Hollow Cylindrical Tubes Research Articles

Experimental investigation behavior of hollow cylindrical composite tubes under axial compression

Experimental investigation behavior of hollow cylindrical composite tubes under axial compression

Experimental examination of the axial compression conduct of filament-wound cylindrical composite tubes at different wall thicknesses and orientation angles

This study presents the results of experimental research on the behavior and stretching of hollow cylindrical epoxy tubes made of glass, carbon, and kevlar fibers subjected to axial compression load. Hollow cylindrical tubes were fabricated by fiber winding method using glass, carbon, and kevlar fiber-reinforced composite materials. In this study, hollow cylindrical composite tubes with constant outer (Ø17 millimeters), two different inner diameters (Ø12 and Ø13 millimeters; 2 ve 2,5 millimeters wall thickness), and 80 millimeters in height. Experimental research was carried out for two dissimilar wall thicknesses and four fiber orientation angles. The compressive strengths of all samples were investigated experimentally by applying loads in the axial direction. Twenty-four configurations of composite specimens were fabricated (three reinforcement materials, four winding angles, and two wall thicknesses) to research the impact of axial compression stress. Experimental results revealed that polymer reinforcement material, fiber winding angle, and wall thickness have a significant impact on the compressive stress of cylindrical composite tubes as a result of applied load in the axial direction. The conclusions show that the compressive stress of all reinforcement rises as the orientation angle and wall thickness increase under an axial compression load, and the compressive stress reaches a maximum when the orientation angle is 90° under an axial compression load. It was observed that the axial compressive stress was highest in glass/epoxy samples with 217 MPa, followed by carbon/epoxy samples with 173 MPa and kevlar/epoxy samples with 145 MPa, respectively. The axial compressive stress of all samples was highest at a 90° orientation angle and lowest at a 15° orientation angle. were found to have low values. It was observed that the axial compressive stress value increased in all reinforcement materials as the wall thickness increased.
 *CRITICAL: Do Not Use Symbols, Special Characters, Footnotes, or Math in Paper Title or Abstract.

Effect of process parameters on the ductile failure behavior of flow forming process

Flow forming is a metal forming technique used to manufacture hollow cylindrical tubes with favorable mechanical properties and high surface finish quality. The current work is concerned with the effect of process parameters on ductile failure during the forming process. The process is simulated using commercial finite element solver Abaqus/Explicit, and a user defined field subroutine is developed for the implementation of damage into the finite element framework. Johnson-Cook plasticity model is used to define the constitutive behavior of 4340 steel alloy. Modified Mohr-Coulomb damage model is utilized, and it is extended to include temperature and strain rate effects. The model parameters are adopted from the literature. The effect of temperature on damage evolution is studied through three different modelling approaches. Incorporation of temperature related parameters into the constitutive framework changes both the maximum damage values and distribution of damage through the thickness. Furthermore, the effect of roller feed rate and revolution speed on damage is examined. It is concluded that the feed rate has a stronger influence on damage evolution than roller revolution speed. Increasing feed rate or revolution speed results in higher damage levels. However, under a constant ratio of feed rate to revolution speed, the damage is found to be insusceptible to increase in feed rate.

Experimental investigation of the crush performance of prepreg platelet molding compound tubes

This work presents an experimental study characterizing the crush performance of hollow cylindrical tubes made with prepreg platelet molding compound (PPMC). PPMC is a composite material system that uses platelets from chopped and slit unidirectional prepreg as the basis for a molding compound. This material system has a higher fiber volume fraction and better mechanical properties than traditional short fiber systems and can be molded into complex geometries unlike continuous fiber systems. As such, this material system shows promise for use with complex structural members in vehicles. The failure morphology and specific energy absorption of the material are evaluated with different thickness-to-diameter geometries and test speeds. In addition, this work investigates how PPMC components compare to traditional continuous fiber components and finds that PPMC performs as well as continuous fiber layups with similar effective laminate stiffnesses.

MODERN ASPECTS OF THE USE OF NERVE CONDUCTORS IN PERIPHERAL NERVOUS SYSTEM INJURY

Peripheral nerve injuries account for 4 % of all injuries, and the consequences of trauma are a major medical and social problem, since they are characterized by a significant and long-term decline in limb function, and a high level of disability in patients. According to our data, up to 40% of patients sought specialized care for more than 6 months after the injury, and 19.9% were treated conservatively for an unreasonably long period of time. It led to an increase in the portion of unsatisfactory treatment results, since the prognosis of the further functional and useful degree of nerve recovery worsens with increasing time after injury. The main objective was to select the optimal option of biocompatible material for implementation in practice in case of traumatic peripheral nerve damage. Materials and methods. The analysis of medical literature for 2015–2020 was conducted. First of all, it should be noted that modern non-biological resorbable tubes are made of polyglycolic and polylactic acids. Non-resorbable tubes, including silicone, have shown undesirable effects, including axon compression during regeneration and the reaction of a fibrous foreign body. Hollow cylindrical tubes can be manufactured in several ways, such as electrospinning, crosslinking, physical film rolling, injection molding, melt extrusion, and braiding. Adequate surgical treatment of peripheral nerve injuries requires that the surgeon, in addition to an accurate knowledge of the anatomical details of the affected area, would also be familiar with microsurgical methods and had necessary equipment to operate. The main procedure in peripheral nerve surgery is the restoration of nerve continuity, which can be obtained by direct coaptation between the two ends of a severed nerve or by the introduction of nerve grafts to replace a defect in nerve tissue. Polyester is the most common synthetic material used in neural tissue engineering, along with polylactic acid, polycaprolactone, and polyglycolic acid. In combination with mesenchymal stem cells of the bone marrow, polylactic acid showed better results and accelerated the recovery of peripheral nerves. Polylactic acid directed the migration of Schwann's cells and induced the formation of a normal nervous structure. It was proved that the polycaprolactone material had an effect similar to that of autografts in nerve repair, and its characteristics were better than in a polylactic acid tube. Polyglycolic acid also possesses sufficient mechanical properties and can be used to repair a nerve defect. Artificial synthetic materials have good biocompatibility and biodegradability with minimal toxicity. For the production of high-purity polymer monomers, which are necessary for the manufacture of the frame, much time and financial costs are required. Moreover, the elasticity and hardness of such materials are imperfect. Three main natural biomaterials are used in tissue repair: collagen, silk, and gelatin. Collagen tube is the most widely used biological material in clinical practice. Silk materials with the protein fibroin, which promote the release of certain substrates, such as nerve growth factor particles, and provide more nutrients and a more favorable microenvironment for nerve repair, are worth noticing. Silk fibroin has good compatibility with the neurons of the dorsal root ganglia and supports cell growth. Gelatin materials are preferred due to the reduction of micromanipulation during nerve recovery. Natural biomaterials are easy to obtain in sufficient quantities; they have good biocompatibility and biodegradability and are easily absorbed by the body. However, each natural biomaterial has its drawbacks. Some of them are brittle or break down in a humid environment. Some natural materials are insoluble in water and traditional organic solvents, which limits their use. One of the most widely used biopolymers of natural origin is chitosan. Chitosan, derived by chitin deacetylation, plays a supporting, protective, and guiding role in the early stage of recovery of peripheral nerves and can provide a relatively stable, localized microenvironment during regeneration. Chitosan is absorbed and gradually decomposed in the late phase of recovery and regeneration of the nervous system. Issues regarding graphene-based nanomaterials use are considered. Graphene is a two-dimensional carbon nanomaterial with good optical, electrical and mechanical properties. It should be noted that when graphene nanoparticles incorporate into a chitosan or gelatin frame and are used to repair peripheral nerve damage in rats, this has contributed to the regeneration of the damaged nerve more quickly. Graphene also reduced the inflammatory response and accelerated the migration of endogenous neuroblasts. Hence, the use of these materials is not well understood due to the significant duration of recovery of the denervated proximal end of the nerve, so further research is needed to identify the advantages or disadvantages of their use.

Simulation of X-ray transmission and spatial imaging of polycapillary lenses with square cross-sections

Conventional polycapillary X-ray lenses are fabricated using an arrangement of hollow cylindrical tubes (i.e., capillaries) in a hexagonal structure, which necessarily includes triangular-shaped non-functional spaces between the capillaries. These non-functional spaces reduce the transmission efficiency of the lens, and can also affect the utilization of the pixels of charge-coupled devices in imaging applications. These disadvantages can be overcome by adopting a polycapillary X-ray lens structure with a square cross-section fabricated from a square matrix array of capillaries, each with equivalent square cross-sections. We develop a mathematical model of a square poly-capillary X-ray lens, and also present a simulation-driven numerical method for calculating the X-ray transmission efficiency, intensity distribution of the exit plane and the focal spot based on a ray-tracing technique.

Conceptual design of a compact high gradient quadrupole magnet of varying strength using permanent magnets

A concept is presented to design magnets using cylindrical-shaped permanent-magnet blocks, where various types of magnetic fields can be produced by either rotating or varying the size of the magnetic blocks within a given mechanical structure. A general method is introduced to calculate the 3D magnetic field produced by a set of permanent magnets. An analytical expression of the 2D field and the condition to generate various magnetic fields like dipole, quadrupole, and sextupole are derived. Using the 2D result as a starting point, a computer code is developed to get the optimum orientation of the magnets to obtain the user-specific target field profile over a given volume in 3D. Designs of two quadrupole magnets are presented, one using 12 and the other using 24 permanent-magnet blocks. Variation of the quadrupole strength is achieved using tuning coils of a suitable current density and specially designed end tubes. A new concept is introduced to reduce the integrated quadrupole field strength by inserting two hollow cylindrical tubes made of iron, one at each end. This will not affect the field gradient at the center but reduce the integrated field strength by shielding the magnetic field near the ends where the tubes are inserted. The advantages of this scheme are that it is easy to implement, the magnetic axis will not shift, and it will prevent interference with nearby devices. Around 40% integrated field variation is achieved using this method in the present example. To get a realistic estimation of the field quality, a complete 3D model using a nonlinear $B\text{\ensuremath{-}}H$ curve is also studied using a finite-element-based computer code. An example to generate around an $80\text{ }\text{ }\mathrm{T}/\mathrm{m}$ quadrupole field gradient is also presented.

Fabrication of Micron-Scale Cylindrical Tubes by Two-Photon Polymerization

Hollow cylindrical tubes grown directly from flat glass substrates as well as spherical glow-discharge-polymer substrates were made using two-photon polymerization. The tube diameters were as small as 10-μm outer diameter and 4- to 5-μm inner diameter, and lengths were as long as 450 μm. Such structures could conceivably be used as fill tubes on inertial confinement fusion capsules. Two resin materials were examined, giving tubes with different flexibilities. One resin was an organic-inorganic hybrid silicon-zirconium sol gel, the second being Ormocomp, a commercially available ultraviolet-curable material. The strength of attachment of the zirconium-based sol gel tubes to their substrates was measured to be around 100 MPa. The times measured to remove uncured resins from high-aspect-ratio tubes during the development process were several hours.

Self-referenced interferometer for cylindrical surfaces.

We present a new interferometric method for shape measurement of hollow cylindrical tubes. We propose a simple and robust self-referenced interferometer where the reference and object waves are represented by the central and peripheral parts, respectively, of the conical wave generated by a single axicon lens. The interferogram detected by a digital camera is characterized by a closed-fringe pattern with a circular carrier. The interference phase is demodulated using spatial synchronous detection. The capabilities of the interferometer are experimentally tested for various hollow cylindrical tubes with lengths up to 600mm.

Negative Poisson's ratio for six‐constant tetragonal nano/microtubes

Analytical and numerical features of the elastic properties of curvilinearly anisotropic six‐constant tetragonal nano/microtubes are considered. The analytical formulas for Young's modulus and Poisson's ratio are obtained in the case of axial extension. Numerical calculations are performed using these formulas and data on the elastic constants from the Landolt–Börnstein Handbook. The parametric dependences of Young's modulus and Poisson's ratios for nano/microtubes are analyzed in detail. The basic parameters are elastic compliances, chiral angles, and ratios of the radii of hollow cylindrical tubes.

Brazier effect of single- and double-walled elastic tubes under pure bending

The cross sections of hollow cylindrical tubes ovalise under a pure bending condition, and this reduces their flexural stiffness as their curvatures increase. It is important to accurately evaluate this phenomenon, known as the 'Brazier effect', to understand the bending behaviour of the systems considered. However, if the tubes are supported by an elastic medium or foundation, the ovalisation displacements of their cross sections may decrease. From this point of view, the purpose of this research is to analytically investigate the bending characteristics of single- and double-walled elastic tubes contacted by an elastic material by considering the Brazier effect. The Brazier moment, which is the maximum moment-carrying capacity of the ovalised cross section, can be calculated by introducing the strain energy per unit length of the tube in terms of the degree of ovalisation for the tube and the curvature. The total strain energy of the double-walled system is the sum of the strain energies of the outer and inner tubes and that of the compliant core. Results are comparatively presented to show the variation in the degree of ovalisation and the Brazier moment for single- and double-walled tubes.

STRUCTURAL ANALYSIS OF SANDWICH THIN-WALLED HOLLOW CYLINDRICAL TUBES WITH ALUMINUM FOAM FILLER SUBJECTED TO LOW VELOCITY AXIAL LOAD USING NUMERICAL SIMULATION

Impact safety and weight-saving are two important criteria for energy-absorbing structures in train, car and aircraft design. Innovations in light-weight material such as metallic cellular material, aluminum foam have developed significantly; it opens many researches to enhance capability of energy absorber. Research on structure of sandwich thin-walled cylindrical tubes with aluminum foam filler has been conducted much; however, the number of researches focusing on sandwich thin-walled hollow cylindrical tubes with aluminum foam filler is limited. This paper presents numerical analyses of sandwich thin-walled hollow cylindrical tubes with aluminum foam filler subjected to low velocity axial loading using a non-linear finite element method. The objective is to predict and compare the behavior of these structures in absorbing energy.

Spiral Structure of 7 Å Halloysite: Mathematical Models

AbstractHalloysite is used for targeted delivery of drugs and other biomolecules. Renewed interest in examination by X-ray diffraction (XRD) to predict the size of particles that can be loaded onto the nanotubes has resulted. Anhydrous halloysite consists of spiraled tubules the length and diameter of which can be determined by measurement using an electron microscope. In spite of ample evidence regarding the spiral structure of halloysite, current programs to evaluate the structure of halloysite nanotubes consider it to be a hollow tube or a cylinder which prevents accurate prediction of its structure and leads to misinformation about the sizes of materials that can be loaded onto the nanotubes. The overall objective of the current study was to derive equations to estimate the structure of halloysite nanotubes which take into consideration its spiral structure. The study of Fourier transform either by electron diffraction or XRD led to the measurement of the spiral thickness and the nature of the spiral. Calculations of the nanotube dimensions may determine the ability of these carriers to allow the mechanical delivery of certain drugs. Here the structure of hydrated halloysite (hollow cylindrical tubes with a doughnut-like cross-section) and anhydrous halloysite (spiraled or helical structure) are described as previously reported in the literature. The Fourier transform of the spiraled structure was selected based on three different kinds of spirals: the Archimedean spiral, the Power spiral, and the Logarithmic spiral. Programs used to define the crystal structure of materials and to calculate the Fourier transform need to take the spiral structure into consideration.

Design and homogenization of metal sandwich tubes with prismatic cores

Hollow cylindrical tubes with a prismatic sandwich lining designed to replace the solid cross-sections are studied in this paper. The sections are divided by a number of revolving periodic unit cells and three topologies of unit cells (Square, Triangle and Kagome) are proposed. Some types of multiple-topology designed materials are also studied. The feasibility and accuracy of a homogenization method for obtaining the equivalent parameters are investigated. As the curved elements of a unit cell are represented by straight elements in the method and the ratios of the lengths of the curved elements to the lengths of the straight elements vary with the changing number of unit cells, some errors may be introduced. The frequencies of the first five modes and responses of the complete and equivalent models under an internal static pressure and an internal step pressure are compared for investigating the scope of applications of the method. The lower bounds and upper bounds of the number of Square, Triangular and Kagome cells in the sections are obtained. It is shown that treating the multiple-topology designed materials as a separate-layer structure is more accurate than treating the structure as a whole.

Carbon Nanotubes-Based Electrochemical Sensors and Drug Delivery Systems: Prospects and Challengesc

CNTs are hollow cylindrical tubes made up of carbon, having a very high aspect ratio (length/diameter). They have one, two or several concentric graphite layers, capped by fullerenic hemispheres. The single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) are the most commonly used CNTs (Figure 1), although double-walled CNTs, bamboo CNTs and herringbone have also been developed. The developments in the technology during the last two decades have considerably improved the synthesis and functionalization of CNTs, thereby, resulting in the cost-effective production of CNTs in bulk quantities, and their extensive use for bioanalytical applications. The chemical vapor deposition is the most widely used technique for CNTs synthesis, whereas, arc discharge and laser ablation have also been employed. Various strategies have been devised for the functionalization of CNTs with different chemical groups; conjugation of CNTs to biomolecules; and the preparation of CNT-based electrodes. CNTs have several unique features, i.e. high mechanical strength, high thermal conductivity and chemical stability, which make them prospective nanomaterial for ECS. The main characteristic of CNTECS is their rapid response with low limit of detection, which is mainly due to their high surface area, low overvoltage and rapid electrode kinetics [2].CNT-ECS have been developed for the detection of glucose, neurotransmitters/neurochemicals, proteins, cells, DNA, microorganisms, pharmaceutical substances and other biomolecules. The direct electron transfer between the enzyme and the CNT-based electrode has further led to the development of mediatorless CNTECS with highly precise analyte detection, as they have negligible interferences from electroactive physiological substances and drug metabolites. The chemically-functionalized, vertically-aligned CNTs have also been developed by several researchers and shown to be more sensitive. But, these are highly expensive for the end-users’ applications. A wide range of CNT-based nanocomposites and ionic gels have also been developed, to improve the analytical performance of CNT-ECS. CNTs are very promising candidates for the development of next-generation DDS. CNT-DDS enable the delivery of drugs and biomolecules with a very high efficiency due to their large surface area; unique structural, electrical and optical properties; well-defined physico-chemical properties; and no toxicity (using functionalized CNTs). Several conjugation strategies have been developed to covalently/non-covalently bind the drugs/biomolecules to CNTs. CNT-DDS have been extensively employed for the delivery of anticancer, anti-inflammatory and other drugs, in addition to the delivery of biomolecules, i.e. DNA, RNA and proteins [3]. Various formats of CNT-DDS, such as CNT bottles have also been developed [4]. However, despite the significant developments, there are still numerous challenges that need to be tackled before CNT-ECS and CNT-DDS become commercially-viable. The synthesis of ultrapure CNTs without any metallic impurities at a low cost is the main challenge. The pristine CNTs, being intrinsically hydrophobic, cannot disperse uniformly in most solvents and biological media. Therefore, the development of biocompatible CNTs by strategies involving surface modification, surface functionalization or bioconjugation, is critical in order to avoid the toxicity of CNTs. Moreover, the current market price of CNTs is too high and needs to be significantly reduced for realistic commercial applications.

Two new sponges of the genus halichondria (halichondrida: Halichondriidae) from Korea

Two new marine sponges in the family Halichondriidae, Halichondria gageoenesis n. sp. and Halichondria muanensis n. sp. are collected from Gageodo Island and Yongjeong‐ri, Hyeongyeong‐myeon, Muan‐gun, Korea during 2006–2007. H. gageoenesis n. sp. is similar to H. oshoro (Tanita, 1961) in type of spicule, but is different from the latter in growth form and size of spicule. The oxea of the new species is larger than H. oshoro's. The growth form of H. gageoenesis n. sp. is thick and consists of encrusting with numerous erect hollow cylindrical tubes, but H. oshoro is of massive form. H. muanensis n. sp is similar to H. retiderma (Dendy, 1921) in type of spicule and choanosomal skeleton, but it is different from the latter in growth form and size of spicule. The oxea is smaller than that of H. retiderma. The growth form is thick and consists of encrusting, with numerous erect hollow cylindrical tubes, compared with the massive lobose of H. retiderma.

A hollow spherical non-closed-packed face-centered cubic uniaxial structure with a photonic band gap

A calculation of band structure is carried out and demonstrates that a hollow spherical non-closed-packed face-centered cubic uniaxial structure possesses a robust complete photonic band gap between the low-frequency bands (2nd and 3rd bands). The results show that the relative gap size can reach a value of 6.1% at a low dielectric contrast of 7.84 appropriate to the transparent TiO 2 . The influence of structure variations on the band gap, such as hollow spheres, cylindrical tubes and dielectric contrast, is also discussed.

One-step growth of silica nanotubes and simultaneous filling with indium sulfide nanorods

A high temperature approach has been utilized for the mass production of ultra-long, straight silica nanotubes and indium sulfide filled cable-like structures by heating of an Si wafer and In2S3 powder under a stream of hydrogen/argon gases at 950 °C. Transmission electron microscopy, scanning electron microscopy and X-ray diffraction analysis demonstrate the formation of hollow cylindrical amorphous silica tubes with lengths up to hundreds of micrometers and outer diameters in the range of 70 to 300 nm, silica tubes encapsulating indium sulfide nanorods with a cubic structure and S-filled silica tubes with high sensitivity to a focused electron beam. A modified vapor–liquid–solid growth was proposed for the formation of amorphous silica nanotubes under the coexistence of low melting point In and S. The capillary induced filling promoted simultaneous formation of indium sulfide nanorods upon further crystallization.

Rheological Properties of Plastic Clay Body

In order to study the rheological preperties of plastic clay body, cyclic tortion test method by Astbury was examined on a plastic mass for electrical insulators. Thin hollow cylindrical tubes, 10φ-20φ×100, were formed by extruding. One end of specimen was fixed, and the other free end was oscillated torsionally, while the rotating angle was changed in a sinusoidal way. By analyzing the hysteresis loops of the stress-strain curves, the following results were obtained. (1) By the sinusoidal torsional motion, S-S curve was constricted in a steady hysteresis loop, showing that the phenomenon of the “Memory” was lost. (2) The remanent sterin depended markedly on the maximum strain (torsional strain amplitude). (3) The coercive force and the maximum stress much decreased on the increase of the moisture content. (4) The ratio of the coercive force to the maximum stress was constant regardless of experimental conditions. (5) The energy absorbed during one cycle was directly proportional to the maximum strain, and was reduced with increasing moisture content. (6) If the torsional strain amplitude and the frequency of sinusoidal oscillation were taken as the same condition, the ratio of energy lost during one cycle to the one for the perfectly plastic body was equal to the ratio of the coercive force to the maximum stress, which was constant, irrespective of experimental conditions. (7) The critical value of the strainen ergy, which determines the ratio of the number of the elastic elements to the that of viscous elements was not constant.The writers, on the basis of the results, pointed out, (1) the plastic property should be added to the Astbury's model as one of the mechanical components, (2) the assumption that the elastic elements would be changed to the same number of the viscous elements due to the increase of strain energy, shoud be modified, (3) the term which gives the effect of moisture content on the behaviour of plastic clay body must be added in the fundamental rheological equation, (5) the model by Astbury should be revaluated after determining more precisely the model parameters.

Comparison between theoretical and experimental resonant behaviour of a hollow cylindrical plasma

Theory using an equivalent permittivity approach predicts that a hollow cylindrical plasma column should have two resonance frequencies. Such frequencies had not yet been experimentally observed. Two hollow cylindrical discharge tubes of different sizes have been built with great care and have enabled the observation of two well-defined resonance peaks. The agreement between theory and experiments for both the frequencies and the amplitudes is very close. A comparison with the ordinary cylindrical plasma column is made and it is suggested that the method used ought to give a quite satisfactory measurement of the average plasma density.