Tubular Shell Research Articles

Developing lightweight steel profile and lattice polymeric core composite for structural use

Embracing modular construction, advanced materials, and digital technologies can drive innovation in the building industry, address global material consumption challenges, and foster a sustainable future. This paper presents the innovative concept of the lightweight hybrid lattice-filled profile (HLFP) for modular engineering, which combines a thin-walled steel tubular shell and additively manufactured lattice structure (AMLS) as a lightweight core. The AMLS achieves precise shape, internal structure, and stiffness, ensuring the decided structural performance with minimum materials. This study provides a theoretical model of HLFP, focusing on adhesively bonded AMLS. The experimental verification demonstrates that the adhesively bonded AMLS ensures an additional 130 % during the elastic stage and, even after partial debonding, maintains 50 % of the mechanical resistance compared to the theoretical sum of the HLFP components. Reducing the infill density does not severely affect the load-bearing capacity of the HLFP—a fourfold decrease of the ALMS density (from 10 % to 2.5 %) results in a 20 % decrease in the ultimate load. However, the sparse lattice structure alters the failure mechanism of ALMS, changing it from favorable ductile to dangerous brittle and determining the object for further optimization. The parametric study reveals the efficiency of the theoretical model for predicting the load-bearing capacity of HLFP. However, the finite element model developed in this study should be used for a more detailed analysis of the HLFP's structural behavior.

Design and optimization of a corrugated tubular shell structure based on triply periodic minimal surface

A novel corrugated tubular shell structure based on triply periodic minimal surface (TPMS) was proposed in this study. The initial diamond tubular thin-walled structure (D-TTS) and corrugated tubular thin-walled structures (C-TTS) model were designed and then fabricated using selective laser melting (SLM). The 3D-printed model deviation distribution was obtained by using computed tomography (CT) scanning. Compressive behaviors and energy absorption capacity of the tubular thin-walled structures were investigated using experimental and numerical methods. To obtain optimal designs of C-TTS, a surrogate model was established and multi-objective optimization was carried out. The maximal specific energy absorption (SEA) and the minimal peak crushing force (PCF) were obtained by non-dominated sorting genetic algorithm II (NSGA-II). Compared with the initial D-TTS, maximal SEA is increased by 9.34%, and the minimal PCF is reduced by 58.96%. This structure enhances the diversity of tubular structure designs while also inspiring innovative approaches for developing energy absorption devices and structures utilizing TPMS.

Comprehensive evaluation on the performance of a novel solar seawater desalination system

To address the scarcity of freshwater in isolated coastal areas without electricity, a novel solar seawater desalination system consisting of an efficient evacuated U-tube solar collector and hydrophilic modified tubular still is theoretically proposed. Based on the laws of thermodynamics, mathematical expressions for the freshwater yield rate, exergy efficiency and energy efficiency of the solar seawater desalination system are derived and used to predict the performance features. Under a solar irradiation intensity of 1000 W m−2, the freshwater yield rate, exergy efficiency and energy efficiency are, respectively, 2.75 kg m−2 h−1, 5.17 %, and 46.58 %, showing a bright prospect. To further enhance the performance, extensive parametric studies are conducted. Results indicate that increasing the working fluid flow rate, environment temperature, while decreasing the inlet water temperature of evacuated U-tube solar collector, wind velocity, as well as the hydrophilic modified tubular still tubular shell diameter and length, have a positive impact on the performance of solar seawater desalination system. Local sensitivity analyses further reveal that the wind velocity is the most sensitive variable, while the working fluid flow rate is the least sensitive variable. Based on the weather data from Ningbo, China, case studies reveal that, under realistic solar irradiation intensities of 964.25 W m−2 and 248.67 W m−2, the system demonstrates a freshwater yield rate, exergy efficiency, and energy efficiency of 2.62 kg m−2 h−1, 5.06 %, 46.18 %, and 0.45 kg m−2 h−1, 1.72 %, 31.21 %, respectively. Over a 21-year period (2002–2022), case studies demonstrate that the solar seawater desalination system can achieve an average annual freshwater yield rate of 1302.78 kg m−2.

Performance prediction and regulation of a tubular solid oxide fuel cell and hydrophilic modified tubular still hybrid system for electricity and freshwater cogeneration

Tubular solid oxide fuel cells (TSOFCs) are a promising technology for electricity generation; however, they also generate high-temperature waste heat, leading to reduced efficiency and energy wastage. To address this challenge and unlock the full potential, a novel geometry-matching hybrid system incorporating methane reforming TSOFC and hydrophilic modified tubular still (HMTS) is proposed and modelled. Considering various irreversible losses, vital performance indicators including power output, energy efficiency and exergy efficiency are firstly derived, through which comprehensive thermodynamic performance features of the TSOFC/HMTS hybrid system are predicted. The proposed system design demonstrates a significant advantage by achieving a maximum output power density that is 99.7 % higher and a corresponding energy efficiency that is 57.3 % higher compared to the standalone TSOFC. Extensive parametric analyses reveal that raising the operating temperature or stream/carbon ratio positively enhances the system's performance. Conversely, increasing electrode tortuosity, electrolyte thickness, wind velocity, or tubular shell diameter negatively degrades the system's performance. In addition, the anode thickness is an optimizable parameter. Local sensitivity analyses identify that the operation temperature and electrode tortuosity are, respectively, the most and least sensitive parameters for performance regulation. The findings make a significant step forward in the field of sustainable and innovative energy solutions.

Effect of impurities on charge and heat transport in tubular nanowires

We calculate the charge and heat currents carried by electrons, originating from a temperature gradient and a chemical potential difference between the two ends of tubular nanowires with different geometries of the cross-sectional areas: circular, square, triangular, and hexagonal. We consider nanowires based on InAs semiconductor material, and use the Landauer-Büttiker approach to calculate the transport quantities. We include impurities in the form of delta scatterers and compare their effect for different geometries. The results depend on the quantum localization of the electrons along the edges of the tubular prismatic shell. For example, the effect of impurities on the charge and heat transport is weaker in the triangular shell than in the hexagonal shell, and the thermoelectric current in the triangular case is several times larger than in the hexagonal case, for the same temperature gradient.

Numerical analysis of tubular solar still with rectangular and cylindrical troughs for water production under vacuum

This study compares and contrasts the desalination efficiency of tubular solar still using cylindrical and rectangular troughs when operating under a vacuum. For this, a two-dimensional code was created using the Comsol Multiphysics. The mass and heat transfer, inside the tubular solar still with the two different types of troughs, was simulated parametrically. The effect of the radius of the cylindrical trough, the square rib of the rectangular trough and the vertical elevation of the trough on heat and mass transfer were investigated at the same volume of seawater introduced initially. The numerical results revealed that the efficiency of the water productivity using cylindrical trough is significantly better than with rectangular trough when it is placed in the middle of the tubular shell. The opposite case of the 2 types of troughs is established when the trough advances towards the upper side of the glass cover where the condensation occurs.

Stretchable Conductive Tubular Composites Based on Braided Carbon Nanotube Yarns with an Elastomer Matrix.

We report an innovative approach to creating stretchable conductive materials composed of a tubular shell made from braided carbon nanotube yarns (CNTYs) embedded in an elastomeric matrix. For stretchable electronics, both mechanical properties and electrical conductivities are of interest. Consequently, both the mechanical behavior and electrical conductivities under large deformations were investigated. A new hyperelastic composite model was developed to predict the large deformation response to applied stress for a braid in a tubular elastomer composite. The composite demonstrated a hyperelastic response due to the architecture of the braid, and the behavior was affected by the braiding angle, braid modulus, and volume fraction of fibers. The elastomer matrix was considered a neo-Hookean material and represented by the Yeoh model. An interaction parameter was proposed to account for the effect of the elastomer/braid cooperative restriction as observed in experimental and calculated results. This novel approach enabled the determination of the constitutive behavior of the composite in large deformations (>150%), taking into account the elastomer and yarn properties and braid configurations. The model exhibited good agreement with the experimental results. As the CNTYs are conductive, a stretchable conductive composite was obtained having a resistivity of 5.01 × 10-4 and 5.67 × 10-5 Ω·cm for the 1-ply and 4-ply composites, respectively. The resistivity remained constant through cyclic loading under large deformations in tension until mechanical failure. The material has potential for use in stretchable electronics applications.

The Curvature – Energy Relations in Buckling Analysis of Tubular Wind Turbine Towers

AbstractA former study on wind turbine tower collapse incidences throughout the past 40 years revealed that among the various types the buckling failure was the most catastrophic as led to collapse of tubular tower shell structures. As the modern harvesting of wind energy is usually performed by wind turbine towers being cylindrical shells of thin walls, the need of thorough investigation of the buckling behaviour of shell structures operating under extreme environmental actions is obvious. The present paper addresses such knowledge gap through the study of a series of 100 numerical models underpinned by the well‐established Riks Method for buckling analysis. The method enables the scrutiny of tower shell elements under axial load and bending moment. Within the proposed framework of curvature–energy analysis, the energy stored within an imperfect shell structure is expressed and quantified through cross‐section diaphragms and symbolic lines, covering pre‐buckling, transient stage, and post‐buckling performance close to the bifurcation point. The analysis unveils changes of local surface curvature and energy flows with multiple longitudinal and circumferential wavenumbers taking place during the pre‐buckling process. Wavenumbers and curvature changes induce the energy magnitude jumping over to the adjacent buckling eigenmodes. Furthermore, the mode jumping sees a faster and more convergence result with higher bending moments. The diversity of the final buckling mode largely determined by the variance of shell geometry, compression–bending ratio and boundary conditions.

Gradient Hierarchically Porous Structure for Rapid Capillary-Assisted Catalysis.

Synthesis of hierarchically porous structures with uniform spatial gradient and structure reinforcement effect still remains a great challenge. Herein, we report the synthesis of zeolite@mesoporous silica core-shell nanospheres (ZeoA@MesoS) with a gradient porous structure through a micellar dynamic assembly strategy. In this case, we find that the size of composite micelles can be dynamically changed with the increase of swelling agents, which in situ act as the building blocks for the modular assembly of gradient mesostructures. The ZeoA@MesoS nanospheres are highly dispersed in solvents with uniform micropores in the inner core and a gradient tubular mesopore shell. As a nanoreactor, such hierarchically gradient porous structures enable the capillary-directed fast mass transfer from the solutions to inner active sites. As a result, the ZeoA@MesoS catalysts deliver a fabulous catalytic yield of ∼75% on the esterification of long-chain carboxylic palmitic acids and high stability even toward water interference, which can be well trapped by the ZeoA core, pushing forward the chemical equilibrium. Moreover, a very remarkable catalytic conversion on the C-H arylation reaction of large N-methylindole is achieved (∼98%) by a Pd-immobilized ZeoA@MesoS catalyst. The water tolerance feature gives a notable enhancement of 26% in catalytic yield compared to the Pd-dendritic mesoporous silica without the zeolite core.

Effect of geometric irregularities induced during manufacturing of a crash-box on its crashworthiness performance

Imperfections associated with the geometric features of any component are inevitable during its fabrication and some of those can even have a drastic impact on its functionalities. One such case arises while fabricating one of the essential passive safety devices in an automobile called as 'thin-walled collapsible energy absorbers'. Thin-walled collapsible energy absorbers also known as crash-boxes are the tubular shell structures located in between the bumper and front side rails of an automobile. Crash-boxes collapse in a stable progressive manner to absorb kinetic energy of an external impact to protect the occupants during an accident. Tubular crash-boxes are generally manufactured by extrusion. Geometric imperfections in the form of irregularities in the shell thickness may be induced during extrusion of the crash-boxes. The present study aims to gauge the effects of irregularities present in the thickness of the extruded crash-box on it’s crashworthiness performance, numerically. Cylindrical aluminium alloy tubes are modelled as crash-boxes using ABAQUS/Explicit. The irregularities in the thickness of the tubular crash-box are modelled with the help of three different imperfect models. In every imperfect model, maximum variation in the thickness is kept within the tolerance value, provided by the standards DIN EN-755-9. The quasi-static axial collapse of these ‘imperfect’ cylindrical tubes is simulated and their crashworthiness performance indicators are compared with those of an ‘ideal’ circular crash-box. It is seen that the energy absorption and the mean crushing force reduced drastically due to these shell thickness irregularities in comparison to the ideal model. It is also observed that the mode of collapse of the circular tube changed from axi-symmetric concertina mode to the diamond mode due to irregularities in their thickness. Such significant change in the crashworthiness performance of crash-box may lead to a huge disaster in terms of human lives. Hence, crash-boxes should be fabricated carefully with more tight geometric and dimensional tolerances.

Holdfasts of Sphenothallus (Cnidaria) from the early Silurian of western North Greenland (Laurentia)

ABSTRACT Well-preserved holdfasts and early growth stages of the tubular cnidarian Sphenothallus are described from the early Silurian (Llandovery Series) of Washington Land, North Greenland. The diameter of the holdfast is determined by the formation of a basal disc attached to the substrate, upon which the initially conical, but subsequently tubular shell is formed. The characteristic opposing longitudinal thickenings are developed at each angular margin as the initially circular tube acquires an elliptical form.

Gigantic scaphopods (Mollusca) from the Permian Akasaka Limestone, central Japan

AbstractPaleozoic scaphopods are among the most poorly known mollusks because of their featureless tubular shell morphology and fragmentary preservation. An apical orifice at the posterior end of a conch is a diagnostic character of Scaphopoda that distinguishes them from other groups of animals that produce similar calcareous tubes, but this structure is rarely preserved. A rich molluscan fauna from the Permian Akasaka Limestone in central Japan includes scaphopod shells, and past studies have reported four species, all of which were based on fragmentary specimens. This study recognizes six species in the Akasaka Limestone mainly on the basis of museum/institution collections, and a new genus (Minodentalium) and three species (Prodentalium onoi,M.hayasakai, andM.okumurai) are described, two known species (P.akasakensisandP.neornatum) are redescribed in more detail, and one species (Prodentaliumsp.) is described under open nomenclature. The following eight known species are allocated to the new genusMinodentalium:Plagioglypta furcataWaterhouse, 1980;Pl.girtyiKnight, 1940;Pl.subannulataEaston, 1962;Dentalium ingensDe Koninck, 1843;D. meekianumGeinitz, 1866;Pl.prosseriMorningstar, 1922;Dentalium priscumMünster in Goldfuss, 1842; andD.herculeumDe Koninck, 1863. All the species, except forM.hayasakai, are gigantic, reaching 200 mm or more in length. The species richness is the greatest known from a single locality/formation worldwide.UUID:http://zoobank.org/35405b9d-3ba7-40bf-87c5-3f2b550b1a6d

Calculation of the parameters of the magnetic-pulse connection of the tip and multi-wire cable

The main provisions of the calculation method and the results of numerical modeling of the process of compression of the tubular shell of the tip onto a stranded wire by the pressure of a pulsed magnetic field are presented. The analysis of the features of the deformation process at different intensity of force loading is carried out. The rational modes of loading and the necessary conditions for minimizing the specific discharge energy while ensuring a high assembly density are determined.

Software package of mathematical modeling and structure for solving the dynamics problems of structurally-inhomogeneous shell structures

On the basis of the principle of modularity, an algorithm and software package for dynamic calculation of structurally-inhomogeneous multiply connected shell units that are the elements of hydro-technical structures are developed in the paper. The purpose of the module is to carry out certain transformations of the initial (source) information into a unique result. The development prospects of construction of various hydro-technical structures, aircraft, rocket and space machinery, shipbuilding, chemical engineering and many other branches of modern technology are characterized by a complication of design decisions in projecting and calculation of objects that present multiply connected spatial shell structures subjected to static and dynamic effects. Multiply connected structures, (such as hydro-technical structures), usually include a wide range of elastic and visco-elastic deformable elements with significantly different rheological properties in the form of blocks of plate stacks, tubular, cylindrical and prismatic shell structures of complex geometry, with attached masses, various types of reinforcement, supports, containing a large number of elastic and visco-elastic couplings with significantly different functions of heredity. Obviously, the search for exact analytical solutions to dynamic problems for structurally inhomogeneous visco-elastic shell structures is doomed to failure, the only possibility of engineering implementation is to build numerical and numerical-analytical algorithms with the subsequent use of modern computers. The solution to dynamic problems involves a numerical simulation of the stress-strain state (SSS) of the structures under consideration.

Thermodynamic Analysis for Different Type of Heat Exchangers

Bu çalışmada çift borulu ısı değiştirici, gövde borulu ısı değiştirici ve plakalı ısı değiştirici için termodinamik analiz yapılmıştır. Bu 3 tip ısı değiştiricinin performansları deneysel olarak test edilmiştir. Isı değiştirici test bölgesinin soğuk su debisi 1.5 L/dk değerinde sabit tutulurken sıcak su debisi 0.8 L/dk, 1.6 L/dk ve 2.4 L/dk değerlerinde değiştirilmiştir. Sıcak su beslemesi 50°C, 60°C ve 70°C olarak seçilmiştir. Deneyler hem karşıt akışlı hem de paralel akışlı olarak yapılmıştır. Yapılan deneyler neticesinde sıcaklığın ve debinin artışı ile ısı değiştiriciden alınan gücün arttığı tespit edilmiştir. Birim alandan elde edilen ısı transferi miktarı değerinin en yüksek olduğu ısı değiştirici tipi gövde borulu ısı değiştirici iken en düşük performansı çift borulu ısı değiştirici tipi göstermiştir.

EFFECTS OF WELDING PARAMETERS, TIME INTERVAL AND PREHEATING ON RESIDUAL STRESS AND DISTORTION OF JOINING ST52 STIFFENER RING IN AN AISI 4130 TUBULAR SHELL

Stiffener rings and stringers are used commonly in offshore and aerospace structures. Welding the stiffener to the structure causes the appearance of residual stress and distortion that leads to short-term and long-term negative effects. Residual stress and distortion of welding have destructive effects such as deformation, brittle fracture, and fatigue of the welded structures. This paper aims to investigate the effects of preheating, time interval and welding parameters such as welding current and speed on residual stress and distortion of joining an ST52-3N (DIN 1.0570) T-shape stiffener ring to an AISI 4130 (DIN 1.7218) thin-walled tubular shell by eleven pairs of welding line in both sides of the ring by means of finite element method (FEM). Results in tangent (longitudinal), axial and radial directions have been compared and the best welding methods proposed. After the comparison of the results, simultaneous welding both sides of the ring with preheating presented as the best method with less distortion and residual stresses among the studied conditions. The correctness of the FEM confirmed by the validation of the results.

The characteristics of combustion reactions involving thermite under different shell materials.

To study the influence of tubular shell materials on the combustion of thermite, numerical simulations and experimental comparisons of the combustion efficiencies of thermite with PVC and stainless-steel shell materials were carried out. The thermal conductivity coefficient and heat radiation correlation coefficient of a shell material directly affect heat transfer during a heat-transfer process, that is, the lower the thermal conductivity and the higher the heat radiation reflectance coefficient, the lower the heat flux through the material and the less heat is lost. The experimental results show that compared with the stainless-steel tube material, the temperature distribution of thermite is more concentrated and the effect of melting through a steel target plate is more apparent when PVC is used as the shell material. The simulation results show that thermite in the PVC shell can produce a higher temperature, reaching 2200 °C at the loading port and 1700 °C on the steel target plate, which is maintained for 0.9 s. However, the corresponding maximum temperatures for the stainless-steel shell are only 2000 °C and 1500 °C, not yet reaching the melting point of the steel plate. The simulation results are consistent with the experimental phenomena. This work is of great significance for improving the design of thermite shells, enhancing performance, and guiding future combustion process research.

Three-effect tubular solar desalination system with vacuum operation under actual weather conditions

Solar still is an environmentally friendly technology to mitigate water scarcity in remote area. However, the high cost and low efficiency limits its application. To this end, this study presents a novel three effects tubular solar still (TSS) with greatly improved productivity. This still features a cascade feed design and vacuum operation system, and consists of three enveloped distillation chambers, where each chamber comprises a water trough and a tubular shell. A prototype was fabricated and tested in an experiment conducted over four sunny days in Chengdu, China. The prototype TSS was powered by an evacuated heat pipe solar collector. The freshwater yield of the still was measured at four operating pressures: 95 (local atmospheric), 60, 40, and 20 kPa. Both the operating temperature and the temperature difference between the three chambers decreased when the operating pressure was reduced. The freshwater yields were 3.27, 6.323, 7.056, and 4.287 kg/d, respectively, with energy utilisation efficiencies of 0.77, 1.28, 1.39, and 0.88, respectively. The best overall performance was seen at an operating pressure of 40 kPa. At 20 kPa, freshwater yield and energy utilisation efficiencies were relatively low because of heat transfer deterioration on the outer shell at such low pressure. Based on the experimental results, the optimum operating pressure for the small-scale solar still was determined to be 40–60 kPa.

Morphology of cylindrical cell sheets with embedded contractile ring

The behavior of large deformations of cellular tissues is usually affected by the local properties of cells and their interactions, resulting in folding which acts as an important role in the embryonic development, as well as growing and spreading of a tumor, which can rapidly promote the stereo complexity of the architecture of the tissues. In the present study, a cylindrical vertex model is constructed to explore the morphology of the tubular cell sheets subject to an embedded contractile ring. It is found that an inner region of the contractile ring in equilibrium will protrude from the tube wall, and it will suddenly collapse when the contractile strength exceeds a threshold, indicating the occurrence of a bifurcation. These results on the effect of embedded contraction in the tubular shell are quite different from the planar cases, which can reveal the importance of the interaction between the geometric and material non-linearity in cylindrical geometry. The dependence of the large deformation on the bending modulus parameters and contraction strength is also analyzed for the cylindrical cell shell.

Encapsulating lithium and sodium inside amorphous carbon nanotubes through gold-seeded growth

Metallic lithium promises the ultimate anode material for building next-generation Li batteries, though some fundamental hurdles remain unsolved. Li growth induced by hetero particles/atoms has recently emerged as a highly efficient route enabling spatial-control and dendrite-free Li deposition on anode hosts. However, the detailed mechanism of Li nucleation and its interaction with heterogeneous seeds are largely unknown. Herein, we investigate this issue by visualizing Au-seeded Li nucleation processes that guide Li deposition inside the one-dimensional hollow space of individual amorphous carbon nanotubes by in-situ transmission electron microscopy. A reversible two-step conversion process during Au–Li alloying/dealloying reactions is revealed, suggesting that the formation of Li3Au plays the actual role in inducing Li nucleation. We propose a front-growth scenario to explain the spatially confined Li growth and stripping kinetic behaviors, which involves the mass addition and removal at the deposition front through ion diffusion along the tubular carbon shell. As a comparison, nanotubes without gold seeds inside exhibit uncontrolled dendrite-like Li growth outside the carbon shell. We further demonstrate that Au-seed growth can be successful in encapsulating sodium metal for the first time. These findings provide mechanistic insights into heterogeneous seeded Li/Na nucleation and space-confined deposition for design of high-performance battery anodes.