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Two-dimensional (2D) materials with honeycomb, kagome or star lattice have been intensively studied because electrons in such lattices could give rise to exotic quantum effects. In order to improve structural diversity of 2D materials to achieve unique properties, here we propose a new quasi-2D honeycomb-star-honeycomb (HSH) lattice based on first-principles calculations. A carbon allotrope named HSH-C10 is designed with the HSH lattice, and its mechanical properties have been intensively investigated through total energy, phonon dispersion, ab initio molecular dynamic simulations, as well as elastic constants calculations. Besides the classical covalent bonds, there is an interesting charge-shift bond in this material from the chemical bonding analysis. Additionally, through the analysis of electronic structure, HSH-C10 is predicted to be a semiconductor with a direct band gap of 2.89 eV, which could combine the desirable characteristics of honeycomb and star lattice. Importantly, by modulating coupling strength, a flat band near the Fermi level can be obtained in compounds HSH-C6Si4 and HSH-C6Ge4, which have potential applications in superconductivity. Insight into such mixed lattice would inspire new materials with properties we have yet to imagine.

To address the problem of the poor stability of ultrasonic machining of wave-absorbing honeycomb materials, this paper takes ultrasonic cutting of wave-absorbing honeycomb materials with a disc cutter as the research object and establishes a multi-degree-of-freedom mathematical model of the cutting system based on the relative positions of the tool and the honeycomb material and the motion characteristics of the tool. On this basis, modal analysis of the disc tool and the honeycomb cellular element wall plate is carried out to draw the Lobe diagram of ultrasonic cutting stability, the process experimental parameters are determined according to the solved stability Lobe diagram, and machining stability verification experiments are carried out. The experimental results show that the machining parameters in the stable region of the Lobe diagram result in a neat and clean surface, less fibre pullout, a complete outer substrate, and less tool wear than those in the critical and unstable regions, thus verifying the correctness of the theoretical model and the stability Lobe diagram.

This work presents an experimental thermal evaluation of new and innovative porous morphologies suitable for volumetric solar receivers. Five new morphologies, four of them based on the repetition of single unit cells: diamond, rotated cube, tetrakaidecahedron, cube shifted, and a random morphology following the Voronoi tessellation technique were tested. In addition, for emerging geometries, two different cell size configurations were evaluated: one with constant cell size dimension and one with cell's size changing with flux direction. All the lattices were analysed experimentally in a lab-scale solar simulator. The results were compared with the ones of the already established and more conventional silicon carbide honeycomb and random foams proving that a gain in performance is achievable with the Voronoi morphology, both with constant cell size and increasing cell size pattern.

Honeycomb is widely used because of its excellent energy absorption characteristics during compression. However, offset defects in the manufacturing process are inevitable and affect the energy absorption characteristics. In order to study the effect of offset defect, the finite element model was established firstly. The verified finite element model was used to simulate the honeycomb structure under different offsets. The simulation shows that with the increase of the offset λ, the deformation mode of the honeycomb can be divided into three stages and the platform strength increased first and then decreased, and the decrease was obviously greater than the increase. Then the theoretical calculation formula of platform strength of the honeycomb under offset defect was obtained by simple folding theory. The results show that for commonly used honeycomb specifications, when λ = 0.4, the platform strength increases the most, which is 7.99%, and when λ = 1.0, the platform strength decreases the most, which is 18.03%. The theoretical results are similar to the simulation results. For Y-shaped element, the errors are 2.13% and 2.04% at λ = 0.4 and 1.0 respectively, for whole honeycomb, the errors are 0.29% and 4.82% at λ = 0.4 and 1.0 respectively. Therefore, the platform strength of honeycomb can be improved by increasing the offset appropriately.

In this study, an analytical solution is presented to determine the buckling load of composite cylindrical shells with an auxetic honeycomb layer under a uniform axial load. The composite shell con...

The 3D honeycomb-like fabric decorated with MXene is woven as solar evaporator.The honeycomb structure enables light-trapping and recycling of convective and radiative heat.The 3D honeycomb-fabric evaporator possesses high solar efficiency up to 93.5% under 1 sun irradiation and excellent salt harvesting ability. Solar steam generation technology has emerged as a promising approach for seawater desalination, wastewater purification, etc. However, simultaneously achieving superior light absorption, thermal management, and salt harvesting in an evaporator remains challenging. Here, inspired by nature, a 3D honeycomb-like fabric decorated with hydrophilic Ti3C2Tx (MXene) is innovatively designed and successfully woven as solar evaporator. The honeycomb structure with periodically concave arrays creates the maximum level of light-trapping by multiple scattering and omnidirectional light absorption, synergistically cooperating with light absorbance of MXene. The minimum thermal loss is available by constructing the localized photothermal generation, contributed by a thermal-insulating barrier connected with 1D water path, and the concave structure of efficiently recycling convective and radiative heat loss. The evaporator demonstrates high solar efficiency of up to 93.5% and evaporation rate of 1.62 kg m−2 h−1 under one sun irradiation. Moreover, assisted by a 1D water path in the center, the salt solution transporting in the evaporator generates a radial concentration gradient from the center to the edge so that the salt is crystallized at the edge even in 21% brine, enabling the complete separation of water/solute and efficient salt harvesting. This research provides a large-scale manufacturing route of high-performance solar steam generator. Supplementary Information The online version contains supplementary material available at 10.1007/s40820-021-00748-7.

Honeycomb composites are now common materials in applications where high specific stiffness is required. Previous research has found that honeycombs with polymer infills in their cells, here referred to as honeycomb-polymer composites (HPCs), exhibit effective stiffnesses greater than the honeycomb or polymer alone. Currently, the state of analytic models for predicting the elastic properties of these composites is limited, and further research is needed to better characterize the behavior of these materials. In this research, a nonlinear finite element analysis was employed to perfor2m parametric studies of a filled honeycomb unit cell with isotropic wall and infill materials. A rigid wall model was created as an upper bound on the deformable wall model’s performance, and an empty honeycomb model was employed to better understand the mechanisms of stiffness amplification. Parametric studies were completed for infill material properties and cell geometry, with the effective Young’s modulus studied in two in-plane material directions. The mechanisms by which the stiffness amplification occurs are studied, and comparisons to existing analytic models are made. It has been observed that both the volume change within the honeycomb cell under deformation and the mismatch in Poisson’s ratios between the honeycomb and infill influence the effective properties. Stiffness amplifications of over 4000 have been observed, with auxetic behavior achieved by tailoring of the HPC geometry. Additionally, the effect of large effective strains up to 10% is explored, where the cell geometry changes significantly. This research provides an important step toward understanding the design space and benefits of HPCs.

The functionally graded honeycomb has the characteristic of light weight, low density, high impact resistance, noise reduction, and energy absorption as a kind of new composite inhomogeneous materials. It has the advantages of both functionally graded materials and honeycombs. In this paper, a functionally graded honeycomb sandwich plate with functionally graded distributed along the thickness of the plate is constructed. The equivalent elastic parameters of the functionally graded honeycomb core are given. Based on Reddy’s higher-order shear deformation theory (HSDT) and Hamilton’s principle, the governing partial differential equation of motion is derived under four simply supported boundary conditions. The natural frequencies of the graded honeycomb sandwich plate are obtained by both the Navier method from the governing equation and the finite element model. The results obtained by the two methods are consistent. Based on this, the effects of parameters and graded on the natural frequencies of the functionally graded honeycomb sandwich plate are studied. Finally, the dynamic responses of the functionally graded honeycomb sandwich plate under low-speed impacts are studied. The results obtained in this paper will provide a theoretical basis for further study of the complex dynamics of functionally graded honeycomb structures.

This paper proposes a finite element method (FEM) for the free vibration analysis of sandwich nanoplates with an auxetic honeycomb core. The proposed method uses a third-order shear deformation theory accounting for both shear deformation and stretching effects without any need for shear correction factors. The size-dependent effect is solved using the nonlocal elasticity theory. The auxetic sandwich nanoplate with negative Poisson’s ratio is applied to achieve ultra-light features and high strength. The obtained numerical results by the proposed method are compared with other published works to demonstrate the accuracy and reliability. Moreover, the influence of the nonlocal factor, geometrics parameters, and material properties (especially the auxetic honeycomb parameters) on the free vibration behavior of sandwich nanoplates is also examined in the numerical examples.

The special energy-absorbing structure of beak protects the head of woodpecker from being hurt when pecking tree. Inspired by the micro wavy structure of the woodpecker beak, a novel bionic sinusoi...

International audience; Fe4Nb2O9 and Co4Nb2O9 are antiferromagnetic compounds belonging to the M4M′2O9 series (M = Mn, Fe, Co; M′ = Nb, Ta), whose structure (P[3 with combining macron]c1) derives from the Cr2O3 corundum one. By mixing cobalt and iron in a 1 : 1 ratio, an Fe2Co2Nb2O9 oxide has been synthesized. Its structural, magnetic and electric characterization studies confirm that its unit cell volume (V = 331.19(1) Å3), Néel temperature (TN = 58 K) and dielectric permittivity are intermediate between those of the Fe4Nb2O9 and Co4Nb2O9 end members. The neutron diffraction study evidences an Fe:Co random occupation of the (4d) Wyckoff sites. Its antiferromagnetic structure, refined in the C2/c′ magnetic space group, shows magnetic moments in the planes of the honeycomb (HC) layers of the M4M′2O9 structure, and stacked along c, as for Fe4Nb2O9 and Co4Nb2O9. However, the magnetic field induced magnetization M(H) of Fe2Co2Nb2O9 below TN differs strongly from both end members, exhibiting a sublinear dependence. A similar rounded shape of the electric polarization P(H) curve is evidenced, in marked contrast to the linear M(H) and P(H) behaviours observed below the spin-flop magnetic field for this class of linear magnetoelectric materials. As a result, Fe2Co2Nb2O9 exhibits larger P values and steeper P responses to H at low H than both Fe4Nb2O9 and Co4Nb2O9 end members. This result is explained by a microscopic model based on the Fe and Co mixed occupation. Substitutional disorder locally allows for stronger magnetoelectric couplings and its effect does not cancel on average. This chemical substitution effect opens a new route to enhance the magnetoelectric response of honeycomb antiferromagnets.

En este trabajo se presentan los resultados de la modificación en la cámara estabilizadora del túnel de viento de la Facultad de Ciencias de la Ingeniería y Tecnología (FCITEC), utilizando un honeycomb y cuyo objetivo fue reducir la intensidad de la turbulencia en la zona de pruebas. Se presentan los resultados experimentales y se comparan con un análisis de CFD realizado con el software ANSYS-Fluent. La modificación permitió una reducción de la intensidad de la turbulencia en un 2% en la zona de pruebas.

Reconstruction of critical-sized defects (CSDs) in bone shafts remains a major challenge in orthopedics. Honeycomb (HC) scaffolds are considered promising as their uniaxial channels bridge the amputation stumps of bones and promote the ingrowth of bone and blood vessels (BV) into the scaffolds. In this study, the ability of the HC scaffolds, composed of the bone mineral or carbonate apatite (CAp), was evaluated by reconstructing 10, 15, and 20 mm segmental defects in the rabbit ulnar shaft. Radiographic and μ-computed tomography evaluations showed that bony calluses were formed around the scaffolds at 4 weeks post-surgery in all defects, whereas no callus bridged in the ulna without scaffolds. At 12 weeks post-surgery, the scaffolds were connected to the host bone in 10 and 15 mm defects, while a slight gap remained between the scaffold and host bone in the 20 mm defect. New bone formation and scaffold resorption progressed over 12 weeks. Histological evaluations showed that mature bones (MB) and BV were already formed at the edges of the scaffolds at 4 weeks post-surgery in 10, 15, and 20 mm defects. In the central region of the scaffold, in the 10 mm defect, MB and BV were formed at 4 weeks post-surgery. In the 15 mm defect, although BV were formed, a few MB were formed. It is concluded that CAp HC scaffolds have good potential value for the reconstruction of CSDs.

A novel angle graded auxetic honeycomb (AGAH) core is designed for sandwich structures in the present study. The angle of the cells is varied through the thickness of the AGAH core using linear functions. Therefore, the thickness of the cell walls is kept constant along the gradation of the cell angle, and the length of the cell walls is changed through the core thickness as the result of angle variation. New analytical relations are proposed to predict the equivalent elastic properties of the AGAH core. The performance of the new proposed core is analytically assessed for the vibrational behavior of a sandwich plate. The governing equations are deduced adopting Hamilton’s principle under the assumption of quasi-3D exponential plate theory. Three-dimensional finite element (3D-FE) simulation is accomplished to verify the analytical results of the vibrational response of the sandwich structure. The influence of variation of the cell wall, the cell angle and cell aspect ratio of AGAH core, and geometric parameters of the sandwich structure are investigated on the vibration response of the sandwich panel. The present graded design of the auxetic honeycomb enhances the specific stiffness (i.e., stiffness to density ratio) and consequently increases the natural frequencies of sandwich structures with this type of core.

The nonpneumatic tire (NPT), as the name suggests, is a type of tire that does not use air to support the load. Because of their outstanding advantages, such as durability and low rolling resistance, these tires have attracted much interest. The study of NPTs has drawn considerable recent attention, and some research was conducted to investigate their mechanical response. However, these studies did not consider an analysis of an NPT against obstacles. Therefore, in this article, the static and dynamic behaviors of an NPT with honeycomb structures rolling over different obstacles are investigated using numerical simulation. The flexible spokes, which are the most important part of NPTs, are assumed to have a honeycomb structure with the same cell wall thickness and angle. Based on the mesostructures hypothesis, these spokes are considered to be made of polyurethane material. To perform a more precise analysis, various parameters such as nonlinear properties of the material and contact condition are taken into account to establish the finite element model. The results, which can be used as a benchmark and are suitable for design purposes, are presented elaborately.

In this paper, the mechanical properties of Nomex® paper coated with resin and composite Nomex® honeycomb sandwich structures (CNHSS) were obtained by tensile tests and flatwise tests respectively. The fundamental mechanical properties of the Nomex® paper were used as input materials parameters of finite element model generated at meso-scale level for the CNHSS, and the mechanical properties of CNHSSs were used to validate the numerical results. Based on the test and numerical results, the theoretical equations were modified to predict the flatwise compressive buckling strength and modulus of the CNHSS. The numerical and theoretical results clearly revealed that the CNHSS had two flatwise compressive elastic moduli. However, the flatwise test can only capture the second flatwise compressive elastic modulus due to manufacturing geometric defects of the cell walls. The numerical and test results showed that the manufacturing geometric defects of the cell walls showed little influence on the ultimate flatwise compressive strength. And the modified equation can predict the flatwise compressive buckling strength and modulus of the CNHSS with sufficient accuracy.

Sandwich composite structures are comprised of a low-density core (commonly honeycomb) and facesheets. They are typically used in applications that require lightweight for efficient design, such as in the marine and aerospace industries. This work investigates the feasibility of adopting triply periodic minimal surface (TPMS) cellular structures as the core for sandwich composites. Sandwich structures were manufactured using a carbon fiber-reinforced polymer (CFRP) facesheet and three different 304 L stainless steel core structures (honeycomb, gyroid TPMS, and diamond TPMS). Three mechanical tests, namely edgewise compression, three-point bend, and impact test, were carried out to evaluate the performance of each sandwich configuration. The experimental results of the non-traditional sandwich configurations were compared against those of a honeycomb core sandwich composite. The edgewise compression test showed that the ultimate edgewise compressive strength increased by 7% when the honeycomb core was replaced by the gyroid core and reduced by 2% when the diamond core replaced the honeycomb core. The three-point bend test showed that the traditional honeycomb core sandwich configuration had a higher shear yield stress when compared to the non-traditional sandwich structures. The shear yield stress was reduced by 54% when non-traditional sandwich cores were used. The shear ultimate stress was reduced by 41% and 37% when the honeycomb core was replaced by the gyroid and diamond structure, respectively. Impact test results, on the other hand, showed that the peak force recorded during the impact event was reduced, while the absorbed energy was increased when non-traditional cores were used. Peak force was reduced by 28% and 39%, while the absorbed energy was increased by 9% and 16% when the honeycomb core was replaced by the gyroid and diamond cores, respectively.

The equivalent in-plane elastic modulus [Formula: see text] of a honeycomb sandwich in the direction of cell vertical wall can be assessed by the law of mixture from the modulus of face sheet [Formula: see text] and the equivalent modulus of honeycomb core [Formula: see text]. However, significant errors as large as 40% can be made depending on material and geometry parameters, when the used [Formula: see text] is obtained from a cellular model of core alone without considering the skin effect of face sheet. The main reason of the error is that the rigidity to deformation of y-direction is different greatly between the vertical cell wall of core and inclined cell wall of core. In the present paper, an analytical model is proposed to assess [Formula: see text] of honeycomb sandwich with considering the interference effect of the core with the face sheet. In the proposed model, the influence of the face sheet rigidity on [Formula: see text] is taken into account. The results demonstrate that the contribution of the core to [Formula: see text] is also dependent on the face sheet rigidity significantly. The validity of presented model is verified by comparing the results with numerical results of FEA.

A new electromagnetic scattering model of target with honeycomb composite material is proposed in this letter by combining equivalent reflection coefficient model with high frequency method. First, the honeycomb composite is regarded as a uniaxial media based on strong interference theory. Then, the reflection coefficient of honeycomb composite with perfect electric conductor is derived with generalized propagation matrix method. Finally, the derived reflection coefficients are introduced in shooting and bouncing rays and physical optics (SBR-PO) method to obtain the scattering characteristic of complex target covered with honeycomb material. Moreover, the SBR-PO method is accelerated by the Compute Unified Device Architecture and OptiX from Nvidia. The accuracy of our method was demonstrated by comparing with full-wave method and measured data, respectively. The scattering of target covered with honeycomb material are simulated and discussed in this letter.

Some of the three-dimensional (3D) crystal structures are constructed by stacking two-dimensional (2D) layers. It remains unclear whether this geometric concept is related to the stability of ordered compounds and whether this can be used to computational materials design. Here, using first principles calculations, we investigate the dynamical stability of copper-based compounds Cu$X$ (a metallic element $X$) in the B$_h$ and L1$_1$ structures constructed from the buckled honeycomb (BHC) structure and in the B2 and L1$_0$ structures constructed from the buckled square (BSQ) structure. We demonstrate that (i) if Cu$X$ in the BHC structure is dynamically stable, those in the B$_h$ and L1$_1$ structures are also stable. Although the interrelationship of the metastability between the BSQ and the 3D structures (B2 and L1$_0$) is not clear, we find that (ii) if Cu$X$ in the B2 (L1$_0$) structure is dynamically stable, that in the L1$_0$ (B2) is unstable, analogous to the metastability relationship between the bcc and the fcc structures in elemental metals. The total energy curves for Cu$X$ along the tetragonal and trigonal paths are also investigated., 8 pages, 7 figures

To obtain new nonlinear optical (NLO) materials with a large second harmonic generation (SHG) effect has always been a great challenge. We have synthesized the first metal borate-iodate NLO crystal, Be2 (BO3 )(IO3 ) (BBIO), by multicomponent modification of KBe2 BO3 F2 (KBBF), in which the structural features of KBBF were maintained and (IO3 )- groups were connected to honeycomb [Be2 BO3 O2 ]∞ layers. As the first KBBF family member with mixed anionic groups, BBIO benefited from the synergistic effect of (IO3 )- , (BO3 )3- and (BeO4 )6- groups, and exhibited a very strong SHG response of ≈7.2×KH2 PO4 (KDP, @1064 nm) and a large birefringence (Δn) of 0.172 at 1064 nm. BBIO may, unexpectedly, optimize growth habits via van der Waals forces. This study presents borate-iodate as a new NLO material and it demonstrates opportunities in KBBF structural engineering.

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 t...

Purpose Volumetric air receivers experience high thermal stress as a consequence of the intense radiation flux they are exposed to when used for heat and/or power generation. This study aims to propose a proper design that is required for the absorber and its holder to ensure efficient heat transfer between the fluid and solid phases and to avoid system failure due to thermal stress. Design/methodology/approach The design and modeling processes are applied to both the absorber and its holder. A multi-channel explicit geometry design and a discrete model is applied to the absorber to investigate the conjugate heat transfer and thermo-mechanical stress levels present in the steady-state condition. The discrete model is used to calibrate the initial state of the continuum model that is then used to investigate the transient operating states representing cloud-passing events. Findings The steady-state results constitute promising findings for operating the system at the desired airflow temperature of 700°C. In addition, we identified regions with high temperatures and high-stress values. Furthermore, the transient state model is capable of capturing the heat transfer and fluid dynamics phenomena, allowing the boundaries to be checked under normal operating conditions. Originality/value Thermal stress analysis of the absorber and the steady/transient-state thermal analysis of the absorber/holder were conducted. Steady-state heat transfer in the explicit model was used to calibrate the initial steady-state of the continuum model.

Colloidal particles fabricated with anisotropic interactions have emerged as building blocks for designing materials with various nanotechnological applications. We used coarse-grained Langevin dynamics simulations to probe the morphologies of self-assembled structures formed by lobed particles decorated with functional groups. We tuned the interactions between the functional groups to investigate their effect on the porosity of self-assembled structures formed by lobed particles with different shapes (snowman, dumbbell, trigonal planar, tetrahedral, square planar, trigonal bipyramidal, and octahedral) at different temperatures. The dumbbell, trigonal planar, and square planar shaped particles, with planar geometries, form self-assembled structures including elongated chains, honeycomb sheets, and square sheets, respectively. The particles with non-planar geometries (tetrahedral, trigonal bipyramidal, and octahedral) self-assemble into random aggregate morphologies. The structures formed by trigonal bipyramidal and octahedral particles exhibit smaller and homogeneous pores compared to the structures formed by trigonal planar and square planar particles. The porosity in self-assembled structures is substantially enhanced by the functionalization of particles.

Based on the hyperbolic tangent shear deformation theory, free vibration and sound insulation of two different types of functionally graded (FG) honeycomb sandwich plates with negative Poisson’s ratio are studied in this paper. Using Hamilton’s principle, the vibration and vibro-acoustic coupling dynamic equations for FG honeycomb sandwich plates with simply supported edges are established. By applying the Navier’s method and fluid–solid interface conditions, the derived governing dynamic equations are solved. The natural frequencies and the sound insulation of FG honeycomb sandwich plates obtained in this work are compared with the numerical results by the finite element simulation. It is proven that the theoretical models for the free vibration and the sound insulation are accurate and efficient. Moreover, FG sandwich plates with different honeycomb cores are investigated and compared. The corresponding results show that the FG honeycomb core with negative Poisson’s ratio can yield much lower frequencies. Then, the influences of various geometrical and material parameters on the vibration and sound insulation performance are systematically analyzed.

In this paper, the effects of lattice stiffeners and blast load on nonlinear dynamic response and vibration of auxetic sandwich honeycomb plates on Pasternak elastic foundations are considered. The remarkable point of this study is that the outer surfaces of the system reinforced by lattice stiffeners (including orthogonal stiffeners and oblique stiffeners) are made of functionally graded materials. Based on the analytical solution, the Reddy’s FSDT, the Airy’s stress functions, the Galerkin and the fourth-order Runge-Kutta methods, fundamental frequency, dynamic response and frequency–amplitude curves of the plates reinforced by lattice stiffeners under blast and mechanical loads are determined. Then, the result analyses the effect of lattice stiffeners, blast and mechanical loads, elastic foundations on nonlinear dynamic response and vibration of auxetic honeycomb plates. The optimal angle of oblique stiffeners which maximizes natural frequency and contemporaneously minimizes amplitude when changing geometrical parameters of auxetic honeycomb is also determined.

A porous material –Bi-directional Trapezoid Honeycomb (BDTH) which is different from the traditional honeycomb structure, has same energy absorption properties in the Y and Z directions was studied. The structural parameters (cell size, cell thickness) have a great influence on the compression performance. 3 kinds of cell size ( a) and 4 kinds of cell thickness ( t0) totally 7 kinds of BDTH were manufactured. The quasi-static compression test was carried out with experiment and numerical simulation, and the results were obtained. The effects of material deformation modes and energy absorption are analyzed. Next, based on Gibson-Ashby theory, the relationship between density, initial peak stress, plateau stress, densification strain and the ratio of t0/a were deduced.

Honeycomb structures are one type of structure that has the geometry of a honeycomb to allow the minimization of the amount of used material to reach minimal material cost and minimal weight. For t...

The quantum anomalous Hall (QAH) effect has attracted enormous attention since it can induce topologically protected conducting edge states in an intrinsic insulating material. For practical quantu...

Three-dimensional finite element (FE) models of the honeycomb NPWs with three different spokes’ configurations, realized by varying the cell angle, were formulated. The validity of the proposed NPW FE models was demonstrated by comparing the predicted wheel responses with the reported data. A FE model of the pneumatic wheel of identical size was also formulated and verified on the basis of the measured vertical force-deflection and cornering properties. The verified NPW models were subsequently employed to study their feasibility through comparisons of in-plane as well as out-of-plane properties with those of the pneumatic wheel. The influences of the cell angle and normal wheel load on the static and dynamic properties of the NPWs were also investigated. The results showed load-dependent longitudinal stiffness of the wheel due to strong coupling between radial and longitudinal deformations of the honeycomb spokes. The lateral stiffness, however, was observed to be load-independent due to negligible coupling between radial and lateral deformations of the spokes. The spokes of the honeycomb NPWs could thus be easily tuned to achieve vertical and longitudinal stiffness comparable to those of the reference pneumatic wheel. The lateral and cornering stiffness of the NPWs with the planar spokes, however, were substantially higher, irrespective of the spokes’ configuration considered. The significantly higher cornering stiffness resulted in rapid saturation of the cornering force of the NPWs at side-slip angles about 1.1°, which is likely to cause lateral sliding of the wheels and potential loss of directional control under higher side slip conditions.

A development in the field of using adhesives in three-layer honeycomb structures is described. Information on the use of phenolic resin adhesives, epoxy film adhesives, and adhesive prepregs for the manufacture of honeycomb cores and honeycomb structures is given. Various types of honeycomb cores are discussed.

Lightweight panels for indoor constructions are typically made from composite materials with honeycomb and corrugated structures. The reinforcements are used in this study, one is fiberglass and the other is cellulose fiber, which cellulose from recycled paper. Experimental results indicate that the weight of honeycomb paper panel is light, only 13.6% of fiberglass composite and 32.6% of plywood. The presence of honeycomb structure has a significant effect on mechanical behaviors of composite panels. Both flexural and compressive strengths increase by replacing corrugated structure into honeycomb structure. During compression, the compressive strength and modulus of two-layer honeycomb/core panel are higher than those of monolayer honeycomb/core. Particularly, the honeycomb cell-wall thickness has a little effect on the weight, but has an important effect on mechanical properties. These results can be created low cost and lightweight environment-friendly panels by using recycled paper honeycomb structure.

In this article, we propose to apply 3-D printing technology to the design and realization of honeycomb microwave absorbers. First, printability of simple honeycomb structures, made of a lossy dielectric material, was evaluated and validated by measurement in the 2–18 GHz frequency band. Effective dielectric properties of honeycomb structures with different dimensions are also discussed. Then, the interest of 3-D printing technology was highlighted by the design, fabrication, and measurement of a multiscale honeycomb absorber that can significantly increase the relative bandwidth. The 3-D printed honeycomb absorbers are compared with others technologies. The potential of this technology was also illustrated by the fabrication and measurement of a pyramidal honeycomb absorber that demonstrates an absorption level of more than 22.9 dB over the 2–18 GHz frequency band.

When applying the modal summation method to the sound transmission loss (STL) prediction of various plates, the assumption of the blocked sound pressure, or alternatively speaking, ignoring sound radiation terms, has obvious simplicity and is sometimes used for the single-layered panels, rib-stiffened plates or heavily damped sandwich plates. For light-weighted sandwich plates with honeycomb and foam cores, however, this assumption is somewhat in doubt and worth examining. Based on sixth-order differential equations governing the flexural vibration of sandwich plates, the prediction formula of STL is derived by the modal summation approach. Theoretical predictions were validated by measurement data. Next, the theoretical formula of STL under the assumption of the blocked sound pressure was examined. The STL discrepancies of sandwich plates caused by sound radiation terms are illustrated. It was found that the STL discrepancies of sandwich plates were closely related to frequency, reached their peak value at the coincidence frequency region. The results indicate that the sound radiation terms, or the couplings between the radiated sound pressure and the plate response, should not be ignored for the prediction of STL for sandwich plates with honeycomb and foam cores.

The aim of this study is to characterize and assess failure modes and the effect of structural parameters of honeycomb sandwich structure. The semi-finite element model of honeycomb sandwich structure under four-point bending load is established by a parametric method. Laminate delamination is exhibited by a contact algorithm with the mixed-mode damage model. Experiments are conducted to obtain load-displacement curves of honeycomb sandwich structure and thereby verify the applicability of finite element model. The failure modes of honeycomb sandwich structure have also been identified by comparing the experimental results with the numerical results. The effects of structural parameters on the mechanical properties of honeycomb sandwich structure are discussed. Results demonstrate that the overall stiffness of honeycomb structure is closely related to the honeycomb cell size such as length, height and foil thickness. In addition, the strength of honeycomb sandwich structure is sensitive to stacking sequence of composite laminate with different fiber orientation. The main failure modes of honeycomb sandwich structure are laminate fracture, delamination, core buckling and wrinkling. The achievements in this study have guiding significance to design high-performance sandwich structure.

Based on the symmetric re-entrant honeycomb (S-RH) structure with negative Poisson’s ratios, a novel asymmetric and rotatable re-entrant honeycomb (AR-RH) structure was proposed. Both the S-RH structure and AR-RH structure were produced by the 3D printing technology. Through experimental test and finite element simulation, the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared. The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure, and it has been verified that the rotatability of AR-RH can indeed absorb energy. Furthermore, the degree of asymmetry of the AR-RH structure was discussed.