Search

Lennard-Jones potential parameters have been determined for the interlayered interaction in 12 elemental layered crystals. The layered crystals include corrugated borophene, buckled honeycomb structures with elements from the group IV (Si, Ge, and Sn) and group V (P, As, Sb, and Bi), as well as four puckered structures in the aw-phase (Sb and Bi) and sw-phase (P and As). We first calculated the minimal interfacial energy and the interlayer equilibrium distance for two typical shifted stackings, AA and AB, for every bilayer crystal using the density functional theory with a long-range dispersion correction. Then, we use the Lennard-Jones potential and the corresponding derivative to graphically match the calculated adhesion energy and the zero resultant force along the out-of-plane direction, determining the energy parameter and the size parameter for both stackings. The Lennard-Jones model with the obtained parameters can be in good agreement with the first-principles calculations for the AA and AB stackings in describing the relationship between the interfacial energy and the interlayer distance, and the Lennard-Jones parameters for the other stackings are directly determined according to Lorentz–Berthelot combining rules. The parameters can be applied in molecular dynamics simulations for the interfacial effect of elemental layered materials such as mechanical peeling and interlayer friction, as well as stacking formation, and the analytical method can be extended to determine the parameters of the Lennard-Jones potential for the compound layered crystals and the interlayer heterojunction structures. [ABSTRACT FROM AUTHOR]

Tert-butyl functional groups can modulate the self-assembly behavior of organic molecules on surfaces. However, the precise construction of supramolecular architectures through their controlled thermal removal remains a challenge. Herein, we precisely controlled the removal amount of tert-butyl groups in tetraazaperopyrene derivatives by stepwise annealing on Ag(111). The evolution of 4tBu-TAPP supramolecular self-assembly from the grid-like structure composed of 3tBu-TAPP through the honeycomb network formed by 2tBu-TAPP to the one-dimensional chain co-assembled by tBu-TAPP and TAPP was successfully realized. This series of supramolecular nanostructures were directly visualized by high resolution scanning tunneling microscopy. Tip manipulation and density functional theory calculations show that the formation of honeycomb network structure can be attributed to the van der Waals interactions, N–Ag–N coordination bonds, and weak C–H⋯N hydrogen bonds. Further addition of two tert-butyl groups (6tBu-TAPP) leads to a completely different assembly evolution, due to the fact that the additional tert-butyl groups affect the molecular adsorption behavior and ultimately induce desorption. This work can possibly be exploited in constructing stable and long-range ordered nanostructures in surface-assisted systems, which can also promote the development of nanostructures in functional molecular devices. [ABSTRACT FROM AUTHOR]

Higher-order topological states, as emergent topological phases of matter, originating from condensed matter physics, have sparked a vibrant exploration of topological insulators. Their topologically protected multidimensional localized states are typically associated with nontrivial bulk band topology, and the significant impact of lattice geometry is unconsciously overlooked. Here, we construct coupled acoustic cavities on a two-dimensional honeycomb lattice to investigate the sensitivity of higher-order topological modes to the variations of edge contour. Fractional charge is utilized to accurately predict topological modes with distinct topological orders, in spite of the minimal bulk bandgaps inherent in the honeycomb lattice and bound states in the continuum. It is found that the presence and absence of the first-order and higher-order topological modes in the same topological phase are tightly linked to the sample boundaries, which can be demonstrated by both theoretical analysis and numerical calculation. Our study also discusses potential physical realization of geometry-dependent topological states across different platforms, providing inspiration for the prospective application of topological devices in acoustics. [ABSTRACT FROM AUTHOR]

Using the Full Potential Linear Augmented Plane Wave and the pseudo-potential method based on the Density Functional Theory, we investigate the physical properties of two-dimensional (2D) boron nitride, carbon nitride, and boron carbide as well as their ternary system boron carbon nitride (BCN). The structural and optoelectronic properties are determined and discussed in detail with available theoretical and experimental results. We show that the studied physical properties are influenced and tunable by atom concentration. A high concentration of nitrogen (> 50%) disturbs the honeycomb structure of binary and ternary alloys. Additionally, the optoelectronic properties are very sensitive to the amount of boron and nitrogen atoms. The zero bandgap is only conserved for B3C12N3 and B6C6N6 ternary systems. A large bandgap was observed for B9N9 (∼3.9 eV) and a moderate one for B6N12 and B3N15 (∼2 eV). The coexistence of boron, carbon, and nitrogen atoms with different concentrations has important optical properties as they can absorb light in all spectra. However, they have more active absorption in the ultraviolet than visible regions. It is more interesting to use ternary BCN than binary or pristine alloys with tunable optoelectric properties, by varying the nitrogen content in nanodevices. [ABSTRACT FROM AUTHOR]

This paper introduces novel mathematical optimisation models for the 2-Dimensional guillotine Cutting Stock Problem with Variable-Sized Stock that appears in a Spanish company in the honeycomb cardboard industry. This problem mainly differs from the classical cutting stock problems in the stock, which is considered variable-sized, i.e. we have to decide the panel dimensions, width, and length. This approach is helpful in industries where the stock is produced simultaneously with the cutting process. The stock is then cut into smaller rectangular pieces that must meet the customers' requirements, such as the type of item, dimensions, demands, and technical specifications. Furthermore, in the problem tackled in this paper, the cuts are guillotine, performed side to side. The proposed mathematical models are validated using real data from the company, obtaining results that drastically reduce the produced material and leftovers, reducing operation times and economic costs. [ABSTRACT FROM AUTHOR]

In this study, we experimentally demonstrate a class of lightweight acoustic metamaterial barriers that block low-frequency sound. The acoustic metamaterial barrier is composed of a thin rubber membrane coated over a stiff honeycomb plate. Our findings, combined with high-fidelity finite element simulations, demonstrate that the sound insulation performance of the acoustic metamaterial surpasses the mass law in three distinct frequency ranges: (a) the stiffness law dominates insulation up to 140 Hz, (b) degeneracy and destructive superposition of high-order natural modes dominate within the frequency range of 300–500 Hz, and (c) destructive interference between high-order resonance and membrane resonance dominates in the frequency range of 800–1200 Hz. Notably, our study highlights the potential of high-order shear vibration of the periodic structure for the resonant bending waves of the honeycomb cell that coincide with the wavelengths of longitudinal sound waves in air, thereby offering new design guidelines for lightweight acoustic metamaterial barriers. This study reports for the first time the coincidence of high-order and membrane resonance modes within the honeycomb cell by employing an accurate finite element model and experimental validation. [ABSTRACT FROM AUTHOR]

This study investigates free vibration analysis of a microplate featuring a honeycomb (HC) core and incorporates two nanocomposite piezoelectric (NP) layers. Carbon nanotubes (CNTs) are hired to enhance the electro-mechanical performance of the piezoelectric patches, which are subjected to an externally applied electric voltage. All layers are tightly bonded together and are supported by an elastic substrate according to the Pasternak model, capable of withstanding both normal and shear loads. To establish the kinematic relations, a trigonometric plate theory is employed. The governing equations of motion are deduced through the application of Hamilton's principle and variational technique. The modified strain gradient theory, which includes three material length-scale parameters (MLSPs), is used to account for the scale effect. An analytical approach based on Fourier series functions is employed to solve the differential equations of motion. Subsequently, the impact of various factors, such as the geometrical characteristics of the HC core, distribution patterns of CNTs, and other significant parameters, on the normalized frequencies of the model is assessed after validating the accuracy of the results. The outcomes of this research have the potential to facilitate the advancement and production of lightweight and intelligent structures and devices, ultimately enhancing their efficiency. [ABSTRACT FROM AUTHOR]

The auxetic structure with negative Poisson's ratio has broad application prospects in many engineering fields. Although it is often simplified as a linear elastic problem in theoretical models, the generally used slender structure, such as the reentrant honeycombs, will inevitably undergo large deformation resulting in significant non-conservative load effects in the service conditions. Therefore, a numerical framework for modeling nonlinear deformation of the auxetic structures under follower loads with the complex variable element-free Galerkin method is developed in this paper. The application of the complex variable meshfree method is to deal with the numerical difficulties caused by mesh distortion that may occur in large deformation problems, and at the same time, it can improve the construction efficiency of meshfree shape functions through the complex variable moving least-squares approximation. The Galerkin weak form of the incremental total Lagrangian formula for large deformation problems with the enforced essential boundary conditions using the penalty method is derived and then discretized in the complex variable meshless implementation. Five numerical examples are presented with detailed convergence study to demonstrate the accuracy of the proposed approach in dealing with non-conservative large deformation of the slender auxetic structures. [ABSTRACT FROM AUTHOR]

A detailed numerical analysis has been accomplished to explore the influence of geometrical parameters of geocell reinforcement on the load carrying behavior of footing using three-dimensional finite element techniques. The influencing parameters considered such as shape, height, pocket size, stiffness of geocell reinforcement, and friction angle of infill materials. Results indicate that the inclusion of the geocell reinforcement irrespective of the shape of geocells significantly enhances the strength and stiffness of the foundation system. However, the pressure-settlement behavior is noticeably influenced by the shape of the geocells. The load carrying capacity is found to be minimum for square shaped (i.e., 400 kPa) followed by circular, diamond, and honeycomb shapes (i.e., 1000 kPa) of geocells. With increase in height of geocell mattress, the performance of the foundation system increases noticeably. The findings indicate that the load bearing capacity increases significantly up to a height ratio (H/B) of 1.5, beyond which further increment found to be marginal. Additionally, the efficacy of the system improves with increase in stiffness of reinforcement and reduces with increase in geocell pocket size. Furthermore, it is evident that the higher frictional angle of the soil mobilizes enhanced resistance on the interface, improving the overall performance. [ABSTRACT FROM AUTHOR]

Recently, auxetic honeycombs have attracted widespread attention with characteristics of lightweight, excellent energy absorption capacity and high shear stiffness. The present paper proposes the hybrid star-shaped tetra-chiral honeycomb (STCH) by embedding the tetra-chiral honeycomb (TCH) into the star-shaped honeycomb (SSH). The deformation mode and compression behavior of the STCH were studied numerically and compared with that of the SSH and TCH. Particularly, under the impact velocity of 2 m/s, the specific energy absorption (SEA) of the STCH increases by 80 and 179% than that of the SSH and TCH, respectively. Through investigating the effect of impact velocity and relative density on the crushing behavior of the STCH, the deformation modes map was summarized, and the empirical formula of the plateau stress was presented. Subsequently, the detailed parameter analysis of the STCH revealed that in a certain range, the SEA and stability of the STCH increase with the increase of N x , θ , and R , and with the decrease of L 2 and L 1. Finally, the improved STCH (ISTCH) with stable deformation and better crashworthiness was further proposed, and the crashworthiness of it was comprehensively compared with other structures. The result shows the excellent crashworthiness of the ISTCH. Particularly, the SEA of ISTCH can be nearly 8 times higher than that of the TCH. The novel star-shaped tetra-chiral honeycomb (STCH) can absorb more energy due to the increase of plastic hinges and the complex coupling deformation. The deformation modes map of the STCH was summarized and the plateau stress was fitted. The change of radius and cell wall angle can greatly change the Poisson's ratio from positive to negative. The STCH and improved STCH have excellent crashworthiness. [ABSTRACT FROM AUTHOR]

Compared with traditional honeycomb and stiffened sandwich structures, lattice-based structures are considered an ideal substitute for traditional core structures due to their high stiffness and other potential multifunctional application characteristics. Based on that, the sound radiation characteristics of the sandwich plate with different truss cores under structure borne excitation were investigated in the current paper, wherein three truss cores, including pyramidal, tetrahedral and 3D-kagome cores types, are considered. The governing equations for the vibration and sound radiation analysis of the sandwich plate structure are carried out using the static equilibrium method, and then solved via the Navier approach and Rayleigh integral. By comparing the experimental results, the validity of the proposed theoretical model is verified. The theoretical model is subsequently used to investigate the influences of truss core geometric parameters and types, face sheet-core face sheet thickness ratio and aspect ratio on sandwich plate sound radiation characteristics. The results indicate that, in the range [ 5 ∘ ≤ θ ≤ 52 ∘ ] and [ 52 ∘ < θ ≤ 85 ∘ ] , the tetrahedral and 3D-Kagome core types have the maximum natural frequency values, respectively, while the resonance peaks of sound pressure level curves move to lower frequency region with the increase in truss core radius and face sheet-core face sheet thickness ratio, and the sandwich plate with the 3D-kagome core shows better sound radiation characteristics in the wide frequency range. [ABSTRACT FROM AUTHOR]

This paper describes the in-plane impact behavior of 3D woven honeycomb sandwich composites comprising glass fiber reinforced epoxy composite. In this study, 3D woven honeycomb structures with similar cell shapes were developed with different cell geometry by varying the cell size, free wall length, bonded wall length, opening angle, and the number of honeycomb layers keeping the overall thickness of the composite constant. The variation of cell geometry was carried out by changing the number of picks in the honeycomb walls. Composite samples were made using VARIM (vacuum-assisted resin infusion method) process. The behavior of the force-displacement curve and the energy-time relationship under impact loading of 100 J were analyzed. The total energy absorption was determined for different cell geometry and the number of layers of the honeycomb composites. The results showed that structural changes in honeycomb composite significantly affect the specific energy absorption. The specific energy absorption increases with a large cell size, less opening angle, higher wall length, and a greater number of layers. [ABSTRACT FROM AUTHOR]

In this paper the silver ions in a silver nitrate solution were reduced to the Ag element by silk sericin (SS); then, N-isopropylacrylamide (NIPAAm) was added into the mixed solution of SS and silver nitrate to form the bifunctional SS/NIPAAm-Ag3 hydrogel with interpenetrating network structure with N,N-methylenebisacrylamide (BIS) as a cross-linking agent, ammonium persulfate (APS) as a initiator and N, N, N', N-tetramethylethylenediamine (TEMED) as a co-initiator. SEM showed that the SS/NIPAAm-Ag3 hydrogel had a regular honeycomb structure and high porosity. It was confirmed by DSC that the SS/NIPAAm-Ag3 hydrogel exhibited temperature sensitivity, and its Lower Critical Solution Temperature (LCST) was about 35 °C. The swelling degree of the SS/NIPAAm-Ag3 hydrogel was obviously higher than that of SS/NIPAAm hydrogel at 25 °C and 37 °C. The time required for deswelling equilibrium was shortened by 2 h compared with SS/NIPAAm hydrogel, showing that the introduction of a certain amount of nano-Ag could give hydrogel excellent swelling and deswelling properties. The bacteriostatic rates against Esherichia coli (E.coli) and Staphylococcus aureus (S. aureus) reached 99.8% and 93.38%, respectively. A cytotoxicity test proved that SS/NIPAAm-Ag3 hydrogel had no adverse effects on the human cell health. The development of this temperature-sensitive and antibacterial hydrogel provides a new possibility for the preparation of hydrogel medical dressing. [ABSTRACT FROM AUTHOR]

Copyright of Acta Edulis Fungi is the property of Acta Edulis Fungi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To improve the energy absorption capacity of honeycomb, four novel curved‐ligaments auxetic cellular structures (CLACS‐i [i = 1, 2, 3, 4]) based on the Diabolo‐shaped honeycomb (DSH) are introduced in this article. In the simulation results, it is demonstrated that the energy absorption performance of CLACS‐i (i = 1, 2, 3, 4) surpasses that of DSH under low‐, medium‐, and high‐velocity impacts. However, the negative Poisson's ratio effect of novel structures is inferior to that of DSH. With the increase in impact velocity, the inertial effect of the structure is enhanced, and the deformation mode of the structure changes from global deformation to local deformation. Furthermore, different impact velocities and geometric parameters also affect the energy absorption capacity of the structures. Platform stress and specific energy absorption (SEA) of CLACS‐i (i = 1, 2, 3, 4) increase with the increase of velocity. Under medium‐velocity impact loading, the platform stress and SEA of CLACS‐i (i = 1, 2, 3, 4) increase as the geometric parameter θ decreases and the wall thickness t increases. In this study, a reference is provided for the optimal design and application of honeycomb energy‐absorbing components. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to explore structural design of conductive core-spun yarn woven composites to improve their electromagnetic shielding effectiveness. Conductive core-spun yarns were woven into single-layer and double-layer fabrics with different structural parameters, and their electromagnetic shielding effectiveness was compared. Between different structures, in general, woven composites with high compact ratio have high shielding effectiveness. However, for honeycomb structures, due to their honeycomb appearance, they exhibit a higher electromagnetic shielding effectiveness when its compact ratio is slightly lower than other structures. The electromagnetic shielding effectiveness of double-layer woven composites is higher than that of single-layer woven composites. In double-layer woven composites, especially double-layer honeycomb woven composites with opposite sides, their electromagnetic shielding effectiveness is the best. The electromagnetic shielding effectiveness of woven composites can be improved through structural design. For example, the compact rate of the composite is increased, the surface of the composite is formed into a concave and convex shape, the number of conductive core-spun yarns per unit area is increased, and a double-layer or multi-layer structure with intermediate air layer and multiple reflections is formed. [ABSTRACT FROM AUTHOR]

Na+/vacancy ordering in sodium‐ion layered oxide cathodes is widely believed to deteriorate the structural stability and retard the Na+ diffusion kinetics, but its unexplored potential advantages remain elusive. Herein, we prepared a P2‐Na0.8Cu0.22Li0.08Mn0.67O2 (NCLMO‐12 h) material featuring moderate Na+/vacancy and transition‐metal (TM) honeycomb orderings. The appropriate Na+/vacancy ordering significantly enhances the operating voltage and the TM honeycomb ordering effectively strengthens the layered framework. Compared with the disordered material, the well‐balanced dual‐ordering NCLMO‐12 h cathode affords a boosted working voltage from 2.85 to 3.51 V, a remarkable ~20 % enhancement in energy density, and a superior cycling stability (capacity retention of 86.5 % after 500 cycles). The solid‐solution reaction with a nearly "zero‐strain" character, the charge compensation mechanisms, and the reversible inter‐layer Li migration upon sodiation/desodiation are unraveled by systematic in situ/ex situ characterizations. This study breaks the stereotype surrounding Na+/vacancy ordering and provides a new avenue for developing high‐energy and long‐durability sodium layered oxide cathodes. [ABSTRACT FROM AUTHOR]

Highlights This paper investigates a honeycomb sandwich structure that draws inspiration from the craft of origami. A specific folding pattern was applied to the honeycomb to create the origami‐based re‐entrant honeycomb (ORH), aimed at improving the energy absorption properties of the sandwich structure. The study on the energy absorption properties of structures under low‐velocity impact (LVI) utilized both experimental and numerical approaches. The energy absorption properties of the sandwich structure were examined by conducting LVI tests with different impact energy and then compared to the mechanical properties of the traditional re‐entrant honeycomb sandwich structures (TRHSS). Additionally, a refined finite element model has been established and its accuracy verified. Numerical studies were conducted to explore the effects of structural parameters on the energy absorption properties of ORH sandwich structure (ORHSS). The results show that the ORHSS exhibited a significant reduction in peak force when subjected to LVI, in contrast to the TRHSS. Furthermore, the ORHSS exhibit significant efficiency in energy absorption. Enhancing the wall thickness t$$ t $$ or folding angle V/H$$ V/H $$ can significantly improve the energy absorption properties of the ORHSS, thereby boosting the honeycomb's contribution to this process. This optimization results in an improved absorptive effect of the structure. The findings offer new recommendations for developing lightweight absorbent materials with potential applications across various industries. A novel composite sandwich structure serves as an efficient device for absorbing energy. This sandwich structure exhibits excellent cushioning and energy absorption capabilities. Changing geometric parameters can enhance the impact performance of the structure. A larger folding angle V/H$$ V/H $$ makes the core more prone to deformation. The greater the forward length V$$ V $$ of the ORH, the lower specific energy absorption (SEA) of the ORHSS. [ABSTRACT FROM AUTHOR]

The imperative for lightweighting technologies, paramount in mission-critical cyber-physical systems (CPSs) including aerospace, automotive and allied sectors, hinges upon optimizing energy efficiency and curbing product weight. Honeycomb structures, celebrated for their exceptional strength-to-weight ratio, have indisputably guided the pursuit of lightweight design. This paper expounds upon the versatility of honeycomb structures by scrutinizing their in-plane mechanical attributes. Leveraging finite element simulations and polynomial fitting, we enhance the prevailing equivalent elastic modulus model for uniform honeycomb structures, expanding its domain to encompass a broader spectrum of relative density values. Deliberations ensue concerning the model's constraints and its inapplicability to nonuniform honeycomb structures. The investigation introduces nodes as pivotal influencers in the mechanical comportment of nonuniform honeycomb structures, delineating the nexus between the equivalent elastic modulus and node dimensions through a fusion of finite element simulations and mechanical experimentation. Furthermore, this research delves into the tenets and constructs of density-based variable density methodologies within the ambit of topology optimization, with an overarching goal of maximizing stiffness. We furnish a holistic design protocol for optimizing honeycomb structures, underscored by a pragmatic instantiation of the density-based variable density approach. Scrutinizing the geometric interplay between honeycomb structures and design spaces, we posit an innovative paradigm employing concentric circles to approximate cellular envelopes, streamlining numerical cartography and the conversion of optimization outputs into variable density honeycomb configurations. Evaluation of the in-plane mechanical attributes of variable density honeycomb structures reveals that TPU material augments the resilience of both uniform and variable density honeycomb structures, whereas topology optimization amplifies specific stiffness and resilience modulus in variable density honeycomb structures relative to their uniform counterparts. This study sheds light on the complexities of honeycomb structures, providing valuable insights for their optimization in lightweight applications. [ABSTRACT FROM AUTHOR]

This paper proposed a composite sandwich structure containing multilayer honeycombs, and a multi-objective optimization model containing its load-bearing and wave-absorbing properties, which were correlated with the geometric parameters of the honeycomb, was developed. The critical elastic buckling load was performed as an indicator to characterize the load-bearing capacity, and the bandwidth of the sandwich was employed as an indicator to characterize the wave-absorbing characteristics. This multi-objective optimization model was optimized based on JAYA algorithm and the results showed that the optimized structure had a significant improvement in both load-bearing and wave-absorbing capacities compared to the original structure. [ABSTRACT FROM AUTHOR]

As a highly efficient and environmentally friendly gas fuel, hydrogen has emerged as one of the most promising sources of energy. However, the hydrogen explosion limit is low, the explosion risk is high, and the production, storage and transportation processes are prone to explode. Therefore, it is necessary to explore hydrogen explosion inhibitor to prevent and mitigation hydrogen explosions. In this study, the synergistic effect of the combination of inert gas and ultrafine water mist on the suppression of hydrogen explosion was studied by using a standard 20 L spherical explosive container bomb. The results of the study indicate that the combined use of inert gas and ultrafine water mist yields better suppression effects in terms of explosion pressure, flame propagation speed, and flame cellular structure formation, compared to the use of a single inert gas. Inert gas and ultrafine water mist have synergistic effects, but the synergistic effect of N 2 was significantly stronger than that of CO 2. Through chemical kinetic simulation, it was found that the formation rate of O, H, and OH, which were three active free radicals, decreased significantly compared with that of the single inhibition condition in the process of inhibiting the hydrogen explosion reaction by inert gas and ultrafine water mist. The pairing of nitrogen with ultrafine water mist demonstrates a superior collaborative effect in comparison to the combination of carbon dioxide and ultrafine water mist. • Synergistic explosion suppression effect of inert gas and ultra-fine water mist. • Twin-fluid can effectively slow down the formation of flame honeycomb structures. • Analyzed the synergistic explosion suppression mechanism of twin-fluid. • N 2 is more synergistic than CO 2 with ultra-fine water mist. [ABSTRACT FROM AUTHOR]

For the harsh entry environment and higher thermal protection requirements, two structures of three‐dimensional woven gradient thermal protection materials were designed and prepared with the deep space exploration thermal protection system as the object. They are 3D orthogonal woven, 2.5D layer‐to‐layer angle interlock woven, 2.5D layer‐layer angle interlock woven structure(OLL) composite and 3D orthogonal woven, angle 2.5D layer‐to‐layer angle interlock woven, honeycomb structure(OLH) composite. Two materials were prepared and examined by ablation in an oxygen‐acetylene flame. A three‐dimensional macroscopic ablation model was established on the basis of the experiment, and the model was verified to be accurate and effective, which can well respond to the pyrolytic ablation process of the materials. The two designed materials are applied to the outsole of MSL by simulation, and the three‐dimensional response during the entry into Mars is simulated and analyzed in comparison with the thermal protection performance of PICA material. Both materials show better thermal protection than PICA and can be used as a reference in the selection of thermal protection materials. Highlights: Two kinds of 3D gradient woven thermal protection materials are designed.A 3D thermal protection system response model is established.The three‐dimensional response during entry was analyzed.Thermal protection of the material is superior to that of PICA. [ABSTRACT FROM AUTHOR]

The aesthetics and functionality of honeycomb woven assemblies qualifies them for a range of applications expanding across home textiles, fashion, functional apparels, and technical products. Researchers have explored honeycomb assemblies with the focus on shrinkage, sound absorption, thermal conductivity, and heat protection properties analysis via variation in their cell sizes. However, very minimal research is found on analysis of honeycomb woven fabric assemblies' thermal comfort characteristics by employing different weft insertion sequence and materials (cotton and stretchable yarns). This study reflects the thermal conductivity, dry fluid transmission (air permeability), wet fluid transmission (moisture management), and stiffness attributes of twelve stretchable honeycomb woven assemblies consisting of single ridge, double ridge, and brighton honeycomb weave structures along with different weft sequences of cotton and Type 400 (T-400) stretch yarns. Characterization data showed that single ridge honeycomb structure supports the highest dry fluid transmission property; however, brighton honeycomb offers the highest heat retention property. Double ridge honeycomb highlights the capability of the highest wet fluid transmission property, and brighton honeycomb has immense stiffness. Statistical analysis (ANOVA) also showed that honeycomb structures, weft yarn sequence and material have a statistically significant impact on thermal conductivity and fluid transmission behaviors with p -values less than 0.05. [ABSTRACT FROM AUTHOR]

In this study, the effects of different silicon carbide (SiC) particle sizes on the viscosity and curing behavior of alumina (Al 2 O 3) ceramic suspensions were thoroughly investigated. The findings revealed that increasing the size of SiC particles led to a noticeable decrease in the viscosity of the suspension. The Al 2 O 3 ceramic suspension with 0.6 μm SiC powder demonstrated a shallower cure depth and wider excess width compared to the suspension with 1.0 μm SiC powder. Sintering tests demonstrated that the properties of the SiC–Al 2 O 3 ceramics improved at higher sintering temperatures. Moreover, a high-performance honeycomb ceramic was successfully designed and fabricated with a porosity and compressive strength of 30.8 % and 188 MPa, respectively. Finally, the SiC–Al 2 O 3 honeycomb ceramics were effectively applied in heat insulation and oil-water separation applications, demonstrating their remarkable capabilities. [ABSTRACT FROM AUTHOR]

Highlights: The stable periodic porous shielding materials were prepared by combining the strategies of 3D printing and metamaterial design. The relationship between porous material structure and electromagnetic interference shielding efficiency (EMI SE) effectiveness was deeply explored, revealing the important structural parameters for realizing tunable EMI SE property. The optimized design of the periodic porous shielding box achieves effective EMI shielding in a wide wavelength range (over 2.4 GHz). The new-generation electronic components require a balance between electromagnetic interference shielding efficiency and open structure factors such as ventilation and heat dissipation. In addition, realizing the tunable shielding of porous shields over a wide range of wavelengths is even more challenging. In this study, the well-prepared thermoplastic polyurethane/carbon nanotubes composites were used to fabricate the novel periodic porous flexible metamaterials using fused deposition modeling 3D printing. Particularly, the investigation focuses on optimization of pore geometry, size, dislocation configuration and material thickness, thus establishing a clear correlation between structural parameters and shielding property. Both experimental and simulation results have validated the superior shielding performance of hexagon derived honeycomb structure over other designs, and proposed the failure shielding size (Df ≈λ/8 − λ/5) and critical inclined angle (θf ≈43° − 48°), which could be used as new benchmarks for tunable electromagnetic shielding. In addition, the proper regulation of the material thickness could remarkably enhance the maximum shielding capability (85 − 95 dB) and absorption coefficient A (over 0.83). The final innovative design of the porous shielding box also exhibits good shielding effectiveness across a broad frequency range (over 2.4 GHz), opening up novel pathways for individualized and diversified shielding solutions. [ABSTRACT FROM AUTHOR]

In this article, the numerical and experimental free vibration analyses of PLA-based composite plates with different filling geometries were carried out. Firstly, the natural frequencies and modal shapes were obtained from finite element (FE) methods to characterize the vibration behavior of the plates. The obtained results were compared with experimental testing of the three-dimensional (3D) produced plates. In the comparison, it was seen that the finite element analysis and the experimental results were quite close to each other. It was also observed that the highest frequencies are measured by a triangle, then the grid and honeycomb. Moreover, higher frequencies and lower weights are possible with the triangle pattern fill. On the other hand, it is noted that the types of filling structures do not affect the modal shapes of the 3D plates. Thus, the results of this paper are of utmost importance for getting light structure and high frequencies. [ABSTRACT FROM AUTHOR]

This study investigated the thermal and mechanical properties of polyurethane foam (PUF) sandwich panels reinforced with varying amounts of clay nanoparticles (0, 0.5, 1 and 2 wt%) fabricated using the compression molding process. However, these composites were fixed to cores with a honeycomb structure. The morphology of PUF sandwich panels reinforced with clay nanoparticles was examined by scanning electron microscopy (SEM). The presence of clay nanoparticles in the honeycomb structure let to a reduction in cell size and an increase in the number of cells per unit volume. The impact of clay nanoparticles on the thermal properties of PUF reinforced with clay nanoparticles was investigated using thermogravimetric and dynamic mechanical thermal analysis (DMTA). The results indicated that the incorporation of clay nanoparticles as reinforcement enhanced the thermal properties of the PUF sandwich panel samples. Mechanical characterization technique including compression, three-point bending and drop weight impact tests displayed that the PUF reinforced with 1 wt% clay nanoparticles exhibited the most significant improvement in mechanical properties. [ABSTRACT FROM AUTHOR]

Honeycomb structures made of carbon-fiber-reinforced plastic (CFRP) are increasingly used in the aerospace field due to their excellent energy absorption capability. Attention has been paid to CFRP structures in order to accurately simulate their progressive failure behavior and discuss their ply designability. In this study, the preparation process of a CFRP corrugated sheet (half of the honeycomb structure) and a CFRP honeycomb structure was illustrated. The developed finite element method was verified by a quasi-static test, which was then used to predict the low-velocity impact (LVI) behavior of the CFRP honeycomb, and ultimately, the influence of the ply angle and number on energy absorption was discussed. The results show that the developed finite element method (including the user-defined material subroutine VUMAT) can reproduce the progressive failure behavior of the CFRP corrugated sheet under quasi-static compression and also estimate the LVI behavior. The angle and number of plies of the honeycomb structure have an obvious influence on their energy absorption under LVI. Among them, energy absorption increases with the ply number, but the specific energy absorption is basically constant. The velocity drop ratios for the five different ply angles are 79.12%, 68.49%, 66.88%, 66.86%, and 60.02%, respectively. Therefore, the honeycomb structure with [0/90]s ply angle had the best energy absorption effect. The model proposed in this paper has the potential to significantly reduce experimental expenses, while the research findings can provide valuable technical support for design optimization in aerospace vehicle structures. [ABSTRACT FROM AUTHOR]

This study proposes a new, doubly re-entrant auxetic unit-cell design that is based on the widely used auxetic honeycomb structure. Our objective was to develop a structure that preserves and enhances the advantages of the auxetic honeycomb while eliminating all negative aspects. The doubly re-entrant geometry design aims to enhance the mechanical properties, while eliminating the buckling deformation characteristic of the re-entrant deformation mechanism. The effects of the geometric modification are described and evaluated using two parameters, offset and deg. A series of experiments were conducted on a wide range of parameters based on these two parameters. Specimens were printed via the vat photopolymerization process and were subjected to a compression test. Our aim was to investigate the mechanical properties (energy absorption and compressive force) and the deformation behaviour of these specimens in relation to the relevant parameters. The novel geometry achieved the intended properties, outperforming the original auxetic honeycomb structure. Increasing the offset and deg parameters results in increasing the energy absorption capability (up to 767%) and the maximum compressive force (up to 17 times). The right parameter choice eliminates buckling and results in continuous auxetic behaviour. Finally, the parameter dependency of the deformation behaviour was predicted by analytical approximation as well. [ABSTRACT FROM AUTHOR]

The Circulating Water Channel (CWC) is a device commonly utilized in maritime engineering for hydrodynamic experiments. The ability to generate a high-quality flow field is a critical criterion for evaluating the device, and thus, improving key parts of the CWC device can significantly increase this ability. In this paper, a numerical model based on the RANS method is established to investigate the hydrodynamic performance of the circulating water channel's finite section. First, associated analyses and optimizations for the turning vanes and contraction section are performed. Following confirmation that adding a honeycomb can greatly improve the flow field, the hole type and length diameter ratio are investigated further. After integrating the components, the flow field properties are examined at various flow velocities. The main findings demonstrate that flow field's uniformity can be enhanced using the right number of turning vanes. Applying the Witozinsky transition curve to the contraction section can produce a better pressure gradient and increase the efficiency of contraction selection. The best rectification result is achieved by a honeycomb with a square shape and a slenderness ratio of 9. By varying flow velocities, the most uniform flow field area occurs at 4 m to 16 m from the outlet of the contraction section. This model can better simulate the dynamic characteristics of the flow field in the 3D CWC and serve as the foundation for the design of multifunctional CWC equipment for wind, wave, and flow. [ABSTRACT FROM AUTHOR]

Performance of rotary ultrasonic machining (RUM) system greatly influences by appropriate design of ultrasonic horn. Ultrasonic stepped horn gives high amplitude of vibration and better cutting efficiency but design and integration of horn with RUM system is highly intricate. Therefore, systematic study on design and implementation of ultrasonic stepped horn was needed in order to achieve better efficiency of RUM process. This paper focuses on design aspects of ultrasonic stepped horn by theoretical, FE simulations and modeling techniques. The designed horn was integrated with RUM system, performance was measured in terms of ultrasonic resonant frequency through FE simulations and modeling on ANSYS workbench. Finally, fabricated ultrasonic stepped horn was validated by performing experiments on rotary ultrasonic machine tool for Nomex honeycomb composites (NHCs). FE simulations and experimental results prove that the designed ultrasonic stepped horn achieves reasonable vibration amplitude at desired resonant frequency to perform RUM process on NHCs materials. [ABSTRACT FROM AUTHOR]

Honeycombs are commonly used as core materials in sandwich panels, and the core geometry significantly impacts the bending behaviour of these structures. Understanding how core characteristics influence the mechanical properties of sandwich panels is essential. The comparison between different honeycomb sandwich panel configurations is quite complex. This study delves into the intricate comparison between various honeycomb sandwich panel configurations, serving as a benchmark for integral 3D printed panels featuring hexagonal cores in both L- and W-directions, and circular cores. Notably, wrinkling phenomena are observed in the L-direction of the hexagonal cores. Circular cell panels exhibit increased load capacity, flexural modulus, and toughness. Additionally, hexagonal L-core panels demonstrate a higher toughness modulus than their W-core counterparts, making them less rigid yet stronger. Furthermore, L-cell core panels possess a lower density than circular cores, whereas W-cell cores exhibit higher density, compromising their specific mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract3D additive manufacturing of metamaterials, especially honeycomb structures, has gained prominence in industrial manufacturing for their exceptional mechanical properties and energy absorption (EA) capabilities. This study introduces a novel circular tubular honeycomb structure to enhance EA characteristics. Through quasi-static compression experiments and finite element simulations, specific energy absorption (SEA) of various circular structures is analyzed. Results show that the circular tubular honeycomb structure excels in SEA performance, lightweight construction, and reduced Poisson’s ratio. An equation for structural neutral layer offset is derived and validated, showcasing potential in thin-walled pipe-in-pipe (PIP) interlayers. [ABSTRACT FROM AUTHOR]

The polygonal honeycomb core has been vertically rotated and spliced to form a new three-dimensional polygonal honeycomb (TPH) structure lattice. Young's modulus and Poisson's ratio for the three main directions of the TPH structure had been derived from Castigliano's second theorem and Moore's theorem. The theoretical results show good agreement with the numerical and experimental results. Meanwhile, the compressive strength of the TPH structure has been analyzed. The results show that the geometric parameters have a significant effect on the elasticity and strength of TPH structures, and the mechanical properties of the TPH structures can be programmed by adjusting the geometric parameters. In addition, the TPH structure exhibits a bidirectional zero Poisson's ratio (ZPR) during compression. This structure shows promise for applications in aerospace, construction, and other fields. This study provides guidance for further research on polygonal honeycomb structures. [ABSTRACT FROM AUTHOR]

Sandwich panel structures are widely used for light-weight applications due to their high strength and stiffness to density ratios. They are composed of two main parts: the skins and the core. This paper investigates a Miura-ori structural sandwich core with open cells that can be used as an alternative to the existing honeycomb structures. A fully parametric design approach, starting from drawing to Finite Element Analysis (FEA), is presented to efficiently analyze the effect of different geometries on the resulting structure. The geometric model was built based on the kinematic model, which can represent the folding process of the foldcore using the Matlab script. The obtained coordinates of the vertices of the folding pattern were exported to ANSYS APDL where the surfaces were automatically created and meshed. The created mesh was imported to LS-Dyna where explicit compression analyses were performed to evaluate the compression stiffness and strength of the studied geometries. The developed parametric model aims to find the best configuration for a given application, based on three sets of geometric parameters that define the shape of the Miura Ori folding pattern. Therefore, in the range of the studied geometries, the best parameter combination for specific compression stiffness and specific compression strength was found. To evaluate the performance of the foldcore and to validate the FE model, experimental quasi-static compression tests were undertaken with two kinds of specimens ('strip' and "panel"), and the measured force-displacement curves were obtained. The result of the test agrees with that of the FE simulations, with an error of <6.6% in the elastic region. [ABSTRACT FROM AUTHOR]

A sandwich plate with a corrugation and auxetic honeycomb hybrid core is constructed, and its sound insulation and optimization are investigated. First, the motion governing equation of the sandwich plate is established by the third-order shear deformation theory (TSDT), and then combined with the fluid-structure coupling conditions, and the sound insulation is solved. The theoretical results are validated by COMSOL simulation results, and the effects of the structural parameter on the sound insulation are analyzed. Finally, the standard genetic algorithm is adopted to optimize the sound insulation of the sandwich plate. [ABSTRACT FROM AUTHOR]

In this article, the effects of circular, cylindrical, square, and hexagonal crater shapes on cooling performance were analyzed by numerical simulation and experimental verification, and then a new honeycomb cooling structure for cylindrical batteries (18650 type for example) was proposed. The effects of honeycomb depth, side length and wall thickness on the cooling performance were investigated. A quadratic response regression model was numerically calculated based on the experimental scheme obtained from the Box-Behnken central combination test. The results showed that the hexagonal crater cooling structure can reduce the maximum battery temperature by 5.3% compared to the non-crater cooling structure. Therefore, the proposed honeycomb structure was reasonable. In addition, increasing the depth and the hedge length could effectively reduce the maximum battery temperature and temperature difference, and when a certain value was exceeded, a reverse temperature growth trend occurs. Within the range of variation, wall thickness had little effect on the cooling performance. The cooling performance was optimal when the depth is 0.475 mm, the side length is 1.250 mm, and the wall thickness is 0.125 mm. The novel cooling structure proposed in this study can provide a new idea for the structural design of air-cooled thermal management system for cylindrical batteries. [ABSTRACT FROM AUTHOR]

The sandwich panel incorporated a honeycomb core, a widely utilized composite structure recognized as a fundamental classification of composite materials. Comprised a core resembling a honeycomb, possessing thickness and softness, and is flank by rigid face sheets that sandwich various shapes and materials. This paper presents an examination of the static and dynamic analysis of lightweight plates made of aluminum honeycomb sandwich composites. Honeycomb sandwich plate samples are 300 mm long, and 300 mm wide, the heights of the core have been varied at four values ranging from 10 to 25 mm. The honeycomb core is manufactured from Aluminum material by using a novel technique namely resistance spot welding (RSW) instead of using adhesive material, which is often used when an industrial flaw is detected. Numerical optimization based on response surface methodology (RSM) and design of experiment software (DOE) was used to verify the current work. A theoretical examination of the crashworthiness behavior (maximum bending load, maximum deflection) and vibration attributes (natural frequency, damping ratio, transient temporal response) of honeycomb sandwich panels with different design parameters was also carried out. In addition, the finite element method-based ANSYS software was used to confirm the theoretical conclusions. The findings of the present work showed that the relationship between the natural frequency, core height, and cell size is direct. In contrast, the relationship between the natural frequency and the thickness of the cell wall is inverse. Conversely, the damping ratio is inversely proportional to the core height and cell size but directly proportional to the thickness of the cell wall. The study indicates that altering the core height within 10-25 mm leads to a significant increase of 82% in the natural frequency and a notable decrease of 49% in the damping ratio. These findings are based on a specific cell size value of 0.01 m and a cell wall thickness of 0.001 m. Also, the results indicate that for a given set of cell wall thickness and size values, an increase in core height from (0.01-0.025) m, leads to a reduction of the percentage of maximum response approximately 76%. Conversely, the increasing thickness of the wall of cell wall, ranging 0.3-0.7 mm with a constant core height equal to 0.015 m, resulted in a de crease of maximum transient response by 7.8%. [ABSTRACT FROM AUTHOR]

Here, we present a unique method to enhance the low-frequency absorption performance of a honeycomb absorber by integrating a metasurface. The geometrical dimensions of the proposed metasurface have been numerically optimized. The introduction of the metasurface allows exploitation of its robust resonance and superior impedance matching in low-frequency bands, thereby improving microwave absorption properties. The incorporation of the metasurface does not impact the wave transmission performance of the honeycomb core absorber at high-frequency band, thus preserving its high-frequency performance. This broadens the absorption range, leading to an expanded bandwidth. Simulation results reveal that the composite absorber (CA) exhibits strong absorption performance with an incident angle stability up to 45° for both transverse electric (TE) and transverse magnetic (TM) modes. The absorption mechanism of the CA has been investigated by using an equivalent circuit model and electromagnetic field analysis. A prototype was designed, fabricated, and tested to validate the proposed method. Both simulation and measurement results demonstrate that the prototype can achieve an average absorption rate exceeding 90% across a 1.0–18.0 GHz range. This study introduces an innovative technique for creating microwave absorbers for low-frequency wideband applications. [ABSTRACT FROM AUTHOR]

Based on the traditional re-entrant honeycomb, a novel re-entrant octagon honeycomb (ROH) is proposed. The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation, and the results are in good agreement with the experimental ones. The deformation modes, mechanical properties, and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities. The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed. In addition, gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase. Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH, especially for ROH, with wall thickness increasing from the inside outwards. Compared to ROH with uniform wall thickness at the same relative density, ROH with a gradient design can increase the plateau stress by over half. With the elevation of impact velocity, the plateau stress and specific energy absorption exhibit an upward trend, aligning with the dynamic performance pattern observed in conventional honeycombs. The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials. [ABSTRACT FROM AUTHOR]

Tool surface texturing is a new sustainable method for machining hard-to-machine materials. The present study focuses on the new honeycomb texture (mimic of bee's honeycombs) containing hexagons forming between thin vertical walls. The important novelty in this work is the cutting performance of honeycomb texture on Inconel 713C was examined under cutting parameters and different cooling conditions: dry untextured (T1), dry textured (T2) tool, impregnated solid lubricant (hexagonal boron nitride (hBN)) textured tool (T3), MQL (coconut oil) with textured tool (T4), and NMQL (0.20 wt.% hBN + coconut oil) with textured tool (T5). Compared to plain tools, NMQL to honeycomb texture reduced flank wear by 53.2%, roughness by 43.2%, turning force by 27%, and cutting temperature by 47.7%. Honeycomb texture with MQL (T4) and NMQL (T5) reduces flank surface Ni element diffusion during turning. Nanofluid-textured inserts (T5) demonstrated higher shear angles, lower chip curl diameter, and shorter tool-chip contact length than other conditions. [ABSTRACT FROM AUTHOR]

In this paper, we prove the existence of periodic tessellations of ℝN minimizing a general nonlocal perimeter functional, defined as the interaction between a set and its complement through a nonnegative kernel, which we assume to be either integrable at the origin, or singular, with a fractional type singularity. We reformulate the optimal partition problem as an isoperimetric problem among fundamental domains associated with discrete subgroups of ℝN, and we provide the existence of a solution by using suitable concentrated compactness type arguments and compactness results for lattices. Finally, we discuss the possible optimality of the hexagonal tessellation in the planar case. [ABSTRACT FROM AUTHOR]

Studies of graphene show that robust chemical bonds such as covalent bonds with trigonal‐planar atoms afford layered atomic 2D crystals possessing unique properties. Although layered molecular crystals are of interest to diversify elements and structures of 2D materials, the structural diversity of molecules as well as weak intermolecular interactions inevitably makes the design to be one‐off and individual. We herein report a versatile method to assemble layered molecular crystals. By developing a D3‐symmetry host at vertices to form a honeycomb layer, a diverse range of layered 2D host–guest crystals were obtained. Substituents on the host, elements/structures of the guest, the stereochemistry of the host and types of intercalants were diversified, which should allow for 6×32×3×2 combinations for structural diversification. [ABSTRACT FROM AUTHOR]

AbstractAfter lower limb amputation, the primary challenge is to facilitate the patient’s adoption of a prosthetic limb seamlessly, without encountering complications or discomfort. Elevated stress levels within the residual limb, experienced when wearing the socket and while standing or walking, contribute to patient discomfort. As an initial step in this study, we developed a finite element model of above-knee amputation. Additionally, we designed a prototype orthopedic implant composed of several parts, with the lower section featuring a honeycomb structure aimed at absorbing and diminishing stresses at the interface of the residual limb and prosthetic. In this study, finite element models with and without orthopedic implants were analyzed to assess the feasibility and impact of incorporating a honeycomb structure within the implants on stress distribution, particularly at the stump-prosthetic interface. Models with honeycomb-structured implants, at varying densities, showed a reduction in interface stress to approximately 2.15e-2 MPa and 2.01e-2 MPa, compared to 4.5e-2 MPa in model without honeycomb structure in the implant and 7.97e-2 MPa in models without any implants. [ABSTRACT FROM AUTHOR]

The polarization balance of M1/M2 macrophages with different functions is important in osteogenesis and bone repair processes. In a previous study, we succeeded in developing honeycomb tricalcium phosphate (TCP), which is a cylindrical scaffold with a honeycomb arrangement of straight pores, and we demonstrated that TCP with 300 and 500 μm pore diameters (300TCP and 500TCP) induced bone formation within the pores. However, the details of the influence of macrophage polarization on bone formation using engineered biomaterials, especially with respect to the geometric structure of the artificial biomaterials, are unknown. In this study, we examined whether differences in bone tissue formation due to differences in TCP geometry were due to the polarity of the assembling macrophages. Immunohistochemistry for IBA-1, iNOS, and CD163 single staining was performed. The 300TCP showed a marked infiltration of iNOS-positive cells, which are thought to be M1 macrophages, during the osteogenesis process, while no involvement of CD163-positive cells, which are thought to be M2 macrophages, was observed in the TCP pores. In addition, 500TCP showed a clustering of iNOS-positive cells and CD163-positive cells at 2 weeks, suggesting the involvement of M2 macrophages in the formation of bone tissue in the TCP pores. In conclusion, we demonstrated for the first time that the geometrical structure of the artificial biomaterial, i.e., the pore size of honeycomb TCP, affects the polarization of M1/2 macrophages and bone tissue formation in TCP pores. [ABSTRACT FROM AUTHOR]

The incorporation of viscoelastic layers in laminates can markedly enhance the damped dynamic characteristics. This study focuses on integrating viscoelastic layers into the composite facesheet of the bowtie-shaped honeycomb core composite sandwich panel (BHC-CSP). The homogenization of the damped BHC-CSP is performed by employing the variational asymptotic method. Based on the generalized total energy equation, the energy functional of the representative unit cell of the damped BHC-CSP is asymptotically analyzed. The warping function, derived following the principle of minimum potential energy, provides a basis for obtaining the corresponding Euler–Lagrange equation to ascertain the equivalent elastic properties of the damped BHC-CSP. Utilizing the developed two-dimensional equivalent model, the free-vibration characteristics of the damped BHC-CSP are examined across diverse boundary conditions while delving into the impact of an external viscous damping layer on the natural frequency of the damped BHC-CSP. The results reveal that intensified boundary constraints effectively diminish the effective vibration region of the damped BHC-CSP, thereby enhancing its overall stability. The introduction of a PMI foam layer proves effective in adjusting the stiffness and mass distribution of the damped BHC-CSP. Resonance characteristics are explored through frequency and time-domain analyses, highlighting the pivotal roles of the excitation position and receiver point in influencing the displacement and velocity responses. Although the stiffness is improved by incorporating a PMI foam layer, its effect on the damping performance of the damped BHC-CSP is minimal when compared to the T-SW308 foam layer. [ABSTRACT FROM AUTHOR]

To optimize the assembly methods of honeycomb structures and enhance their design flexibility, this study investigated the impact mechanical responses of tandem honeycomb-core sandwich structures with varying misalignment assembly lengths. Impact tests were conducted across different energy levels on single-layer and tandem honeycomb-core sandwiches to observe their impact processes and failure behaviors. Our findings indicate that tandem honeycomb cores significantly enhance the impact resistance compared with single-layer configurations, even though a misaligned assembly can deteriorate this property. A finite element model was developed and validated experimentally; the model showed good agreement with the experiments, thereby allowing the simulation and evaluation of the impact responses. Herein, we reveal that specific misalignment lengths can either increase or decrease the impact resistance, providing insights into improving the resilience of tandem honeycomb-core structures. Our results not only contribute to enhancing the impact resistance of honeycomb-core sandwich structures but also offer a valuable basis for their practical applications in engineering. [ABSTRACT FROM AUTHOR]

A full triangular chiral (Tri-Chi) honeycomb, combining a honeycomb structure with triangular chiral configuration, notably impacts the Poisson's ratio (PR) and stiffness. To assess the random vibration properties of a composite sandwich panel with a Tri-Chi honeycomb core (CSP-TCH), a two-dimensional equivalent Reissner–Mindlin model (2D-ERM) was created using the variational asymptotic method. The precision of the 2D-ERM in free and random vibration analysis was confirmed through numerical simulations employing 3D finite element analysis, encompassing PSD curves and RMS responses. Furthermore, the effects of selecting the model class were quantified through dynamic numerical examples. Modal analysis revealed that the relative error of the first eight natural frequencies predicted by the 2D-ERM consistently remained below 7%, with the modal cloud demonstrating high reliability. The PSD curves and their RMS values closely aligned with 3D finite element results under various boundary conditions, with a maximum error below 5%. Key factors influencing the vibration characteristics included the ligament–rib angle of the core layer and layup modes of the composite facesheets, while the rib-to-ligament thickness ratio and the aspect ratio exert minimal influence. The impact of the ligament–rib angle on the vibration properties primarily stems from the significant shift in the core layer's Poisson's ratio, transitioning from negative to positive. These findings offer a rapid and precise approach for optimizing the vibration design of CSP-TCH. [ABSTRACT FROM AUTHOR]

To enhance the out-of-plane mechanical performance, a novel honeycomb with arc-curved edge is proposed. The numerical model is built based on the elastoplastic failure criterion. The impact performance of proposed honeycomb is investigated and revealed. The influence of central angle and thickness on the crashworthiness is researched. The results show that the numerical result is in agreement with that of experimental test. The central angle has great influence on the deformation mode. The global buckling of edge tube is exhibited for the small central angle, and the consistent deformation mode is demonstrated for the central area. With the increasing of central angle, the energy absorption ability is enhanced for the plastic hinge could absorb more impact energy. The more stable deformation mode is exhibited for the larger central angle. The honeycomb with relatively large central angle has the best crashworthiness performance for the balance of energy absorption and structural mass. Compared with traditional honeycomb, the proposed honeycomb could improve the out-of-plane energy absorption characteristics. [ABSTRACT FROM AUTHOR]

AbstractVortex-bladeless wind power generators are revolutionary concepts that use wind vortex-induced vibration to generate electricity through oscillation and vibration. This unique approach allows for a simpler design, environmental friendliness, on-site production, and lower initial costs than traditional wind turbines. This article presents a vibration analysis on the rod of a vortex bladeless wind power generator for a sandwich Timoshenko beam with various face sheets, including carbon nanotube (CNT), graphene platelets (GPL), and carbon nanorods (CNR), and cores, including positive and negative Poisson’s ratios in honeycomb structure, porous material, and metal foam. The governing equations of motion are derived using Hamilton’s principle and solved using trigonometric functions for different boundary conditions. The results of this research are compared with previous studies, and the maximum error is 3.05%. This study examined the effects of various parameters on the dimensionless natural frequencies. To obtain the highest peak amplitude for maximum energy harvesting, to choose the best rod for the bladeless wind power generator among the four types of cores and three types of factsheet layers, the honeycomb core with a positive Poisson’s ratio and the GPL-reinforced composite with the SNUPD distribution are selected because they have the most deflection. Some researchers have worked in the field of sandwich beams. Still, in this study, the main goal is to investigate the Timoshenko sandwich beam by examining all types of cores and reinforcements to increase efficiency and optimize bladeless wind generators to achieve maximum power. [ABSTRACT FROM AUTHOR]