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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]

Selective laser melting (SLM) of heat-resistant nickel alloy VZh159 is used to show that at constant energy density the key factor determining the texture and the internal stresses is the hatching distance. At multiple increase in the exposure rate and decrease in the hatching distance, the micropore proportion increases exponentially due to enhancement of the dissipation of the laser radiation caused by reflection in the track overlapping zone. [ABSTRACT FROM AUTHOR]

Analysis of published data on the effect of the exposure algorithms, energy, and scanning speed on the geometric characteristics of the molten pool and its fine structure, on the texture and grain structure of metallic materials synthesized by selective laser melting (SLM) is presented. A regression model describing the correlation between the required laser energy density and the powder composition characteristic temperatures during SLM of heat-resistant nickel- and cobalt-based alloys is obtained. [ABSTRACT FROM AUTHOR]

This study introduces a novel and versatile method for synthesizing honeycomb‐structured silicon carbide (SiC). The innovative approach utilizes a sucrose solution as the carbon source and nonporous silica spheres, which serve both as silicon precursors and templates, allowing for precise control over pore sizes. Notably, the process is characterized by its cost‐effectiveness, eco‐friendliness, and the utilization of milder conditions attributed to magnesiothermic reduction. The tunable pore sizes achieved through adjustments in the size of silica particles offer a versatile platform for customizing SiC materials to meet specific application requirements. Beyond its customizable nature, the method reduces the environmental footprint of SiC synthesis by utilizing eco‐friendly materials. Its combined attributes of accessibility, sustainability, and performance optimization underscore its potential for driving advancements in SiC‐based applications across various industrial and scientific domains. [ABSTRACT FROM AUTHOR]

In this study, a three-rib intersecting composite diamond honeycomb structure is fabricated by interlocking technology. The mechanical properties of the composite interlocked diamond honeycomb (CIDH) and corresponding sandwich structure (CIDHSS) are experimentally tested. The stiffness, strength, and failure characteristics of CIDH and CIDHSS are analyzed. The results show that CIDH has better mechanical properties than the interlocked Kagome and square honeycombs. The edge effect limits the edge compressive strength and stiffness of CIDH. Debonding is the main failure mode that limits both bending and compressive strength of CIDHSS. The reinforced plate added to the edge effectively improves the anti-debonding ability. [ABSTRACT FROM AUTHOR]

The disposal of plastic foam, mostly composed of polystyrene, poses significant environmental challenges due to its high popularity, slow degradation, and low cost. To address this problem, recycling polystyrene foam waste (PF) has emerged as a promising solution to reduce plastic pollution. This paper presents a novel approach to mass‐produce highly ordered, porous honeycomb‐patterned film (hc‐film) using wasted PF as the raw material. The hc‐film is produced using an improved phase separation (IPS) method that utilizes methanol as a suitable pore inducer and template droplet stabilizer. Methanol provides the hc‐film with customizable features such as pore ordering, size, and separation. The freestanding hc‐film, achieved by adopting a water‐soluble polystyrene sulfonate as a scarified layer, can be transferred and utilized as a flexible mold to pattern various solid substrates with complicated surface morphologies using the pre‐impregnated technique. This study demonstrates the potential of this cost‐effective and efficient approach for various applications, such as super/anti‐wetting surfaces, microelectronics, optical devices, sensors, and nanogenerators. [ABSTRACT FROM AUTHOR]

Sandwich structures are often used as protective structures on ships. To further improve the energy-absorbing characteristics of traditional honeycomb sandwich structures, an energy-absorbing mechanism is proposed based on the gradient folding deformation of lotus root nodes and a leafy stem vein homogenizing load mechanism. A honeycomb sandwich structure is then designed that combines lotus root nodes and leafy stem veins. Four types of peak-nest structures, traditional cellular structure (TCS), lotus root honeycomb structure (LRHS), leaf vein honeycomb structure (LVHS), and lotus root vein combined honeycomb structure (LRVHS), were prepared using 3D printing technology. The deformation modes and energy absorption characteristics of the four honeycomb structures under quasistatic action were investigated using a combination of experimental and simulation methods. It was found that the coupling design improved the energy absorption in the structural platform region of the LRHS by 51.4% compared to that of the TCS due to its mechanical mechanism of helical twisting and deformation. The leaf vein design was found to enhance the peak stress of the structure, resulting in a 4.84% increase in the peak stress of the LVHS compared to that of the TCS. The effects of the number, thickness, and position of the leaf vein plates on the honeycomb structure were further explored. The greatest structural SEA effect of 1.28 J/g was observed when the number of leaf vein plates was four. The highest SEA of 1.36 J/g was achieved with a leaf vein plate thickness of 0.6 mm, representing a 7.3% improvement compared to that of the 0.2 mm thickness. These findings may provide valuable insights into the design of lightweight honeycomb sandwich structures with high specific energy absorption. [ABSTRACT FROM AUTHOR]

A honeycomb structure is a sandwich structure widely used in fuselage, among which the hexagonal honeycomb core is the most widely used. The energy absorption characteristics and impedance ability of the structure are the main reasons that directly affect the energy absorption characteristics of the honeycomb sandwich structure. Therefore, it is necessary to study the out-of-plane mechanical properties of the composite honeycomb sandwich structure. Based on the numerical simulation results, the energy absorption characteristics of several composite honeycomb sandwich structures are verified by drop hammer impact experiments. The research shows that the transient energy absorption characteristics of the composite honeycomb sandwich structure are mainly related to the cell size of the honeycomb structure. The smaller the size of the front cell, the stronger the overall impact resistance; the strength of the composite honeycomb sandwich structure exceeds that of 7075 aluminum alloy-NOMEX and carbon fiber-NOMEX honeycomb sandwich structures. In this paper, the energy absorption characteristics of composite honeycomb sandwich structures under different impact energy are compared and studied. The displacement, force and energy curves of energy absorption characteristics related to time variables are analyzed. The difference in protective performance between the composite honeycomb sandwich structure and existing airframe structure is compared and studied. The optimal structural design parameters of composite honeycomb sandwich under low-speed impact of drop hammer are obtained. The maximum energy absorption per unit volume of the designed honeycomb sandwich structure is 171.7% and 229.8% higher than that of the NOMEX-AL and NOMEX-C structures. The 6.4 mm and 3 mm cell sizes show good characteristics in high-speed buffering and crashworthiness. The composite honeycomb sandwich airframe structure can improve the anti-damage performance of the UAV airframe structure, ensure the same thickness and lightweight conditions as the existing honeycomb sandwich airframe structure, and improve the single-core bearing mode of the existing airframe structure. [ABSTRACT FROM AUTHOR]

المخلص: أهداف البحث: كان الهدف من هذه الدراسة هو التحقيق في تأثير سعة الاهتزاز للموجات الميكانيكية بالموجات فوق الصوتية (27 كيلو هرتز) على قدرة الخلايا اللثوية البشرية على الحياة وتشكلها التي تم زرعها على مادة حيوية. طرق البحث: تم زرع الخلايا اللثوية البشرية على أطباق زرع الأنسجة وسطح سبائك التيتانيوم ''تي آي 6 ايه 14 في'' في مجموعتين تشمل ثلاثة أيام وسبعة أيام من زرع الخلايا. تعرضت الخلايا لثلاث سعات اهتزاز لمدة 20 دقيقة يوميا. تم استخدام صور مجهر المسح الإلكتروني لتحديد شكل الخلايا. النتائج: لأول مرة، عند مستوى معين من سعة الاهتزاز المقارن بشدة 260 مللي وات / سم2، تم تحديد كيفية فقدان الخلايا الملتصقة اتصالها. تكاثرت الخلايا اللثوية البشرية التي تلقت مستوى معين من سعة الاهتزاز المقارن بشدة 50 مللي وات / سم2 بشكل كبير، في حين كانت السعات الأعلى لها آثارا سلبية. الاستنتاجات: أظهر مسح صور المجهر الإلكتروني للأرومات الليفية اللثوية البشرية على أقراص التيتانيوم عند مستوى معين من سعة الاهتزاز مقارنة بكثافة 50 ميغاواط / سم2 بتشكل سداسي ملحوظ، والتي كانت تسمى نمط قرص العسل في هذا البحث التجريبي، وفي اليوم السادس لوحظ أن الخلايا اللثوية البشرية تكاثرت على أطباق زرع الأنسجة بمعدل أعلى وخلايا جديدة متصلة بشكل موحد على طبقة من الخلايا. يشير هذا إلى تأثير الأنسجة الخلوية كركيزة لنمو الخلايا الليفية اللثوية البشرية الجديدة تحت الموجات فوق الصوتية منخفضة الكثافة. Abstract: Objectives: The aim of this study was to investigate the effect of the vibration amplitude of mechanical ultrasound waves (27 kHz) on the viability and morphology of human gingival fibroblasts (hGFs) when cultured on a biomaterial substrate. Method: hGFs were seeded on tissue culture plates (TCPs) and an Ti6Al4V titanium alloy surface in two groups for three days and seven days of cell culture. The cells were subjected to three vibration amplitudes for 20 min each day. Scanning electron microscope (SEM) images were used to characterize cell morphology. Results: Experiments showed that hGF cells became detached from their plates at a vibration amplitude comparable to an intensity of 260 mW/cm2. In addition, hGfs that received a vibrational amplitude comparable to an intensity of 50 mW/cm2 underwent significant proliferation proliferated significantly; however, cells receiving higher amplitudes suffered from adverse effects. Conclusions: SEM images of hGFs on titanium disks at vibration amplitude comparable to an intensity 50 mW/cm2 showed a remarkable hexagonal architecture, which we refer to as a honeycomb pattern. On day 6 the observed hGFs on TCPs, proliferated at a higher rate and new cells attached uniformly on the existing layer of cells. These data indicate the effect of cellular tissue as a substrate on the growth of new hGFs under low-intensity ultrasound.

Because aluminum-based parts cannot be used for long-term applications in large load-wear environments, nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composites were successfully prepared in this study for that purpose. By adjusting the plating solution ratio, nickel–tungsten was used as a carrier to introduce molybdenum disulfide nanoparticles, forming a nickel–tungsten/molybdenum disulfide composite coating on the surface of carbon fibers. To enhance the interfacial bonding strength between the carbon fiber and aluminum matrix, a laser was employed to induce the formation of a honeycomb-like structure on the surface of the aluminum base. This increased the contact area between the carbon fiber, aluminum matrix, and epoxy resin adhesives, forming a nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composite material. The performance of this composite material was tested and analyzed. The results demonstrated that compared with the carbon fiber/aluminum composite material, the shear strength of the nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composite material was increased by 129.7 %, and the friction coefficient and wear rate were reduced by 54.8 % and 83 %, respectively. Next, investigation of the mechanism underlying the honeycomb structure's contribution to the adhesive strength of the composites and their resistance to shear load revealed that the wear-resistant mechanism of molybdenum disulfide nanoparticles reinforced the nickel–tungsten composite coatings. The preparation and study of nickel–tungsten (molybdenum disulfide)/carbon fiber/aluminum composites provide a reference for expanding the applications of aluminum-based composite materials to meet the service requirements of complex environments. [ABSTRACT FROM AUTHOR]

The authors report an experimental investigation on square thin-walled energy absorbers with different topologies and materials. The material was steel SAE 1010 and aluminum AL 6160. Some samples non-filled and filled with polymeric material received patterned windows placed in opposite faces with specific dimensions: 20x20, 15x30, and 20x30 mm2. Quasi-static axial loading crushes hollow specimens and hybrid specimens filled with PET-G honeycomb. The core filling was printed using the FDM technique. The crashworthy ability of specimens was evaluated based on the specific energy absorption (SEA), load ratio (LR) and structural efficiency (η), which showed that windowed-filled specimens with 20x30 mm2 perform better. The maximum increase of SEA was 212%, LR decreased from 4.02 to 1.78 and η increased from 0.45 to 0.89 for steel energy absorbers and in the same manner, the values for aluminum specimens were 123%, 2.97 to 1.28 and 0.46 to 0.71. The effects of the patterned windows and their combination with the honeycomb core for both metallic materials show that such a topology improved the performance in two factors. The windows reduced the peak force, and the PET-G honeycomb furnished a smoothing to the region at the end of the fold formation, contributing to the crashworthy ability. Future work envisages experimental testing of the samples in dynamic tests. [ABSTRACT FROM AUTHOR]

This study presents a novel approach inspired by the hexagonal honeycomb structure found in nature, leveraging image processing algorithms to precisely define complex geometries in thermal systems. Hexagonal phase change material containers and thermally conductive fins were meticulously delineated, mirroring the intricate real-world designs of honeycombs. This innovative methodology not only streamlines setup processes but also enhances our understanding of melting dynamics within enclosures, highlighting the potential benefits of biomimetic design principles in engineering applications. Two distinct honeycomb structures were employed to investigate their impact on the melting process within cavities subject to heating from the left wall, with the remaining walls treated as adiabatic surfaces. The incorporation of a thermally conductive fin system within the enclosure significantly reduced the time required for a complete phase change, emphasizing the profound influence of fin systems on thermal design and performance. This enhancement in heat transfer dynamics makes fin systems advantageous for applications prioritizing precise temperature control and expedited phase change processes. Furthermore, the critical role of the fin system design was emphasized, influencing both the onset and location of the final point of melting. This underscores the importance of tailoring fin systems to specific applications to optimize their performance. Our study highlights the significant impact of the Rayleigh (Ra) number on the melting time in a cavity without fins, revealing a decrease from 6 to 0.4 as the Ra increased from 102 to 105; the introduction of a fin system uniformly reduced the melting time to Ste.Fo = 0.5, indicating fins' universal effectiveness in optimizing thermal dynamics and expediting the melting process. Moreover, the cavity angle was found to significantly affect the fluid fraction diagram in unfanned cavities but had minimal impact when fins were present, highlighting the stabilizing role of fins in mitigating gravitational effects during melting processes. These insights expand our understanding of cavity geometry and fin interactions in heat transfer, offering potential for enhanced thermal system designs in various engineering applications. Decreasing thermal conductivity (λ) by increasing the fin thickness can halve the melting time, but the accompanying disadvantages include a heavier system and reduced energy storage due to less phase change material, necessitating a careful balance in decision-making. [ABSTRACT FROM AUTHOR]

The cuttlebone is known for its ability to possess high specific stiffness, progressive failure and lightweight from the porous chambered structure. Inspired by the microstructural characteristics of cuttlebone and incorporating the wall gradient design, a series of double-asymmetric honeycombs were designed and processed by LPBF. Results indicated that bionic structural units with the junction design can maintain the integrity of the residual parts after local buckling and failure, improving the load-bearing capacity. The double-asymmetric honeycomb with gradation parameter a = 2/3 achieved a maximum specific compressive strength of 70.64 MPa cm3/g. As a decreases, there is an increase in specific energy absorption and a narrowing of the hysteresis loop. The as-build honeycomb had undergone stress-induced martensite transformation during compression. The dissipated mechanical energy (ME) decreased with the increasing cycle number and the decreasing a. The results provide design guidelines and process strategies for developing high-performance honeycombs. [ABSTRACT FROM AUTHOR]

The shape memory alloy (SMA) can deform pseudo-plastically under external load, based on which a reusable impact energy absorption structure was designed. According to the classical SMA constitutive model, the finite element model for thin-wall structures was established, and the dynamic characteristics such as deformation modes and energy absorption of different forms of honeycomb structures under different impacting velocities, were analyzed, and the optimal energy absorption performance of the SMA structures was obtained. In addition, through comparison of the energy absorption performance of the SMA honeycomb with that of the aluminum honeycomb, the energy absorption of the SMA honeycomb with different structure configurations was different from that of the aluminum honeycomb under different-velocity impacts, with the optimal structure changes. The work provides a reference for the selection and design of the SMA honeycomb structures. [ABSTRACT FROM AUTHOR]

In this paper, sorghum and reed, which possess light stem structures in nature, were selected as biomimetic prototypes. Based on their mechanical stability characteristics—the porous structure at the node feature and the porous feature in the outer skin— biomimetic optimization design, simulation, and experimental research on both the traditional hexagonal structure and a hexagonal honeycomb structure were carried out. According to the two types of straw microcell and chamber structure characteristics, as well as the cellular energy absorption structure for the bionic optimization design, 22 honeycomb structures in 6 categories were considered, including a corrugated cell wall bionic design, a modular cell design, a reinforcement plate structure, and a self-similar structure, as well as a porous cell wall structure and gradient structures of variable wall thickness. Among them, HTPC-3 (a combined honeycomb structure), HSHT (a self-similar honeycomb structure), and HBCT-257 (a radial gradient variable wall thickness honeycomb structure) had the best performance: their energy absorption was 41.06%, 17.84%, and 83.59% higher than that of HHT (the traditional hexagonal honeycomb decoupling unit), respectively. Compared with HHT (a traditional hexagon honeycomb decoupling unit), the specific energy absorption was increased by 39.98%, 17.24%, and 26.61%, respectively. Verification test analysis revealed that the combined honeycomb structure performed the best and that its specific energy absorption was 22.82% higher than that of the traditional hexagonal structure. [ABSTRACT FROM AUTHOR]

The performance of catalytic reactors in heterogeneous catalysis is especially dependent on the support structures the catalysts are dispersed on. They determine important properties like the pressure drop as well as the temperature distribution within catalytic reactors. The latter is especially important for reactions like the CO 2 methanation, which is highly exothermic, but thermodynamically favored at low temperatures. Here we present a novel monolithic catalyst support structure inspired by the shape of diatom shells. By coupling a genetic algorithm with an FEM solver, a parametric model is optimized towards good radial heat transport. By comparing the optimized structures with honeycombs already used in industry, the beneficial thermal properties are demonstrated both for a pure conductive case as well as for superimposed fluid convection using Computational Fluid Dynamics. The optimized designs give a good basis for honeycomb-like catalyst support structures with good heat removal while preserving very low pressure drops. [Display omitted] • Coupling of genetic algorithm and FEM simulations to optimize honeycomb-like support structures. • Simple rearrangement of flow channels leads to better radial heat transport properties. • Hotspot temperature is decreased between 18 and 27% for pure conductive cases. • Fluid convection slightly mitigates the gain of optimization for low solid thermal conductivity. [ABSTRACT FROM AUTHOR]

Vitrified-bond diamond composites are materials commonly used for grinding wheels in the grinding process of silicon wafer production. In this study, the mechanism of the in situ honeycomb structure formation in the sintering process of composite materials was explored by changing the binder content without adding a pore-forming agent.The results show when the content of vitrified bond is 55 wt%, the in situ honeycomb structure forms, resulting in a porosity of 60.68 % and bending strength of 23.03 MPa.The X-ray diffraction (XRD), Raman spectroscopy (RS), and thermogravimetry-differential thermal analysis (TG-DTA) results show that no graphitization of diamond grain occurs during sintering. The bonding ability between the vitrified bond and diamond grain, along with the microstructure of vitrified-bond diamond composites, was studied using scanning electron microscopy (SEM). Moreover, the results of energy spectrum analysis (EDS) show that the diffusion and segregation of Na at the interface between the diamond particles and the vitrified bond improve the bonding strength, and the vitrified bond can effectively bond with the diamond particles. Finally, the formation mechanism of the honeycomb structure was elucidated using the surface and interface sintering theory. [ABSTRACT FROM AUTHOR]

This paper proposed a new structural design method for multi-layer honeycomb-filled woven fabrics, and the impact resistance of rope-like core supporting fabrics was studied on multi-layer honeycomb woven fabrics. The effects of the rope-like core filling yarn fineness, the rope-like core surface structure and the multi-layer fabric surface structure on the impact resistance of the filled fabric were analyzed. Nine samples were woven with different factors in accordance with the orthogonal test scheme. The effects of the above factors on the peak transmitted force of the filled fabric were discussed. The study demonstrates that all three factors are significant, and the primary order of influence with the optimal level in the parentheses is rope-like core filling yarn fineness ( 22.22 tex) > multi-layer fabric surface structure ( interweave 2/2 ) > rope-like core surface structure (interweave 3/1). [ABSTRACT FROM AUTHOR]

High-performance and low-cost electrode material is crucial for the development of Na-ion batteries. Herein, a novel honeycomb-structured biochar with high specific area (labelled as HS X-C) was constructed through a simple and scalable method, using Xanthium sibiricum fruits as starting material with the assistance of NaCl template. The HS X-C shows a long-range-disordered but short-range-ordered microstructure. As an anode for Na-ion batteries, it exhibits an initial coulombic efficiency of about 86.5%, a rate capability of 161 mAh g−1 at 4.0 A g−1 and a cyclability of 3000 cycles at 2.0 A g−1. Moreover, the Na-ion full cell matched with the NVP/rGO cathode exhibits an average operating voltage of about 3.3 V and a high energy density of about 180 Wh kg−1(total). Kinetic studies indicate that the reaction rate of this anode is jointly controlled by diffusion and pseudocapacitance. This work not only greatly improves the sodium storage performance of the biochar from Xanthium sibiricum fruits, but also demonstrates the importance of the adopted synthesis techniques for the electrochemical performance of biochar. [ABSTRACT FROM AUTHOR]

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Natural fibers are attracting more and more attention due to their affordability, environmental friendliness and ability to biodegrade. They are gaining more and more popularity compared to synthetic fibers. Composite materials from natural fiber demonstrate excellent strength and stiffness, high resistance to destruction, as well as excellent heat and sound insulation qualities. These properties can bring significant benefits to the automotive industry and increase the comfort of car operation. Automobile manufacturers and researchers are increasingly considering the use of natural fiber reinforced composites in their products. The production of composite materials is developing rapidly and has the prospect of replacing conventional methods of manufacturing vehicle parts, and natural fibers play an important role in this. In the field of composite materials, there is a trend of changing synthetic fibers to natural fibers, this is due to the interest of buyers in environmentally friendly products and progress in innovation, due to which the use of natural fibers becomes an integral part of this process. A wide range of fibers are used, such as: bamboo, kenaf, hemp, jute, flax, coir, sisal, etc. Natural fibers are gradually replacing synthetic fibers due to their biodegradability, environmental friendliness, while offering good strength, high stiffness, low density and low cost compared to synthetic fibers. Although there are a variety of plant fibers in nature, only a few of them are considered suitable for automotive applications, as they provide properties close to synthetic fibers. Despite their advantages and a wide range of uses, composites from natural fibers have a number of disadvantages that negatively affect the operational properties of the car. Some of the main problems are hydrophilicity, uneven fiber strength, poor fire resistance and durability. This article examines the practical use of composite materials based on natural fiber and considers their perspective in the automotive industry.

Considering that it satisfies high strength and stiffness at a low weight, the grid structure is the ideal option for meeting the requirements for developing the wall panel structure for the satellite. The most attractive grid structures for the satellite wall panel industry are isogrid and honeycomb structures. The first part of this work involves studying the mechanical and dynamic performance of five designs for the satellite wall panel made of 7075-T0 Al-alloy. These designs include two isogrid structures with different rib widths, two honeycomb structures with different cell wall thicknesses, and a solid structure for comparison. The performance of these designs was evaluated through compression, bending, and vibration testing using both finite element analysis (FEA) with the Ansys workbench and experimental testing. The FEA results are consistent with the experimental ones. The results show that the isogrid structure with a lower rib thickness of 2 mm is the best candidate for manufacturing the satellite wall panel, as this design reveals the best mechanical and dynamic performance. The second part of this work involves studying the influence of the length of the sides of the best isogrid structure in the range of 12 mm–24 mm on its mechanical and dynamic performance to achieve the lowest possible mass while maintaining the structure’s integrity. Then, a modified design of skinned wall panels was introduced and dynamically tested using FEA. Finally, a CAD model of a hexagonal satellite prototype using the best-attained design of the wall panel, i.e., the isogrid structure with a 2 mm rib width and 24 mm-long sides, was built and dynamically tested to ensure its safe design against vibration. Then, the satellite prototype was manufactured, assembled, and successfully assessed.

The authors derived a mathematical model of geometrically nonlinear vibrations of three-layer shells, which describes the vibrations of the structure with amplitudes comparable to its thickness. The high-order shear theory is used in the derivation of this model. Rotational inertia is also taken into account. At the same time, the middle layer is a honeycomb structure made thanks to additive FDM technologies. In addition, each shell layer is described by five variables (three displacement projections and two rotation angles of the normal to the middle surface). The total number of unknown variables is fifteen. To obtain a model of nonlinear vibrations of the structure, the method of given forms is used. The potential energy, which takes into account the quadratic, cubic, and fourth powers of the generalized displacements of the structure, is derived. All generalized displacements are decomposed by generalized coordinates and eigenforms, which are recognized as basic functions. It is proved that the mathematical model of shell vibrations is a system of nonlinear non-autonomous ordinary differential equations. A numerical procedure is used to study nonlinear periodic vibrations and their bifurcations, which is a combination of the continuation method and the shooting method. The shooting method takes into account periodicity conditions expressed by a system of nonlinear algebraic equations with respect to the initial conditions of periodic vibrations. These equations are solved using Newton's method. The properties of nonlinear periodic vibrations and their bifurcations in the area of subharmonic resonances are numerically studied. Stable subharmonic vibrations of the second order, which undergo a saddle-node bifurcation, are revealed. An infinite sequence of bifurcations leading to chaotic vibrations is not detected.

Sandwich structures are often used as protective structures on ships. To further improve the energy-absorbing characteristics of traditional honeycomb sandwich structures, an energy-absorbing mechanism is proposed based on the gradient folding deformation of lotus root nodes and a leafy stem vein homogenizing load mechanism. A honeycomb sandwich structure is then designed that combines lotus root nodes and leafy stem veins. Four types of peak-nest structures, traditional cellular structure (TCS), lotus root honeycomb structure (LRHS), leaf vein honeycomb structure (LVHS), and lotus root vein combined honeycomb structure (LRVHS), were prepared using 3D printing technology. The deformation modes and energy absorption characteristics of the four honeycomb structures under quasistatic action were investigated using a combination of experimental and simulation methods. It was found that the coupling design improved the energy absorption in the structural platform region of the LRHS by 51.4% compared to that of the TCS due to its mechanical mechanism of helical twisting and deformation. The leaf vein design was found to enhance the peak stress of the structure, resulting in a 4.84% increase in the peak stress of the LVHS compared to that of the TCS. The effects of the number, thickness, and position of the leaf vein plates on the honeycomb structure were further explored. The greatest structural SEA effect of 1.28 J/g was observed when the number of leaf vein plates was four. The highest SEA of 1.36 J/g was achieved with a leaf vein plate thickness of 0.6 mm, representing a 7.3% improvement compared to that of the 0.2 mm thickness. These findings may provide valuable insights into the design of lightweight honeycomb sandwich structures with high specific energy absorption.

A honeycomb structure is a sandwich structure widely used in fuselage, among which the hexagonal honeycomb core is the most widely used. The energy absorption characteristics and impedance ability of the structure are the main reasons that directly affect the energy absorption characteristics of the honeycomb sandwich structure. Therefore, it is necessary to study the out-of-plane mechanical properties of the composite honeycomb sandwich structure. Based on the numerical simulation results, the energy absorption characteristics of several composite honeycomb sandwich structures are verified by drop hammer impact experiments. The research shows that the transient energy absorption characteristics of the composite honeycomb sandwich structure are mainly related to the cell size of the honeycomb structure. The smaller the size of the front cell, the stronger the overall impact resistance; the strength of the composite honeycomb sandwich structure exceeds that of 7075 aluminum alloy-NOMEX and carbon fiber-NOMEX honeycomb sandwich structures. In this paper, the energy absorption characteristics of composite honeycomb sandwich structures under different impact energy are compared and studied. The displacement, force and energy curves of energy absorption characteristics related to time variables are analyzed. The difference in protective performance between the composite honeycomb sandwich structure and existing airframe structure is compared and studied. The optimal structural design parameters of composite honeycomb sandwich under low-speed impact of drop hammer are obtained. The maximum energy absorption per unit volume of the designed honeycomb sandwich structure is 171.7% and 229.8% higher than that of the NOMEX-AL and NOMEX-C structures. The 6.4 mm and 3 mm cell sizes show good characteristics in high-speed buffering and crashworthiness. The composite honeycomb sandwich airframe structure can improve the anti-damage performance of the UAV airframe structure, ensure the same thickness and lightweight conditions as the existing honeycomb sandwich airframe structure, and improve the single-core bearing mode of the existing airframe structure.

This paper contains a comparison of the flexural strength results of two different samples. Both samples were made using additive manufacturing, from ABS (acrylonitrile butadiene styrene) material with the inclusion of an unknown filler designated as X. They also have in common that they are divided into two groups, the first group with a material infill of 100 %, and the second group with a material infill of 50 %. In order to determine that the material infill really affects the flexural strength results, the samples are differentiated by their shape. The first sample consists of tiles, while the second sample consists of pipes. The samples are printed vertically, which doesn't change the material's inherent mechanical qualities but does change the amount of infill and the strength of the bond between the layers. The difference between the values of the stress at failure of the material in the tile group is approximately 20 %, while in the tube group this difference is approximately 6 %. We can conclude that filling with the material in the range of 50 to 100 % during the production of pipes has an insignificant effect on bending strength, while this is not the case with plate samples. Based on this, there definitely is a significant influence of geometry when determining flexural strength. The idea for further research should be to measure the influence of samples treated with acetone on their flexural strength. [ABSTRACT FROM AUTHOR]

The drying process significantly influences the dispersion of metals, physical properties, and performance of monolithic catalysts. In this research, a cordierite-based monolithic catalyst with Co/γ-Al2O3 was prepared using the slurry and impregnation method. The impact of ambient humidity on metal dispersion, mass transfer performance, and catalytic performance was investigated. The findings revealed distinct crystallization-deliquescence curves in the saturated impregnated monolithic catalysts, with alternating crystallization and deliquescence phenomena occurring as the ambient humidity changed. When the coating adhesion was high, the simultaneous occurrence of internal crystallization and surface dissolution resulted in concentrated internal stress, which facilitated the micro-stripping of the coating, leading to the formation of a cobweb-like microstructure. This process affected the distribution of pore sizes and enhanced mass transfer performance. The Co-based catalysts prepared in this study demonstrated a high selectivity for C5+ products (73.93%) when employed in the Fischer-Tropsch synthesis reaction. This research offers an optimization strategy for catalyst preparation, aiming to develop monolithic catalysts with low melting points, high crystallinity, and supersaturated supported transition metals. [ABSTRACT FROM AUTHOR]

Highlights Advanced sandwich structures have emerged as new multifunctional structures with low density and good mechanical performance. Sandwich composites have high strength to weight and high stiffness to weight ratio. Good thermal and sound insulation can be provided using sandwich composite materials. Sandwich composites have high energy absorbing capacity. Multifunctional sandwich composites exhibit mechanical performance and other functional properties such as energy storage, electrical conductivity, etc. Further, the core can be used for routing wires, foam filling, fluid storage, embedding bars, etc. Thus, the multifunctionality can be introduced to the resuting composite materials. This article reviews current research on innovative sandwich structures with integrally woven corrugated core, honeycomb, foam, and 3D printed core architectures, emphasizing their multifunctionality. Aspects of sandwich structure with types of face and core structure design, material design, mechanical properties, and panel performance and damage, including multifunctional benefits, are reviewed. Examples of engineering and modern uses of sandwich structures are presented, covering hypersonic vehicles, civil and marine engineering, electronics, and biological fields. A list of areas for future study initiatives is also included. This review will serve as a baseline for future studies to do more research in the same direction. A detailed review of various types of core materials and sandwich structures is presented. Sandwich structures have high energy absorbing capacity. 3D woven sandwich structures, their manufacturing and failure mechanics is discussed. Modern applications of sandwich structures are detailed. [ABSTRACT FROM AUTHOR]

As an alternative to the conventional concave hexagonal honeycomb structure (CHHS), a negative Poisson's ratio honeycomb structure with power function curve (NHPC) was devised. The relationship between the power function exponent (PFE) and normalized power function coefficient (NPFC) of honeycomb structure and its equivalent Poisson's ratio (EPR) was explored to identify the range of variables required for the negative Poisson's ratio effect. To investigate the in-plane mechanical properties and energy absorption characteristics of NHPC, the deformation mode, dynamic response, and energy absorption characteristics under various impact velocities were studied by constructing an in-plane impact simulation model. The results showed that NHPC obviously exhibited a negative Poisson's ratio effect on medium and low impact velocities, and the deformation was primarily uniform. As the NPFC increased, the honeycomb structure was less prone to stress concentration, while the peak crushing force (PCF) and the specific energy absorption (SEA) declined and the plateau stress increased. A multi-objective optimization experiment was operated with low PCF and high SEA as the targets within the range of design variables in order to generate the optimal NHPC. According to the experimental findings, the improved NHPC showed a 25.48 % reduction in PCF and a 19.29 % increase in SEA. This paper provides theoretical recommendations for improving the energy absorption and structural optimization of the honeycomb structure. [ABSTRACT FROM AUTHOR]

Additive manufacturing of carbon-fiber-reinforced polymer (CFRP) has been widely used in many fields. However, issues such as inconsistent fiber orientation distribution and void formation during the layer stacking process have hindered the further optimization of the composite material's performance. This study aimed to address these challenges by conducting a comprehensive investigation into the influence of carbon fiber content and printing parameters on the micro-morphology, thermal properties, and mechanical properties of PA6-CF composites. Additionally, a heat treatment process was proposed to enhance the interlayer bonding and tensile properties of the printed composites in the printing direction. The experimental results demonstrate that the PA6-CF25 composite achieved the highest tensile strength of 163 MPa under optimal heat treatment conditions: 120 °C for 7.5 h. This corresponds to a significant tensile strength enhancement of 406% compared to the unreinforced composites, which represents the highest reported improvement in the current field of CFRP-fused deposition 3D printing. Additionally, we have innovatively developed a single-layer monofilament CF-OD model to quantitatively analyze the influence of fiber orientation distribution on the properties of the composite material. Under specific heat treatment conditions, the sample exhibits an average orientation angle μ of 0.43 and an orientation angle variance of 8.02. The peak frequency of fiber orientation closely aligns with 0°, which corresponds to the printing direction. Finally, the study explored the lightweight applications of the composite material, showcasing the impressive specific energy absorption (SEA) value of 17,800 J/kg when implementing 3D-printed PA6-CF composites as fillers in automobile crash boxes. [ABSTRACT FROM AUTHOR]

Honeycomb structures with zero Poisson's ratio show promising potential for application in variable-sweep wing aircraft. The shear properties of these honeycomb structures serve as a crucial indicator of their morphing capacity. This paper derives the linear and non-linear shear properties of a honeycomb structure with zero Poisson's ratio. A modified factor is introduced to establish a relationship between the linear and non-linear shear modulus of the honeycomb structure, simplifying the calculation method of the non-linear shear modulus. The validity of theoretical predictions is then confirmed using the finite element method Furthermore, the influences of the geometric parameters on the shear properties of the honeycomb structure with zero Poisson's ratio are investigated, highlighting the varying contributions of these cell geometric parameters to the shear properties. [ABSTRACT FROM AUTHOR]

Most natural materials have rotational and hierarchical properties, so they can show excellent mechanical properties such as shear resistance and impact resistance. In order to further improve the energy absorption characteristics of vibration absorbing structures, a new type of honeycomb structure with integral rotation and group rotation is designed and characterized. The effects of the geometrical parameters of rotation Angle on the impact deformation mode, stress response curve and energy absorption characteristics of the honeycomb structure are studied through numerical simulation and experimental design. The results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is the results show that the overall honeycomb performance of 15° is better than that of 0°, the specific energy absorption is increased by 6%, the bearing capacity is increased by 320 N, and the crushing force efficiency is increased by 2%. Compared with the whole cell and the group cell, the specific absorption energy increased by 35%, 73% and 71%. The results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the results of this paper provide a new insight into the impact performance of monolithic and grouped rotating honeycomb structures, which is helpful for the optimization of crashworthiness structural design. [ABSTRACT FROM AUTHOR]

Nonpneumatic tires (NPTs) have recently gained more attention due to their specific advantages like no run-flat, free of maintenance, and superior load-bearing capability. In the present investigation, finite element analysis of three novel Polyurethane uniform spoke structures such as rhombus (Uni 1), hexagon (Uni 2), auxetic (Uni 3), and three of their hybrids, i.e., rhombus-hexagon (Hyb 1), hexagon-auxetic (Hyb 2), and auxetic-rhombus (Hyb 3) are performed using Ansys static structural analysis with a variety of load from 1 to 4 kN. The maximum equivalent stress at 1 kN is 51 MPa, which decreased to 7, 10, 13, 8, and 19% for Hyb 2, Hyb 3, Uni 1, Uni 3, and Uni 2. An increase in maximum equivalent stress with an increase in load is observed for all the structures. A similar trend is seen for contact pressure as well. The results align with the analytical value of relative density. The pressure distribution results illustrate that the rhombus-hexagon hybrid structure is much more uniform than the other considered structure. Finally, factor of safety results of all the samples are obtained and noted to be lies in the safe range from 1 to 2.5; however, the highest is exhibited by the rhombus-hexagon hybrid structure for potential application as NPT spoke. [ABSTRACT FROM AUTHOR]

Satellites are used for navigation, communication, oceanography, astronomy, etc.. Satellites come in a diversity of sizes and forms. Depending on the satellite's mission, different subsystems are used. These subsystems are installed inside a housing to protect them from the space environment. This housing, which is also known as the satellite primary structure or mechanical structure, is made of durable materials that can endure severe conditions during launch and in the orbit. The optimisation of satellite mass is crucial right now since satellites are losing mass every day to reduce the cost of manufacturing and launching. This review first introduces an overview of the satellite classifications and subsystems. Then, the different types of mechanical load analysis the satellite subjects itself to are demonstrated. The advanced approaches for promoting the performance of the mechanical structures of satellites are explored, with a spotlight on the effect of the optimisation parameters of isogrid and honeycomb sandwich structures on the mechanical performance of the satellite primary structure. The assembly, integration and testing (AIT) of the small satellite are briefly presented. Finally, the important potential designs to improve the mechanical performance of the satellite primary structure and the challenges of further research are summarised. [ABSTRACT FROM AUTHOR]

The current study utilized a two-step laser power bed fusion (LPBF) method to create a heterostructured material (HSM) composed of STS316L and Inconel 718. STS316L enhances ductility, while Inconel 718 improves strength. We examined the tensile deformation behavior of HSMs and found that stress is mainly localized in the cell or grain boundary area. The volumetric ratio of Inconel 718 to STS316L in the HSM affects the tensile properties, although the structural design is crucial for improving tensile strength. Fractographic analysis revealed that fracture occurred and propagated at the STS316L and Inconel 718 interface, with evident unmelted powders due to insufficient energy density. Achieving an optimized process parameter is necessary to ensure a reliable chemical joining which increases the mechanical properties of HSM. [ABSTRACT FROM AUTHOR]

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ObjectivesThis papers aims to analyze the impact resistance of honeycomb structure with different Poisson's ratio. MethodsBased on the explicit dynamic finite element method, this paper analyzes the dynamic mechanical properties of honeycomb structures with different Poisson's ratios under in-plane impact load, and explores the influence laws of Poisson's ratios on their impact resistance. Three typical honeycomb structures with negative/zero/positive Poisson's ratios (reentrant hexagon, hexagon and semi-reentrant hexagon) are selected, their geometric parameters are changed to give them the same relative density and different Poisson's ratios (−2.76 – +3.63), and their dynamic mechanical properties under low/medium/high-speed dynamic displacement loads are analyzed. ResultsThe results show that the zero Poisson's ratio semi-reentrant honeycomb structure has the best structural stability without transverse deformation under compression deformation; without structural instability, the platform stress has little correlation with the Poisson's ratio; and the compact strain and total energy absorbtion increases with the absolute value of the Poisson's ratio. Negative Poisson's ratio honeycomb structures with large t/l and small θ are suitable for applications with high platform stress (strong deformation resistance), and negative Poisson's ratio honeycomb structures with small t/l and small θ are suitable for high total energy absorbtion applications, while zero Poisson's ratio semi-reentrant honeycomb structures are suitable for applications with high platform stress (strong deformation resistance). ConclusionsThis study can provide references for the type selection and geometric parameter design of side impact honeycomb structures.

This study presents a novel approach inspired by the hexagonal honeycomb structure found in nature, leveraging image processing algorithms to precisely define complex geometries in thermal systems. Hexagonal phase change material containers and thermally conductive fins were meticulously delineated, mirroring the intricate real-world designs of honeycombs. This innovative methodology not only streamlines setup processes but also enhances our understanding of melting dynamics within enclosures, highlighting the potential benefits of biomimetic design principles in engineering applications. Two distinct honeycomb structures were employed to investigate their impact on the melting process within cavities subject to heating from the left wall, with the remaining walls treated as adiabatic surfaces. The incorporation of a thermally conductive fin system within the enclosure significantly reduced the time required for a complete phase change, emphasizing the profound influence of fin systems on thermal design and performance. This enhancement in heat transfer dynamics makes fin systems advantageous for applications prioritizing precise temperature control and expedited phase change processes. Furthermore, the critical role of the fin system design was emphasized, influencing both the onset and location of the final point of melting. This underscores the importance of tailoring fin systems to specific applications to optimize their performance. Our study highlights the significant impact of the Rayleigh (Ra) number on the melting time in a cavity without fins, revealing a decrease from 6 to 0.4 as the Ra increased from 102 to 105; the introduction of a fin system uniformly reduced the melting time to Ste.Fo = 0.5, indicating fins’ universal effectiveness in optimizing thermal dynamics and expediting the melting process. Moreover, the cavity angle was found to significantly affect the fluid fraction diagram in unfanned cavities but had minimal impact when fins were present, highlighting the stabilizing role of fins in mitigating gravitational effects during melting processes. These insights expand our understanding of cavity geometry and fin interactions in heat transfer, offering potential for enhanced thermal system designs in various engineering applications. Decreasing thermal conductivity (λ) by increasing the fin thickness can halve the melting time, but the accompanying disadvantages include a heavier system and reduced energy storage due to less phase change material, necessitating a careful balance in decision-making.

In this paper, sorghum and reed, which possess light stem structures in nature, were selected as biomimetic prototypes. Based on their mechanical stability characteristics—the porous structure at the node feature and the porous feature in the outer skin— biomimetic optimization design, simulation, and experimental research on both the traditional hexagonal structure and a hexagonal honeycomb structure were carried out. According to the two types of straw microcell and chamber structure characteristics, as well as the cellular energy absorption structure for the bionic optimization design, 22 honeycomb structures in 6 categories were considered, including a corrugated cell wall bionic design, a modular cell design, a reinforcement plate structure, and a self-similar structure, as well as a porous cell wall structure and gradient structures of variable wall thickness. Among them, HTPC-3 (a combined honeycomb structure), HSHT (a self-similar honeycomb structure), and HBCT-257 (a radial gradient variable wall thickness honeycomb structure) had the best performance: their energy absorption was 41.06%, 17.84%, and 83.59% higher than that of HHT (the traditional hexagonal honeycomb decoupling unit), respectively. Compared with HHT (a traditional hexagon honeycomb decoupling unit), the specific energy absorption was increased by 39.98%, 17.24%, and 26.61%, respectively. Verification test analysis revealed that the combined honeycomb structure performed the best and that its specific energy absorption was 22.82% higher than that of the traditional hexagonal structure.

In this research work, laser powder bed fusion (LPBF) based stainless steel 316L (SS316L) was fabricated and its corrosion behaviour was analysed for the oil-gas piping application. The Field Emission Scanning Electron Microscopy (FESEM) analysis of the LPBF SS316L specimen revealed the presence of 1–2 μ m size honeycomb structure and 2–10 μ m size tabular structures. Nano-size particles in the range of 100 nm–500 nm were formed between the two tabular cells as well as their boundary regions in the LPBF SS316L specimen. The energy-dispersive X-ray spectroscopy (EDS) analysis of the nanoparticle confirmed the presence of Si with a percentage of 1.4% along with 15.9% of Cr and 1.6% of Mo that have the characteristic of dispersion strengthening of the LPBF SS316L specimen. In addition, the δ-ferrite phase was observed in tabular structure boundaries and intercellular regions of solute in the LPBF SS316L specimen. Moreover, among the three crystallographic orientations {001}{101}and {111}, no domination behaviour was observed from the Electron Backscatter Diffraction (EBSD) study. The Transmission Electron Microscopy (TEM) analysis confirmed the presence of nano twin structures that had a span of several nm on the FCC austenite unit cell. These twins came under the {111} category twining that often occurred in FCC metals. A potentiodynamic polarization test was conducted on the LPBF SS316L specimen at five different time periods (i.e., 0, 7, 15, 34 and 56 h) and it was assessed that the 0 and 15 h immersion specimens exhibited superior corrosion resistance compared with other LPBF SS316L specimens. The Nyquist plot revealed that the 0 and 15 h immersion specimens offered the highest resistance value of 1846.1Ω and 1720.3 Ω, respectively against corrosion. The Bode plots of the LPBF SS316L specimen followed a similar trend as the Nyquist plots. [ABSTRACT FROM AUTHOR]

Asymmetry, such as non-centrosymmetry in the crystal or chiral structure and local symmetry breaking, plays an important role in the discovery of new phenomena. The honeycomb structure is an example of an asymmetric structure. Ce 2 Pt 6 Al 15 is a candidate for a frustrated system with honeycomb Ce-layers, which have been reported to show near the quantum critical point. However, the ground state of Ce 2 Pt 6 Al 15 depends on the sample, and analysis of the crystal structure is difficult due to the presence of stacking disorder. We synthesized polycrystalline Ce 2 Pt 6 Al 15 using arc melting method (AM-Ce 2 Pt 6 Al 15 ) and single-crystalline Ce 2 Pt 6 Al 15 using flux method (F-Ce 2 Pt 6 Al 15 ). The prepared samples were characterized by electron probe micro-analysis (EPMA), single and powder X-ray diffraction methods, measured magnetic properties and X-ray absorption spectroscopy (XAS). The composition ratio of AM-Ce 2 Pt 6 Al 15 was stoichiometric, although it contained a small amount (i.e., a few percent) of the impurity Ce 2 Pt 9 Al 16 . Meanwhile, the composition ratio of F-Ce 2 Pt 6 Al 15 deviated from stoichiometry. The X-ray absorption fine structure (XAFS) spectrum of AM-Ce 2 Pt 6 Al 15 at the Ce L 3 -edge was similar to that of CeF 3 , which possesses the Ce 3 + configuration, indicating that the valence of Ce in Ce 2 Pt 6 Al 15 is trivalent; this result is consistent with that for the magnetic susceptibility. To determine the precise structure, we analyzed the extended X-ray absorption fine structure (EXAFS) spectra of Ce L 3 - and Pt L 3 -edges for Ce 2 Pt 6 Al 15 , and found that the EXAFS spectra of Ce 2 Pt 6 Al 15 can be explained not as a hexagonal Sc 0.6 Fe 2 Si 4.9 -type structure but, instead, as an orthorhombic structure with honeycomb structure. [ABSTRACT FROM AUTHOR]

Structural bioinspiration in modern material science and biomimetics represents an actual trend that was originally based on the bioarchitectural diversity of invertebrate skeletons, specifically, honeycomb constructs of natural origin, which have been in humanities focus since ancient times. We conducted a study on the principles of bioarchitecture regarding the unique biosilica-based honeycomb-like skeleton of the deep-sea glass sponge Aphrocallistes beatrix. Experimental data show, with compelling evidence, the location of actin filaments within honeycomb-formed hierarchical siliceous walls. Principles of the unique hierarchical organization of such formations are discussed. Inspired by poriferan honeycomb biosilica, we designed diverse models, including 3D printing, using PLA-, resin-, and synthetic-glass-prepared corresponding microtomography-based 3D reconstruction. [ABSTRACT FROM AUTHOR]

A negative Poisson's ratio honeycomb material has the characteristics of anti-conventional deformation behavior and high impact resistance, which is a new lightweight microstructure material with broad application prospects. However, most of the current research is still at the microscopic level and two-dimensional level, and little research has been carried out for three-dimensional structures. Compared with the two-dimensional level, three-dimensional negative Poisson's ratio structural mechanics metamaterials have the advantages of a lighter mass, higher material utilization, and more stable mechanical properties, and they have great potential for development in the fields of aerospace, the defense industry, and vehicles and ships. This paper presents a novel 3D star-shaped negative Poisson's ratio cell and composite structure, inspired by the octagon-shaped 2D negative Poisson's ratio cell. The article carried out a model experimental study with the help of 3D printing technology and compared it with the numerical simulation results. The effects of structural form and material properties on the mechanical characteristics of 3D star-shaped negative Poisson's ratio composite structures were investigated through a parametric analysis system. The results show that the error of the equivalent elastic modulus and the equivalent Poisson's ratio of the 3D negative Poisson's ratio cell and the composite structure is within 5%. The authors found that the size of the cell structure is the main factor affecting the equivalent Poisson's ratio and the equivalent elastic modulus of the star-shaped 3D negative Poisson's ratio composite structure. Furthermore, among the eight real materials tested, rubber exhibited the best negative Poisson's ratio effect, while the copper alloy showed the best effect among the metal materials, with a Poisson's ratio between −0.058 to −0.050. [ABSTRACT FROM AUTHOR]

In this paper, a honeycomb membrane-type acoustic metamaterial made of a honeycomb structure with embedded membrane layers is investigated using the finite element method. This lightweight material presents excellent transmission loss (TL) at low frequency. Honeycomb structures with two and three embedded membrane layers are analyzed numerically and the effects of the number of membrane layers and of the thickness of the air gap between membranes are illustrated. Also, the influences of the membrane material properties and thickness on the TL and displacement magnitude and mode shape at different frequencies are presented. It is shown that the TL increases over a large frequency band when the honeycomb cell size decreases while the displacement magnitude of the membrane is reduced and the mode shape is affected. It is observed that the TL presents multiple resonant peaks as the thickness of the membranes is reduced. An improvement of the TL is observed around the anti-resonant frequencies by increasing the damping loss factor of the membrane, which causes a reduction of the resonant displacement magnitude and TL peaks amplitude. The investigated metamaterial can be useful in many noise control engineering applications. [ABSTRACT FROM AUTHOR]