Honeycomb Structure Research Articles

Sound absorption performance of honeycomb metamaterials Inspired by Mortise-and-Tenon structures

To address the limitations of traditional honeycomb sandwich structures in attenuating mid to low-frequency sounds, particularly in configurations with minimal thickness and weight, this study introduces an innovative honeycomb acoustic metamaterial incorporating the traditional Chinese mortise-and-tenon joint. We systematically investigate the acoustic absorption characteristics of the modified honeycomb structure through theoretical analysis, empirical validation, and numerical simulations. Our experimental setup maintained consistent geometric parameters across all trials and demonstrated that the resonance frequency of the modified honeycomb structure decreased by 10 % relative to its conventional counterpart. We conducted detailed analyses on the influence of micropore positioning, tenon geometric dimensions, and micropore diameters on the acoustic performance. Notably, elongating the tenon from 2 mm to 6 mm resulted in a 15 % reduction in resonance frequency, whereas increasing the micropore-to-tenon distance from 0 mm to 4 mm led to a 30 % increase. The integration of the mortise-and-tenon joint significantly enhances the mid to low-frequency sound absorption performance of the honeycomb panels. This improvement is achieved while preserving the structural benefits of low panel thickness and shallow cavity depth, alongside simplified processing of micropores. Our findings elucidate a promising approach to augmenting the acoustic properties of lightweight structural materials, thereby extending their application potential in noise control engineering. This study not only contributes a novel perspective to the design and optimization of acoustic metamaterials but also highlights the potential for integrating traditional architectural techniques with modern material science to enhance noise control solutions.

Effect of Honeycomb Geometrical Parameters on Equivalent Radiated Power and Frequency Response of Motor Casing and Gearbox Surface of a Powertrain

ABSTRACTThe powertrain, as a central source of noise and vibration, is crucial in determining the overall NVH (noise, vibration and harshness) performance of vehicles, necessitating the optimisation of its structural components for improved durability and passenger comfort. This paper investigates the influence of key geometrical parameters—cell thickness, skin thickness and cell length—on the complex frequency modes of honeycomb and square sandwich structures using the Altair OptiStruct solver 2022 and fast Fourier transform analyser. The driven and non‐driven ends of a motor casing and a gearbox, represented by honeycomb structures and ribs, were subjected to an evaluation of equivalent radiated power (ERP). The results show that the square structure performs better at higher skin thickness when resisting severe lateral stresses than the honeycomb while being less stiff at higher cell thickness. Notably, smaller cell length had a substantial impact on the modes of the honeycomb structure, whereas larger cell length had an impact on the square structure. Response surface methodology was used to optimise the modal frequencies of both square and honeycomb panels simultaneously. An ideal cell length of 5.88 mm, skin thickness of 1.303 mm and cell thickness of 0.381 mm were found for the honeycomb construction, yielding a composite desirability of 0.981. On the other hand, with a cell length of 5.045 mm, skin thickness of 1.484 mm and cell thickness of 0.331 mm, the square structure achieved a composite desirability of 0.989. It is interesting to note that the driven end casing of the motor casing made more noise with the addition of ribs than the non‐driven end and gearbox. But compared to the original powertrain model, adding a honeycomb structure resulted in a noise reduction of about 10%.

Optimization of the Pixel Design for Large Gamma Cameras Based on Silicon Photomultipliers.

Most single-photon emission computed tomography (SPECT) scanners employ a gamma camera with a large scintillator crystal and 50-100 large photomultiplier tubes (PMTs). In the past, we proposed that the weight, size and cost of a scanner could be reduced by replacing the PMTs with large-area silicon photomultiplier (SiPM) pixels in which commercial SiPMs are summed to reduce the number of readout channels. We studied the feasibility of that solution with a small homemade camera, but the question on how it could be implemented in a large camera remained open. In this work, we try to answer this question by performing Geant4 simulations of a full-body SPECT camera. We studied how the pixel size, shape and noise could affect its energy and spatial resolution. Our results suggest that it would be possible to obtain an intrinsic spatial resolution of a few mm FWHM and an energy resolution at 140 keV close to 10%, even if using pixels more than 20 times larger than standard commercial SiPMs of 6 × 6 mm2. We have also found that if SiPMs are distributed following a honeycomb structure, the spatial resolution is significantly better than if using square pixels distributed in a square grid.

Hydrogen reduction and baking process of Pb-silicate microchannel plate and their performance studies

Microchannel plate (MCP) are honeycomb structures consisting of numerous parallel, hollow micro glass fiber channels renowned for their exceptional secondary electron multiplication. This paper investigates changes in MCP properties under hydrogen reduction temperatures ranging from 300 °C to 500 °C. The findings reveal that higher temperatures reduce surface metal oxides, which then accumulate within and darken the microchannels, affecting electron transport. Bulk resistance decreases before increasing, while gain increases and then decreases. At 350 °C, lead oxide begins to reduce to its conductive state, enhancing electron multiplication. However, increased temperatures cause clustering and roughening of the inner channel walls, which diminishes the efficiency of secondary electron release. These alterations are associated with the reduction dynamics of lead ions and temperature-induced microstructural changes. As the hydrogen reduction temperature increases, internal stresses shift outward, and the uniformity of gain varies, reaching its peak at 400 °C. Additionally, an aluminum oxide film enhances resistance to baking and ensures consistent bulk resistance. This study elucidates the relationship between MCP performance and reduction temperature, providing valuable insights for design improvement.

Soft Robotic Honeycomb-Velcro Jamming Gripper Design

In this paper, using a honeycomb-velcro structure to generate a novel jamming gripper is explored. Each finger of the gripper consists of multi-layers with a honeycomb sandwich structure acting as a core wrapped by a fabric sheet and sealed by a latex membrane. This structure can transit between unjammed (flexible) and jammed (rigid) states thanks to the vacuum pressure. Various materials of honeycomb structure, fabric, and reinforcements are investigated to seek optimal combinations for making the jamming fingers. Then, such fingers are deployed in experiments to evaluate the stiffness and the surface friction with different loads in terms of with or without vacuum. Vacuum pressure boosts the stiffness and friction of all the jamming fingers compared with the without-vacuum case. Attached to a gripper, the jamming finger shows good performance in diverse manipulation with food, a metal component, a toy, a can, and a bottle. Furthermore, the variable-stiffness finger under vacuum pressure can be utilized to perform assembly and installation operations such as pushing a bolt into an aligned hole.

Entanglement harvesting in buckled honeycomb lattices by vacuum fluctuations in a microcavity

We study the entanglement harvesting between two identical buckled honeycomb lattices placed inside a planar microcavity. By applying time dependent perturbation theory, we obtain quantum correlations between both layers induced by the cavity field. Considering the vacuum state as the initial state of the cavity field and tracing out the time-evolved degrees of freedom, we analyze the entanglement formation using the concurrence measure. We show that the concurrence depends on the virtual photon exchanged and the positions of the layer through the interlayer photon propagator. Furthermore, we find that the formation of entanglement between equal energy electrons tends to be enhanced when they move in perpendicular directions. Our results indicate that a buckled honeycomb structure and a large spin-orbit interaction favor the entanglement harvesting.

Compressive Strength Analysis of Additively Manufactured Zirconia Honeycomb Sandwich Ceramic Parts with Different Cellular Structures

In this study, ZrO2 honeycomb sandwich structures with different cellular geometry were manufactured by SLA 3D-printing technology to analyze the compressive strength behaviour. After the printing procedure, the samples were sintered at 1450 °C for 2h. Among the samples with different cellular geometry, ZrO2 parts with circular cells were superior to that of square and triangular honeycomb structures and 1867±320 MPa compressive strength was obtained for this structure. The stress distributions in honeycomb structures were investigated using the COMSOL Multiphysics® for exposing the effect of cellular geometry on compressive strength. While more uniform stress distributions were seen on the inner wall of the circular honeycomb sample, the cellular structure of the square and triangle honeycomb samples mostly displayed compressive stress concentration on the joints of the honeycomb structure. Also, according to Rankine failure criterion, the parts with square cellular geometries were found to be more prone to failure. The highest specific compressive strength was obtained for the ZrO2 parts with circular cellular geometry. These findings demonstrated that the ZrO2 honeycomb sandwich structures with circular cellular geometry produced using SLA ceramic 3D-printing technology may be a suitable material to utilize in lightweight structural designs.

Energy absorption properties of origami‐based re‐entrant honeycomb sandwich structures with CFRP subjected to low‐velocity impact

AbstractThis 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 or folding angle 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.Highlights 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 makes the core more prone to deformation. The greater the forward length of the ORH, the lower specific energy absorption (SEA) of the ORHSS.

Research on a Honeycomb Structure for Pyroshock Isolation at the Spacecraft–Rocket Interface

Honeycomb is a splendid kind of structure for aerospace engineering with the advantages of light weight, good shock absorption, and good structural stability. This article aims to provide methods to isolate Pyroshocks based on a honeycomb structure and guarantee the safety of such equipment against a high-frequency shock response. According to stress wave theory, an equation for stress wave transmittance of the honeycomb structure is derived considering the effect of cell wall length and thickness, where desirable honeycomb parameters are obtained. The complexity of the transfer path of the honeycomb structure is exploited to build the spacecraft–rocket interface, which could increase the impedance of the stress wave dramatically. Both finite element analysis and experiments are carried out to validate the shock isolation strategies. The influence of parameters, such as cell wall length and the thickness of the stainless-steel honeycomb, on the isolation performance is analyzed. It is revealed that the honeycomb structure has a significant effect on Pyroshock isolation performance when the wall length of the honeycomb cell is 8 mm and the thickness of the cell is 0.1 mm.

Z-shaped gate tunnel FET with graphene channel: An extensive investigation of its analog and linearity performance

This work analyzes a graphene channel Z-shaped gate tunnel FET's (ZTFET) analog, and linearity performance. This research aims to introduce graphene with a two-dimensional honeycomb structure that is anticipated to be a strong challenger for the upcoming generation of semiconductor devices. The ZTFET with graphene channel provides a 3-decade increase in ON current, indicating a notable improvement in gate capacitance and transconductance compared to the conventional silicon channel. This improvement further leads to better linearity and analog/RF performance. We delved into various linearity and Radio Frequency (RF) figure-of-merits, including gmn, VIP2, VIP3, IIP3, 1‐dB compression point, GBWP, TFP, unity gain cut‐off frequency, and maximum oscillation frequency. The results of the new GC-ZTFET are compared with those of the traditional ZTFET to establish its superiority. The GC-ZTFET outshines other device structures when speaking of linearity, RF performance, and current-carrying capability.

Design-manufacturing-performance of electromagnetic absorbing/load bearing three-dimensional honeycomb woven composites

Structural electromagnetic wave (EMW) absorbing composites play a critical role in both civilian and military applications. However, traditional sandwich honeycomb EMW absorbing composites have poor out-of-plane mechanical properties and load-bearing performance.This study introduces the development of a three-dimensional honeycomb woven composite (3DHWC) that integrates EMW absorption and load-bearing capabilities. A weaving loom was used to fabricate a three-dimensional honeycomb woven structure fabric (3DHSWF) with varying structural parameters. Subsequently, the composites were formed using carbon black (CB), multi-walled carbon nanotubes (MWCNTs), and carbonyl iron powder (CIP) as hybrid absorbers, epoxy resin as the matrix, combined with the vacuum-assisted resin transfer molding (VARTM) process. Testing confirmed the material’s excellent EMW absorption and mechanical properties, achieving a maximum reflection loss (RL) of −30.9 dB and an adequate EMW absorption bandwidth (EAB) of 14.58 GHz. The maximum bending load reached 5799.1 N, with no delamination observed in the samples. This material demonstrates outstanding EMW absorption performance and exhibits superior load-bearing capacity while maintaining structural integrity. Our research provides valuable insights into the design of honeycomb EMW absorbing composites, offering significant advancements in EMW absorption efficiency and bending mechanical properties.

Response of circular type sandwich panel using JUCO-glass fiber with PU foam under three-point bending loading

In this study, a circular type honeycomb sandwich panel using natural JUCO and synthetic woven glass fiber was fabricated, and the bending properties like bending strength, modulus of rupture (MOR), and modulus of elasticity (MOE) were evaluated. Polyurethane (PU) foam was injected into the core structure to improve the bending strength. The orientation of jute and cotton fiber was varied to investigate the best stiffness and strength. In addition, twill-type JUCO fiber mat and synthetic woven glass fiber were also used to fabricate the circular type honeycomb sandwich panel. Finite element modeling was undertaken to validate the experimental results. Prior to the finite element analysis, a tensile test was carried out to determine the boundary conditions. Injecting polyurethane foam into the honeycomb core does not show any significant impact on bending properties. However, the deformation rate increased considerably by adding PU foam in the core structure. According to the results, honeycomb sandwich panels made of woven glass fiber with PU foam exhibited more homogenous deflection and bending compliance compared with others.

Study on preparation and performance of CoS2/NiS2-CNT@C anode material for high-performance lithium‑sulfur batteries

Functional carbon materials with high porosity have been widely used in energy storage materials. In this work, a porous carbon skeleton was constructed by a rigid template method, and carbon nanotubes grown in situ in the skeleton to realize the organic combination of the honeycomb structure and carbon nanotubes, thereby forming a carrier material with a specific structure. At the same time, bimetallic sulfide (CoS2/NiS2) was introduced as a modification material on the specific structure. The two transition metal sulfides have a matching energy band structure, which can form a high-quality interface in the composite. The electron transfer can be accelerated through the interface between different substances, and the electron regulation and redistribution can be realized, thereby further improving the reaction kinetics. Electrochemical tests also confirmed the superiority of its performance. At a current density of 0.5 A/g, the first discharge-specific capacity reached 1378.9 mAh/g, and there was still a capacity of 993.5 mAh/g after 100 cycles. Even at a high current (5 A/g), the capacity remained at 503 mAh/g.

Comprehensive analysis of charge carriers dynamics through the honeycomb structure of graphite thin films and polymer graphite with applications in cold field emission and scanning tunneling microscopy

Polymer graphite electron sources have performed satisfactorily as field emission emitters and scanning tunneling microscopy probes in the past few years. However, the emission process was characterized by limited total emission currents. This paper introduces the elemental, vibrational, electronic structure, and optical analysis of polymer graphite and glass-graphite composite field emission cathodes to study these limitations. Moreover, the field emission characteristics are studied including the changes in the potential energy barrier of the used materials and structures. Among the studied structures, the cathodes prepared from graphite thin films deposited on a micropointed glass substrate (film-GMF) showed superior performance as random field emission arrays. This includes obtaining much higher emission current values ≈ 20 times) and lower threshold voltages ≈ 1/2) compared to the results obtained from polymer graphite samples. The enhancement factor in such emitters is believed to be the three-dimensional honeycomb structure of graphite. Moreover, the study includes applying graphite coatings to tungsten nano-field emission cathodes and scanning tunneling microscopy probes, which improves the performance of such cathodes/probes in both microscopic techniques.

Laser Powder Bed Fusion of Multifunctional Bio-inspired Vertical Honeycomb Sandwich Structures: For the Application of Lightweight Bipolar Plates of Proton Exchange Membrane Fuel Cells

The bipolar plate (BPP) is a crucial component of proton exchange membrane fuel cells (PEMFC). However, the weight of BPPs can account for around 80% of a PEMFC stack, posing a hindrance to the commercialization of PEMFCs. Therefore, the lightweight design of BPPs should be considered as a priority. Honeycomb sandwich structures meet some requirements for bipolar plates, such as high mechanical strength and lightweight. Animals and plants in nature provide many excellent structures with characteristics such as low density and high energy absorption capacity. In this work, inspired by the microstructures of the Cybister elytra, a novel bio-inspired vertical honeycomb sandwich (BVHS) structure was designed and manufactured by laser powder bed fusion (LPBF) for the application of lightweight BPPs. Compared with the conventional vertical honeycomb sandwich (CVHS) structure formed by LPBF under the same process parameters setting, the introduction of fractal thin walls enabled self-supporting and thus improved LPBF formability. In addition, the BVHS structure exhibited superior energy absorption (EA) capability and bending properties. It is worth noting that, compared with the CVHS structure, the specific energy absorption (SEA) and specific bending strength of the BVHS structure increased by 56.99% and 46.91%, respectively. Finite element analysis (FEA) was employed to study stress distributions in structures during bending and analyze the influence mechanism of the fractal feature on the mechanical properties of BVHS structures. The electrical conductivity of structures were also studied in this work, the BVHS structures were slightly lower than the CVHS structure. FEA was also conducted to analyze the current flow direction and current density distribution of BVHS structures under a constant voltage, illustrating the influence mechanism of fractal angles on electrical conductivity properties. Finally, in order to solve the problem of trapped powder inside the enclosed unit cells, a droplet-shaped powder outlet was designed for LPBF-processed components. The number of powder outlets was optimized based on bending properties. Results of this work could provide guidelines for the design of lightweight BPPs with high mechanical strength and high electrical conductivity.

Highly Stable Ni-B/Honeycomb-Structural Al2O3 Catalysts for Dry Reforming of Methane.

Two-component catalysts have garnered significant attention in the field of catalysis due to their ability to inhibit Ni sintering. In the present work, honeycomb-structuralstructured Al2O3-supported Ni and B were prepared to enhance coke tolerance during dry reforming of methane (DRM). Transmission electron microscopy (TEM) results revealed that the average particle sizes on Ni/Al2O3 and Ni-0.16B/Al2O3 were 7.6 nm and 4.2 nm, respectively, indicating that B can effectively inhibit Ni sintering. After a 100-hour reaction, the conversion of CH4 and CO2 on Ni/Al2O3 decreased by approximately 5 %, whereas on Ni-0.16B/Al2O3, there was no significant decrease in CH4 and CO2 conversion, with values of approximately 81.6 % and 87.2 %, respectively. In situ DRIFT spectra demonstrated that Ni-0.16B/Al2O3 enhanced the activation of CO2, thus improving the catalyst's stability. A Langmuir-Hinshelwood-Hougen-Watson (LHHW) model was developed for intrinsic kinetics, and the resulting kinetic expressions were well-fitted fit to the experimental data, with R2 values exceeding 0.9. ActivationThe activation energies were also calculated. The outstanding stability of Ni-0.16B/Al2O3 can be attributed to its stable honeycomb structure and B's ability to significantly inhibit Ni sintering, reduce catalyst particle size, and enhance coke tolerance.

Application of a novel machine learning model for the prediction and optimization of anti-blast performance of sandwich honeycomb blast walls

Sandwich honeycomb blast wall with the superior energy absorption characteristics could be applied to anti-blast protection of offshore oil and gas platform. Recently, machine learning technique, as an alternative to traditional Finite Element Analysis (FEA), is becoming a powerful tool in understanding structural performance. The aim of this study is to propose a novel data-driven model for fast predictions of structure response of sandwich blast wall under explosion, including the maximum deformation δmax, the maximum internal energy Emax and the energy absorption ratio RE. FEA was firstly conducted to generate sample data for the proposed model by using LS-DYNA software. An improved artificial electric field algorithm (IAEFA) was combined with artificial neural network (ANN) to develop an IAEFA-ANN model. In case studies, the prediction results of IAEFA-ANN approximate the results of FEA well, and comparison results of 9 different ANN models demonstrate that IAEFA-ANN model has the best performance. Then, the effects of explosion parameters (including explosive charge mass Me, stand-off distance d and concave angles θ) on structural response prediction results were investigated by using the proposed model. Moreover, the IAEFA-ANN model was applied to conducting optimal design of the blast wall to obtain optimum anti-blast performance.

Shingled design lightweight photovoltaic modules using honeycomb sandwich structures as backsheets

The expanding scale of the photovoltaic (PV) market has intensified the focus on PV module designs for diverse applications. Research actively pursues lightweight PV modules, replacing front glass with polymer films as a suitable design solution. Lightweight PV modules with front-film structures require additional structures to compensate for their inadequate mechanical rigidity. Hence, we integrated honeycomb sandwich structures into lightweight PV modules, substituting them for traditional PV backsheets. It increased the mechanical rigidity of lightweight PV modules and effectively replaced the PV backsheet through a simple one-step lamination process. Consequently, we successfully fabricated lightweight PV modules with a shingled design, achieving a conversion power of 205.80 W in an area of 1.034 m2, facilitating the integration of more solar cells in a limited space. Additionally, standard reliability tests were performed on a PV module weighing only 6.2 kg/m2.

Carbon-intercalated halloysite-based aerogel efficiently encapsulating phase change materials with excellent photothermal conversion and energy storage

Latent heat storage systems based on organic phase change materials (PCMs) are considered to be an efficient solar energy utilization strategy, but leakage vulnerability and insensitivity to sunlight of PCMs limit their further application in energy storage. In this work, a new hierarchical porous aerogel was constructed with the carbon intercalated halloysite nanotubes (CHNTs) as the assembly units for PCMs encapsulation to improve the load weight, stability and sunlight absorption. The CHNTs were first successfully synthesized through intercalation and carbonization, with the aim of increasing their specific surface area and sunlight absorption.Subsequently, the CHNTs/polyvinyl alcohol (PVA) aerogels with 3D honeycomb structure were prepared by self-assembly using a freeze-drying method, which can significantly promote the encapsulation ratio of lauric acid (LA) in the pores of both aerogels and CHNTs. The CHNTs can not only improve compressive strength of the aerogels and shape stability of the composite PCMs, but also enhance light absorption ability of the composites compared to pristine HNTs. As a support material, CHNTs aerogel (CHNP) loaded more than 92 wt% PCM (LA@CHNP) and exhibited an extremely high latent heat capacity (170.9 J/g). The LA@CHNP had good structural and thermal stability in 300 cycles without visible leakage. Besides, solar energy absorption increased from 43 % to 98 %, and the solar-to-thermal energy conversion efficiency increased to 95.88 %, which could be attributed to 3D porousness and carbon nanolayers of the CHNTs. We have successfully synthesized an eco-friendly and facile composite LA@CHNP, which will contribute to the design of advanced composites with excellent solar energy storage properties, and provide a new direction for the application of carbonized materials.

Analysis of Mechanical Properties and Parameter Dependency of Novel, Doubly Re-Entrant Auxetic Honeycomb Structures.

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.