoplastic elastomer nylon core and 0D/2D hybrid polymer nanocomposite skin was investigated. The cell sizes were varied from 10 to 36 mm, and mechanical performance was evaluated along out-plane and in-plane orientations. Different tests like sandwich compression, bare core flexural, beam deflection and drop over impact test were carried out. The energy absorption ability of sandwich panels was evaluated by compression and drop weight impact test, and it was effectuated by cell size variation. A close agreement between the test results of the drop weight impact tester and FEM simulation was noted. The analysis of test results confirms that nylon honeycomb core with the variation of cell size possesses both compliance and stiffness besides good energy absorption abilities. The possible area of application includes backing layer in the body armor that can provide protection against blunt trauma and scar. [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]

[Display omitted] • PLA/TPU filament for 3D printing was obtained by a screw extruder. • Continuous carbon fiber reinforced PLA/TPU honeycomb structure was prepared. • The self-sensing of strain and damage during cyclic compression was investigated. • The self-sensing of temperature change of honeycomb structure was achieved. Polylactic acid/thermoplastic polyurethanes (PLA/TPU) filament for 3D printing was prepared by screw extruder, and continuous carbon fiber-reinforced PLA/TPU honeycomb structure was fabricated by continuous fiber 3D printer, and the self-sensing performance of the structure during cyclic compression was investigated. The results show that the strain and damage can be sensed by the change of electrical resistance in the honeycomb structure during cyclic compression at small-strain (ε = 0.04) and large-strain (ε = 0.4). Meanwhile, the temperature monitoring of the honeycomb structure can be realized by the change of electrical resistance in the honeycomb structure. This study provides the possibility for developing and applying 3D printed continuous carbon fiber composite smart structures and structural health monitoring. [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]