Fabrication Of Honeycomb Research Articles

3-D woven honeycomb structures and their composites

Honeycomb is regarded as a valuable structural material because of its high strength, shear stiffness, high impact strength, low weight, high crushing stress, and nearly constant force to crush. It is a cellular solid, well-known as a core in creating sandwich structures for use in structural composites. Honeycombs are often utilized in the aircraft sector as the core of sandwich panels and in the automotive industry as effective impact attenuators because of their superior mechanical performance. The hollow spaces in the honeycomb structure not only reduce weight but also ensure the required strength, provided they are designed correctly. In lightweight application areas, because they offer structural integrity, 3-D woven honeycomb composites have a bright future and possess the potential to replace aluminum and other metal alloys. This issue of Textile Progress focuses on the manufacturing of 3-D woven honeycomb fabrics, their mechanical characterization, application areas, different ways of weaving honeycomb cells, and some innovations related to honeycomb-like auxetic and 3-D printed honeycomb structures.

Comparative analysis of the mechanical performance of 3D woven honeycomb composites produced in warp and weft directions

This research work focuses on the design and manufacturing of 3D woven honeycomb fabrics and their composites in both warp and weft directions. An experimental investigation of the mechanical properties of these two composite materials was carried out. For this purpose, at first, a 3D woven honeycomb in both directions was fabricated on a customized multi-beam 3D weaving machine using E-glass fibers. The composites were created by VARIM (Vacuum assisted resin infusion method) process using epoxy resin and Aradur hardener. The mechanical characteristics such as compression, three-point bending, and in-plane impact of composite samples were investigated keeping cell parameters constant. There will be a change in composite properties as tension in warp and weft is different. Crimp and modulus will also be different. The comparison of mechanical properties of these two honeycomb composite samples revealed that warp way honeycomb shows better properties in edgewise compression and three-point bending test while weft way honeycomb shows higher energy absorption under flatwise compression and in-plane impact test. The direction of cell channels gives the direction of loading to the threads, which affects the mechanical properties.

Development and analysis of a three-dimensional braided honeycomb structure

This paper presents the design and development of three-dimensional braided honeycomb structures. The basic principles and braiding process are described. The relationship between braiding parameters and honeycomb geometric parameters is established and several three-dimensional (3D) braided honeycomb fabrics are introduced. Based on the principle of the 3D braiding ‘four-step’ method, the interlaced state of yarns can be changed by controlling the movement of yarn carriers, so the separation and combination of the braid can be controlled, then 3D braided honeycomb fabric can be formed. As the number of braiding cycles of wall length increases, the relative density will gradually decrease, but the number of braiding cycles of free wall length has a greater effect on the relative density. When the number of columns of yarns participating in wall thickness increases, the relative density will gradually increase. The relative density also showed a positive correlation with the braiding angle. With the increase of the opening angle, the relative density gradually decreases, although there is a minimum point after which a little increase is observed. This paper provides significant guidance for designing various 3D braided honeycomb structures and evaluating their relative density, and can be a reference for the design and development of new honeycombs structures.

3D printing of cordierite honeycomb structures and evaluation of compressive strength under quasi‐static condition

AbstractCeramic honeycombs exhibit unique mechanical properties based on engineered formulations and geometry of cells. Extrusion of formable paste through a complex honeycomb die is the commonly practiced technique for the manufacturing of honeycombs globally. Extrusion die fabrication is a complex process which necessitates sophisticated infrastructure facilities that provide high geometrical accuracy and finish to produce defect free honeycombs. Furthermore, every configuration of honeycomb requires a specific tool. Additive manufacturing (AM)/ 3D printing is a rapid prototyping technique which offers flexibility in fabrication of honeycombs with desired geometries from a virtual model directly. Further, this does not require complicated dies. In this study, viscoplastic printable cordierite raw mix paste with a shear rate exponent of 0.87 was printed into honeycombs with hexagonal, square, and triangular cells using a ram type 3D printer. The printed honeycomb samples are found to possess good integrity and near net shape after drying. Sintered 3D‐printed honeycomb samples of all configurations have exhibited cordierite as a major phase along with minor phases of magnesium aluminate (MgAl2O4) spinel, clinoenstatite (MgSiO3), and corundum (Al2O3) with sintered density of 2.41‐2.48 g/cc. The samples are also subjected to compression testing under quasi‐static condition. The study demonstrates 3D printing as a viable and flexible technique for rapid prototyping of honeycombs with desired configurations and engineered properties.

Sonochemical synthesis and fabrication of honeycomb like zirconium dioxide with chitosan modified electrode for sensitive electrochemical determination of anti-tuberculosis (TB) drug.

Herein, novel honeycomb like zirconium dioxide with chitosan (ZrO2@chitosan) nanocomposite have been designed through a facile ultrasound-assisted method and followed by a simple sonication process (bath-type ultrasound washer; Honda Electronics-W-118T; 100 W/cm2 and 300 kHz frequency). After then, as-synthesized ZrO2@chitosan was characterized by FESEM, XRD and EIS. The ZrO2@chitosan nanocomposite modified glassy carbon electrode shows excellent electrochemical sensing performance towards anti-tuberculosis drug (rifampicin). Furthermore, the ZrO2@chitosan modified and fabricated electrochemical sensor showed a wide linear range between 0.015 µM and 547.4 µM and nanomolar detection limit (7.5 nM). Moreover, the ZrO2@chitosan modified electrode showed selectivity towards the detection of anti-tuberculosis drug (rifampicin). The ZrO2@chitosan nanocomposite film modified non-enzymatic sensor has high stable and good reproducible towards the detection of rifampicin. In addition, the as-synthesized ZrO2@chitosan nanocomposite modified electrode has been applied to the determination of rifampicin in biological samples such as human serum and urine samples.

Fabrication of complex shaped ceramic articles from 3D printed polylactic acid templates by replication process

Abstract Porous honeycombs of three ceramic formulations and configurations were replicated from 3D printed polylactic acid (PLA) templates. Sacrificial PLA templates were coated with ceramic slurries of optimum rheology and were subjected to fugitive thermal degradation based on the TG-DTA patterns recorded followed by sintering. Though the polymer replication process is known, 3D printed PLA templates are not explored for fabrication of ceramic complex shapes. 3D printed PLA offers flexibility to produce complex ceramic parts with structural integrity and engineered porosity. In the present study, 3D printed template replication technique has been used to demonstrate fabrication of honeycombs with relative density as low as 0.1 with porosity of 75–85% which is alo complemented by microstructural studies. Further, the samples exhibited cellular behavior under quasistatic compression with high energy absorption capabilities and moderate compressive strength of 1.5–2.2 MPa depending upon the ceramic formulations.

Effect of cell size on tensile strength and elongation properties of honeycomb weave

The fabric developed from honeycomb weave is a multilayer fabric having variable strength and elongation. Properties of these structures depend on the cell size of the honeycomb weave. The aim of the research is to identify the effect of cell size on the tensile strength in terms of breaking force and elongation of the honeycomb weave structures. In this paper, three different cell sizes of honeycomb fabrics were created and analysed in both warp and weft direction for its tensile properties. Analysis shows significant results in the warp direction and weft direction of honeycomb fabric.

Effect of Cotton Cationization Using Copolymer Nanospheres on Ink-Jet Printing of Different Fabrics.

In this study, the cationic Poly[Styrene-Butyl acrylate-(P-vinylbenzyl trimethyl ammonium chloride)] P(St-BA-VBT) nanospheres with N+(CH3)3 functional groups were successfully synthesized by soap-free emulsion polymerization and applied to different fabrics by pad-cure process. After the pad-cure process, the nanospheres were deposited on the surface of the modified cotton fibers successfully without forming a continuous film structure. The X-ray Photoelectron Spectroscopy (XPS) and the Fourier transform infrared (FTIR) results demonstrated that P(St-BA-VBT) nanospheres were adsorbed on the surface of cotton fibers successfully. The excellent color strength value and outline sharpness of the plain, twill, and honeycomb fabrics can be achieved when the nanosphere concentration, sodium bicarbonate, and steaming time were 1 g/L, 10 g/L, and 6 min, respectively. The plain fabrics exhibited the smallest color strength (K/S) values and the best outline sharpness, followed by twill and honeycomb fabrics, which displayed the largest K/S values and the worst outline sharpness after the same treatment. Besides, all the three fabrics showed excellent rubbing fastness and washing fastness. The cationic P(St-BA-VBT) nanospheres modification of the cotton fabrics provides a novel potential approach to obtain good printing efficiency without affecting the tensile breaking strength of cotton fabrics significantly.

Honeycomb structured porous films from a platinum porphyrin-grafted poly(styrene-co-4-vinylpyridine) copolymer as an optical oxygen sensor

The rational design and realization of revolutionary sensing films for improving the sensitivity and photo-stability of oxygen sensors have been long-standing challenges. We presented a facile approach for the fabrication of honeycomb structured porous films for optical oxygen sensors using a platinum porphyrin-grafted poly(styrene-co-4-vinylpyridine) (PtTFPP-PSVP) copolymer. Honeycomb porous films were prepared by the “Breath figure method”, which provides an efficient and cost-effective method to produce highly ordered honeycomb patterns in PtTFPP-PSVP copolymer films at sub-micrometer dimensions. Importantly, the application of these ordered honeycomb structured porous films as oxygen sensors afford exceptional improvement in sensitivity performance and exhibited 200% higher sensitivity than the solid sensing film owing to the higher accessibility of gas molecules and larger specific surface area. Furthermore, the photo-bleaching of sensor molecules for PtTFPP grafted to PSVP copolymer films could also be effectively alleviated and the sensors’ photo-stability was significantly improved compared with the physically incorporated PtTFPP into the same PSVP copolymer. Interestingly, the remarkably light intensity-changing characteristic of the sensing film under lower O2 partial pressures facilitates convenient identification of O2 concentrations even with the naked eye. We believe that the proposed honeycomb structured porous film could be a promising candidate in various oxygen sensing fields such as nearly anoxic systems, unsteady pressure measurements and unsteady flow visualization, etc. Additionally, the “Breath figure method”, owing to its simplicity, high reproducibility and easy processability, is expected to be readily applicable to a rich variety of other high performance gas sensor devices.

Fabrication of honeycomb textured glass substrate and nanotexturing of zinc oxide front electrode for its application in high efficiency thin film amorphous silicon solar cell

A significant part of broad band sunlight remains unabsorbed in a simple structured amorphous silicon solar cell. This absorption can be enhanced by adopting a light-trapping scheme with the help of a textured front surface and back reflector. For this purpose, honeycomb-type texture was fabricated on a glass surface by chemical etching. A 3 μm×3 μm honeycomb patterned optical-mask was used to create an image-pattern of an etch-mask on the glass surfaces. We used 0.5% hydrofluoric acid (HF) as an etchant solution with an optimized etching time ranging between 25 and 28 min. This single textured glass shows an enhancement in diffused transmission of light. In solar cell application, a 630-nm-thick Al-doped ZnO (AZO) layer was deposited over the textured glass surface. An additional random etching was carried out on the AZO with 1% HF acid solution for 10 s. This results to a double textured AZO superstrate on which solar cells were fabricated. The solar cells show higher short circuit current density to 17.2 mA/cm2. Finally, we obtained photovoltaic conversion efficiency of an optimized solar cell as 10.75% (with the corresponding Jsc as 17.03 mA/cm2).

Mechanical Properties of Additively Manufactured Thick Honeycombs.

Honeycombs resemble the structure of a number of natural and biological materials such as cancellous bone, wood, and cork. Thick honeycomb could be also used for energy absorption applications. Moreover, studying the mechanical behavior of honeycombs under in-plane loading could help understanding the mechanical behavior of more complex 3D tessellated structures such as porous biomaterials. In this paper, we study the mechanical behavior of thick honeycombs made using additive manufacturing techniques that allow for fabrication of honeycombs with arbitrary and precisely controlled thickness. Thick honeycombs with different wall thicknesses were produced from polylactic acid (PLA) using fused deposition modelling, i.e., an additive manufacturing technique. The samples were mechanically tested in-plane under compression to determine their mechanical properties. We also obtained exact analytical solutions for the stiffness matrix of thick hexagonal honeycombs using both Euler-Bernoulli and Timoshenko beam theories. The stiffness matrix was then used to derive analytical relationships that describe the elastic modulus, yield stress, and Poisson’s ratio of thick honeycombs. Finite element models were also built for computational analysis of the mechanical behavior of thick honeycombs under compression. The mechanical properties obtained using our analytical relationships were compared with experimental observations and computational results as well as with analytical solutions available in the literature. It was found that the analytical solutions presented here are in good agreement with experimental and computational results even for very thick honeycombs, whereas the analytical solutions available in the literature show a large deviation from experimental observation, computational results, and our analytical solutions.

Transfer and mechanical behavior of three-dimensional honeycomb fabric

Honeycomb woven fabric is a single layer of fabric exhibiting three-dimensional (3D) cellular shape on both fabric sides due to the combination of periodic straight yarn floats and partial plain weave. In a fabric weave repeat, the triangle shape of increased yarn floats and crossed diagonal woven lines form two inverted pyramidal spaces on the fabric surfaces and a closed internal space. This particular 3D architecture is bound to influence the fabric transfer and mechanical properties. This study investigated these properties for honeycomb weaves experimentally, including air resistance, thermal conductivity, water absorption and vapor transmission rate, bending rigidity, compressional energy and tensile behavior. The typical two-dimensional plain woven fabrics with the same yarns and density were set as references and elastic yarns were considered as a factor of effect on the fabric properties. The measurements by the Kawabata Evaluation System and Instron machine show that the honeycomb woven fabric has enhanced air permeability and water absorption, as well as lower thermal conductivity compared to that of the plain woven fabric. Higher bending rigidity, compressional energy and Young’s modulus are also observed for honeycomb fabrics. The mechanical properties are found to be affected significantly by applying the elastic yarns to the honeycomb woven fabrics.

Altering Sound Absorption in Acoustic Fabrics via Different Honeycomb Cell Patterns

This study shows the result of experiments carried out with different weave patterns introduced in honeycombed acoustic fabrics by varying the cell patterns. The designed honeycomb fabrics with regular triangular, hexagonal and kagome lattice woven patterns are introduced into acoustic fabrics. Acoustic fabrics have sandwiched and porous layers for absorbing different sound waves that convert sound energy into thermal energy, thus allowing a minimal number of waves to penetrate. The sound absorption of the prepared samples is tested twice by using the microphone transfer function method according to international standard ISO 10534-2. The results show that regular hexagonal weave patterns have higher noise reduction coefficient (NRC) values at high frequency sound waves. At low frequencies, the kagome lattice weave pattern in fibreglass has high NRC values.

Preparation of 3D Honeycomb Basalt Fibers Woven Composites

The ordinary loom was used to weave different sections of 3D honeycomb fabrics based on the reasonable design of maps and parameters. It could save production cost to ordinary loom used to weave 3D fabrics and controllability of fabrics was good. The fabric was used as enhance phase, 307-3 polyester resin was used as matrix, and VARTM process was used in making 3D honeycomb basalt fibers woven composites. The composites can overcome the shortcomings such as poor integrity, easy to be cracked, low interlaminar strength and easy to be damaged. This study provides theoretical guidance for 3D textile composites.

Simple Fabrication of Honeycomb- and Pincushion-Structured Films Containing Thermoresponsive Polymers and Their Surface Wettability

Honeycomb- and pincushion-structured films with thermoresponsive functionalities were fabricated by using the self-organization process. Amphiphilic copolymers with thermoresponsive functional groups were successively synthesized and used for preparation of honeycomb- and pincushion-structured films. The honeycomb-structured film shows higher water repellency than a flat film; the superhydrophobic pincushion-structured film shows a drastic contact angle change depending on the film temperature.

Design, Manufacture, and Experimental Analysis of 3D Honeycomb Textile Composites Part I: Design and Manufacture

Textile composites have the advantage of being strong and lightweight over the conventional materials, and thus have found applications in many areas, most notably for materials used in aircraft. In this two-part paper, the engineering design and characterization of 3D honeycomb composites are described on the basis of an attempt to create a novel type of composite material which is extra lightweight and voluminous. The first part of the paper explains the basic concept of 3D honeycomb composites, and the procedure of design and manufacture of 3D honeycomb fabrics and composites. An algorithm has been established to create weaves based on the specification of the 3D honeycomb composite parameters, and this algorithm has been implemented into a computerized procedure which gives accurate solutions for making reinforcing fabrics of this type. It has been demonstrated that 3D honeycomb textile composites with various structural parameters can be engineered. Four groups of honeycomb composites, involving 14 varieties, have been systematically created for the first time in order for the experimental analysis of the honeycomb composites to be carried out. A simple yet effective method for making honeycomb textile composite is described in Part I. The experimental analysis and the results will be described in Part II of this paper.

Fabrication of honeycomb ordered polycarbonate films using water droplets as template

In this paper, honeycomb ordered polycarbonate films were fabricated using water droplets as templates. The influencing factors including humidity, concentration, temperature and the solvent properties are investigated. The results show that the polycarbonate films with highly ordered structures can be obtained from CHCl 3 or CH 2Cl 2 solution under certain condition. The pore size and the patterns can be regulated by the influencing factors. On the other hand, the honeycomb patterns cannot be formed using tetrahydrofuran as solvent. The polycarbonate films with ordered structures have many potential applications in electronics, optics etc.

Porous Polymer Films and Honeycomb Structures Based on Amphiphilic Dendronized Block Copolymers

Fabrication of honeycomb patterned films from our synthesized amphiphilic dendronized block copolymer by "on-solid surface spreading" method and "on-water spreading" method was reported for the first time in this paper. The comparison of the two methods indicated honeycomb-patterned films with smaller size, and larger surface density of micropores can be fabricated by spreading on water but with lower regular arrangement. Furthermore, several influencing factors on the formation of the honeycomb structure and the different morphologies, such as the concentration of the copolymer solution and the relative humidity in the atmosphere and the substrates, were investigated. The results showed that comparably high relative humidity from 80% to 95% was needed, and the mica plate as a spreading substrate was suitable to form orderly porous films for such a copolymer. The best ordered pattern could be formed from the copolymer with concentration of 1.00 mg/mL at the relative humidity of 85% using a mica plate. Besides, strong periodicity, regularity, and a large, defect-free area were notable, which made this structure extremely interesting for applications for templated molecular objects formed via intramolecular metal or metal oxide synthesis.