Search

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

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

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

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

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

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

In the developmental phase of passenger automobile hoods, it is crucial to take dent resistance and pedestrian head protection performances into account. And maintaining a performance balance between the two aspects has proven challenging. With few studies on how to effectively maintain the balance, in this paper, a certain passenger car hood was used as a basic model to investigate structural improvement directions that benefit both performances, by modifying several key variables of the honeycomb shaped inner panel one at a time and then outputting results of hood dent resistance and headform impact through Abaqus and LS-DYNA, respectively. The results indicated that raising the honeycomb inner panel structure at positions with poor stiffness contributes to improvements in dent resistance and pedestrian head protection performance, reflecting in a maximum stiffness increase of 50% and a reduction of 2.98% in the average value of HIC15 change rate. And other alternative improvement options, as well as their effects on dent resistance and pedestrian head protection performance, were provided, providing insights for optimizing the structure of vehicle hood inner panels. [ABSTRACT FROM AUTHOR]

Aperiodic crystals constitute a class of materials that includes incommensurate (IC) modulated structures and quasicrystals (QCs). Although these two categories share a common foundation in the concept of superspace, the relationship between them has remained enigmatic and largely unexplored. Here, we show "any metallic-mean" QCs, surpassing the confines of Penrose-like structures, and explore their connection with IC modulated structures. In contrast to periodic approximants of QCs, our work introduces the pivotal role of "aperiodic approximants", articulated through a series of k-th metallic-mean tilings serving as aperiodic approximants for the honeycomb crystal, while simultaneously redefining this tiling as a metallic-mean IC modulated structure, highlighting the intricate interplay between these crystallographic phenomena. We extend our findings to real-world applications, discovering these tiles in a terpolymer/homopolymer blend and applying our QC theory to a colloidal simulation displaying planar IC structures. In these structures, domain walls are viewed as essential components of a quasicrystal, introducing additional dimensions in superspace. Our research provides a fresh perspective on the intricate world of aperiodic crystals, shedding light on their broader implications for domain wall structures across various fields. Aperiodic crystals, including modulated structures and quasicrystals, are fascinating, but their relationship to each other is enigmatic. Here, the authors reveal the pivotal role of aperiodic approximants that unify those crystals under the concept of superspace. [ABSTRACT FROM AUTHOR]

In this paper, a new type of auxetic honeycomb is designed, which introduces arc walls into the concave hexagonal honeycomb cells and has higher specific energy absorption. The deformation modes and energy absorption of the designed honeycomb are analyzed by using three methods including finite element, compression experiment and machine learning methods. A fully connected two-hidden layer backpropagation deep neural network (BP-DNN) is developed to predict the energy absorptions of the honeycomb with different geometric parameters. It is found that the error of the validation set is low, and the average correlation coefficient of the validation set is 99.2%, which indicates that the neural network can obtain good predictions. The sensitivity analysis of the input parameters shows that the thickness t has the highest sensitivity, and the ratio of the length of the straight wall to the height has the lowest sensitivity to the energy. In addition, the neural network developed can also predict the mechanical properties of the honeycombs outside the parameter range of the training set and the results are consistent with that of the sensitivity analysis. The DNN provides a fast and accurate method for the energy absorption of honeycombs, which is expected to speed up the optimization and design process of honeycomb structures. [ABSTRACT FROM AUTHOR]

Highlights: MIL-88C (Fe) with varying aspect ratios as a precursor was synthesized by regulating oil bath conditions, followed by one-step thermal decomposition to obtain carbon-coated iron-based composites. High-efficiency microwave absorption properties were achieved with RLmin value of -67.4 dB (2.13 mm) and wide effective absorption bandwidth (EAB) of 5.52 GHz (1.90 mm) under the low filler loading. A symmetric gradient honeycomb structure was constructed utilizing the high-frequency structure simulator, achieving an EAB of 14.6 GHz and a RLmin of -59.0 dB. The impedance matching of absorbers is a vital factor affecting their microwave absorption (MA) properties. In this work, we controllably synthesized Material of Institute Lavoisier 88C (MIL-88C) with varying aspect ratios (AR) as a precursor by regulating oil bath conditions, followed by one-step thermal decomposition to obtain carbon-coated iron-based composites. Modifying the precursor MIL-88C (Fe) preparation conditions, such as the molar ratio between metal ions and organic ligands (M/O), oil bath temperature, and oil bath time, influenced the phases, graphitization degree, and AR of the derivatives, enabling low filler loading, achieving well-matched impedance, and ensuring outstanding MA properties. The MOF-derivatives 2 (MD2)/polyvinylidene Difluoride (PVDF), MD3/PVDF, and MD4/PVDF absorbers all exhibited excellent MA properties with optimal filler loadings below 20 wt% and as low as 5 wt%. The MD2/PVDF (5 wt%) achieved a maximum effective absorption bandwidth (EAB) of 5.52 GHz (1.90 mm). The MD3/PVDF (10 wt%) possessed a minimum reflection loss (RLmin) value of − 67.4 at 12.56 GHz (2.13 mm). A symmetric gradient honeycomb structure (SGHS) was constructed utilizing the high-frequency structure simulator (HFSS) to further extend the EAB, achieving an EAB of 14.6 GHz and a RLmin of − 59.0 dB. This research offers a viable inspiration to creating structures or materials with high-efficiency MA properties. [ABSTRACT FROM AUTHOR]

This report highlights a novel approach in utilizing the natural properties of a mechanically strong and graphene-like bond structure membrane present inside the casing of the pea pod, a byproduct of the pea processing industry to create flexible gas sensors through the polymerization of polyaniline (PANI). Pea membranes exhibit a distinctive 2-D honeycomb bond structure (like graphene) which serves as a template for polymerization of PANI creating composite flexible conducting membranes suitable for electronic applications. The effect of various parameters such as polymerization time, pH and different initiators were optimized to obtain polymer layer with ~ 5 µm thickness for the best performance of the composite material. The synthesized polymerized pea membrane was found to act as room temperature chemo-resistive ethanol gas sensor with appreciable sensor responses in the range ~ 2.42 and rise time of 20 s and a fall time of 25 s. For applications where rapid detection is crucial (e.g., real-time breath alcohol checkers), the current composite's fast response time is a significant advantage. This natural template structure gives a fast response time and reproducible results and could be explored for multiple industries opening avenues for further innovation. [ABSTRACT FROM AUTHOR]

Very recently, the two-dimensional (2D) structure of poly-benzimidazobenzophenanthroline (C5N) has been effectively synthesized [Javeed Mahmood et al., Adv. Mater. 2021, 33, 2,004,707]. Inspired by interesting experimental findings on 2D layered C5N structures, we employ DFT study to examine the electronic, structural, and optical features of C5N in bulk, bilayer, and monolayer honeycomb crystal configurations. The obtained results demonstrate that all configurations of the C5N structures have a strong bond network with cohesive energies comparable to graphene. In the ground state, the C5N bulk, bilayer and monolayer honeycomb crystal structures are a semiconductor. It is found that the bandgap of the C5N structures slightly increases with the decrease in the number of layers. The optical properties indicate the bulk structure possesses a greater capacity to absorb a broad range of visible light compared to the monolayer and bilayer. [ABSTRACT FROM AUTHOR]

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

The specific surface area of attapulgite was significantly enhanced (from 128 to 212 m2/g) by its purification with sodium hexametaphosphate and nitric acid. Subsequently, an acid modification method was employed to prepare a coated attapulgite cordierite honeycomb with a specific surface area approximately 39 times larger than that of the bare cordierite honeycomb. SEM images showed that the surface of the cordierite was rough and uneven, with the attapulgite filling the large pores on its surface, forming a "nail-like" interaction between the coating and the carrier. After loading the catalyst, no significant mass loss was observed after 1 h of ultrasonic testing, indicating good adhesion stability of the coating. Furthermore, under test conditions of GHSV (Gas Hourly Space Velocity) = 10 000 h–1 and a toluene concentration of 1500 ppm, the prepared integrated catalyst exhibited excellent activity for the catalytic oxidation of toluene, with T50 and T90 values of 261 and 290°C, respectively, suggesting broad application prospects. [ABSTRACT FROM AUTHOR]

This paper presents the leakage characteristics of stepped labyrinth seals, considering the impact of rotation in the circumferential direction. Two types of casing, honeycomb and solid lands, were applied to the labyrinth seal, and a numerical study was performed with a wide operating range of the rotational speed, pressure ratio and clearance. The effect of the rotational speed on the sealing performance was analyzed for each clearance size through a parametric study. Regardless of the casing type, the flow function decreased as the rotational speed increased, and the smaller the clearance was, the more the leakage performance was affected by the rotation effect. In particular, it was confirmed that the honeycomb seal had a stronger tendency to decrease the flow function due to the rotation than the solid seal. The honeycomb seal allowed a larger leakage flow in comparison to the solid seal, and the rotational speed played an important role when the clearance was small or moderate. However, when the clearance became large, the leakage flow of the two seal types became almost the same, and the rotational effect became marginal. [ABSTRACT FROM AUTHOR]

The structure and microhardness of a multilayer surfaced on an R2M9 high-speed steel in a nitrogen atmosphere and subjected to high tempering and electron-beam treatment are studied. The surfaced layer structure consists of a tempered martensite, with the carbides and carbonitrides located along the grain boundaries. It is shown that high tempering increases the steel microhardness and gives rise to a transformation of the retained austenite into martensite. An electron-beam treatment forms a honeycomb structure in the surface layer, which provides a factor of 1.1–1.6 increase in the surface layer microhardness over the initial state and that after tempering. [ABSTRACT FROM AUTHOR]

Aluminum honeycomb sandwich structure with panels made of carbon fiber reinforced polymer (CFRP) are widely used in aerospace and other fields. Simulation of the eddy current (EC) testing of the sandwich structure using the finite element (FE) method is challenging as the traditional FE method has difficulties in mesh division and the solution of the algebraic equations. This paper proposes to use the domain decomposition FE method to solve such problems. The top CFRP panel, the aluminum honeycomb core, and the bottom CFRP panel of the sandwich structure and the ferrite core of the coil are placed in different subdomains and the subdomains are meshed independently. This method simplifies the mesh generation and does not require regenerating the meshes when simulating the scanning testing with the ferrite-core coil. In this way, the efficiency of simulation is greatly improved. The EC distributions in the sandwich structure are computed and the influence of defect on EC distribution is analyzed. The C scans of the sandwich structures are simulated. The images of the EC responses to the defects, such as wall fracture, node disconnection, and core wrinkle, are obtained. The simulation results are validated by experiments. [ABSTRACT FROM AUTHOR]

The free vibration analysis of a rotating sandwich conical shell with a reentrant auxetic honeycomb core and homogenous isotropic face layers reinforced with a ring support is studied. The shell is modeled utilizing the first-order shear deformation theory (FSDT) incorporating the relative, centripetal, and Coriolis accelerations alongside the initial hoop tension created by the rotation. The governing equations, compatibility conditions, and boundary conditions are attained using Hamilton's principle. Utilizing trigonometric functions, an analytical solution is derived in the circumferential direction, and a numerical one is presented in the meridional direction via the differential quadrature method (DQM). The effects of various factors on the critical rotational speeds and forward and backward frequencies of the shell are studied. The present work is the first theoretical work regarding the dynamic analysis of a rotating sandwich conical shell with an auxetic honeycomb core strengthened with a ring support. [ABSTRACT FROM AUTHOR]

Auxetic honeycomb sandwich structures (AHS) composed of a single material generally exhibit comparatively lower energy absorption (EA) and platform stress, as compared to traditional non-auxetic sandwich structures (TNS). To address this limitation, the present study examines the use of aluminum foam (AF) as a filling material in the re-entrant honeycomb sandwich structure (RS). Filling the AHS with AF greatly enhances both the EA and platform stress in comparison to filling the TNS with AF, while the auxetic composite honeycomb sandwich structure effectively addresses interface delamination observed in traditional non-auxetic composite sandwich structures. Subsequently, the positive–negative Poisson's ratio coupling designs are proposed to strengthen the mechanical features of a single honeycomb sandwich structure. The analysis results show that the coupling structure optimizes the mechanical properties by leveraging the high bearing capacity of the hexagonal honeycomb and the great interaction between the re-entrant honeycomb and the filling material. In contrast with traditional non-auxetic sandwich structures, the proposed auxetic composite honeycomb sandwich structures demonstrate superior EA and platform stress performance, suggesting their immense potential for utilization in protective engineering. [ABSTRACT FROM AUTHOR]

We use elastic and inelastic neutron scattering (INS) to study the antiferromagnetic (AF) phase transitions and spin excitations in the two-dimensional (2D) zig-zag antiferromagnet FePSe3. By determining the magnetic order parameter across the AF phase transition, we conclude that the AF phase transition in FePSe3 is first-order in nature. In addition, our INS measurements reveal that the spin waves in the AF ordered state have a large easy-axis magnetic anisotropy gap, consistent with an Ising Hamiltonian, and possible biquadratic magnetic exchange interactions. On warming across TN, we find that dispersive spin excitations associated with three-fold rotational symmetric AF fluctuations change into FM spin fluctuations above TN. These results suggest that the first-order AF phase transition in FePSe3 may arise from the competition between C3 symmetric AF and C1 symmetric FM spin fluctuations around TN, in place of a conventional second-order AF phase transition. [ABSTRACT FROM AUTHOR]

Based on the proposed multi-arc curved edge concave adjustable Poisson's ratio cell, five kinds of sandwich panels with negative Poisson's ratio (NPR) were constructed by changing the in-plane thickness of cells: homogeneous, positive gradient, negative gradient, symmetrical positive gradient, and symmetrical negative gradient. The failure mechanical properties of the sandwich panels under the action of local impact were numerically studied. The influences of impact speed and gradient arrangement modes on the failure mode of the sandwich panels, the punch contact force (PCF) and the energy absorption effect (EAE) were investigated. It is found that the failure behavior of sandwich panels is different under different impact speeds. At the same impact speed, the thickness distribution pattern of the sandwich panel core layer will significantly affect the shock resistance of the panel. The study shows that the EAE of sandwich panels can be effectively enhanced by introducing gradient design method, and the sandwich panels with negative gradient arrangement show the best energy absorption effect. [ABSTRACT FROM AUTHOR]

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

The bandgap properties of elastic metamaterials can be efficiently utilized to tailor the propagation characteristics of elastic and acoustic waves, which have promising applications in noise and vibration reduction and isolation. In this paper, an elastic metamaterial with a multilayered honeycomb structure (EMHS) is proposed to enlarge the bandgaps in the low-frequency range and its bandgap properties are analyzed. To meet the requirement of the lightweight design, an optimization model for maximizing the total relative bandgap width with a mass constraint is established. A novel optimization approach combining the Kriging surrogate model with the genetic algorithm (GA) is proposed to reduce the huge computational cost of the corresponding optimization problem. In the Kriging-GA approach, a high-precision Kriging-based surrogate model with addition of supplementary points is constructed to predict the bandgap objective function value, and the GA is employed to search for the optimal parameters. The performance of the proposed Kriging-GA approach is investigated by numerical examples, and the results are compared with those obtained by the commonly used FEM-GA method. The results show that the proposed Kriging-GA approach is highly efficient for the design optimization of the EMHS and can remarkably reduce the computational cost of the considered optimization problem, which has promising prospects in a wide range of engineering applications. [ABSTRACT FROM AUTHOR]

This study explores the design and performance of axisymmetric hexachiral honeycombs, utilizing the hexachiral honeycomb framework and axisymmetric design method. Four axisymmetric hexachiral honeycombs with distinct arrangements were developed: left–right symmetry hexachiral honeycomb (LSHH), up–down symmetry hexachiral honeycomb (USHH), central symmetry hexachiral honeycomb (CSHH), and subunits symmetry hexachiral honeycomb (SSHH). The deformation patterns and compression behaviors of these honeycombs were comprehensively examined through experimental and numerical simulations, and comparisons were made with a non-symmetric hexachiral honeycomb (NHH). The results indicate that symmetrically designed honeycombs exhibit a larger mean plateau stress than the asymmetrically designed the NHH during low-velocity impacts. The study further discusses deformation patterns, specific energy absorption, and the negative Poisson's ratio effect across the five honeycombs under different parameters. Notably, symmetrically designed honeycombs demonstrate superior specific energy absorption, and the negative Poisson's ratio effect becomes evident at an impact velocity of 10 m/s. However, the advantages of axisymmetric honeycombs diminish at higher impact velocities of 50 m/s and 100 m/s. The Poisson's ratio effects of symmetric honeycombs weaken with an increase in the circular ligament r of the honeycomb. Additionally, the study identifies that platform stress and SEA increase for honeycombs with horizontal cell numbers greater than 6. [ABSTRACT FROM AUTHOR]

Composites of honeycomb-structured high-chromium cast iron matrix reinforced with zirconia-toughened alumina particles (ZTAP) were successfully fabricated by a non-pressure infiltration casting process. Different preform hole patterns were designed in this study, following the principle of keeping the same area of the honeycomb holes with the same outline size. The hardness and modulus continuously increased from the high-chromium cast iron matrix through the interfacial layer to the ZTA ceramic particle. The residual thermal stress in the samples with the circle hole pattern was the lowest at 389.7 ± 20.2 MPa. The wearing volume loss of the composites with the regular hexagon pattern was minimal after four periods. [ABSTRACT FROM AUTHOR]

The primary reason for the decrease in power output from the PV array is partial shading. During partial shading conditions (PSCs) PV modules experience a mismatch in current and voltage generated. Also, the power voltage (P–V) characteristics of the PV array possess multiple peaks under PSCs. To mitigate the effects caused by PSCs, the configuration of the PV array is the finest solution. This paper proposes a novel Reduced Cross Tied (RCT) configuration to enhance maximum power output from a symmetrical PV array under PSCs. The RCT configuration has fewer cross-ties compared to the TCT configuration and is applicable to a square array of any size. The proposed RCT configuration along with conventional configurations such as Total Cross Tied (TCT), Series–Parallel, Bridge-Link, and Honey-Comb are validated in simulation and hardware for 7 × 7 and 8 × 8 symmetrical PV arrays under Short and Narrow (SN), Short and Wide (SW), Long and Narrow (LN) and Long and Wide (LW) shading patterns. A comparative analysis is done between the proposed configuration and conventional configurations in terms of mismatch loss (ML), fill factor, efficiency (η ), Wiring Loss, and Global Maximum PowerPoint (GMPP). The proposed RCT configuration is able to achieve GMPP equal to the TCT configuration under the LN shading pattern and on par with the TCT configuration under SN, SW, and LW shading patterns. RCT-configured PV array possesses a minimum reduction of 25% in wiring loss for any array size. RCT configuration applies to a square array of any size.The results replicate the efficacy of the proposed RCT configuration compared to existing configurations. [ABSTRACT FROM AUTHOR]

In this study, the pore structure of carboxymethyl chitosan aerogel (CCSA) was modulated by adjusting the concentration of carboxymethyl chitosan (CCS) in combination with targeted freezing. The hierarchically porous structures were obtained by the freeze-drying process. The results show that the CCSAs prepared by directional freezing have excellent broadband acoustic absorption properties, and also expand the scope of application of CCSAs in practical applications due to the excellent thermal and mechanical properties of the prepared CCSAs. Since the CCSAs prepared by directional freezing still has excellent antimicrobial properties, it also provides a new strategy for aerogels with acoustic properties to be used in medical industry applications. [ABSTRACT FROM AUTHOR]

A method for measuring the resistive characteristics of channels in the blanks of microchannel plates was developed. Two probes were used for measurements, which minimized leakage currents through adjacent channels. The resistive properties of single channels of the microchannel insert in the reduced blank of MCP 18-10 were studied. It was established that the resistance of the channels depends on their position in the microchannel honeycomb. It was shown that the channels located in close proximity to the monolithic frame have less resistance compared to those located in the middle of a multicore glass honeycomb. [ABSTRACT FROM AUTHOR]

A potential solution to environmental problems associated to the use of fossil fuels and the exploitation of natural resources for energy production is the development of renewable energies with greater capacity, adaptability and integration, as well as their use for the improvement of this systems. Researchers turned their attention to biological and natural processes such as honeycombs at a structural level to increase the mechanical properties of various technologies. This investigation shows the results of the thermal analysis of a novel solar collector designed based on a Honey-Comb conjecture studied under different connections. Several structures were proposed considering a serial and parallel connections. Each one was designed and simulated in SolidWorks® software Flow Simulation. The study considers different boundary conditions as mass flow and solar radiation on the surface of the collectors. In the analysis, the maximum temperature was achieved at the highest solar radiation of 1050 W / m 2 and the lowest flow mass of 0.052 kg/s. On the other hand, the peak performance of the heat thermal parameter in the whole study was achieved at solar radiation of 1050 W / m 2 and the maximum mass flow of 0.17 kg/s. A honey-comb structure conformed by three collectors (AC1) shows an increase of around 187%, against a single collector (A0), comparing the other structures two collectors in series (AS1) and two collectors in parallel (AP1) connections the total increase in the useful heat obtained with AC1 was 52% and 49% respectively. [ABSTRACT FROM AUTHOR]

Bamboo is an environmentally friendly building structural material. This work investigated the cavity structural characteristics and physical and mechanical properties of honeycomb sandwiches and natural bamboo in the longitudinal direction. The effective elastic parameters of periodically arranged hexagonal bamboo honeycomb cells under in-plane and out-of-plane loads were modeled using analytical and numerical approaches. Then, the effective elastic parameter model of bamboo honeycomb cells was validated by experiments and finite element analysis. The average errors between the calculated and experimental equivalent modulus of elasticity, Poisson's ratio, and shear modulus in the three principal axis directions were 7.43, 4.37, and 8.68%, respectively. The average relativities between the model values of the elastic parameters of the bamboo honeycomb cell and the simulation results in the three directions were 5.46, 5.40, and 6.12%, respectively. The experimental and finite element analysis showed that the constructed effective elastic parameter model of the bamboo honeycomb cell better reflected the state of the bamboo core when subjected to force. This study provides insights for further research on the mechanical properties of bamboo materials and their application in bamboo-based lightweight and high-strength sandwich structures. [ABSTRACT FROM AUTHOR]

The dredging sand taken from riverbeds mixing cement can be a potential solution to construct earth levees against annual floods in the Southern Vietnam. The strength, permeability, and microstructure of the dredging sand sample mixed with the OPC cement (soilcrete) at various cement contents of 200, 250, 300, 350, and 400 kg/m3, respectively, were investigated. The soilcrete strength was tested following the ASTM D2166 standard. The soilcrete hydraulic conductivity was determined using the flexible wall permeameter applying the falling head method according to the ASTM D5084 standard. XRD and SEM–EDS examinations were carried out to observe soilcrete microstructure change. The results indicate that the strength and the permeability of the soilcrete specimens were significantly improved with increasing in curing time and cement contents. The soilcrete strength reached 6.13 MPa at a cement content of 400 kg/m3 at 28 days. The soilcrete hydraulic conductivity varied from 8.07 × 10−8 to 2.3 × 10−11 m/s at the cement contents of 200 to 400 kg/m3. The soilcrere microstructure was denser to compare with the untreated sand. The products of CSH, ettringite, and portlandite were detected in the soilcrete specimens by the XRD and SEM–EDS analysis. These products developed with curing time and cement contents. The cementitious products filled voids and arranged as the frame and honeycomb structure which contribute to increase in strength and decrease in permeability in the soilcrete specimens. [ABSTRACT FROM AUTHOR]

Highlights: Aligned graphene building blocks take full advantages of the outstanding properties of graphene. Comprehensive review of recent advancements in the utilization of highly aligned graphene aerogels for multifunctional applications. By systematically summarizing the controlled assembly, aligned structural attributes, quantitative characterization methods, anisotropic properties, and multifunctional applications of graphene aerogels, this review enhances understanding of the material's potential for diverse applications, offering tailored properties and novel functionalities. Stemming from the unique in-plane honeycomb lattice structure and the sp2 hybridized carbon atoms bonded by exceptionally strong carbon–carbon bonds, graphene exhibits remarkable anisotropic electrical, mechanical, and thermal properties. To maximize the utilization of graphene's in-plane properties, pre-constructed and aligned structures, such as oriented aerogels, films, and fibers, have been designed. The unique combination of aligned structure, high surface area, excellent electrical conductivity, mechanical stability, thermal conductivity, and porous nature of highly aligned graphene aerogels allows for tailored and enhanced performance in specific directions, enabling advancements in diverse fields. This review provides a comprehensive overview of recent advances in highly aligned graphene aerogels and their composites. It highlights the fabrication methods of aligned graphene aerogels and the optimization of alignment which can be estimated both qualitatively and quantitatively. The oriented scaffolds endow graphene aerogels and their composites with anisotropic properties, showing enhanced electrical, mechanical, and thermal properties along the alignment at the sacrifice of the perpendicular direction. This review showcases remarkable properties and applications of aligned graphene aerogels and their composites, such as their suitability for electronics, environmental applications, thermal management, and energy storage. Challenges and potential opportunities are proposed to offer new insights into prospects of this material. [ABSTRACT FROM AUTHOR]

By performing isothermal–isochoric Monte Carlo simulations with depletion force, the author investigated the dependence of the epitxial layer structure on the differences in the particle size between the substrate in colloidal heteroepitaxy. By changing the size of epitaxial particles and performing simulations comprehensively, various structures including the structures observed in a experiment, such as a honeycomb, one created by hexagonal heptamers, and one consisting of both pentagonal tiles and triangular tiles, were created. When the ratio of particle sizes between the epitxial layer and substrate takes a specific value, two types of hexagonal structures were created. One is the hexagonal layer parallel to the substrate layer and the other layer is rotated by 60 ∘ from the substrate layer. The former structure was created over a wide range of particle-size ratios, whereas the latter structure was created when the particle-size ratio was only around the specific ratio, and it seemed a metastable structure. [ABSTRACT FROM AUTHOR]

Due to its advantages in terms of enhancing the performance of structures in the desired applications, the bio-inspired design approach has recently attracted the interest of researchers in a number of engineering disciplines. A hybrid bio-inspired design is suggested for the sandwich structures to absorb the energy of the blast loads in the current study. The sandwich structure's core, which often has a regular grid pattern resembling a honeycomb structure, is crucial to how well the panel absorbs energy. In order to achieve the best results, we first chose the structure of the core grid by taking into account potential 2D grids (polygons and multi-pointed stars) through Genetic Algorithm optimization. Next, we combined a bio-inspired bi-tubular thin-walled structure with the core grid to take advantage of its high energy absorption capacity. Finally, the performance of the suggested design is compared with four frequently implemented ones. The results show that the hybrid design has better energy absorption characteristics compared with the bionic and conventional designs presented in the literature. [ABSTRACT FROM AUTHOR]

The influence of platinum additives on the properties of rhodium catalysts in the processes of steam reforming and autothermal reforming of diesel fuel was investigated. It was found that Rh/CZF was more active compared to the bimetallic sample Rh–Pt/CZF: the degree of fuel conversion in its presence was higher, and the concentration of reaction by-products was lower. The proposed two-zone Pt/CZF + Rh/CZF structured honeycomb catalyst demonstrated stable performance and high activity in the autothermal reforming of commercial diesel fuel. However, the presence of platinum in the frontal zone of the catalyst reduced its resistance to coking compared to the rhodium-containing sample. The results obtained are of practical significance in the development of efficient systems for the conversion of heavy hydrocarbons into synthesis gas. [ABSTRACT FROM AUTHOR]

For the support structure of wind tunnel tests, a honeycomb sandwich structure is used to embed the wind tunnel tail brace to form a honeycole test process. Using Rayleigh beam theory and equivalent method, the lateral bending dynamic model of the support rod is solved and the natural frequency expression of the lateral bending vibration of the support rod is obtained. Taking the static strength of the support rod as the optimization design objective, the honeycomb sandwich structure was quantitatively described and the optimal design scheme was obtained through orthogonal experiments. The simulation and calculation results of the proposed support and hollow support are verified and compared with each other. The error between the first three natural frequencies of the honeycomb sandwich support given in this article and the simulation results is less than 9.52 %, which proves that the calculation results are relatively accurate. On the premise of meeting the constraints and load requirements, the low order resonant deformation of the transient dynamics simulation analysis is reduced by 30.27 %, significantly improving the vibration damping ability of the wind tunnel support system. [ABSTRACT FROM AUTHOR]

Honeycomb panels made of aluminum and composite materials—aramid, or Kevlar—are widely used in aviation, space, automotive, and other fields due to their unique characteristics: high strength and rigidity, low density, and good thermal insulation properties. However the mechanical processing of products made of honeycomb materials faces several difficulties, and one of the technologies that effectively solves the problems of cutting products made of honeycomb materials is ultrasonic cutting. In this paper, the finite element method is used to study the frequency properties necessary for designing tools for ultrasonic cutting of products made of honeycomb materials with operating frequencies around 20 kHz and various geometric parameters for cutting different variants of honeycomb constructions. The results of analyzing the wave dimensions of specialized ultrasonic triangular and disk-type instruments depending on geometry features are shown, along with the experimental results for a number of developed variants. [ABSTRACT FROM AUTHOR]

This paper presents a novel rhombic star-shaped honeycomb (RSSH) configuration with tunable Poisson's ratio and elastic modulus, and an RSSH with the U-shaped ligaments (URSSH) configuration is generated to analyze the effect of the curved ligaments on the elastic properties of RSSH. Cellular structure of RSSH combines with a rhombic and an improved star-shaped geometry, which can also be subdivided into flexible segments and rigid segments. In-plane elastic properties of the RSSH cell, including Poisson's ratio and elastic modulus, are both derived by analytical model based on flexibility modeling method and Castigliano's second theorem. Based on the guidance of theoretical model, quasi-static tensile experiments and finite element simulation of RSSH and URSSH specimens are carried out with different Poisson's ratio. The experimental results are in good agreement with the theoretical predictions and finite element analysis results. Length of cellular ligaments Lt1, dt have linear relationship with mechanical properties of the RSSH cell under constant angle θ1 and make the cellular configurations with different Poisson's ratio more obtainable. The effect of the symmetry of the flexible segments on the cellular mechanical properties is also analyzed through theoretical prediction. The introduction of asymmetry can bring wider design space of RSSH mechanical properties, especially Poisson's ratio. This work demonstrates the promising potential for applying RSSH configurations in 2D morphing structures with tunable auxetic behaviors. [ABSTRACT FROM AUTHOR]

Object: The dynamic behavior of sandwich cylindrical shell with fused deposition processed of flexible honeycomb core and carbon nanotube reinforced composite faces sheets is analyzed. Method: The every layer of the sandwich cylindrical shell is described by three displacements projections and two rotations angles of the normal to the middle surface. The faces sheets displacements projections are expanded up to the quadratic terms with respect to transverse coordinates. The honeycomb core displacements projections are expanded up to the cubic terms with respect to a transverse coordinate. The compatibility conditions for layers are used. The Rayleigh–Ritz method is applied to analyze linear vibrations of sandwich cylindrical shell. Results: The properties of the eigenfrequencies and eigenmodes of the structure vibrations are analyzed in detail. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to synthesizing honeycomb carbon quantum dots (CQDs) from cigarette smoke by a hydrothermal process. A comprehensive characterization of these CQDs, conducted through high-resolution transmission electron microscopy (HRTEM), showcases their unique honeycomb structure, with an average particle size of 6.3 nm. Photoluminescence (PL) in CQDs is a captivating phenomenon where these nanoscale carbon structures emit strong blue luminescence at 461 nm upon exposure to ultraviolet light, with their excitation peak occurring at 380 nm. Fourier Transform Infrared (FTIR) analysis also identifies specific functional groups within the CQDs, offering valuable insights into the mechanisms governing their photoluminescence. Analysis of excitation spectra indicates the presence of both aromatic C=C bonds at 254 nm and C–O bonds from 280 to 420 nm. [ABSTRACT FROM AUTHOR]

In this paper, we study the quantum correlations, particularly entanglement, between two qubits in graphene lattices. This study considers the short-range electron–electron Coulomb interactions as introduced by the Hubbard model and examines entanglement and other quantum correlations using the logarithmic negativity E N and the measurement-induced disturbance (MID) quantifiers, respectively. The results show that the on-site repulsion U, the nearest-neighbor interaction V between two qubits can promote entanglement up to a certain limit of U and V, but beyond entanglement, they can destroy other quantum correlations. These parameters can be seen as potentials generated near the two qubits, and they have a significant impact role in determining the amount and nature of quantum correlations in the system. Additionally, we have noted that the temperature T and the hopping parameter t also affect the quantum correlations in the system. Moreover, we found that MID is more robust than E N . That is means that even when there is no entanglement present, quantum correlations are still present in the interacting two-qubit states, which can be detected by MID quantifier. [ABSTRACT FROM AUTHOR]

To improve the impact resistance of the honeycomb, a self-similar spider-web hierarchical structure is introduced by adding smaller hexagons to the centers of the primitive cells in the underlying hexagonal network and connecting the vertices of the smaller hexagons to the center points of the cell walls via straight beams. The hierarchical structure is introduced into the regular hexagonal honeycomb (RH) cells, and some novel hierarchical bio-honeycombs are proposed for the development of innovative hierarchical bio-honeycombs. Compression simulation was performed to validate the finite element model. Subsequently, a finite element model of the bio-honeycomb was developed to investigate its out-of-plane crashworthiness. The results show that the introduction of bionic cells and the RH cell walls produces significant interaction effects, with more severe plastic deformation at their intersections and the formation of more folded flaps in the cell walls. The effect of geometric parameters on the crashworthiness of the novel biomimetic bio-honeycomb structures is further discussed. It is shown that smaller bionic honeycomb pore sizes are beneficial for improving the efficiency of material utilization. [ABSTRACT FROM AUTHOR]

Quantum spin liquids are elusive but paradigmatic examples of strongly correlated quantum states that are characterized by long-range quantum entanglement. Recently, signatures of a gapped topological Z 2 spin liquid have been observed in a system of Rydberg atoms; however, the full capability of these platforms to realize quantum spin liquids extends far beyond this state alone. Here, we propose the realization of a different class of spin liquids in a honeycomb array of Rydberg atoms. Exploring the system's quantum phase diagram using density-matrix renormalization group and exact diagonalization calculations, we identify several density-wave-ordered phases and a trimer spin liquid ground state with an emergent U(1) × U(1) local symmetry. This liquid state originates from superpositions of classical trimer configurations on the dual triangular lattice in the regime where third-nearest-neighbor atoms lie within the Rydberg blockade radius. Finally, we discuss the conditions to enhance the preparation fidelity of this state by a general Rydberg-blockade-based projection mechanism, test the robustness of the trimer spin liquid phase in a range of realistic parameters, and outline methods for its experimental detection. Quantum spin liquids, with their fractionalized excitations, are intriguing yet challenging to realise. In this work, the authors demonstrate the feasibility of preparing a trimer spin liquid in a honeycomb array of Rydberg atoms through numerical studies. [ABSTRACT FROM AUTHOR]

In this study, an adsorbent (LCB) with rich honeycomb structure was prepared from cork waste generated from furniture factories for efficient adsorption of excess phosphorus (P) from wastewater. This adsorbent was successfully prepared in only one step, in situ precipitation method, which greatly simplified the synthesis process. Kinetic studies showed that when the initial concentration (C0) of wastewater was 10 mg P L−1, the P in the water could be completely adsorbed within 20 min. The adsorption efficiency of phosphorus was significantly improved compared to previous studies. When the C0 of pollutant and the dosage of LCB were 20 mg P L−1 and 0.5 g L−1, respectively, the removal rate of P exceeded 99% in the pH range of 3–10, which indicates the wide applicability of LCB. In addition, the P adsorption capacity of LCB was 82.4% of its initial value after nine adsorption–desorption cycles, indicating that LCB has a high stability and can be widely used in different water environments. Therefore, LCB is a promising material for the treatment of P-containing wastewater. Article Highlights: Highly efficient P-absorber with honeycomb structure and high specific surface area (2093.1 m2 g-1) was prepared. LCB had an adsorption capacity of up to 280.4 mg P g-1 La-1 and its reusability was outstanding. LCB maintained good P-removal effect at a solution pH of 3~10 and can be used in a wide range of applications. [ABSTRACT FROM AUTHOR]

The nonlinear static and vibration response of micro composite sandwich plate with honeycomb core have been investigated in this paper. The displacement–strain of skins via higher-order shear deformation theory (HSDT) is obtained. In frame work Halpin–Tsai model the composites plate with two layers of Graphene platelet reinforcement (GPLRC) with uniform distribution pattern and a hexagonal honeycomb core is considered. The governing equations of sandwich plate are derived by implementing Hamilton's principle and solved Perturbation method. For investigating the accuracy, this paper is validated with other previous researches and a good correlation is observed between the results. Finally, the important findings of this research indicate that the ratio of core thickness, inclined angle, and thickness to inclined length have significant effects on nonlinear frequencies–amplitude and deflection response. Based on the results of this article designers can development of different parts of aircraft. [ABSTRACT FROM AUTHOR]

Herein, for the first time, a simple, green, direct immersion immobilisation method is reported for graphene oxide (GO) nanosheets using pomelo peel (PL) as a substrate. A GO/PL porous sponge was successfully prepared and used to remove methylene blue (MB) from dye wastewater. Considering the porosity, hydrophilicity and elasticity of the PL, the PL was placed in a GO aqueous suspension through direct immersion immobilisation. The carboxyl and hydroxyl groups in the peel could effectively capture and immobilise the GO nanosheets. GO was adsorbed into the PL pores and dispersed throughout the PL. Finally, the prepared super-hydrophilic and elastic GO/PL exhibited excellent adsorption performance towards MB in dye wastewater. The adsorption results revealed that the adsorption behaviour was consistent with the Langmuir isotherm and quasi-secondary kinetic models. The maximum equilibrium adsorption capacity of GO/PL towards MB was 124.2 mg/g, exceeding the values obtained for most of the previously reported adsorbents. Moreover, after five consecutive adsorption–desorption cycles, GO/PL retained 75% of its initial adsorption capacity. Mechanistic analysis revealed that pore filling, electrostatic attraction, ion exchange and hydrogen bonding interactions are the primary driving forces facilitating MB adsorption. [ABSTRACT FROM AUTHOR]

Lattice materials formed by hinged springs or linear elastic bonds may exhibit diverse anisotropy and asymmetry features of the overall elastic behavior depending on their unit cell configuration. The recently developed singum model transfers the force-displacement relationship of the springs in the lattice to the stress-strain relationship in the continuum particle, and provides the analytical form of tangential elasticity. When a pre-stress exists in the lattice, the stiffness tensor significantly changes due to the effect of the configurational stress; existing methods like the lattice spring method, relying on a scalar energy equivalence, are insufficient in such situations. Instead, a tensorial homogenization method with the new definition of singum stress and strain, should be preferred. Different lattice structures lead to different symmetries of the stiffness tensors, which are demonstrated by five lattices. When all bonds exhibit the same length, regular hexagonal, honeycomb, and auxetic lattices demonstrate that the stiffness changes from an isotropic to anisotropic, from symmetric to asymmetric tensor. When the central symmetry of the unit cell is not satisfied, the primitive cell will contain more than one singums and the Cauchy–Born rule fails by the loss of equilibrium of the single singum. A secondary stress is induced to balance the singums. Displacement gradient d i j = u j , i is proposed to replace strain in the constitutive law for the general case because d 12 and d 21 can produce different stress states. Although the hexagonal and honeycomb lattices may exhibit isotropic behavior, for general auxetic lattices, an anisotropic and asymmetric elastic tensor is obtained with the loss of both minor and major symmetry, which is also demonstrated in a square lattice with unbalanced central symmetry and a chiral lattice. The modeling procedure and results can be generalized to three dimensions and other lattices with the anisotropic and asymmetric stiffness. [ABSTRACT FROM AUTHOR]

The conventional star-shaped honeycomb (CSSH) structure is inherently rich in mechanical properties. Based on the CSSH structure, the Poisson's ratio and Young's modulus can be improved by adding the tip re-entrant angle (ISSH). In this paper, a new concave four-arc honeycomb (CFAH) structure is proposed by designing the straight rod as a curved rod and retaining the tip re-entrant angle from the ISSH structure. The Young's modulus, specific stiffness and Poisson's ratio of CFAH structures are derived from Castigliano's second theorem and Moore's theorem. The theoretical results show good agreement with the numerical and experimental results. The results show that the normalized effective specific stiffness and normalized effective Young's modulus of the CFAH structure are further improved by about 12.95% and 16.86%, respectively, compared with the ISSH structure, and more significant auxiliary effects are obtained. CFAH structures show good promise in aerospace, construction and other applications due to their enhanced mechanical property. Meanwhile, the present work provides guidance for the study of concave four-arc honeycomb structures. [ABSTRACT FROM AUTHOR]

There has been significant research focused on the development of stretchable materials that can provide a large area with minimal material usage for use in solar cells and displays. However, most materials exhibit perpendicular shrinkage when stretched, which is particularly problematic for polymer-based substrates commonly used in stretchable devices. To address this issue, biaxial strain-controlled substrates have been proposed as a solution to increase device efficiency and conserve material resources. In this study, we present the design and fabrication of a biaxial strain-controlled substrate with a re-entrant honeycomb structure and a negative Poisson's ratio. Using a precisely machined mold with a shape error of less than 0.15%, we successfully fabricated polydimethylsiloxane substrates with a 500 μm thick re-entrant honeycomb structure, resulting in a 19.1% reduction in perpendicular shrinkage. This improvement translates to a potential increase in device efficiency by 9.44% and an 8.60% reduction in material usage for substrate fabrication. We demonstrate that this design and manufacturing method can be applied to the fabrication of efficient stretchable devices, such as solar cells and displays. [ABSTRACT FROM AUTHOR]

There is a growing demand to comprehend the orthotropic properties of composite sandwich structures. Indentation stress is often experienced on the surfaces of sandwich beams, particularly during maintenance procedures. The objective of the present investigation is to evaluate the performance of these structures under such circumstances. The mechanical behavior of the composite sandwich structures is assessed by analyzing the results of edgewise compression and flexure tests conducted after indentation. The experiments encompass variations in carbon composite face thicknesses, core types, and indentation depths. The overall outcomes highlight a notable effect of indentation, particularly in the case of foam-core sandwiches, which exhibit lower elasticity compared to honeycomb-core sandwiches. Interestingly, the specific properties of both foam and honeycomb core beams, relative to their weight ratios, are found to be comparable. Furthermore, the results demonstrate that sandwich beams with reduced face material display lower stiffness but higher flexibility, enabling them to greater resistance to damage. [ABSTRACT FROM AUTHOR]