Thin Tube Research Articles

Porosity and microstructure of L-PBF printed AlSi10Mg thin tubes in laser shock peening

Laser powder bed fusion (L-PBF) has emerged as one of the most promising technologies for producing complex geometries that are difficult to achieve with other methods. However, its widespread adoption is hindered by issues such as deleterious microstructure, tensile residual stresses, and porous structure, mainly while working with aluminum alloys. To address these challenges, laser shock peening (LSP) offers a potential solution by mitigating the negative effects associated with aluminum L-PBF. This study investigates the impact of the important LSP parameters, namely energy, spot size, and overlap on L-PBF printed thin AlSi10Mg tubes. A total of 17 specimens were examined by varying the mentioned parameters at three levels each. The outcome of the study was evaluated in terms of residual stresses, porosity, microstructure and surface roughness. The results have shown significant improvements in residual stresses, where a maximum improvement of over 200% was observed and a decrease in porosity by 70%. Furthermore, the microstructure analysis revealed grain refinement and dislocation redistribution as material reactions, aligning with the observed microhardness increase. These findings demonstrate the viability of LSP as a post-processing method for demanding applications, effectively addressing the limitations of the L-PBF process.

A catalog of pressure and deformation profile for thin walled hyperelastic tubes conveying inertialess flow and undergoing large deformation

Slender tubes constituted of hyperelastic materials undergoing large deformations and conveying inertialess flow of Newtonian fluids are a model representation of several systems including those in soft robotics, biology and in industry. In this paper, we undertake a systematic study of this system. The tube’s hyperelastic behavior is modeled by five (5) different constitutive laws: Neo-Hookean, Mooney–Rivlin, Fung, Gent and Ogden. Invoking the principles of finite elasticity, we delineate the local pressure — deformation relationship for the tube for each of the hyperelastic models. The structural mechanical field of the tube is then coupled with fluid flow field, which is simplified using the principles of lubrication approximation. The resultant fluid–structure interaction problem then throws up a set of interesting results including the deformation and pressure profile across the tube, and tube laws for five (5) hyperelastic models. Analyzing these results, we posit that the behavior of Neo-Hookean and Mooney–Rivlin tubes is converse of Fung’s and Gent’s tubes; the latter show a strain hardening behavior whilst the former exhibit a strain softening one. A sensitivity analysis which underscores the relative importance of geometrical nonlinearity in the problem then follows.

Esophageal Infusion of Menthol Does Not Affect Esophageal Motility in Patients with Gastroesophageal Reflux Disease.

Menthol is thought to trigger gastroesophageal reflux disease (GERD) symptoms by influencing esophageal peristalsis and lower esophageal sphincter (LES) function. We evaluated the effect of esophageal menthol infusion on esophageal motility and the LES in healthy volunteers and in patients with GERD. High resolution manometry (HRM) catheter with attached thin tube for menthol infusion was placed transnasally. Protocol which included baseline recording, 16 water swallows (5ml, 10ml, and 15ml) and the multiple rapid swallows was performed before and after esophageal infusion of menthol (3mM, 20min, 8ml/min). We evaluated the effect of this infusion on the HRM parameters of esophageal peristalsis (distal contractile integral, distal latency, contractile front velocity) and the lower esophageal sphincter (LES) barrier function (integrated relaxation pressure and the inspiratory augmentation of the LES). Simultaneously we evaluated the quality and intensity of the symptoms during the menthol infusion. Esophageal infusion of menthol did not appreciably affect HRM measurements characterizing esophageal peristalsis and LES pressure in healthy subjects (N = 13) or GERD patients (N = 11). The magnitude of the distal contractile integral (5ml) was changed neither in the healthy volunteers' group, (735 ± 127 vs. 814 ± 117mmHg, p = 0.5), nor in the GERD patients (295 ± 78 vs. 338 ± 96mmHg, p = 0.99). In healthy volunteers menthol did not change the inspiratory augmentation of the LES (8.67 ± 1.09 vs. 7.69 ± 0.96mmHg, p = 0.15) and neither did for GERD patients (8.8 ± 1.18 vs. 8.22 ± 0.91mmHg, p = 0.43). We observed no significant difference in any HRM parameter following menthol infusion, except for distal latency in 10ml swallows. By contrast, menthol infusion induced significantly more intense discomfort in GERD patient than in healthy volunteers. Our results suggest no significant temporal effect of menthol on the esophageal motility or LES function, neither in healthy volunteers, nor in GERD. Arguably, other mechanisms are responsible for menthol-related heartburn.

Durability of the Blood Pressure Effects of Renal Pelvic Denervation in Patients with Hypertension during a 12-Month Observation

Plain Language SummaryHigh blood pressure, usually called hypertension, is a major cause of strokes, heart attacks, heart failure, and kidney disease. Reducing blood pressure helps prevent these serious problems but medicines prescribed to do this do not always work well, or may cause annoying side effects. So, there is growing interest in procedures that doctors can perform in people with high blood pressure that can reduce blood pressure for up to a year or more. One such procedure that appears promising is called renal denervation, which means that we disable the nerves that go to the kidney and increase blood pressure. One way this is done is through a procedure performed by kidney doctors similar to ones already widely used in outpatient centers for conditions like kidney stones. A very thin tube (called a catheter) is passed through the bladder into the kidneys and disables the nerves that raise blood pressure. This article describes the effects of this treatment in patients whose blood pressure was high despite taking blood pressure medicines. Their blood pressures fell soon after the procedure, but importantly we can report that these benefits were just as strong 12 months later. There was no evidence that this procedure causes harm to the kidneys or other important organs. The next step in developing this treatment is a large study in 300 patients to confirm its benefits and safety, hopefully making it available to people whose blood pressures cannot be controlled with currently available treatment.

Asymptotic Domain Decomposition Method for Approximation the Spectrum of the Diffusion Operator in a Domain Containing Thin Tubes

The spectral problem for the diffusion operator is considered in a domain containing thin tubes. A new version of the method of partial asymptotic decomposition of the domain is introduced to reduce the dimension inside the tubes. It truncates the tubes at some small distance from the ends of the tubes and replaces the tubes with segments. At the interface of the three-dimensional and one-dimensional subdomains, special junction conditions are set: the pointwise continuity of the flux and the continuity of the average over a cross-section of the eigenfunctions. The existence of the discrete spectrum is proved for this partially reduced problem of the hybrid dimension. The conditions of the closeness of two spectra, i.e., of the diffusion operator in the full-dimensional domain and the partially reduced one, are obtained.

Roles of Carbon Nanotube Confinement in Modulating Regioselectivity of 1,3-Dipolar Cycloadditions.

DFT-based calculations were employed to investigate mechanisms of 1,3-dipolar cycloadditions between phenylacetylene and an azide (phenylazide or benzylazide) inside carbon nanotubes, whose diameters range from 10 to 14 Å, by obtaining their reaction species (reactant complex, transition state (TS), and product (Pro)). The reactions yield 1,4- and 1,5-triazoles, whose paths are denoted by 1,4- and 1,5-approaches, respectively. We found different geometrical features of reaction species between 1,4- and 1,5-approaches. Reflecting different reaction species, nanotube confinement has the power to enhance kinetically and thermodynamically controlled regioselectivity of 1,3-dipolar cycloadditions to form 1,4-triazoles. In inner 1,4-approaches, the reaction species have planar structures, being small relative to the cavity of tube hosts, and then, their activation energies are slightly lowered relative to those without tube surroundings, independent of the tube diameter. In inner 1,5-approaches, reaction species have phenyl groups overlapping each other, depending on the tube diameter: L-shaped and stacking fashions are found in thick and thin tubes, respectively. Particularly, the stacking fashion in thin tubes results in repulsive orbital interactions between two phenyl rings, destabilizing their TS and Pro. The presence of overlapping phenyl groups increases the activation energies in the 1,5-approaches with a decrease in the tube diameter, being larger than those without tube surroundings.

Microstructure Effects on the Machinability of AM-Produced Superalloys

This paper discusses the microstructure effects on the machinability of Inconel 718 by conducting machining tests on an additively manufactured (AM) workpiece with a strongly textured grain structure and a wrought workpiece incorporating a finer and more equiaxed grain structure. The AM workpiece was produced as a thin tube using Laser Melting Powder Bed Fusion and optimal processing conditions for this alloy. A lathe was used to conduct instrumented orthogonal machining tests on the two workpiece materials under dry cut and coolant conditions using a semisynthetic emulsion coolant. The process parameters studied were feed from 0.05 to 0.15 mm/rev and cutting speed from 60 to 120 m/min with a cut time of 2 sec duration for each process condition. Measures for each process condition included cutting forces in the feed and main cut direction, and images of chip forms were obtained. The grain structures of the workpiece materials were characterized using Electron Back Scattered Diffraction (EBSD). New findings suggest that grain structures can significantly affect the machinability of the superalloy at a higher feed for all cutting speeds studied, and insights into the cause are discussed. Other important findings comment on the effectiveness of the coolant as a lubricant for reducing friction in machining.

Collisional Solitons Described by Two-Sided Beta Time Fractional Korteweg-de Vries Equations in Fluid-Filled Elastic Tubes

This article deals with the basic features of collisional radial displacements in a prestressed thin elastic tube filled having inviscid fluid with the presence of nonlocal operator. By implementing the extended Poincare–Lighthill–Kuo method and a variational approach, the new two-sided beta time fractional Korteweg-de-Vries (BTF-KdV) equations are derived based on the concept of beta fractional derivative (BFD). Additionally, the BTF-KdV equations are suggested to observe the effect of related parameters on the local and nonlocal coherent head-on collision phenomena for the considered system. It is observed that the proposed equations along with their new solutions not only applicable with the presence of locality but also nonlocality to study the resonance wave phenomena in fluid-filled elastic tube. The outcomes reveal that the BFD and other physical parameters related to tube and fluid have a significant impact on the propagation of pressure wave structures.

Asymptotics and discretization of a weakly singular kernel: Application to viscous flows in a network of thin tubes

Kernels obtained from the heat equation arise in several modeling contexts, like some double porosity models, or viscous flows in networks of thin tubes. These kernels are weakly singular at initial time. An accurate approximation must therefore take this singularity into account. In this paper we obtain an asymptotic expansion for small times, which we use to build a numerical scheme for approximating the kernels. Convergence of the scheme and relevance of a correction through the asymptotics are proven both analytically and numerically. Finally, we show that this approximation applies to the model on the graph studied by the authors in Canon et al. [4] (2021).

Effects of entropy generation and magnetic field on blood flow of jeffrey fluid in a catheterized artery: A mathematical study

Catheters are long, hollow, and thin silicone tubes inserted into the bladder, veins, and arteries. The purpose of the current work is to find entropy formation in a blood flow through a non-concentric catheterized artery with stenosis. The model is compressed by the useful limitations of mild stenosis and non-turbulence. We used HPM to discuss work results. Simpson's 3/8 rule and Mathematica's built-in tool combined impedance, shear stress, and the Nusselt number. From a visual representation, we may construct a catheter with a lower radius to minimize fluid speed and a magnetic field to manage flow intensity. Large temperature ratios and Jeffrey parameters reduce entropy formation. The findings of the study may have implications for cardiovascular medical devices.

Nonthermal Emissions from a Head–Tail Radio Galaxy in 3D Magnetohydrodynamic Simulations

We present magnetohydrodynamic simulations of a jet–wind interaction in a galaxy cluster and the radio to gamma-ray and neutrino emissions from this “head–tail galaxy.” Our simulation follows the evolution of cosmic-ray (CR) particle spectra with energy losses and stochastic turbulence acceleration. We find that the reacceleration is essential to explaining the observed radio properties of head–tail galaxies, in which the radio flux and spectral index do not drastically change. Our models suggest that hard X-ray emissions can be detected around the head–tail galaxy in the Perseus cluster by hard X-ray satellites, such as FORCE, and they will potentially constrain the acceleration efficiency. We also explore the origin of the collimated synchrotron threads, which have been found in some head–tail galaxies by recent high-quality radio observations. Thin and elongated flux tubes, connecting the two tails, are formed by strong backflows at an early phase. We find that these threads advect with the wind for over 300 Myr without disruption. The radio flux from the flux tubes is much lower than the typical observed flux. An efficient CR diffusion process along the flux tubes, however, may solve this discrepancy.

Study of effect on parameters of bend quality for tubes

Tube bending is a metal forming process that is used to shape pipes or tubing. Bending machines take straight tube stock and create a shape involving single or multiple bends. This allows the tubing to be formed in any fashion to fit the application's specific needs. The process of tube bending involves using mechanical force to push stock material pipe or tubing against a die, forcing the pipe or tube to conform to the shape of the die. There are three basic bends that are commonly used: the 90° bend, the common offset, and the saddle. Wrinkles occur when the mandrel inside the tube is no longer able to provide enough counteractive force. Wipers are always used in combination with mandrels inserted inside the tube during bending. The mandrel's primary job is to control the shape on the outside radius of the bend. They are excessively used in everything from the automotive industry to aviation, shipbuilding, aerospace, oil and gas, etc. The automotive sector heavily relies on mandrel bending machines to minimize thin wall tubing's ovality when it's bent.

Challenges to the integrity of calandria, the CANDU PHWR moderator vessel, under serious accident loads and consequences of its failure

This paper summarizes the technical and analytical basis for a more advanced examination of structural integrity of a CANDU PHWR Calandria vessel under certain reactor accident conditions. Of foremost interest is the early Boiling Liquid Expanding Vapour Explosions (BLEVEs) induced challenge to vessel structural integrity following a spontaneous in-core rupture of a fuel channel. A sudden, flashing jet discharge of over 100 kg/s of the 10 MPa, 300 °C saturated primary coolant into its 70 °C subcooled near atmospheric pressure moderator water inventory will cause an explosive, shock wave impact. This results from rapid nucleation and vaporization of the discharged superheated liquid. Consequential pressure pulse, pipe-whip and bundle debris impact will induce damage to adjacent channels and cause widespread failure of fuel channel calandria tube rolled joints. These thin tubes inevitably deform to create serious challenges to vessel integrity. On the other extreme of reactor accidents, is the matter of an in-vessel-retention (IVR) of high temperature molten fuel debris in the reactor vessel after a severe core damage accident, such as one caused by an unmitigated station blackout. This scenario has understandably drawn greater attention after Fukushima and potential IVR in the > 200 mm thick PWR vessels when partly submerged in water is viable.It is highly unlikely that we will see reactor debris melt retention in this 19 to 29 mm thick, stepped shell with a tapestry of welds. This is because partial shell melting, diminished strength beyond 650 °C across 2/3 of the thin shell thickness and severe thermal stresses adds to underlying residual stresses near the welded seams. The result is inevitable catastrophic off-site consequences as energetic interactions upon vessel breach of water with hot debris can cause additional steam & hydrogen explosions, containment failures, and large off-site releases.This paper presents technical arguments to illustrate the problem in accepting faulty assumptions conveniently made in licensing safety assessments to simplistically claim survival of the thin-walled welded structure under these two illustrative accidents. I propose pathways to further investigations. Therefore, the issue of Calandria vessel survival under a wide range of accident conditions must be given a second, thoughtful look. Extending boundaries of a safe operating envelope as pressure tubes age needs to be avoided. We need to be more realistic in our severe accident analysis and consequence assessments. Fukushima taught us that the consequences of continuing to rely on convenient but technically faulty rationale, along with hype of eternal safety, can be very unforgiving.

Selective electrochemical boring of thin-walled tubes: Methodology, mechanism, and characteristics

Corrugated tubes having internally turbulated surface find intensive application in heat-exchangers. Fabrication of thin-walled tubes with turbulated internal surface using conventional machining processes is difficult due to the inability of tube wall to withstand the cutting force. With non-contact type machining processes, a methodology is yet to be developed for selective boring of thin walled tubes. In this research, we propose a novel approach to bore a thin-walled tube at selective locations using electrochemical route and the operation is termed as selective-electrochemical boring (SECB). Machining centre is fabricated in-lab and experiments are carried out using a partially-insulated single-point tool. Experiments are performed to study the influence of process parameters on different characteristic features of a groove profile. With the developed machining centre and the proposed machining methodology, multiple internal grooves with sub-micron level surface roughness are fabricated and subsequently characterized. Minimum surface roughness (Ra) of 0.064 μm is achieved inside the groove on SS-304 tube. The unique feature of this invention is its ability to machine internal as well as external grooves at the selected location without the need for a specifically-shaped tool. Application of the proposed methodology can be extended to machining of turbulated profile on pre-drilled holes in turbine blades for enhancing heat transfer rate.

An experimental model of the pharyngoesophageal segment in tracheoesophageal phonation.

Tracheoesophageal (TE) speech is an important method of speech rehabilitation for those who undergo a total laryngectomy. Despite the many advantages over other methods, there is still room for improvement in terms of the overall quality of the TE voice as well as its success rate. These points could be greatly assisted by an improved knowledge on the mechanics of TE speech. Here, an experimental model of the pharyngoesophageal segment (PES), based on the idea of a collapsible tube, is proposed. To implement the model, considerable simplifications had to be made, most notably in the use of a thin flexible tube to represent the PES. The model was used to assess the minimum amount of tonicity required for the onset of phonation in terms of the flow rate and longitudinal tension. Additionally, comparisons with a mathematical model [Tourinho, da Silva, dos Santos, Thomaz, and Vieira, J. Acoust. Soc. Am. 149, 1979-1988 (2021)] have been made, yielding similar trends for sufficiently large flow rates. The measurements also suggest that the phonation frequency is most affected by the tonicity of the PES, which highlights the question of which physiological mechanism is responsible for the control of the fundamental frequency of phonation.

The Design of a Biomimetic Hierarchical Thin-Walled Structure Inspired by a Lotus Leaf and Its Mechanical Performance Analysis.

Inspired by the macro- and microstructures of the lotus leaf, a series of biomimetic hierarchical thin-walled structures (BHTSs) was proposed and fabricated, exhibiting improved mechanical properties. The comprehensive mechanical properties of the BHTSs were evaluated using finite element (FE) models constructed in ANSYS, which were validated by the experimental results. Light-weight numbers (LWNs) were used as an index to assess these properties. The simulation results were compared with the experimental data to validate the findings. The compression results indicated that the maximum load carried by each BHTS was very similar, with the highest bearing load being 32,571 N and the lowest being 30,183 N, resulting in only a 7.9% difference between them. In terms of the LWN-C values, the BHTS-1 exhibited the highest value at 318.51 N/g, while the BHTS-6 had the lowest value at 295.16 N/g. For the torsion and bending results, these findings suggested that increasing the bifurcation structure at the end side of the thin tube branch significantly improved the torsional resistance properties of the thin tube. For the impact characteristics of the proposed BHTSs, enhancing the bifurcation structure at the end of the thin tube branch significantly increased the energy absorption capacity and improved the energy absorption (EA) and the specific energy absorption (SEA) values of the thin tube. The BHTS-6 had the best structural design in terms of both the EA and SEA among all the BHTSs, but its CLE value was slightly lower than that of the BHTS-7, indicating slightly lower structural efficiency. This study provides a new idea and method for developing new lightweight and high-strength materials as well as designing more effective energy absorption structures. At the same time, this study has important scientific value in understanding how biological structures in nature exhibit their unique mechanical properties.

The effect of flow on transverse oscillations of two parallel magnetic tubes

ABSTRACT We study oscillations of two parallel interacting magnetic tubes in the presence of plasma flow along the tubes. Using the cold plasma and thin tube approximations we derive the system of two equations describing these oscillations. This system of equations is valid for equilibria where the plasma density and flow velocity can vary along the tube axes and in time. This system of equations is used to study the effect of flow in the tubes on the frequency of standing waves. There are two modes of oscillations, fast and slow. We calculated the dependence of frequencies of fast and slow modes of the Alfvén Mach number. We found that the effect of flow in coronal loops on the oscillation frequency is fairly weak for typical flow velocities observed in coronal loops. However it can be substantial in the case of prominence threads. We discuss the implication of the obtained results on coronal seismology.

A new species of the mysterious genus Spirodiscus (Annelida: Serpulidae) of the eastern Australian abyss

In May–June 2017 an expedition on board RV Investigator sampled benthic communities along the lower slope and abyss of Australia’s eastern margin from off mid-Tasmania to the Coral Sea. Over 200 annelids of the family Serpulidae collected during the voyage were collected and deposited in the Australian Museum in Sydney. Among them there was a new species of the poorly known abyssal (3754–4378 m) genus Spirodiscus. Serpulids typically build cylindrical calcareous tubes attached to hard substrates. Until now, only three serpulid species inhabiting free-lying polygonal tubes were reported from the deep sea: Spirodiscus grimaldii Fauvel, 1909 with quadrangular spirally coiled tubes, Bathyditrupa hovei Kupriyanova, 1993 with quadrangular tusk-shaped tubes, and Spirodiscus groenlandicus (McIntosh, 1877) with octagonal tusk-shaped tubes. The new species, S. ottofinamusi sp. nov. has very characteristic thin tusk-shaped unattached fluted tubes similar to those found in S. groenlandicus, but it differs by the details of collar, thoracic tori and abdominal chaetae. Morphologically, it has a pinnulated opercular peduncle and flat geniculate abdominal chaetae like filogranin serpulids but lacks thoracic Apomatus chaetae like serpulins. The first DNA sequences of this mysterious taxon places the new species within the filogranins in sister group relationship with Chitinopoma serrula.

A low-loss polarization-maintaining terahertz fiber

A novel low-loss THz polarization-maintaining fiber is analyzed numerically. The proposed fiber consists of two small thin dielectric tubes nested in a large dielectric tube. Numerical simulations performed using the full-vector finite element method show that the difference between the effective refractive index of LPx01 and the adjacent modes is up to 10−2 orders of magnitude in the frequency range from 0.32 to 0.7 THz. At the same time, the proposed fiber has low loss characteristics, and the total loss of LPx01 is only 0.17 dB/cm at 0.35 THz. In addition, near-zero flat dispersion of 0.3 ± 0.36 ps/THz/cm can be achieved by adjusting the structural parameters of the fiber.

Acoustic black and white holes of potential flow in a tube

We propose a new simple model of acoustic black hole in a thin tube, where the difference in the gravitational potential is used to create a transonic flow. The main merit of our transonic flow model is that the Euler equations can be solved analytically. In fact, we can obtain an exact solution to the equation in terms of a height function in the monatomic case $\gamma=5/3$. For arbitrary $\gamma$, we find that it takes a simple form by the near-sonic approximation. Moreover, we obtain two analytic solutions describing a backward wave and a forward wave, from which we can confirm the existence of sonic horizons.