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This article reports a carbon fiber–reinforced plastic Kagome composite honeycomb sandwich structure reinforced with polymethacrylimide (PMI) foam (PKCSS). Low‐velocity impact performances on the node, rib, and two cell centers of the PKCSS were experimentally compared with those on a composite Kagome honeycomb sandwich (CKHS), and the failure mechanism of the PKCSS was investigated. The impact process was analyzed through an explicit numerical analysis using ABAQUS. A three‐dimensional Hashin failure criterion was introduced using the VUMAT subroutine. Results confirmed that the PKCSS exhibits higher impact and specific loads than the CKHS, with the maximum improvements of 69.7% and 39.5%, respectively, under 50‐J impact energy. As an uncrushable material, the PMI foam provides strong impact resistance during its plateau stage. This technology of cell filling can be used to fabricate lightweight all‐composite honeycomb sandwiches for potential use in ultrahigh engineering applications. Highlights: Cell filling is applied in an all‐composite Kagome honeycomb sandwich.The LVI performances of the PKCSS and CKHS are experimentally compared.C‐scanning is used to analyze the failure of the considered structures.The PKCSS's numerical model is established to investigate the impact process.The enhancement mechanism of the PMI foam is analyzed. [ABSTRACT FROM AUTHOR]

The honeycomb pattern possesses a distinctive hexagonal structure capable of seamless repetition on a flat surface, leaving no gaps. Moreover, all arm thicknesses and angles are equal to one another. This remarkable configuration is deemed biomimetic, with numerous examples found in nature. Notably, it exhibits remarkably low density and exceptional mechanical strength. MAX phase films have gathered significant attention due to their exceptional capacity to amalgamate the essential properties of both metals and ceramics. Additionally, they possess the unique ability to effectively mend surface cracks that may arise as a result of friction-wear, restoring the material to a certain degree of integrity. In this study, Ti2AlN MAX phase thin films were deposited on M2 steel substrates by a closed field unbalanced magnetron sputtering system (CFUBMS). 750 °C heat treatment was applied to obtain the produced films in crystalline form. In addition, plasma etching parameters suitable for the phase structure of the deposited film were determined. With the inductive coupling plasma etching (ICP) process, the honeycomb pattern was given to the Ti2AlN MAX phase films with a continuous and smooth geometry at a depth of 2 μm. This study gives ideas for the development of multi-coating systems in which patterns of different geometries are included in a single layer. [ABSTRACT FROM AUTHOR]

Composite materials, particularly honeycomb composites, are widely utilized in various industries, including aerospace, due to their high energy absorption against the impact and exceptional strength-to-weight ratio. This study aims to leverage the plastic and elastic properties of these materials to develop a simplified numerical model that incorporates orthotropic properties for core modeling. By doing so, the need for detailed honeycomb structure modeling is eliminated, resulting in reduced computational costs and time. A comprehensive three-dimensional finite element model, accounting for structural intricacies, is presented based on experimental data from a reputable source (isotropic model) and its equivalent finite element model (orthotropic model). The model is validated by the experimental results, demonstrating good agreement. The study also investigates parameters such as energy absorption, the internal energy of the core and faces, maximum displacement, and maximum contact force under low-velocity impact scenarios with spherical and cylindrical projectiles. These findings highlight the effectiveness of the orthotropic model, particularly in showcasing greater energy absorption in the core of the sandwich panel when subjected to a cylindrical impactor. [ABSTRACT FROM AUTHOR]

In response to the shortcomings of concentrated stress, difficult forming, and short service life of commonly used honeycomb ceramic thermal storage materials with square lattice holes, the author has developed a new type of low stress honeycomb ceramic thermal storage material by studying the structure, forming mold, and extrusion forming material of the thermal storage body. The author introduced the changes in specific surface area and porosity of heat storage materials with different geometric structures, and analyzed and compared the structural characteristics of two types of heat storage materials, namely heat storage balls and honeycomb bodies, under the premise of equal heat storage capacity. The trajectory of air-flow in the heat storage chamber was simulated using CFD software, and the pressure loss and centerline velocity changes of different shapes of honeycomb were analyzed. The flow characteristics, pressure distribution, and heat transfer performance of gas inside different shapes of honeycomb were calculated. The experimental results showed that the closer to the circular shape, the smaller the pressure loss of the centerline. The larger the equivalent diameter, the smaller the resistance along the path. From the perspective of cold pressure loss alone, regular quadrilateral holes and regular circular holes are the best choices for the shape of honeycomb openings. The centerline velocity of the equilateral triangle hole is the largest, indicating that the smaller the equivalent diameter is, the greater the average velocity at the outlet is. The resistance along the path of the round hole is the smallest, the regular quadrilateral hole is slightly larger, and the pressure loss of the equilateral triangle hole is the largest, which exceeds the round hole by nearly 1/3. Taking into account factors such as heat storage, specific surface area, flow characteristics, and heat transfer characteristics, quadrilateral honeycomb cells are the best choice. [ABSTRACT FROM AUTHOR]

Honeycomb cores made of phenol resin impregnated paper are widely used in sandwich structures of aircraft. Owing to the rather weak core material, this kind of sandwich is prone to a range of damages as a result of impact loading which may accidentally occur during operation. When employed in aircraft these structures have to be damage tolerant. This means barely visible damages have to be considered in the structural design process. In the standard design process for damage tolerant aircraft structures especially the effect of impacts has to be considered but is mostly investigated on unloaded sandwich components. However, aircraft structures are not completely stress free, even when the aircraft is in parking position. At least the structural weight will cause a permanent static preload. In the literature there are only few investigations dealing with the impact behaviour of preloaded honeycomb sandwich structures. In general, studies on composite structures have shown that tension preloads lead to higher structural impact resistance, while prestressing in compression reduces mechanical properties such as impact strength and stiffness of the structure. For this reason, a compression preload is considered as the more critical load case. In order to evaluate the effect of static compression preloads an experimental study on five different honeycomb sandwich configurations was conducted. The experimental investigations showed that even low preloads cause a higher structural damage area, which results in a lower residual strength of the structure. The results indicated that it is recommendable to consider structural compression preloads in the aircraft structural design process. [ABSTRACT FROM AUTHOR]

3D printed honeycomb structures constituted by neat polylactic acid (PLA) and conductive PLA (PLAc) with different cell sizes and thicknesses were manufactured through 3D printing technology based on material extrusion (MEX). These structures were arranged into bi‐layer honeycomb structures (BHS) for evaluation of the microwave absorbing properties at the X‐band (8.2–12.4 GHz) and Ku‐band (12.4–18 GHz) frequency ranges. The effects of cell size, sample thickness, layer thickness ratio and the nature of the top layer on the electromagnetic attenuation performance of BHS samples were investigated in terms of reflection loss (RL). The components geometric characteristics and the arrangement of the layers exerted great influence on the RL values and effective absorption bandwidth (EAB). Overall the bilayer structures with 5 mm total thickness presented the best EM response in terms of EAB and minimum RL, where the component with the larger cell size (7.7 mm), PLAc (1 mm) as the top layer and PLA (4 mm) as the bottom layer exhibited the best results with RL values of −41 dB and EAB of 9.5 GHz. The BHS system with 7.7 mm cell size was more efficient in Ku band frequency range, whereas that with 3.5 mm cell size gave better response in the X‐band frequency range. Therefore, RL values and EAB can be adjustable by modifying the building strategy of the printed parts, such as thickness of the sample, cell size and thickness distribution of the conductive and non‐conductive layers. The findings in this work show the importance of the building strategy to fabricate components with controllable BHS and improved properties for microwave absorption application. [ABSTRACT FROM AUTHOR]

Aluminium honeycomb core is a thin-walled cellular structure extensively used in crash resistance applications in automotive industry. To overcome current challenges in adhesive-bonded honeycomb, new fabrication route using micro friction stir lap welding has been proposed. With a specific energy absorption capacity as high as 28.2 kJ/kg in flatwise impact testing, fabricated honeycomb demonstrated its potential for industrial applications. The structure exhibited no weld cracks or cell wall delamination, unlike adhesive-bonded honeycombs. However, in friction stir welding of thin sheets (0.5 mm), achieving an optimized heat input is challenging due to limited scope for variation in process parameter and tool design. Therefore, control of heat outflow by proper selection of backing plate material is the alternative approach for achieving desirable joint performance. Experiments with backing plates having a range of thermal diffusivities demonstrated that joint produced with mild steel backplate exhibited maximum shear-tensile strength. Conversely, joint with aluminium backplate exhibited poor plastic flow of material. Effective sheet thickness and lap width were predominantly affected by heat accumulation in weld, resulting in different failure modes. [ABSTRACT FROM AUTHOR]

The response of sandwich structures under the synergistic effects of blast wave and fragments is a topic of interest for researchers and designers. Thus, the performance of a sandwich structure used for enhancing the protection of a target structure is numerically investigated because it may experience such complex loading conditions resulting from combined blast and fragment impact. A conventional sandwich structure modelled using aluminium alloy resists a bare blast load imposed on it. Analysis, however, reveals that fragments penetrate through the front facesheet of a conventional sandwich structure, indicating a lower resistance of the front facesheet to combined blast and fragment effects. Thus, the behaviour of conventional aluminium honeycomb sandwich structures is compared with enhanced sandwich configurations consisting of a front facesheet covered with multilayer lightweight composite Kevlar fabric material. The Kevlar fabric arrests the maximum number of fragments, and reduces their momentum, thereby reducing the damage level in the sandwich structure. The effect of the charge weight and shape of the fragments on the damage modes of the sandwich structure is also assessed. With the increase in charge weight, the momentum of the fragments is found to increase, and these penetrate the back facesheet of the sandwich structure. [ABSTRACT FROM AUTHOR]

To realize the one‐dimensional deformation of morphing wings, zero Poisson's ratio (ZPR) honeycomb metamaterials have become a popular research topic due to their lightweight, low in‐plane modulus, and high out‐of‐plane strength. A ZPR honeycomb metamaterial is designed and prepared from short‐cut carbon fiber‐reinforced polyetheretherketone (CF/PEEK) by a 3D printer. The mechanical properties of ZPR honeycomb metamaterials were tested to determine their tensile and bending stiffness. The results show that the metamaterial can achieve 62.3% ± 3.3% in‐plane elastic deformation after optimized structure design. At the same time, metamaterial has a certain bending resistance to keep the airfoil from normal buckling deformation. Moreover, a new test method for evaluating the cycle deformation behavior of flexible morphing wings is proposed. The high‐speed cyclic tension‐compression test showed that H22‐t0.6‐CT has the best stability, which may be related to its lower porosity (2.15% ± 0.12%). These results indicate that ZPR honeycomb metamaterials have great application prospects in the field of morphing wings. Highlights: The printed CF/PEEK wire is treated as a transversely isotropic material.ZPR honeycomb metamaterial allows for more than 50% in‐plane deformation.A new test method to evaluate the cyclic deformation behavior. [ABSTRACT FROM AUTHOR]

This paper presents an innovative method of constructing energy absorbers, whose primary function is to effectively transform kinetic energy into strain energy in events with high deformation rates. Hybrid specimens are proposed considering thin-walled windowed metallic tubes filled with 3D-printed hexagonal honeycombs made of PET-G and ABS thermoplastic. The patterned windows dimensions vary from 20 × 20, 20 × 30, 15 × 20 and 15 × 30 mm2. Although using polymers in engineering and thin-walled sections is not new, their combination has not been explored in this type of structure designed to withstand impacts. Specimens resist out-of-plane quasi-static axial loading, and test results are analyzed, demonstrating that polymer core gives the samples better performance parameters than unfilled samples regarding energy absorption (Ea), load rate (LR), and structural effectiveness (η). An optimization procedure using specialized software was applied to evaluate experimental results, which led to identifying the optimal window geometry (16.4 × 20 mm2, in case) and polymer to be used (ABS). The optimized sample was constructed and tested for axial compression to validate the optimization outcomes. The results reveal that the optimal sample performed similarly to the estimated parameters, making this geometry the best choice under the test conditions. [ABSTRACT FROM AUTHOR]

Honeycomb materials as reinforcements for shape memory polymers have been considered for their commercial availability, ease of geometric tailoring, and high in-plane stiffnesses. The design optimization of these honeycomb cells remains an open field of research, with many approaches taken in formulating the structural optimization problems. This investigation focuses on implementing a shape variable parametrization of the honeycomb to study the possible value of both cell asymmetry and spatially varying cell geometries in multicell networks. A unit cell finite element model framework was developed to predict the in-plane elastic properties of these composites, and two design objectives were selected to be optimized. Pareto fronts were estimated for multiple loading cases and cell wall material models, and experimental results were collected for model validation. The optimization results find that these composites can achieve a large range of performances, with maximum moduli as high as 17.2 GPa. Large asymmetry is found in the optimized cell geometries, and relationships are identified between loading cases and for different wall materials. Furthermore, the experimental results validate the finite element model predictions, with relative errors as low as 20% for the predicted maximum modulus and 2% for the modulus ratio. [ABSTRACT FROM AUTHOR]

The aim of current research was to improve water quality by constructing a single slope basin type solar water distillation system with honeycomb, as well as to increase distilled water productivity. In this investigation, honeycomb structure of 2.25 cm and a diameter of 6 mm in a square section (100 cm x100 cm) have been proposed to enhance the efficiency of the solar still. An experimental analysis was done to investigate the performance of the honeycomb structure. Thermal efficiency of the standard solar distillation system was obtained approximately 18.48%, while the thermal efficiency and productivity of the solar distillation system with honeycomb was obtained 25.45% and 749.58 ml/m² respectively. It was concluded that, the solar distillation system with honeycomb structure was more efficient that a simple conventional solar distillation system. The addition of honeycomb structure in simple solar desalination system increased the productivity and efficiency by 35.36% and 37.71% respectively. [ABSTRACT FROM AUTHOR]

Panels made using honeycomb sandwich technique can help aerospace manufacturers maintain weight and fulfill certain strength requirements. Rigidity, stress absorption, fatigue resistance, and resistance to weather, chemicals, fire and isolation are some of the key benefits of honeycomb panels. Due to mechanical and acoustical requirements for high strength and weight target, it is common to select a sandwich design with a cheap and recyclable core material. Among other things, honeycomb sandwich structures are used in ship hulls, automobiles and civil constructions. Usage of these designs is the best way to obtain high strength and title material utilization. In this paper, the designs of hexagonal and square honeycomb constructions are evaluated for the most favorable structural outcomes. A honeycomb panel was produced using SolidWorks software. The proposed model was subjected to structural analysis using LS-DYNA software for four distinct kinds of materials: copper, steel, titanium and aluminum. Finally, the simulation results are presented and discussed. [ABSTRACT FROM AUTHOR]

This paper reports a new annular honeycomb that shows tunable Poisson's ratio. The presented honeycombs can provide both the in-plane negative Poisson's ratio (NPR) and in-plane zero Poisson's ratio (ZPR) while the shapes of the honeycomb core change. The developed honeycomb core is constructed by an annulus with four ligaments distributed bi-axial symmetrically, which shows great diversity of mechanical properties. The developed theoretical models of the in-plane elasticity are based on Castigliano's Second Theorem and energy principle. Two parameters were used to describe the deformation mechanisms of the unit cell concisely. The effect of two parameters on the Poisson's ratio and Young's modulus was investigated. The Young's modulus derived from the Finite Element (FE) analysis all have an good agreement with that derived from theoretical results, and the experiments were carried out to confirm the validity of them convincingly. [ABSTRACT FROM AUTHOR]

Sandwich structure is one of the blasts protecting and energy absorbing materials with different types of light weight cores. This article aimed at investigating blast response of hexagonal honeycomb sandwich structure having perforations along the cell height of core over conventional honeycomb cores. The study discussed the mechanics of deformation behavior of perforated sandwich structure to improve the energy absorption characteristics of the bare honeycomb core sandwich structure. Detailed numerical analysis is conducted to accurately produce the deformation process with finite element analysis using explicit software LS-DYNA®. Blast load resulting from 1 kg TNT on the sandwich structure is applied using Conventional Weapons Effects Program (ConWep) function available in LS-DYNA. Several different parameters consisting of varying sizes of perforation by changing d/l ratio, shape, number of perforations and different facesheet and backsheet thicknesses, and different scaled distances are investigated in detail. The results indicated that both size and shape and number of perforations have significant influence on reduction of blast impulse. The variation of facesheet and backsheet thicknesses without changing the overall thickness of the structure also has evident effect in blast resistance capability of perforated honeycomb sandwich structure. The blast mitigation and energy absorption capacity of honeycomb core sandwich structure can be improved with the provision of perforations and optimizing the arrangement of holes. The perforated honeycomb core is further investigated based on analytical formulation developed using single degree of freedom (SDOF) system analysis approach. Optimization study is done further to get the best configuration based on different design variable limits. [ABSTRACT FROM AUTHOR]

The crashworthiness of embedded composite structures that couple carbon fiber reinforced plastic tubes and aluminum honeycomb (CFRP-AH) was assessed through quasi-static compression tests and finite element simulation. Experimental results show that CFRP tubes tilt, when the AH fits with the CFRP tubes is not tight enough. With an increasing number of embedded CFRP tubes, the CFRP-AH composite structures are found to have a larger mean crush force (MCF) and specific energy absorption (SEA). Among the four experimental groups, CFRP-AH composite structures in Group S3, which used a larger size of CFRP tube, are found to have significantly improved energy-absorbing performance, and SEA of S3-t25 is improved by 576% compared with that of the pure AH S3-t0 without tubes. The S2 group's CFRP tube is tilted, which used a smaller size, and the structure is improved to obtain the NS2 structure, so that only tearing deformation occurs in the AH-CFRP structure's CFRP tube. The SEA of NS2-t25 was improved by 29.70% over S2-t25 and 22.83% over S3-t25, which has the best energy absorption characteristics among the filled tube structures. [ABSTRACT FROM AUTHOR]

Modern aerostructures, including wings and fuselages, increasingly feature sandwich structures due to their high‐energy absorption, low weight, and high flexural stiffness. The face sheet of these sandwich structures are typically thin composite laminates with interior honeycombs made of Nomex or aluminum. Standard cores are structurally efficient, but their design cannot be varied throughout the structure. With additive manufacturing (AM) technology, these core geometries can be altered to meet the design requirements that are not met in standard honeycomb cores. This study used a modified aluminum honeycomb core, with increased surface area on the top and bottom, as the core material in sandwich panels. The modified honeycomb core was produced through the laser powder bed fusion method. The behavior of the modified sandwich composite panels was evaluated through three‐point bend, edgewise compression, and impact tests, and their performance was compared to that of a conventional honeycomb core sandwich panel. The three‐point bend test results indicated that the sandwich structure's ultimate shear strength improved by 12.6% with the modified honeycomb core. Additionally, the displacement at the failure of the structure increased by 11%. The edgewise compression tests showed that the ultimate edgewise compressive strength improved by 19.1% when using the modified core. The impact test results revealed that the peak force increased by 8% and the energy‐absorbing capacity of the sandwich structure increased by 20% with the use of the modified honeycomb core. [ABSTRACT FROM AUTHOR]

Energy-absorbing materials have extensive applications in aerospace and automotive applications. Research has shown buckling initiators, or triggers, in energy-absorbing tubular structures increase the energy absorbed by encouraging the side panels to fold when loaded out of plane in compression conditions. Additively manufactured TPE honeycombs were designed in this study to include these buckling initiators, which introduced a slight decrease in initial weight, as well as initial stress concentrations, while improving crashworthiness characteristics. The samples with buckling initiators (1BI) showed an increase in crush efficiency when directly compared to their no buckling initiator (0BI) counterparts. The 1BI samples maintained an increased crush efficiency regardless of the strain rate used. The samples with 1BI were able to better equilibrate the peak stress with the plateau stress. These honeycomb samples were found to maintain their crush efficiency, even after multiple rounds of compression testing. The quasi-static 0BI samples experienced a 23.4% decrease in the peak stress after multiple rounds of compression testing, while the 1BI samples saw approximately a 23.0% decrease. The 1BI samples averaged a decrease in crush efficiency of 0.5%, while the 0BI samples saw a decrease in crush efficiency of 5%. As the strain rate increased, the crush efficiency for the 1BI samples showed an increase in performance, with a smaller degradation in crush efficiency over multiple uses. Visco-elastic honeycomb with buckling initiators has a higher energy absorption than samples with no buckling initiators when exposed to multiple impact cycles. [ABSTRACT FROM AUTHOR]

In this study, aluminum honeycomb cells were filled with polymethacrylimide (PMI) foam of high strength and stiffness, and carbon fiber reinforced composite (CFRC) skins were added to create a composite sandwich structure. Nine types of specimens with varying cell node spacing and foam density were constructed, and stiffness equations were derived. To compare the performances of aluminum honeycomb and PMI foam sandwich structures, their compressive responses were examined using edgewise and flatwise compression tests. Moreover, the failure was analyzed using finite element methods (FEM). Analytical and numerical models were used to investigate the size effects of rib width, rib angle, and node spacing. [ABSTRACT FROM AUTHOR]

The honeycomb structures, due to minimal density, relative high out-of-plane compression properties, and out-of-plane shear properties, have attracted a lot of attention. Regarding this issue, in the current research, fundamental frequency analysis of the annular plate with two angle-ply multiscale hybrid nanocomposite face sheets and a honeycomb core is investigated. Halpin-Tsai as well as Hamilton's principle, are presented for obtaining the effective material properties and governing equations of the presented composite system. For modeling the thermal environment, three-kind of thermal loading is presented. Also, the current structure is covered with the Kerr elastic foundation. The generalized differential quadrature method is presented for obtaining the exact fundamental frequency of the annular plate with two angle-ply multiscale hybrid nanocomposite face sheets and a honeycomb core. Finally, the result section is given to illustrate the influences of two angle-ply multiscale hybrid nanocomposite reinforcement, the geometry of honeycomb core, thermal loading, elastic foundation, the weight fraction of nanocomposites, and structural parameters of the annular plate on the fundamental frequency of the annular plate with two angle-ply multiscale hybrid nanocomposite face sheets and a honeycomb core. The outcomes of the current report show that for the clamped edge in the boundary conditions and each t h / l h , increasing θ h / π is a reason for falling down the frequency of the annular plate with a honeycomb core. Another consequence is that the impact of temperature changes on the frequency of the disk is hardly dependent on the fiber angle. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study is to find the best geometries among the cylindrical, enamel and honeycomb geometries based upon the mechanical properties (tensile test, compression test and shear test). Further this obtained geometry could be used to fabricate products like exoskeleton and its supporting members. Design/methodology/approach: The present research focuses on the mechanical testing of cylindrical, enamel and honeycomb-shaped parts fabricated through multi-jet printing (MJP) process with a wall thickness of 0.26, 0.33, 0.4 and 0.66 mm. The polymer specimens (for tensile, compression and shear tests) were fabricated using a multi-jet fusion process. The experimental results were compared with the numerical modelling. Finally, the optimal geometry was obtained, and the influence of wall thicknesses on various mechanical properties (tensile, compression and shear) was studied. Findings: In comparison to cylindrical, enamel structures the honeycomb structures required less time to fabricate and had lower tensile, compressive and shear strengths. The most efficient geometry for fully functional parts where tensile, compressive and shear forces are present during application – cylindrical geometry is preferred followed by enamel, and then honeycomb. It was found that as the wall thickness of various geometries was increased, their ability to withstand tensile, compressive and shear loads also enhanced. The enamel shape structure exhibits greater strain energy storage capacity than other shape structures for compressive loads, and the strength to resist the compressive load will be lower. In the case of cylindrical geometries for tensile loading, the resisting area toward the loading will be higher in comparison to honeycomb- and enamel-based structures. At the same time, the ability to store the stain energy is less. The results of the tensile, compression and shear load finite element analysis using ANSYS are in agreement with those of the experiments. Originality/value: From the insight of literature review, it is found that a wide range of work is done on fused deposition modeling (FDM) process. But in comparison to FDM, the MJP provide the better dimensional accuracy and surface properties (Lee et al., 2020). Therefore, it is observed that past research works not incorporated the effect of wall thickness of the embedded geometries on mechanical properties of the part fabricated on MJP (Gibson, n.d.). Hence, in this work, effect of wall thickness on tensile, compression and shear strength is considered as the main factor for the honeycomb, enamel and cylindrical geometries. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries (SIBs) are becoming promising candidates for energy storage devices due to the low cost, abundant reserves, and excellent electrochemical performance. As the most important unit, layered cathodes attract much attention, where honeycomb‐layered‐oxides (HLOs) manifest outstanding structural stability, high redox potential, and long‐life electrochemistry. Here, recent progress on HLOs as well as Na3Ni2SbO6 and Na3Ni2BiO6 as two representative materials are introduced, and the crystal and electronic structure, electrochemical performance, and modification strategies are summarized. The advanced high nickel HLOs are highlighted toward development of state‐of‐the‐art sodium‐ion batteries. This review would deepen the understanding of superstructure in layered oxides, as well as structure–property relationship, and inspire more interest in high output voltage, long lifespan sodium‐ion batteries. [ABSTRACT FROM AUTHOR]

Auxetic honeycomb has unique mechanical properties such as good energy absorption capacity, tensile strength and fracture toughness, etc. Therefore, honeycomb with a negative Poisson's ratio is used widely in medical, biological, aerospace and other fields. This honeycomb has large deformations in energy absorption and vibration reduction. It is very important to study the nonlinear constitutive of the honeycomb structure. Therefore, this paper establishes the nonlinear constitutive relationship of the auxetic honeycomb structure under large deformations. This constitutive relation includes the in-plane stress, in-plane strain, Young's modulus and Poisson's ratio of the negative Poisson's ratio honeycomb. The finite element model of the negative Poisson's ratio honeycomb cells is established, and the calculated results of finite element model are compared with that of the theoretical calculation results. On this basis, the influence of the geometric parameters on the mechanical properties of the structure is studied. The results of this paper will provide a theoretical basis for the further study of the auxetic honeycomb sandwich structure and provide a basis for the engineering application of honeycomb structures. [ABSTRACT FROM AUTHOR]

Due to the need for alternative materials for the realization of lightweight structures, the analysis of sandwich structures that have a semi-open thermoplastic honeycomb core as an internal support structure is of great technical and scientific interest. Sandwich components with a honeycomb-structured core layer between two continuous fiber-reinforced face sheets exhibit maximum weight-specific stiffnesses and strengths. The folded thermoplastic honeycomb cores have some characteristic properties not found in conventional honeycomb cores due to their special production, which causes the semi-open structure. As a result of the folding process, the cell walls of the honeycombs are not joined together in the folding direction, as would be the case, for example, with glued or expanded honeycombs. This specificity has a great influence on the structural mechanical behavior of the honeycomb. To characterize the mechanical material properties, one possibility is to examine the honeycomb structure based on data obtained by the computed tomography method and, building on this, to analyze these properties in more detail by means of modeling a representative volume element that reflects the cell geometry of the honeycomb core as closely as possible. The aim of this approach is to determine effective material parameters that can be applied to mechanical simulation using the finite element method. The validation of these characteristic values was carried out based on results that can be obtained through standardized, mechanical, quasi-static experiments. [ABSTRACT FROM AUTHOR]

As for high resolution satellite application field, novel C/SiC honeycomb sandwich structure is the first to propose and develop on account of such many attractive properties as excellent ultrahigh dimensional stability in thermal and moisture coupling environment, lightweight and high load-bearing. Three types of C/SiC honeycomb sandwich structures were fabricated for the first time as opto-mechanical structure in satellite. The innovative interlayer-crosslinking method to weave the continuous carbon fiber fabric of honeycomb core was proposed. The compressive properties of novel C/SiC honeycomb sandwich structures were investigated. Meanwhile, the damage mechanism for sandwich structures were analyzed by non-destructive testing. The results showed that the innovative fabrication processing possessed the capability to prepare high quality C/SiC honeycomb, which was shown from the volume and distribution of pores in the X-ray tomography. The compression modulus and strength of the C/SiC honeycomb reached 927 MPa and 10.76 MPa, and showed better rigidity and higher strength compared with classical honeycombs. Two main types of cracks wall were found in the C/SiC honeycomb, i.e., the horizontal ones in the wall with t thickness and the inclined ones in the wall with 2 t thickness. The outstanding compressive performance was attributed to the high mechanical property of ceramic-matrix composite with fiber pull-out mechanism. The exceptional lightweight capacity was inherited from the low bulk density of honeycomb structure ranged from 0.08 g/cm3 to 0.15 g/cm3. This study can help for the development of lightweight materials for opto-mechanical structure in aerospace optical remote sensing technology. [ABSTRACT FROM AUTHOR]

This paper presents the design and development of three-dimensional braided honeycomb structures. The basic principles and braiding process are described. The relationship between braiding parameters and honeycomb geometric parameters is established and several three-dimensional (3D) braided honeycomb fabrics are introduced. Based on the principle of the 3D braiding ‘four-step’ method, the interlaced state of yarns can be changed by controlling the movement of yarn carriers, so the separation and combination of the braid can be controlled, then 3D braided honeycomb fabric can be formed. As the number of braiding cycles of wall length increases, the relative density will gradually decrease, but the number of braiding cycles of free wall length has a greater effect on the relative density. When the number of columns of yarns participating in wall thickness increases, the relative density will gradually increase. The relative density also showed a positive correlation with the braiding angle. With the increase of the opening angle, the relative density gradually decreases, although there is a minimum point after which a little increase is observed. This paper provides significant guidance for designing various 3D braided honeycomb structures and evaluating their relative density, and can be a reference for the design and development of new honeycombs structures. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA)—based honeycomb samples with different cell sizes and thickness were prepared using the fused filament fabrication (FFF) 3D printing technology and used to build sandwiched multilayer structures consisted of the honeycomb as the core component and poly(vinylidene fluoride) (PVDF) and/or PVDF/carbon nanotube (CNT) nanocomposites as top and bottom layers. The effect of the honeycomb design (cell size and thickness) and the presence and nature of the impedance matching layer on the microwave absorbing properties of the corresponding structures was investigated in the X‐band (8.2–12.4 GHz) and Ku‐band (12.4–18 GHz). For the systems without matching layer or with neat PVDF film as the matching layer, the honeycomb with larger thickness (5 mm) and larger cell size resulted in better electromagnetic wave attenuation but narrow frequency bandwidth with RL below −10 dB. The best combination minimum RL value (−18 to −14 dB) and broad frequency bandwidth with attenuation higher than 90% (around 8 GHz) was achieved with honeycomb of 2 mm thickness sandwiched by PVDF/CNT05 as the matching layer and bottom layer constituted by PVDF/CNT1 film, regardless the cell size of the honeycomb. These results indicate the PLA honeycomb as promising candidate as component for multilayer microwave absorbing materials and open new possibilities of applications of FFF technology for designing flexible, lightweight, and low‐cost materials to be used in both civil and military industries. [ABSTRACT FROM AUTHOR]

In present scenario, efficient energy conservation has been the greatest focus in Mobile Adhoc Networks (MANETs). Typically, the energy consumption rate of dense networks is to be reduced by proper topological management. Honeycomb based model is an efficient parallel computing technique, which can manage the topological structures in a promising manner. Moreover, discovering optimal routes in MANET is the most significant task, to be considered with energy efficiency. With that motive, this paper presents a model called Improved Energy Efficient Honeycomb based Routing (IEEHR) in MANET. The model combines the Honeycomb based area coverage with Location-Aided Routing (LAR), thereby reducing the broadcasting range during the process of path finding. In addition to optimal routing, energy has to be effectively utilized in MANET, since the mobile nodes have energy constraints. When the energy is effectively consumed in a network, the network performance and the network longevity will be increased in respective manner. Here, more amount of energy is preserved during the sleeping state of the mobile nodes, which are further consumed during the process of optimal routing. The designed model has been implemented and analyzed with NS-2 Network Simulator based on the performance factors such as Energy Efficiency, Transmission Delay, Packet Delivery Ratio and Network Lifetime. [ABSTRACT FROM AUTHOR]

Due to a tremendous increase in mobile traffic, mobile operators have started to restructure their networks to offload their traffic. Newresearch directions will lead to fundamental changes in the design of future Fifthgeneration (5G) cellular networks. For the formal reason, the study solves the physical network of the mobile base station for the prediction of the best characteristics to develop an enhanced network with the help of graph theory. Any number that can be uniquely calculated by a graph is known as a graph invariant. During the last two decades, innumerable numerical graph invariants have been portrayed and used for correlation analysis. In any case, no efficient assessment has been embraced to choose, how much these invariants are connected with a network graph. This paper will talk about two unique variations of the hexagonal graph with great capability of forecasting in the field of optimized mobile base station topology in setting with physical networks. Since K-banhatti sombor invariants (KBSO) and Contrharmonic-quadratic invariants (CQIs) are newly introduced and have various expectation characteristics for various variations of hexagonal graphs or networks. As the hexagonal networks are used in mobile base stations in layered, forms called honeycomb. The review settled the topology of a hexagon of two distinct sorts with two invariants KBSO and CQIs and their reduced forms. The deduced outcomes can be utilized for the modeling of mobile cellular networks, multiprocessors interconnections, microchips, chemical compound synthesis and memory interconnection networks. The results find sharp upper bounds and lower bounds of the honeycomb network to utilize the Mobile base station network (MBSN) for the high load of traffic and minimal traffic also. [ABSTRACT FROM AUTHOR]

Numerical simulations were carried out in this study to explore the response of the reinforced honeycomb sandwich structure with varying cell sizes (7, 10, and 15 mm), node lengths (25, 37.5, and 50 mm), and cell wall thicknesses (0.1, 0.2, 0.3, and 0.4 mm). The honeycomb structure made of aluminum alloy 8011 was subjected to low intensity blast loads by varying masses of TNT (10 g, 15 g, 20 g, and 25 g) and standoff distances (200 mm, 250 mm, and 300 mm). Commercial finite element code LS-DYNA was employed to carry out numerical simulations for both conventional and reinforced honeycomb sandwich structures keeping identical geometrical and blast load parameters. The deformation of the back facesheet was a major parameter to establish blast resistance of the core. Failure mechanisms of reinforced honeycomb were characterized as fully folded region, partially folded region, and clamped region. Reinforced honeycomb sandwich outperformed the conventional honeycomb sandwich structure of identical geometry parameters under similar blast loads. The increase in cell-wall thickness and node length enhanced the blast resistance, whereas the increment in cell size reduced the blast resistance of the reinforced honeycomb sandwich structure. [ABSTRACT FROM AUTHOR]

Aluminum honeycomb structures are used in the construction of protective materials due to the positive relationship between their mass and their energy-absorbing properties. Applying such materials in the construction of large machinery, such as military vehicles, requires the development of a new method of finite element modeling, one that considers conditions with high strain rates, because a material model is currently lacking in the available simulation software, including LS-DYNA. In the present study, we proposed and verified a method of numerically modeling honeycomb materials using a simplified Y element. Results with a good level of agreement between the full core model and the Y element were achieved. The obtained description of the material properties was used in the subsequent creation of a homogeneous model. In addition, we considered the influence of increases in pressure and the leakage of the air entrapped in the honeycomb cells. As a result, we were able to attain a high level of accuracy regarding the stress values across the entire range of progressive failure, from the loss of stability to full core densification, and across a wide range of strain rates. [ABSTRACT FROM AUTHOR]

We proposed a novel class of honeycomb structures inspired by triply periodic minimal surfaces (TPMS) architecture with tuneable mechanical responses. The design procedure based on the level-set approximation was first introduced for two TPMS-based honeycombs, namely GHoneycomb and P-Honeycomb. A numerical model was developed and validated by experimental results to evaluate the mechanical properties of G-Honeycomb and P-Honeycomb lattices. The results showed that P-Honeycomb exhibited higher elastic modulus and plateau stress than G-Honeycomb at various relative densities. Meanwhile, both TPMS-based honeycombs showed higher in-plane elastic modulus than conventional square honeycombs, although they had the same nodal connectivity. The idea of designing lattices with tuneable mechanical responses was achieved by introducing a density gradient or creating a G-P hybrid structure with the topology of G-Honeycomb and P-Honeycomb in different regions. The graded structures showed gradual stiffening and progressive collapse under compression, while the G-P hybrid structure can exhibit distinct properties at different compressive strains. [ABSTRACT FROM AUTHOR]

This study proposes a honeycomb with a sine waveform to increase the impact resistance against bird strike on the vertical stabilizer leading edge. A 2-stage comparison was made using the experimental test results in the literature to validate the model in the finite element environment. At first, the change in diameter, velocity, pressure, and scattering of particles when the bird model hits a square plate was compared with experimental data. In the second stage, an impact was made on the vertical stabilizer leading edge made of composite sandwich material. The deformation in the Z-direction occurring in the vertical stabilizer leading edge's center and the ribs' convergence were compared. The Ls-Dyna results show reasonable qualitative agreement with the experimental result. Finally, the straight walls of the honeycomb in the vertical stabilizer leading edge were modeled as a sine wave. The analyses were diversified using design parameters with different values. According to the analysis results, improvements of up to 9.79%, 28.58%, and 5.02% were observed in the deformation, the approach of the ribs, and sum of the reaction forces, respectively. These results contribute to bird strikes where strength per unit weight is essential. [ABSTRACT FROM AUTHOR]

This research aims to obtain the optimal honeycomb hybrid crash box design. Finite elements, parametric studies, and multi-objective optimization are carried out sequentially. Parametric studies are carried out to obtain important parameters to increase energy absorption and minimize mass. The effect of structure angle, honeycomb side length, and structure thickness are selected as the design parameter. Energy absorption and crash box mass are observed as design responses. Based on the results, it can be determined the optimal design from multi-objective optimization is angle structure of 21.1310, side length of 8.006 mm, and thickness of 1.2 mm. The model validation results for the optimal solution are appropriate; it is characterized by a honeycomb-filled structure that supports the folding of the outer wall of the crash box. [ABSTRACT FROM AUTHOR]

Honeycomb cores are widely used in the aerospace and automotive fields as a part of protective structures. Unfortunately, standard prismatic honeycomb cores offer a limited amount of energy absorption under lateral loads and suffer from degradation of their impact-deadening properties when their dimensional scale is increased. In this work, a multiscale study on energy absorption under quasi-static load is carried out on 3D-printed honeycomb core samples constituted by a variable section and compared to the cases of standard hexagonal honeycomb samples having the same mass and external dimensions. When doubling the dimensional scale in the case of lateral loads, the novel core geometry showed a substantial absence of specific energy absorption degradation, whereas the hexagonal core suffered from a 12.2%-degradation. Furthermore, by increasing the dimensional scale, the novel core geometry shows a delay in the densification onset. The variable-core geometry showed an average increase, in terms of energy absorption under lateral loads, of 46.8% for the regular scale and 71.4% for the double scale. Under axial loads, a 12.4%-decrease in energy absorption was observed for the samples with novel geometry, which, nevertheless, showed a relatively constant profile of reaction force under compression: this property could potentially allow it to avoid pre-crushing. [ABSTRACT FROM AUTHOR]

To further improve the low-frequency broadband sound absorption capability of the underwater anechoic layer (UAL) on the surface of marine equipment, a novel sound absorption structure with cavities (NSSC) is designed by adding resonators and honeycombs to the traditional sound absorption structure with cavities (SSC). Based on the principle of shear dissipation, the original intention of the design is to allow more parts of the viscoelastic material to participate the dissipation of acoustic energy. The approximate multilayer sound absorption theoretical model based on the modified transfer matrix method is used to verify the accuracy of finite element calculations. In the frequency range of 1100 Hz–10,000 Hz, the sound absorption coefficient (α) of NSSC can reach 0.8. The effects of the presence and size of cylindrical oscillators and honeycomb structures on sound absorption are discussed in detail. The results show that expanding the effective sound absorption range of the damping area of the structure is the key to improve the wideband sound absorption effect. This design concept could guide the structural design of the UAL. [ABSTRACT FROM AUTHOR]

In this review, we present a comprehensive summary of the formation of honeycomb microstructures and their applications, which include tissue engineering, antibacterial materials, replication processes or sensors. The history of the honeycomb pattern, the first experiments, which mostly involved the breath figure procedure and the improved phase separation, the most recent approach to honeycomb pattern formation, are described in detail. Subsequent surface modifications of the pattern, which involve physical and chemical modifications and further enhancement of the surface properties, are also introduced. Different aspects influencing the polymer formation, such as the substrate influence, a particular polymer or solvent, which may significantly contribute to pattern formation, and thus influence the target structural properties, are also discussed. [ABSTRACT FROM AUTHOR]

For a policy of 100% renewable energy, most renewable‐energy research is aimed at decarbonization; particular emphasis is being placed on increasing the portion of electricity generated by photovoltaics (PVs). As the application fields of PVs broadens from PV power plants and rooftop to various urban environments, achieving high energy yields requires expansion beyond current PV module structures. To satisfy these demands, honeycomb‐structured PV modules with incorporated mechanical metamaterials are proposed, to overcome the aforementioned problems associated with the limited mechanical properties of PVs, and to advance the development of 3D PV modules with enhanced energy yield. The honeycomb structures provide 28% greater power compared with flat cells by utilizing extra reflected or scattered light inside a 3D tetrahedron structure. For mechanical robustness, the 3D concave tetrahedron units are supported by a 3D‐structured mechanical metamaterial that exhibits a negative Poisson's ratio and is arranged in a 3D pattern. [ABSTRACT FROM AUTHOR]

Paper honeycomb and EPE are widely used in the field of packaging protection and safety transportation. Given the cushioning and protective function of unilateral and bilateral composite layered structures (CLSs) including polyethylene foam (EPE) and paper honeycomb, this work focused on analyzing the energy absorption (EA) and compression deformation of honeycomb thickness (HT) CLS under diverse drop impact (DI) status. Experimental observation showed that the increase of HT can improve the impact resistance of EPE and its CLSs. For the CLS with the HTs of 10, 15, 20, and 25 mm, the increase of paper HT may reduce the EA at low impact energy, while enhancing the EA capability at high impact energy. However, the EA of CLSs with a large HT of 70 mm is relatively poor. For the same drop weight mass or impact energy, the stroke efficiency (SE) and specific energy absorption (SEA) of the unilateral CLS with the same HT are, respectively, increased by 39.1% and 16.2%, so the EA of the unilateral CLS is superior to the bilateral CLS. [ABSTRACT FROM AUTHOR]

As the performance improvement of gas turbines becomes marginal, it is required to develop a seal geometry that can reduce unwanted leakage more effectively than conventional seals. Accordingly, in this paper, a new honeycomb structure with improved sealing performance was suggested. The proposed seal is a mixed honeycomb seal (MHS), where honeycomb cells with a smaller diameter (D′) are inserted into the base honeycomb structure with a cell diameter (D) to reduce the effective clearance. To compare the performance of the mixed honeycomb seal and a uniform honeycomb seal (UHS), computational fluid dynamics (CFD) analyses were performed by altering the pressure ratios and clearance sizes. At the same pressure ratio and clearance size, the MHS shows a performance improvement of up to 19 % (i.e., less leakage flow rate) compared to the UHS. In addition, the effects of D and D′ on the leakage performance were examined through a parametric study. [ABSTRACT FROM AUTHOR]

Honeycomb materials are commonly used as cores for sandwich panels. While empirical evidence exists showing that the transverse shear strength of a honeycomb core is affected by its thickness, the accuracy of empirical guidelines and the reasons for the changes in strength are not well understood. Four-point flexural testing of sandwich beams and a detailed cellular finite element model are used to investigate transverse shear failure of Nomex™ honeycomb core material. Transverse shear strengths at varying core thicknesses were compared to manufacturer specifications and used to determine normalised strength correction factors for thickness. These factors correlated well with trends shown in previous literature, where core shear strength decreases with increasing core thickness. The failure mode investigation showed a transition between modes as core thickness increased. The thinner cores experience shear fracturing of individual cell walls followed by local cell wall buckling, intermediate thickness cores initially failed by cell wall local buckling, then fractured and larger thickness cores appeared to fail by overall cell column buckling. [ABSTRACT FROM AUTHOR]

In this study, it was aimed to experimentally compare the mechanical properties of the traditional honeycomb structure, which is one of the cellular structures with its own specific area of use with its features such as lightness and load absorption, and the new generation re-entrant, chiral and hybrid structure (re-entrant + honeycomb) with negative Poisson behavior. In this context, standard test samples with honeycomb, reentrant, chiral and hybrid structures were produced with fused deposition modelling (FDM) under optimum conditions by using PLA material and different geometric parameters. Tensile and compression tests, hardness tests and surface roughness measurements were carried out with the specimens that were additively manufactured. According to the results, it was determined that the direction of the unit cells in the cellular structure and the rib thickness affect the energy absorption properties of the cellular structures. While the tensile and compressive strengths of the cellular structures increased with increasing rib thickness, the average Ra value and hardness value were measured as 14 μm and 75 Shore D respectively. Although negative Poisson ratio was observed depending on the amount of deformation in re-entrant, chiral and hybrid structures, positive Poisson behavior was observed in honeycomb structures. [ABSTRACT FROM AUTHOR]

Additive manufacturing technologies enable the production of components with lightweight cores, by means of infills with various patterns and densities. Together with reduced mass and material consumption, infill geometries must ensure that strength and stiffness conditions are fulfilled. For the proper correlation of the infill type with the loading case of the part, the mechanical behavior of the infill along all three principal axes of inertia has to be known. In this paper, the behavior in symmetric and asymmetric bending of three infill geometries, commonly used in 3D printing processes (honeycomb, grid and triangles) is analyzed. The variations of deflections as a function of force orientation are presented, showing that honeycomb and triangular structures exhibit similar behaviors along the Y and Z principal axes of inertia. Furthermore, the displacements obtained for the three types of structures are compared, in relation to the consumed volume of material. The larger displacements of the grid structure compared to the honeycomb and triangular structures are highlighted. [ABSTRACT FROM AUTHOR]

Honeycombs are essential elements in mechanical systems where low weight and high strength are required. Aluminum and Nomex® are the most commonly used honeycomb materials in structures exposed to compression stress. The primary purpose of this study is to verify the compression behavior of honeycombs in Ls-Dyna using experimental values and theoretical equations. Additionally, it is aimed to evaluate the honeycombs parameters such as cell diameter, cell wall thickness, and material. A correlation matrix was created using the Python/Seaborn program to examine the impact coefficients of the parameters. In this way, the effect of design parameters on compression strength and internal energy was investigated. [ABSTRACT FROM AUTHOR]

In this work, we reported a theoretical model for a novel piezoelectric micromachined ultrasonic transducer (PMUT). The sensing cells with hexagonal transduction diaphragms in the PMUT array are designed and arranged in a bioinspired honeycomb structure. Based on the classical piece-wise approach commonly used for PMUT with circular diaphragm, an enhanced theoretical model is developed. In this model, the deflection of the honeycomb diaphragm is analytically determined by the volume deflection, rather than the path deflection commonly used in the previous models. The hexagonal diaphragm is converted as a circular one, whose radius is derived by correcting the characteristic size of the hexagonal diaphragm multiplied by a correction factor. The calculated parameters by the reported theoretical model of a transduction cell in the PMUT array, such as resonant frequency and static deflection, matched well with the data obtained by finite element analysis and experiment. Special investigations are made on the effects of top electrode coverage and transduction layer thickness towards PMUT’s performance. The reported theoretical model in this work is suitable not only for PMUTs with circular and hexagonal transduction cells, but also for square and other arbitrary shape diaphragms. This enhanced theoretical model provides an interesting insight on design optimizations of PMUT with various transduction cell geometries. [2022-0093] [ABSTRACT FROM AUTHOR]

A designer of metallic energy absorption structures using additively manufactured cellular materials must address the question of which of a multitude of cell shapes to select from, the majority of which are classified as either honeycomb, beam-lattice, or Triply Periodic Minimal Surface (TPMS) structures. Furthermore, there is more than one criterion that needs to be assessed to make this selection. In this work, six cellular structures (hexagonal honeycomb, auxetic and Voronoi lattice, and diamond, gyroid, and Schwarz-P TPMS) spanning all three types were studied under quasistatic compression and compared to each other in the context of the energy absorption metrics of most relevance to a designer. These shapes were also separately studied with tubes enclosing them. All of the structures were fabricated out of AlSi10Mg with the laser powder bed fusion (PBF-LB. or LPBF) process. Experimental results were assessed in the context of four criteria: the relationship between the specific energy absorption (SEA) and maximum transmitted stress, the undulation of the stress plateau, the densification efficiency, and the design tunability of the shapes tested—the latter two are proposed here for the first time. Failure mechanisms were studied in depth to relate them to the observed mechanical response. The results reveal that auxetic and Voronoi lattice structures have low SEA relative to maximum transmitted stresses, and low densification efficiencies, but are highly tunable. TPMS structures on the other hand, in particular the diamond and gyroid shapes, had the best overall performance, with the honeycomb structures between the two groups. Enclosing cellular structures in tubes increased peak stress while also increasing plateau stress undulations. [ABSTRACT FROM AUTHOR]

Manufacturing aircraft components through 3D printing has become a widespread concept with proven applicability for serial production of certain structural parts. The main objective of the research study is to determine whether a chlorinated polyethylene material reinforced with milled carbon fibers has the potential of replacing the current 5052 NIDA aluminum alloy core of the IAR330 helicopter tail rotor blade, under the form of a honeycomb structure with hexagonal cells. Achieving this purpose implied determining the tensile and compression mechanical properties of the material realized by fused deposition modeling. The tensile tests have been conducted on specimens manufactured on three printing directions, so that the orthotropic nature of the material may be taken into account. The bare compression tests were realized on specimens manufactured from both materials, with similar honeycomb characteristics. All the mechanical tests have been performed on the Instron 8872 servo hydraulic testing system and the results have been evaluated with the Dantec Q400 Digital Image Correlation system. The experimental tests have been reproduced as finite element analyses which have been validated by results comparison, in order to determine if the compression model is viable for more complex numerical analysis. [ABSTRACT FROM AUTHOR]

In this article, we present a unique combination of techniques focusing on the immobilization of noble metal nanoparticles into a honeycomb polystyrene pattern prepared with the improved phase-separation technique. The procedure consists of two main steps: the preparation of the honeycomb pattern (HCP) on a perfluoroethylenepropylene substrate (FEP), followed by an immobilization procedure realized by the honeycomb pattern's exposure to an excimer laser in a noble metal nanoparticle solution. The surface physico-chemical properties, mainly the surface morphology and chemistry, are characterized in detail in the study. The two-step procedure represents the unique architecture of the surface immobilization process, which reveals a wide range of potential applications, mainly in tissue engineering, but also as substrates for analytical use. [ABSTRACT FROM AUTHOR]

[Display omitted] • We fabricated carbonate apatite honeycomb scaffolds with vertical uniaxial channels. • At 4 weeks post implantation, all honeycomb scaffolds augmented new bone. • The augmentation happened close to the top surface of the scaffold. • In the following 8 weeks, the height and amount of new bone increased. • HC300 resisted compression from fasciae at 12-weeks post implantation. • Honeycomb structure is inherently suitable for vertical bone augmentation. Cases of intractable dental implant require vertical bone augmentation; however, the predicted bone height and volume are difficult to obtain. In vertical bone augmentation, the contact surface between the scaffold and the bone is limited to the bottom face of the scaffold. Furthermore, the strength decrease caused by scaffold resorption leads to collapse of the augmented site, leading to a decrease in the bone volume and height. To promote bone ingrowth, we fabricated carbonate apatite (i.e., bone mineral) honeycomb (HC) scaffolds with uniaxial channels vertically penetrating the scaffold. Furthermore, we controlled the scaffold resorption rate, eventually the endurability for compression, and the bone height and volume by controlling the strut thickness. The channel aperture was controlled to be 230–260 μm to promote bone ingrowth. Furthermore, the strut thicknesses of the HC scaffolds were adjusted to 100, 200, and 300 μm to control the scaffold resorption; these scaffolds were designated as HC100, HC200, and HC300, respectively. At 4 weeks post-implantation on rabbit calvarium, all scaffolds had already vertically augmented new bone close to the top surface of the scaffold. In the following 8 weeks, the height and amount of new bone in all scaffolds increased. Notably, HC300 was resorbed synchronously with new bone formation, allowing it to endure the compression from the fasciae for 12 weeks post-implantation. Furthermore, HC300 formed larger-diameter blood vessels than those of HC100 and HC200. The HC scaffolds surpassed the various combined scaffolds and growth factors or stem cells in the ability for vertical bone augmentation. Thus, the HC structure is inherently suitable for vertical bone augmentation. Notably, the HC scaffolds with 300-μm-thick struts enhanced both new bone formation and angiogenesis. This study revealed a structurally suitable design for achieving an outstanding outcome in vertical bone augmentation. [ABSTRACT FROM AUTHOR]