Hexagonal Tubes Research Articles

Crashworthiness of double-gradient hierarchical multi-cell hexagonal tubes under multi-load impacts

Crashworthiness of double-gradient hierarchical multi-cell hexagonal tubes under multi-load impacts

Hydrogen‐Bonded Organic Frameworks as a Carrier for Nanodrugs with Host–Guest Interaction for Smart Wound Dressing Applications

AbstractThis study introduces surface modification to conventional dressings utilizing adducts of a hydrogen‐bonded organic framework (HOF) with curcumin, curcumin–silver, curcumin‐zinc oxide nanoparticles, and citric acid drugs. Accordingly, eight HOF‐AMs and dressings modified with them were studied. The synthesized structures underwent characterization using various methods, including IR, 1H NMR, XRD, FE‐SEM, and EDX. FE‐SEM results show that the hexagonal morphology is maintained along with the crystal growth in the form of hexagonal tubes. In order to confirm the nanoscale nature of the structures, TEM analysis was conducted specifically for curcumin‐Ag nanoparticles and curcumin–ZnO nanoparticles which confirms the particle size smaller than 50 nm. Knowing the sensitivity of the release of the incorporated substances to temperature and pH, the controlled release of the drugs at two different temperatures (37 °C and 40 °C) and pH levels of 5.5, 7.4, and 9 at the modified dressings was investigated. Investigating the release of HOF‐AMs particles and modified dressings indicates that these products in both cases provide the possibility of drug release in alkaline and acidic pHs. Also, the results showed that increasing the temperature increases the release of curcumin particles in all its types. The modified dressings showed a loading capacity of more than 50 mg g−1.

Enhanced UV photodetector using Mg-doped ZnO sub-micro tube films synthesized through laser-assisted chemical bath growth

This study presents the fabrication of MgxZn(100-X)O thin films (TFs) with Mg concentration levels (x) of 0.5 at%, 1.0 at%, 1.5 at%, and 2.0 at% on glass substrates using the novel laser-assisted chemical bath growth (LACBG) method, aimed at investigating their photo-response for potential UV photodetector applications. Utilizing a continuous wave semiconductor laser with a 444.5 nm wavelength, 1 W power, and 6 min of irradiation, the LACBG method successfully produced high-quality Mg-doped ZnO TFs. These films were deposited on glass substrates coated with silver (Ag) to serve as electrode contacts for constructing a metal-semiconductor-metal (MSM) UV photodetector. The structural, optical, and electrical properties of the TFs were thoroughly analyzed. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to examine the crystal microstructures and surface morphologies, revealing vertically aligned hexagonal symmetrical sub-micro tubes. In contrast, energy dispersive X-ray (EDX) analysis confirmed successful Mg incorporation into the ZnO lattice. UV–visible absorbance spectra indicated a blue shift in the absorption edge and increased band gap energy from 3.24 eV to 3.67 eV with rising Mg content. The UV photodetectors, particularly those with 2.0 at% Mg-doped ZnO TFs, demonstrated significantly enhanced UV responsiveness attributed to optical confinement, high surface-to-volume ratio, and superior structural quality. Performance metrics for the 2.0 at% Mg-doped ZnO TFs included a responsivity of 10.60 A/W, external quantum efficiency of 34.10, specific detectivity of 2.25 × 107 Jones, noise equivalent power of 5.34 × 10−11 W, rise time of 86.9 ms, and decay time of 324.4 ms. These findings underscore the potential of Mg-doped ZnO TFs for high-performance UV photodetection applications. The novelty of this study lies in utilizing LACBG to achieve high-quality Mg-doped ZnO TFs, offering a cost-effective, low-temperature method that enhances UV photodetector performance.

EVALUATION OF TECHNOLOGICAL PLASTICITY OF HIGH BORON CORROSION-RESISTANT STEEL DURING HOT DEFORMATION OF PIPES USED FOR SPENT NUCLEAR FUEL STORAGE

Statement of the problem. The sustainable development of the global nuclear power industry in the future depends on how effectively the problems of radiation safety and nuclear proliferation are addressed. Such problems occur, among other things, at the final stage of the nuclear fuel cycle – spent fuel management. This task is currently on the agenda of both the international community and national governments of countries that develop or intend to develop nuclear energy [1−3]. Today, in connection with ensuring the safety of nuclear energy, boron-containing steels are widely used in the world practice as a material for biological protection and for the manufacture of special equipment parts. This is due to the fact that the B10 isotope in steels provides neutron capture [4]. Hexagonal pipes made of high-boron steel were needed to shield the support cover of the compacted spent fuel storage facility at nuclear power plants. Corrosion-resistant steels alloyed with boron are widely used in the nuclear power industry due to their special nuclear properties. During the operation of nuclear power plants, fuel assemblies that have served their useful life must be stored in special storage facilities using containers – hexagonal tubes made of 04Сr14Ti3B2V steel. To reduce costs during in the construction and operation of NPPs, part of the spent nuclear fuel management should be performed at Ukrainian enterprises. This will provide a significant import substitution effect. To manufacture hexagonal tubes from 04Сr14Ti3B2V steel according to the ingot-hot deformation-profiling-heat treatment scheme, it is necessary to develop the parameters of hot deformation and subsequent technological operations. The use of these pipes in compacted spent fuel storage facilities of NPPs will allow to increase the storage capacity by 2 times, which will give a significant national economic effect Material and methods of research. Material used for the study was steel 04Сr14Ti3B2V (CS-82), smelted using two variants (vacuum-induction – “VI” and vacuum-induction followed by vacuum-arc remelting – (“VD”). Steel grade 04Сr14Ti3B2V belongs to high-alloy, corrosion-resistant ferritic steels with a high boron content of up to 2 %. The method of differential thermal analysis was used to study the phase transformation temperatures in the steel. X-ray diffraction and micro-X-ray spectral analysis were used to assess the phase state. The steel samples were tested for weldability After cooling, the welded samples were subjected to X-ray transmission [5]. Hot twisting tests and mechanical tests at high temperatures were also performed. The macro- and microstructure of the metal was studied. Results. The macro- and microstructure of steel was evaluated depending on the smelting method. The phase composition of the steel was studied. The study of the plastic properties of steel ChS-82 by means of penetration and hot twisting tests showed that the temperature range of maximum plasticity is in a wide range (from 1 025 to 1 150 0C) with a rather low resistance to deformation. During hot deformation in the temperature range of 1 175 0C and above, metal fracture was observed along the grain boundaries at the melting points of the Cr−Fe−B boride phase. The optimal temperature range for hot deformation of steel ChS-82 is 1 000−1 050 ⁰С. Scientific novelty. For corrosion-resistant high boron steel used for spent nuclear fuel storage, the temperature range of hot deformation was selected and the structural and phase composition was estimated, which will allow deforming the metal on the piercing mill and manufacturing pipes.

Energy absorption performance of Kresling origami tubes under impact loading

Thin-walled tubes with an origami design, particularly the Kresling pattern, exhibit superior mechanical properties compared to traditional straight tubes, including a more constant reaction force and predictable deformation. Despite their potential, research on these patterned structures, especially when made from structural materials like metal and tested under dynamic conditions, remains limited. This study investigates the compressive performance of aluminium Kresling origami tubes (KOTs) under quasi-static and impact scenarios (up to 30 m/s) in the axial direction. Results show that increased impact velocity leads to more localized deformation and improved energy absorption metrics. A validated numerical model was used to analyze the influence of hierarchy rotation, sector angles, and loading velocity on mechanical performance. Comparisons with Miura-ori patterned tubes and hexagonal cross-section straight tubes of the same relative density revealed that KOTs have superior energy absorption performance. An empirical model was developed to effectively predict the mean crushing stress of KOTs. In addition. a generative machine learning model was introduced to synthesize a large dataset from initial simulations, providing an efficient and reliable solution for energy absorption analysis in origami structures, addressing the challenge of limited specimen datasets.

Novel twisted hexagonal tubular crystallizer used for thiourea cooling crystallization: Improving crystal qualities

The stirred-tank crystallizer (STC) is the widely used apparatus in industrial crystallization. However, it presents notable challenges, including a broad crystal size distribution (CSD) and fouling. Herein, the twisted hexagonal tube (THT) was employed for thiourea cooling crystallization. The THT exhibited superior heat transfer performance compared to the circular tube (CT) under identical conditions. Furthermore, the THT exhibited longer induction times and wider metastable zone width compared to STC and CT, indicating that the THT can effectively mitigate the nucleation rate. Crystals formed in the THT exhibited elliptical shapes, with a purity of 99.3 % and a target-product (425 μm) proportion of 78 wt%. Thiourea crystallized using the THT met the first-class in China standard HG/T 3454–2013, whereas those crystallized using STC and CT met the second-class standard. Consequently, the THT, as a novel tubular crystallizer, demonstrated considerable potential.

Analyzing Heat Transfer: Experimental and Theoretical Studies on Metal Oxide-Based Binary Nanofluid in Mini Hexagonal Tube Heat Sink

Analyzing Heat Transfer: Experimental and Theoretical Studies on Metal Oxide-Based Binary Nanofluid in Mini Hexagonal Tube Heat Sink

A filling lattice with actively controlled size/shape for energy absorption

This study unveils a groundbreaking development: the chain lattice structure (CLS), a unique lattice with the capability to actively adjust its size and shape for filling diverse thin-walled structures, thereby enhancing their energy absorption characteristics. Traditional lattice structures, known for excellent energy absorption, are constrained by fixed sizes and shapes post-fabrication, limiting their adaptability to various energy-absorbing structures. The CLS introduces a revolutionary lattice structure dynamically modifying dimensions and shape. Employing selective laser sintering (SLS), we craft CLS prototypes using nylon 11 material, followed by rigorous quasi-static compression experiments. The congruence between experimental and simulation analyses validates our model's accuracy. CLS actively adjusts within varying cross-sectional thin-walled square tubes, demonstrating substantial improvements in energy absorption and compression stability compared to empty tubes (ETs). Additionally, CLS adapts to diverse cross-sectional shapes, including circular, hexagonal, and triangular tubes. Comparative assessments reveal significant enhancements in energy absorption and compression stability for CLS-filled tubes. Moreover, the pre-deformed CLS model was filled with different shapes of front rails, and its axial crashworthiness and deformation pattern stability were significantly improved compared with the unfilled front rails. In summary, CLS's flexibility in adjusting to thin-walled structures of varying dimensions and shapes holds immense promise for enhancing their performance across a wide range of applications.

Experimental and numerical investigations on the axial compression performance of precast geopolymer concrete sandwich wall panel

This paper investigated a novel precast concrete sandwich panel (PCSP) which made by the geopolymer concrete and enabled by the glass fiber reinforced polymer (GFRP) hexagonal tube connector. Six precast geopolymer concrete sandwich wall panel (PGCSP) specimens were fabricated and tested under axial compression load. The investigating parameters included the connector spacing, panel height, and panel thickness. The failure mode, axial load capacity, load-axial deflection relationship, and load-concrete strain relationship were studied and discussed. Moreover, two-dimensional (2D) finite-element (FE) analysis was conducted to reproduce the test. Parameter analysis was then performed to modify the axial load capacity formula in the Chinese code GB50010-2010. The results indicated that: all specimens exhibited large eccentric compression failure due to the second-order effect, which was caused by concrete crushing and horizontal cracking in the two wythes, respectively; with the decrease of the connector spacing, the crushing area of the specimens would be enlarged, the out-of-plane lateral deformation would be decreased, and the axial load capacity decreased by 17 % and 42 % when the connector spacing changed from 300 mm to 600 mm and 900 mm, respectively; with the decrease of the panel height and the increase of concrete wythes thickness, the axial load capacity of the specimens almost presented a linear increase; the established 2D FE model and the modified formula effectively reflected the axial load capacity of the specimens.

Crashworthiness analysis of novel bidirectional gradient hierarchical double tubes inspired by the leaf tissue

Inspired by the cross-sectional view of leaf tissue, a bidirectional gradient hierarchical double tube (BGHDT) was proposed and its crashworthiness performance was investigated by finite element simulation. The results indicate that the proposed BGHDT has better energy absorption capacity than the conventional hexagon tube under the same mass condition. The folding wavelength of BGHDT is shorter than that of conventional hexagonal tubes, resulting in a larger number of folds. Compared with conventional hexagon tubes, the energy absorption of BGHDT with 3rd hierarchical level increases by 139.39% and its peak crush force (PCF) decreases by 16.29% at the same mass. Finally, the effects of wall thickness and the number of connecting units on the crashworthiness performance of BGHDT are systematically studied.

Crashworthiness analysis of okra biomimetic corrugated multi-cellular structure

This study introduce an innovation okra biomimetic corrugated multi-cellular Taper tube (OBCMT) designed for the energy absorption, drawing inspiration from the okra, which comprises a Fourier curve wall and X-shaped ribs. Validation is accomplished through quasi-static crushing experiments, ensuring the accuracy of the finite element simulation model. Numerical simulations investigate the influence of critical interaction structural parameters on the performance of the OBCMT, and a theoretical model based on the super folding theory is deduced to predict the mean crushing force of the OBCMT. The result show that the specific energy absorption(SEA) exhibited the heightened sensitivity to the variation of C_height under the same C_R, approximately reached 8.36 kJ/kg which increased by 43.2 % compared to the minimum value in the identical group. Simultaneously, the structure parameters of height coefficient(C_height) and radiu coefficient(C_R) have the most significant impact on the deformation mode of OBCMT. Comparative analysis demonstrates that the OBCMT exhibits the extraordinal crashworthiness compared to the contemporary typical energy absorption structures under identical mass, with the SEA reaching 21.8 kJ/kg. This represents approximately 290.7 %, 205.7 %, 187.9 %, 189.6 %, and 174.4 % relative to the six-cell hexagonal tube (SHT), quadruple-cell circular tube (QCT), multi-cell bicircular tube (MBT), five-cell square tube (FST), and quadruple-cell square tube II (QST_Ⅱ), respectively. This research significantly advances the development of high-performance bionic energy-absorbing structures for crash applications and enhances our comprehension of the biomimetic engineering.

Ionic copolymer-modified hexagonal carbon nitride tube as a high-performance catalyst for regioselective synthesis of hexahydroquinoline frameworks

The conventional structure of carbon nitride materials presents limitations, especially in the catalysis field, attributed to a restricted number of active sites and a low surface area. To address these challenges, we developed a unique design for a mesoporous carbon nitride tube (CNT), which was constructed by incorporating the ionic imidazole-epichlorohydrin copolymer ([IMEP][Cl]) as a template in the fabrication process. The self-assembly behavior of [IMEP][Cl] influences the formation of the melamine-cyanuric acid aggregate (as precursors) through electrostatic forces and polarity, potentially resulting in the creation of a thin-wall CNT with unique pore morphology. Synthesized three-dimensional hollow CNT demonstrated key factors of a high-performance catalyst in terms of high thermal stability (up to 550 °C), good specific surface area (108 m²/g), and significant recoverability (seven runs without a significant decrease in reaction yield). The CNT architecture was employed as a heterogeneous catalyst, and its catalytic efficiency was investigated in the regioselective synthesis of hexahydroquinoline ring systems. Based on the obtained results, CNT shows super-fast synthesis (5 min) of different pharmaceutical quinoline frameworks with exceptional yields (94–98 %) under ultrasound agitations. For the first time, an effective synthesis method is introduced for constructing hollow carbon nitride tubes, utilizing an ionic polymer (produced via chemical crosslinking rather than radical chain polymerization) as a template. This work offers a new viewpoint on improving the catalytic capability of traditional graphitic carbon nitrides through the utilization of ionic copolymers, presenting potential advancements for various technological applications.

Crashworthiness Analysis of Self-Similar Nested Hierarchical Hexagonal Tubes

To enhance the crashworthiness of thin-walled structures, this study proposes a self-similar nested hierarchical hexagonal tube. This innovative design incorporates the hierarchical technique into the structural configuration of hexagonal thin-walled tubes. Numerical analysis, conducted using a validated finite element model, reveals that the proposed self-similar nested hierarchical hexagonal tube (SNHHT) significantly enhances energy absorption compared to traditional hexagonal tubes, maintaining consistent wall thickness and mass conditions. Particularly noteworthy is the improvement in energy absorption indexes under the same mass condition, with SNHHT-4 demonstrating enhancements of up to 76.45% and 86.84% in energy absorption and crushing force efficiency, respectively, while concurrently achieving a 4.11% reduction in initial peak crash force. Subsequently, a parametric study exploring wall thickness, shape factor, and various rib thicknesses was performed to investigate structural crashworthiness. Finally, employing the simplified super-folded element method, the theoretical formulation of mean crushing force was derived, and its accuracy was validated through numerical simulations.

Non-dimensional parameters governing the crashworthy performance of tubes with complex cross-sections

The crashworthiness of thin-walled tubes with various designs under axial compression has been extensively investigated. Despite this, the parameters that govern the performance of tubes and can be applied across different cross-sectional topologies have not hitherto been available. In this paper, twenty types of thin-walled tubes with different cross-sectional shapes (e.g., multi-celled, bi-tubular, and hierarchical square, hexagonal and circular tubes) have been numerically simulated and theoretically analysed. All the tubes are made from identical material and possess identical apparent cross-sectional area, height and mass. Six indicators are employed to characterise the crashworthiness performance of the tubes. Two novel non-dimensional indices, the geometric complexity index (RG) which is the ratio of the total length of solid segments in the cross-section of a tube to that of the square tube, and the topological index (RT) which is the non-dimensional coefficient in the expression of plastic energy dissipation closely related to the types and numbers of the wall junctions in cross-section, are identified for the first time. Both the indices RG and RT are used in a regression analysis of the indicators that characterise the crashworthiness of the tubes. The results reveal that the crashworthiness indicators of the tubes, the mean crushing force (MCF), the specific energy absorption (SEA) and the effectiveness of energy absorption (EEA) do not exclusively vary with RG. Instead, MCF, SEA and EEA are all properly fitted by linear relations with a single non-dimensional parameter ω, which is a simple function of RG and RT, i.e., ω=RT/RG. Increasing the magnitude of ω ultimately improves the crashworthiness of tubes, including enhanced specific energy absorption, effectiveness of energy absorption and crushing force efficiency, while reducing the force fluctuation during the crushing process. Of the tubes studied, the edge-based hierarchical circular tube (EH_C) has the highest SEA of 22.17 J/g, which is 133%, 60% and 41% larger than that of single-celled square, hexagonal and circular tubes, respectively.

Li/La and Cu modified ZnO semiconductor: Highly boosted of dielectric and sunlight-treatment of thiamethoxam and brilliant green contaminants

Solving the global environmental problem which related to the dissolved organic pollutants into water systems is an essential issue for human-health and aquatic life. This study represents the simple synthesis of new Li/La and Cu modified ZnO compositions as active photocatalysts and proper dielectric materials for electrical energy storage devices. The synthesized powders have one phase nature with hexagonal lattice indexed to ZnO structure. The field emission scanning electron microscopy (FESEM) clearly showed that (Li, La) modified ZnO powder consist of a mixture of particles having open hexagonal tube and spherical shapes. The FESEM picture of (Li, Cu, La) modified ZnO powder revealed lumps like cabbage shape mainly composed of pieces like sheets or papers. The purity and elemental composition were also verified by energy dispersive spectroscopy (EDS) analysis. The addition of (Li, La) and (Li, Cu, La) ions to ZnO semiconductor extremely improved the dielectric constant which is a benefit for application in solid state energy storage systems. (Li, Cu, La) modified ZnO sample is a suitable catalyst for removal of organic waste owing to its high response to visible light spectrum with measured band gap energy of 2.76 eV. The synergistic effect of Li+, Cu2+ and La3+ dopants induced high visible light photodegradation activities against thiamethoxam pesticide and brilliant green dye with measured efficiencies of 92 and 96 % after reaction time of 50 min, respectively. The high stability and mineralization properties of (Li, Cu, La) modified ZnO catalyst leads to the conclusion that this composition has a potential use in wastewater treatment.

Blast protection of vehicle underside through fireball extinction by water

The aim of this research is the study of blast mitigation using water within the context of underbelly vehicle protection. The interaction of a shock wave generated by an explosive charge, with a relatively small quantity of water, in a vehicle underside environment has been investigated. The simulant vehicle underside was almost a cube with open side faces and a volume of about 7 m3. The deformation of target plates bolted onto the vehicle simulant floor was assessed. These were either unprotected or protected by plastic bags filled with water. Three quantities of water were tested: 4, 10 and 15 kg. Both the residual deformation of the test plate and the maximum dynamic deformation were assessed. This latter was obtained by the squeezing of a hexagonal aluminum tube and by digital image correlation. The results showed that both deformations, residual and dynamic, of a 5 mm thick steel plate decreased when it was protected by water. Water was more effective in reducing deformation parameters than using an equivalent mass of steel. The protective effect of water was also tested with a 1 kg TNT equivalent charge in a steel-pot on a 5 mm thick armor plate. In this case as well, it could be shown that for both deformations – residual and dynamic - the armor plate was less deformed when protected by water.

Grain boundary localized damage in hexagonal titanium

Fully recrystallized hexagonal titanium tubes were processed through industrial cold pilgering. Two different pilgering sequences, generalized as case I and case II, were used. Both pilgering processes involved identical effective pilgering strains, but they had different strain modes. Case I, for example, used a pilgering pass with more (∼2.5 times) deviation from ideal plane strain compression. Both fully pilgered tubes showed similar grain fragmentations, misorientations, and tensile properties. However, their crystallographic textures and residual stresses significantly differed. Further, the inner surfaces of case II tube showed localized intergranular damage. Direct experimental observations, combining interrupted tensile tests with high-resolution electron backscattered diffraction (HR-EBSD), revealed that the damage originated only at select grain boundaries. In particular, dislocation pile-up plus stress localization appeared to be responsible for the grain boundary damage initiation. Microstructurally, this originated from the relative difference in elastic moduli between neighboring grains and the Luster-Morris parameter, representing slip transfer across the grain boundary.

Energy absorption characteristics of corrugated hexagonal gradient hierarchical tube

Energy absorption characteristics of corrugated hexagonal gradient hierarchical tube

Energy absorption characteristics of asymmetric tree-like fractal gradient hierarchical structures

Bionic gradient hierarchy design as a design method that can effectively improve the structural crashworthiness, but its current research only focuses on the symmetric fractal method related to the discussion. In view of this, this article carries out the innovative design and research of asymmetric tree-like fractal gradient hierarchy structure (ATFGHS). The results show that the crashworthiness of the structure can be greatly improved by using the asymmetric tree-like fractal gradient hierarchy design method. Specifically, the ATFGHS-P3 showed a 98% increase in energy absorption (EA), a 98% increase in specific energy absorption (SEA), and an 84% increase in crush force efficiency (CFE) compared to a conventional hexagonal multicellular tube. The completion of this study provides valuable insights into the design and optimization of novel lightweight thin-walled energy-absorbing structures.

Numerical investigation of an amalgamation of two phase change materials thermal energy storage system

In the last three decades, many researchers have published their findings on the storage of thermal energy using various phase transition materials (both organic and non-organic). One of their goals was to have a higher heat storage capacity with a shorter heat charging cycle for thermal energy storage. This study looked into a floating capsule thermal energy storage system (TESS). A number of spherical capsules filled with beeswax were placed in a paraffin-filled cylindrical shell. With heat transfer fluid flowing through three hexagonal tubes arranged at 120° inside the TESS core, the two phase change materials (beeswax with a thermal conductivity of 0.25 W/mK and paraffin with a thermal conductivity of 0.23 W/mK) were charged and discharged. For the proposed TESS, a mathematical model was created and utilised to forecast thermal energy storage capacity and charging/discharge times for various configurations. In TESS, a 70–30% mixture of the two PCMs results in a 21.5 percent increase in heat storage capacity when beeswax alone is used, and an 8.4 percent decrease in storage capacity when paraffin alone is used. For a heat storage capacity of 7300 kJ, the model estimates charging and discharging times of around 2.6 and 3.2 hours, respectively.