Periodic Honeycomb Research Articles

Anomalous Proton Blocking Property of Pore-Free Graphene Oxide Membrane.

Graphene oxide (GO) has been attracting intensive attention as a flexible barrier film, however, provides no barrier for proton transfer due to its out-of-plane proton conductivity (10-6Scm-1) based on nanoscale defects with oxygen functional groups. In this study, it is reported that a pore-free GO (Pf-GO) membrane with controlled oxygen functional groups exhibits unexpected proton blocking behavior (10-11Scm-1). Proton permeation tests conducted in aqueous solution demonstrate that proton permeation is below the detection limit, and lithium metal foils coated with the Pf-GO show higher chemical stability to water than those coated with previously reported GO. The Pf-GO has periodic honeycomb atomic structure, which is found to impart the Pf-GO membrane with novel performance characteristics distinct from those of conventional GO.

Compression deformation characteristics and mechanisms study of multi‐layer structures with triply periodic minimal surfaces

AbstractTriply periodic minimal surfaces (TPMS) and honeycomb structures are typical representatives of porous structures. In this paper, multi‐layer structures based on the combination of P‐surfaces and honeycomb structures are fabricated and the compression deformation characteristics are investigated based on quasi‐static compression tests and finite element simulation. The results show that the established finite element model can better simulate the deformation and damage modes of the multi‐layer structure, and the multi‐layer structure exhibits layer‐by‐layer deformation and sequential compression collapse in the deformation process. The tensile stress is crucial in the deformation and damage process of the P‐structure layer. The honeycomb structure layers show two different deformation modes: the inverted bell‐shaped “upward extrusion” and the bell‐shaped “downward extrusion.”

Compressive response and energy absorption of additive manufactured Ti-6Al-4V triply periodic minimal surface honeycomb structure

This study proposed a design method of honeycomb structure based on triply periodic minimal surfaces (TPMS), namely gyroid-honeycomb. The honeycomb samples were fabricated by selective laser melting (SLM) with Ti6Al4V (TC4) material. Through the uniaxial quasi-static compression tests and numerical simulations, the mechanical responses and energy absorption capability of honeycomb structures under different compressive velocities were investigated. Compared with conventional truss-honeycomb structure, the gyroid-honeycomb exhibited reduced stress fluctuation and enhanced energy absorption capability under in-plane compressive direction. Particularly, gyroid-honeycomb also demonstrated a superior energy absorption capability under both low and high compressive velocities. According to the scanning electron micrograph (SEM) image of the fracture surface, the gyroid-honeycomb exhibited a unique buckling failure mode along with a large plastic deformation and negative Poisson’s ratio. The different compressive responses can be attributed to the distinct stress distribution in gyroid-honeycomb according to the simulation results. Notably, the gyroid-honeycomb structure displayed a remarkable capacity for energy absorption across various compressive velocities. These findings provide valuable insights into the application of the novel TPMS-based honeycomb structures in enhancing the crashworthiness protection for vehicles.

Modelling, optimization, and testing of novel cuboidal spherical plate lattice structures

ABSTRACT This study investigates the mechanical behavior of a novel set of Cuboidal Spherical Plate Lattice (CSPL) materials. The procedure of constrained-domain topology optimization is implemented with the aim of enhancing stiffness. The micromechanical finite element homogenization approach is used to evaluate the effective elastic-plastic properties of the CSPLs and their topologically optimized counterparts, TOCSPLs (Topologically Optimized Cuboidal Spherical Plate Lattices). The TOCSPLs demonstrate higher uniaxial, shear, and bulk moduli compared to the CSPLs, with an increase of 31%, 14%, and 36% respectively. Moreover, there is an increase in the yield strengths under uniaxial, shear, and hydrostatic loading conditions, with enhancements of 103%, 55%, and 62%, respectively. The topologies are additively manufactured through Fused Deposition Modeling (FDM) out of ABS thermoplastic material. The quasi-static compression experiments demonstrate the superiority of TOCSPL 111+100 over the other topologies in terms of uniaxial modulus. The suffix 111+100 denotes the crystallographic planar orientations in which the solid plate-like disks were formed within a cubic system. The topologies proposed herein outperform certain types of Triply Periodic Minimal Surface, honeycomb, truss-, and plate-based lattice materials. The proposed topologies offer a compelling justification for their utilization in applications that require load-bearing and impact absorption capabilities.

Rounded corner thicken strut re-entrant auxetic honeycomb: Analytical and numerical modeling

An analytical model is formulated for 2-D periodic negative honeycomb thicken strut re-entrant lattice structures and a modified rounded corner negative honeycomb structure that shows negative Poisson’s ratios (NPR). Analytical modeling is done using Castigliano’s second theorem, where each beam is modeled using Timoshenko beam theory, considering bending, stretching, and transverse shearing. Elastic modulus and Poisson’s ratio have been formulated for both structures in the form of non-dimensional geometrical characteristics, such as length ratios, angles of re-entrant arms, shear correction factor, and the material’s Young’s modulus and Poisson’s ratios. Numerical simulations conducted in ABAQUS-CAE explicit solver validate the analytical model. The effect of the non-dimensional parameters on the qualities of the developed structure is demonstrated. It is observed that the structures with a low curvature ratio have a high fluctuation of Poisson’s ratio and Elastic constant when plotted against the other parameters. The slenderness ratio has little impact on Poisson’s ratio but significantly influences elastic modulus. It is shown that various needs can be satisfied by customizing the Poisson’s ratios and elastic constant of both forms of lattice construction over an extensive range by carefully choosing the geometrical parameters and material.

A topological approach for optimizing the dimensional properties of various bioinspired periodic type honeycomb latticed carbon fiber reinforced glycol‐modified poly (ethylene terephthalate) composite materials

AbstractThe present research efforts are directed toward investigating dimensional stability, focusing on bio‐inspired periodic honeycomb lattice structures within carbon fiber reinforced glycol‐modified poly ethylene terephthalate (PETG) composites. These samples are fabricated using extrusion‐based 3D printing, with topological parameters such as shell thickness (ST), unit cell type (UCT), wall thickness (WT), unit cell orientation (UCO), skewing angle (SA), and unit cell size (UCS) being manipulated across three different levels. The experimental findings indicate that achieving the lowest dimensional length error is attainable under specific conditions, including a smaller ST of 0.5 mm, a square UCT, a WT of 0.5 mm, a UCO of 90°, a SA of 0°, and a UCS of 4 mm. Analyzing the results with ANOVA reveals that UCT (28.82%) and WT (18.73%) exert the most significant influence on the dimensional stability response. The regression model closely aligns with experimental outcomes, with an error percentage of 3%, rendering it suitable for large‐scale customization. Under the optimized topological parameters, carbon fiber‐reinforced PETG latticed composites exhibited a dimensional length error of 0.292 mm and a compressive strength of 21.56 MPa. Fractography analysis revealed a brittle mode of fracture across all samples, indicating their stiffness and strength, especially when compared to samples with lower wall thickness. These findings suggest that the designed carbon fiber‐reinforced PETG latticed composite material holds potential for use in minor surgical orthotic and prosthetic applications.Highlights Bio‐inspired periodic honeycomb lattice structured PETG composites. Topological optimization on the dimensional properties. Taguchi optimization is performed on design‐based lattice structures. Unit cell type has highest contribution of 28.82% on dimensional properties.

Nanosecond Laser Fabrication of Novel Micro-/Nanostructured Metal Surfaces: A Dual-Functional Supersurface Combining Antireflectivity and Superhydrophobic Properties.

The research and applications in the field of micro/nano surface manufacturing are progressively shifting their focus toward multifunctional surfaces. In practical applications, objects often need to operate under demanding environmental conditions, and single-function surfaces have inherent limitations in terms of performance, adaptability, and longevity. In this paper, a micro-/nanolayered structural strategy with dual functions of ultrahigh antireflective properties and superhydrophobicity was created on the surface of titanium alloy by using nanosecond pulsed laser processing, and two structural modes of periodic honeycomb and lattice with controllable shapes were designed. In addition, the morphology and formation mechanism of multilevel micro-/nanostructures were investigated in depth, combining laser texturization and silanization of substrate microstructures. The effects of the micro-/nanostructured morphology on the reflection and wettability properties were evaluated with different pulse widths and lateral overlap index. This study also demonstrated that water droplets exhibit excellent bouncing and rolling behavior on superhydrophobic surfaces, further verifying the excellent hydrophobic properties of the prepared samples. Furthermore, in addressing the challenges of susceptibility to dust contamination and performance degradation in extreme environments associated with antireflective surfaces, a series of durability and mechanical stability tests were conducted on controllability periodic micro-/nanostructured surfaces. Successfully meeting this challenge will open up great potential and opportunities for significant improvements in equipment performance and stable operation under extreme operating conditions.

Equivalent orthotropic properties of periodic honeycomb structure: strain-energy approach and homogenization

Equivalent orthotropic properties of periodic honeycomb structure: strain-energy approach and homogenization

Insights into the printing parameters and characterization of thermoplastic polyurethane soft triply periodic minimal surface and honeycomb lattices for broadening material extrusion applicability

Lattice structures with triply periodic minimal surfaces (TPMS) built using flexible materials are soft porous solids applicable in various fields, including biomedicine and tissue engineering. Such structures are also relevant for material extrusion additive manufacturing (MEAM), whose wide diffusion is pivotal to fostering their spread. Although design approaches are available to exploit the potential of soft TPMS, there are still manufacturing constraints that lead to practical limits on the shape and size of the structures that can be produced due to the complexities related to printing flexible materials. Besides, the computational models investigating the effect of cell type, the surface-to-volume fraction, and the combination of different periodic surfaces (i.e., graded or hybrid) on the mechanical behavior of these lattices are design aspects still debated. Here, the capabilities of MEAM to produce tailored soft lattice structures are explored by combining a design tool, numerical analyses, and mechanical testing using thermoplastic polyurethane (TPU) as feedstock material. The study addresses design issues, delves into optimum printing parameters, and analyzes a set of numerical parameters, which can be used for designing specific structures with tunable mechanical behavior, useful for healthcare and bioengineering. The printing parameters of three lattices, i.e., schwartz-P, gyroid, and honeycomb, with unit cell sizes spanning from 3 to 12 mm were studied. Their mechanical behavior was investigated using FEM simulations and mechanical testing. Lastly, the printability of graded and hybrid lattices with enhanced bearing-load capabilities have been demonstrated. Altogether, our findings addressed multiple challenges associated with developing soft lattice scaffolds with MEAM that can be used to fabricate innovative-engineered materials with tunable properties.

3D printable bone-mimicking functionally gradient stochastic scaffolds for tissue engineering and bone implant applications

A number of designs have been used in the field of tissue engineering for the purposes of bone biomimicry (e.g.) triply periodic minimal surfaces (TPMS), honeycomb lattice, and face centered cubic (FCC). While the usage of these structures was met with some success, the results were not optimal due to factors such as lack of localized porosity control and stress concentration at nodes of gradient scaffolds. This led to a push for novel designs, such as, stochastic scaffolds with locally tunable porosity as well as anisotropically varying mechanical properties. A number of methods exist for generating these stochastic structures, such as, random set method, stochastic optimization method, iterative non-linear transformative method and others, but while these techniques led to a greater approximation of the bone microstructure, they did not help in the creation of a structure with controlled modulus along different directions. The novelty of the method used in this paper is that it not only helps in generating stochastic structures in a computationally inexpensive and non-complex way, but also generates a porosity gradient along three different axes in a controlled manner. Various additive manufacturing techniques have been successfully utilized for fabricating these structures at different scales, using different materials, thus, proving their versatility. The proposed design approach was implemented in the case of a 3D reconstructed rabbit model. Magics software was used to extract the internal microstructure of the rabbit model and our design approach was used for generating a stochastic scaffold which accurately mimicked the porosity gradient of the rabbit model in all the three directions. On comparing the mechanical properties of the rabbit microstructure and the gradient mimicking scaffold, the variations were significant as the properties depend not only on the porosity gradient but also on the internal microstructure, which warrants further multi-property optimization.

A skin-core debonding quantitative algorithm based on hexagonal units reconstruction for air-coupled ultrasonic C-scan images of honeycomb sandwich structure

Honeycomb Sandwich Structure (HSS) is widely used in the aerospace industry. The skin-core debonding in HSS can grow to reach a critical size, leading to the sudden failure of structures. Due to the blurry edges on the C-scan image caused by honeycomb units with periodic honeycomb walls, accurate quantification of debonding is still a challenge. In this paper, accurate debonding quantification of HSS based on air-coupled ultrasonic C-scan and hexagonal units reconstruction is proposed. The debonding boundary identification is accurate to the interior of the honeycomb units by partial debonding units division based on calculating the total amplitude of all scanning points within the unit. The detailed process was presented with key steps as ultrasonic air-coupled C-scan for HSS, hexagonal units reconstruction based on peak points on C-scan images, units classification by K-means clustering algorithm, and units division according to the total amplitude. Four types of debonding, including film sticking, adhesive removal, slight subsidence, and severe subsidence, are used to evaluate the effectiveness of the method. The results show that the proposed method can describe and quantify-four kinds of debonding defects reliably and it is ideally suited for air-coupled ultrasonic C-scan image processing of periodic structures.

Optimal Design of Periodic Honeycomb Plate with Unit Cell Structure Based on Genetic Algorithm

Composite honeycomb sandwich plates have been widely used in aerospace, ships, construction bridges, machinery, stationery, and other industries. In order to improve the performance and configuration, taking the structural dynamic characteristics of periodic honeycomb plate as the research object, a structural optimization design method based on natural frequency and stiffness was proposed with the goal of weight reduction. The geometric parameters of the structure system were trained by the multiobjective optimization genetic algorithm (MOGA), and the Pareto optimal solution of variable combination was obtained. This paper presented a decoupling method for complex system optimization design based on dynamic performance from the perspective of basic unit, which could solve the coordination problem of vibration stability and weight reduction in periodic honeycomb plate structure optimization design. It has reference significance for the similar composite material frame base structure design.

Design and modeling of a novel three dimensional auxetic reentrant honeycomb structure for energy absorption

Aiming at achieving excellent energy absorption capacity, a novel periodic auxetic reentrant honeycomb structure is proposed by defining an octagon honeycomb unit cell with various shape parameters and reentrant angles. Additive manufacturing is applied to fabricate three groups of resin samples with different design parameters. Quasi-static compression experimental test is conducted obtaining the effects of negative Poisson’s ratio (NPR) on the compressive stress–strain relationship of the proposed structure. The results show the excellent lateral material shrinkage under axial compression and distinct hardening process with sharp stiffness increase when the structure experiences densification. The experiment results are then used to validate the corresponding 3D finite element models. Good agreements are found between the experiment and finite element simulation results. Furthermore, a geometry parameter study is used to analyze the effect of design parameters on energy absorption capacity of the structure and the results can be a good reference for future optimal design of similar meta-materials. To summarize, in addition to the good energy absorption capacity, thanks to the obvious NPR effects and lateral shrinkage behavior, the newly proposed honeycomb meta-material with specific auxetic reentrant design becomes a solid material with low porosity and high stiffness after full compression to provide further protection or support for its neighbor objectives.

Construction of MoO3/MoSe2 nanocomposite-based gas sensor for low detection limit trimethylamine sensing at room temperature

In this paper, MoO3/MoSe2 nanocomposite was constructed by an improved hydrothermal and spin coating method for fabricating trimethylamine (TMA) gas sensor. The surface morphology and microstructure of the prepared materials were analyzed by XRD, XPS, SEM and TEM characterization methods. The microstructural characterization results demonstrated that the MoO3/MoSe2 nanocomposite had been successfully synthesized, in which the MoSe2 had a flower-shaped structure, and MoO3 had a rod-shaped structure. At the same time, the MoSe2 surface exhibited periodic honeycomb structure. The gas sensitivity experimental results showed that the proposed MoO3/MoSe2 sensor had excellent TMA sensing performance at room temperature, including high response capability, low detection limit (20 ppb), short response/recovery time (12 s/19 s), long-term stability, good repeatability and outstanding selectivity. The heterostructure of MoO3/MoSe2 had made outstanding contributions to the enhanced TMA gas sensing performance at room temperature.

Peierls-Nabarro barrier effect in nonlinear Floquet topological insulators

The Peierls-Nabarro barrier is a discrete effect that frequently occurs in discrete nonlinear systems. A signature of the barrier is the slowing and eventual stopping of discrete solitary waves. This work examines intense electromagnetic waves propagating through a periodic honeycomb lattice of helically driven waveguides, which serves as a paradigmatic Floquet topological insulator. Here it is shown that discrete topologically protected edge modes do not suffer from the typical slowdown associated with the Peierls-Nabarro barrier. Instead, as a result of their topological nature, the modes always move forward and redistribute their energy: a narrow (discrete) mode transforms into a wide effectively continuous mode. On the other hand, a discrete edge mode that is not topologically protected does eventually slow down and stop propagating. Topological modes that are initially narrow naturally tend to wide envelope states that are described by a generalized nonlinear Schrödinger equation. These results provide insight into the nature of nonlinear topological insulators and their application.

The electromagnetic response of composition-regulated honeycomb structural materials used for broadband microwave absorption

The undesirable absorption bandwidth is the main limitation for the application of microwave absorbing materials. Noting that the design of structure and composition of absorbing coating allows it to obtain a satisfying absorption bandwidth and to avoid weight increasing, honeycomb and its sandwich structures coated by various absorbant have been developed and measured using an arch measurement system over 2−18 GHz. To further understand the absorption mechanisms of honeycomb structural materials, simulation based on finite element method and transmission line theory is performed to analyze the different responses to the applied microwave between honeycomb structural materials and uniform-medium slab materials. The proper composition design allows control over the microwave loss mechanisms, which optimize the coating to possess both of the dielectric and magnetic advantages. For the honeycomb structural materials, the magnetic resonation is found for the first time, which is resulting from the periodic honeycomb walls on both sides of the dielectric cavity (consisting of the aramid paper interlayer and vacuum hexagonal prisms). In addition, the conversion of structure from solid to honeycomb brings about changes in impedance, propagating path, effective wavelength, effective attenuation area, microwave phases, and inductive coupling effect, etc., which result in a better microwave absorbing performance. The honeycomb sandwich structure coated by CIP/CB/EP with the weight ratio of 4:0.03:1 shows the absorption bandwidth of ∼9.8 GHz for reflection loss (RL) lower than -10 dB which covers part of the S and C bands and almost the whole X and Ku bands.

Weak topological insulating phases of hard-core-bosons on the honeycomb lattice

We study the phases of hard-core bosons on a two-dimensional periodic honeycomb lattice in the presence of an on-site potential with alternating sign along the different y-layers of the lattice. Using quantum Monte Carlo simulations supported by analytical calculations, we identify a weak topological insulator, characterized by a zero Chern number but non-zero Berry phase, which is manifested at either density 1/4 or 3/4, as determined by the potential pattern. Additionally, a charge-density-wave insulator is observed at 1/2-filling, whereas the phase diagram at intermediate densities is occupied by a superfluid phase. The weak topological insulator is further shown to be robust against any amount of nearest-neighbor repulsion, as well as weak next-nearest-neighbor repulsion. The experimental realization of our model is feasible in an optical lattice setup.

Influence on the Haze Effect of Si Thin-Film Solar Cell on Multi-Surface Textures of Periodic Honeycomb Glass

Double textures were applied to use for multi-junction silicon thin film (Si-TF) solar cells. To improve the longer wavelength, we were formed the microscale periodic honeycomb textured surface on a glass substrate. We achieved the transmittance of 94.26% and found the approximately 52% for haze value. Etched AZO films on the textured glass is crucial role for improving the short-wavelength in Si-TF solar cells. Textured AZO film using a 1% HF solution is suitable for the growth of microcrystalline Si and better light trapping. The transmittance was recorded 80.8% that was 3% higher than that of reference fluorine doped tin oxide (FTO, Asahi-U type) glass. We also achieved for high haze value of 59.8% to enable the light trapping across the entire wavelength region. Using a finite-difference time-domain (FDTD) simulation, we designed a multi-junction Si-TF solar cells with high short-circuit current density of 12.5 mA/cm2. To reduce the plasma damage and surface stress on the μc-Si:H layer during growth, we fabricated an a-Si:H/µc-Si:H tandem cell on a multi-surface textures with a µc-Si:H layer of only 1.5 µm thick and obtained a conversion efficiency of 13.3%. The developed double textures structure and fabrication technique are expected to improve the performance of various multi-junction Si thin-film solar cells.

On the mechanical behaviour of additively manufactured metamaterials under dynamic conditions

High-energy absorption and light-weightiness are two critical properties for impact protection in the aerospace sector. In the past, the use of periodic honeycomb structures or random porous metallic foams were the preferred route to obtain a good specific-energy absorption performance. In recent years, the use of additive manufacturing has increased the design freedom creating a new generation of reticulated and porous materials: the metamaterials or lattice materials. The internal geometries of these lattice structures can be tuned for superior optimal properties, e.g., energyabsorption and density. However, the mechanics of these materials under impact need to be understood with the purpose of mechanical optimisation, and the computational models validated. In this work, we present the experimental compressive behaviour, at room temperature, of two Ti6Al4V lattice structures under static and dynamic conditions. The quasi-static tests were performed by using a universal testing machine while the dynamic tests were conducted at 480s-1 with a split-Hopkinson bar. In all cases, the deformation process was filmed to analyse the failure. Finally, finiteelement simulations were done, employing the Johnson-Cook model, to describe the response of the alloy. The simulations were able to reflect the failure characteristics of each metamaterial but were not able to describe the macroscopic response due to the differences between the experimental and computational volume fraction.

Magnetization dynamics of a Fibonacci-distorted kagome artificial spin ice

We present results of ferromagnetic resonance (FMR) experiments and micromagnetic simulations for a distorted, 2D Kagome artificial spin ice. The distorted structure is created by continuously modulating the 2D primitive lattice translation vectors of a periodic honeycomb lattice, according to an aperiodic Fibonacci sequence used to generate 1D quasicrystals. Experimental data and micromagnetic simulations show the Fibonacci distortion causes broadening and splitting of FMR modes into multiple branches, which accompany the increasing number of segment lengths and orientations that develop with increasing distortion. When the applied field is increased in the opposite direction to the net magnetization of a segment, spin wave modes appear, disappear or suddenly shift, to signal segment magnetization reversal events. These results show the complex behavior of reversal events, as well as well-defined frequencies and frequency-field slopes of FMR modes, can be precisely tuned by varying the severity of the aperiodic lattice distortion. This type of distorted structure could therefore provide a new tool for the design of complicated magnonic systems.