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• A novel honeycomb structure with zero Poisson's ratio is proposed. • Relationships between three elastic constants and geometric parameters are studied. • The zero poisson's ratio property is maintained within a relatively small fluctuation range. The superior performance of honeycomb structure has facilitated its extensive application in various fields. In this paper, a novel honeycomb structure is proposed, which exhibits zero Poisson's ratio behavior. Firstly, the in-plane mechanical properties are analyzed based on the classical Castigliano's theorem to obtain expressions connecting the three elastic constants of the structure and geometric parameters. Then, the theoretical expressions are verified by homogenized finite element methods and 3D-printed experimental models, which help to determine the relationship between the in-plane mechanical properties and the geometric parameters. The results show that the mechanical properties of the honeycomb structure can be tailored by changing the geometric parameters, while ensuring that the zero Poisson's ratio property is maintained within a relatively small fluctuation range. This study reveals that the mechanical properties of the novel honeycomb structure are tunable, which has outperformed some honeycomb structures on adjusting range. [ABSTRACT FROM AUTHOR]

Modified honeycomb parts of Ni-15Fe-5Mo permalloy for magnetic shielding applications were designed and fabricated via laser powder bed fusion (L-PBF) 3D printing. We focused on the L-PBF process and performances of the thin-walled samples with different overhangs. After temperature-field numerical simulations and mechanism analyses on the L-BPF molten pools, the process optimizations were conducted to achieve a high bulk relative density. The thin walls with different wall thicknesses (0.3, 0.4, 0.5, 0.6, 0.7, and 0.8 mm) and overhanging angles (10°, 20°, 30°, 40°, 50°, 60°, 70°, 80°, and 90°) were printed without any supporting struts. The structures, mechanical properties, and formation mechanisms of the thin-walled overhangs were studied. We roughly gained some such trends or inferences about the tensile properties of the thin-walled overhangs. The microstructural anisotropies and surface "step effects" were the primary factors affecting the tensile properties. The numerical simulation and experiment of compression on the modified honeycomb parts with several sidewall inclination angles were performed. The modified honeycomb structures transferred stress and premature failure to other local structures far away from the compression face. The preferential plastic deformation of the modified honeycomb structures occurred at the inclined corners, exhibiting good plastic deformation buffering effect and thus avoiding instantaneous cracking. This work presented some reference significance for high-quality formation and performance evaluation of thin-walled overhanging structures via L-PBF. • Permalloy thin-walled overhangs were 3D-printed without any supporting struts. • Modified honeycomb thin-walled parts for magnetic shield were L-PBF-printed. • Tensile properties of as-printed thin-walled overhangs were comparatively tested. • Numerical simulation and testing were performed on modified honeycomb parts. • Physical mechanism analysis were conducted on printed thin-walled formability. [ABSTRACT FROM AUTHOR]

Abstract: Crashworthiness parameters of aluminum hexagonal honeycomb structures under impact loads are investigated by using finite element methods and conducting experiments. To validate the finite element models, numerical results are compared with experimental measurements and theoretical results reported in literature. In numerical simulations of honeycomb structures, out-of-plane loads are considered while the aluminum foil thickness, cell side size, cell expanding angle, impact velocity and mass are varying, and dynamic behavior and crashworthiness parameters are examined. It is observed that there are good agreements between numerical, experimental and theoretical results. Numerical simulations predict that crashworthiness parameters depend on cell specification and foil thickness of the honeycomb structure and are independent of impact mass and velocity. [Copyright &y& Elsevier]

The structural design of gradient is universally considered to be an effective approach to improve the performance of cellular materials. In this study, the selective laser melting (SLM) was used to fabricate honeycomb components with different gradient configurations and gradient values. The influences of configurations and gradients on the manufacturability, microstructure evolution, and compression behavior were comprehensively investigated. The numerical simulation was conducted to study the deformation mechanism of honeycombs with different configurations. Results revealed that the small wall-thickness caused pore defect and reduced the relative material density of honeycomb components. The variation of the cooling rate of different building parts led to different size of grains. Different configurations and gradients greatly affected the compression behavior of gradient honeycombs. The symmetric positive gradient (SP) configuration exhibited the most excellent compression performance with the highest mean crushing strength, densification strain and CEF. With the increase of gradient values, the compression strength of gradient honeycombs greatly decreased, while the densification strain enhanced visibly. The elevation of gradient values also obviously increased the energy absorption capacity of honeycomb structures, up to 20.41%. The effect of the structure relative density on the compression properties was studied by the numerical simulation. With the increase of the structure relative density, the specific compression strength and the specific energy absorption apparently rose. • Continuous gradient honeycomb structures were fabricated by selective laser melting. • Four different gradient configurations and gradient values were designed. • Microstructure was studied and closely related to the deformation mode. • Increase of gradient values notably improved the energy absorption capacity. [ABSTRACT FROM AUTHOR]

In this study, novel honeycomb structures with twisted feature were designed and manufactured by laser powder bed fusion (LPBF). The manufacturability, microstructure evolution of LPBFed honeycomb components with twisted feature were studied. The influence of twist angle on the compressive behavior of components was experimentally investigated and the underlying mechanism was revealed using FE simulation. Results revealed that the material relative density of LPBFed components was reduced with the increase of twist angle, caused by the enlarging overhanging area. Different cooling rate of melt pool at different parts along the building direction resulted in different microstructures. The twist angle significantly affected the compressive behaviors of honeycomb structures. When the cell number along each side was 3, the honeycomb structure with 30° twist angle exhibited the most uniform stress distribution under compression, leading to the highest specific compressive strength and energy absorption ability. The influence of cell number and wall thickness on compressive properties of honeycomb structures with 30° twist angle were investigated through finite element simulation, and results revealed that the structure with 0.75 mm wall thickness and 3 unit cells along each side showed the highest specific energy absorption ability. • Bio-inspired honeycomb structures with twist feature were designed and made by LPBF. • The effect of twist angle on microstructures of LPBFed components was studied. • The compression behaviors of components with different twist angle were studied. • FE simulation was used to study stress distributions of structures under compression. [ABSTRACT FROM AUTHOR]