Articoli di riviste: "Bulges on the tube"

1

Farley, F. J. M., R. C. T. Rainey e J. R. Chaplin. "Rubber tubes in the sea". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, n. 1959 (28 gennaio 2012): 381–402. http://dx.doi.org/10.1098/rsta.2011.0193.

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Abstract (sommario):

A long tube with elastic walls containing water is immersed in the sea aligned in the direction of wave travel. The waves generate bulges that propagate at a speed determined by the distensibility of the tube. If the bulge speed is close to the phase velocity of the waves, there is a resonant transfer of energy from the sea wave to the bulge. At the end of the tube, useful energy can be extracted. This paper sets out the theory of bulge tubes in the sea, and describes some experiments on the model scale and practical problems. The potential of a full-scale device is assessed.

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2

Liu, Yuyang, Yong Luan, Xinbo Dai, Senyun Liu, Xian Yi e Yu Rao. "A Numerical Study on Swirling Hot Air Anti-Icing with Various Surface Structures on the Internal Wall". Energies 16, n. 3 (20 gennaio 2023): 1179. http://dx.doi.org/10.3390/en16031179.

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Swirling hot air is a promising heat transfer enhancement technology for anti-icing applications in aircrafts, where the swirling flow is accompanied by pretty high turbulence and a quite thin boundary layer. It is of interest to investigate the compound heat transfer characteristics of the swirling air configuration combined with surface structures on the internal wall. This paper carries out a series of numerical computations to obtain the Nusselt number and pressure loss data in such a swirling air heat transfer system with four kinds of surface structures (trenches, ribs, dimples and bulges) on the wall and with different tangential inlet jets placed along the tube. At a tube Reynolds number from 10,000 to 50,000, the results show that the surface dimples and bulges are conducive to improving the Nusselt number, but the surface trenches and ribs show a Nusselt number deterioration relative to the smooth swirl tube. Among the four investigated surface structures, the surface bulges perform best, which can enhance the Nusselt number by up to 15.0%, increase the total heat transfer quantity by up to 17.3% and reduce the hot air pressure loss by up to 15.6%. Furthermore, the circumferential velocity distribution and swirl number are introduced to describe the flow fields. The surface trenches and ribs lead to less of a reduction in the circumferential velocity and swirl intensity, while the surface dimples and bulges could significantly suppress the in-tube swirl intensity.

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3

Wen, Hua Dian, Xiao Ting Xiao, Kai Zhang e Ying Chen. "Metal Flow Rule of Multi-Way Tube Hydro Forming for Air Handling Unit". Advanced Materials Research 239-242 (maggio 2011): 1597–600. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.1597.

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Multi-way tube on air conditioning header is considered as the research objective .Finite element simulation method is utilized to simulate and analyze the deformation process of metal. Through analyzing the distribution law of velocity on work piece neutral plane and displacement law of typical nodes, common law in deformation process for metal flow was revealed. Results suggested that: metal which is on terminal supplementary zone conspicuously flows along horizontal. Metal which is on forming zone conspicuously flows along bulge, metal which is between bulges flows little, these laws provide a reference for the choice of forming technology.

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4

Inoue, Tadanobu, Erina Kitahara, Yuka Hara e Koji Nakazato. "Mud Crab’s Mottled, Deep-Blue Exoskeleton: Surface Morphology and Internal Microstructure". Minerals 12, n. 12 (14 dicembre 2022): 1607. http://dx.doi.org/10.3390/min12121607.

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The claws of the mud crab, Scylla serrata, are huge in comparison with its body size. Many bulges ranging from 5 to 23 μm in height and 90 to 146 µm in diameter were observed on the mottled, deep-blue exoskeleton surface of the mud crab’s claw. These cuticle bulges were closely related to irregularly present exocuticles on the surface layer of the exoskeleton’s cross section. The bulges exist between the exocuticles, and at the apex of these bulges was a tube that bundled many pore canals that penetrated the exoskeleton. This tube was thick (62–66 µm) near the inner side and narrowed (12–22 µm) toward the outer surface. On the other hand, the exocuticles had a heterogeneous tissue structure in a coarse region extending normally to the surface, with a diameter of 3 to 7 µm, and a dense region between them. Calcium concentrations were high in the dense region, and phosphorus and magnesium concentrations were high in the coarse region. As a result, the mechanical properties (hardness: H and modulus: Er) were distributed inside the exocuticle, and the mapping of H and Er using a nanoindentation test clarified the heterogeneity.

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5

Chaplin, J. R., V. Heller, F. J. M. Farley, G. E. Hearn e R. C. T. Rainey. "Laboratory testing the Anaconda". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 370, n. 1959 (28 gennaio 2012): 403–24. http://dx.doi.org/10.1098/rsta.2011.0256.

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Laboratory measurements of the performance of the Anaconda are presented, a wave energy converter comprising a submerged water-filled distensible tube aligned with the incident waves. Experiments were carried out at a scale of around 1:25 with a 250 mm diameter and 7 m long tube, constructed of rubber and fabric, terminating in a linear power take-off of adjustable impedance. The paper presents some basic theory that leads to predictions of distensibility and bulge wave speed in a pressurized compound rubber and fabric tube, including the effects of inelastic sectors in the circumference, longitudinal tension and the surrounding fluid. Results are shown to agree closely with measurements in still water. The theory is developed further to provide a model for the propagation of bulges and power conversion in the Anaconda. In the presence of external water waves, the theory identifies three distinct internal wave components and provides theoretical estimates of power capture. For the first time, these and other predictions of the behaviour of the Anaconda, a device unlike almost all other marine systems, are shown to be in remarkably close agreement with measurements.

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6

Magin, Norbert, Regine Classen e Claudia Gack. "The morphology of false anthers in Craterostigma plantagineum and Torenia polygonoides (Scrophulariaceae)". Canadian Journal of Botany 67, n. 7 (1 luglio 1989): 1931–37. http://dx.doi.org/10.1139/b89-245.

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The ontogenesis of the prominent excrescences of the filament of two melittophilous species is investigated and the biological implications are discussed. In Craterostigma plantagineum Hochst. the bases of the filament bulges are fused with the lower lip of the corolla. The bulges are bright yellow, of grainy structure, and they flank the entrance of the flower tube. This character syndrome can be interpreted as a plastic (three-dimensional) false anther or anther dummy. The flower of Torenia polygonoides Benth. carries a yellow, spotlike anther dummy in the centre of the lower lip. The staminal excrescences of T. polygonoides are completely free of the lower lip of the corolla, pin-shaped, and of a light pink colour. Thus, they lack the characteristic, yellow signal colour that is typical for anther dummies in general. Possibly, they have no optical function at all, but act as a guide rail.

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7

Boonpuek, P., S. Jirathearanat e N. Depaiwa. "Flow Stress Determination of Steel Tube for Hydroformability Evaluation". Advanced Materials Research 622-623 (dicembre 2012): 656–60. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.656.

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This study aims to determine flow stress of a steel tube by using hydraulic bulge test. A new proposed analytical model for analyzing bulge shapes of hydroformed tubes is postulated. Bulge test apparatus designed using FEA simulation of hydroforming and STKM 11A steel tubes are used in the hydraulic bulge test. Bulge heights and internal pressures are measured during bulge testing. Tube thicknesses at vertex of a bulge shape are measured by a dial caliper gauge. Bulge curvatures and contact points are measured by taking digital photos of bulge shapes combined with measurement methods in CAD software. Effective stress - strain relationships are obtained from the newly developed analytical model using those measured values. Flow stress curves obtained from the effective stress – strain relationships are compared with those by other researchers and tensile test. Finite element analysis methods are used to conduct simulation of tube hydroforming using the flow stress curves. Predicted internal pressures versus bulge heights and tube thicknesses are compared with experimental results. Verification of the developed analytical model is presented. The flow stress at neck point of formed tube is determined.

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8

Hwang, Yeong-Maw, H. C. Chuang e B. J. Chen. "Hydraulic Bulge Tests of Magnesium Tubes at Elevated Temperatures". Advanced Materials Research 83-86 (dicembre 2009): 1135–42. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.1135.

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Evaluation of the formability of tubes is an important issue in tube hydroforming processes. Since tubular materials during tube hydroforming are under a biaxial even triaxial stress state, other biaxial-stress-based testing methods are needed. In this paper, uniaxial tensile tests at different temperatures are firstly employed to evaluate the material properties of magnesium alloy AZ61 tubes. A hydraulic bulge warm forming machine, which is used for hydraulic bulge tests with a fixed tube length, is also designed and manufactured. Using this self-designed testing machine, experiments of bulge tests of magnesium alloy AZ61 tubes at elevated temperatures are carried out. From the experimental results, the bulge formability of the magnesium alloy tubes at different temperatures is discussed.

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9

Opryshko, L. V., e T. V. Golovnyak. "Study of surface defects in tubes made from nondeformed continuously cast billets". Metaloznavstvo ta obrobka metalìv 98, n. 2 (7 giugno 2021): 54–62. http://dx.doi.org/10.15407/mom2021.02.054.

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Defects of outer and inner surfaces of hot-rolled tubes of various steel grades and sizes manufactured on tube-rolling unit with a continuous mill (TPA 30-102) at Interpipe Nikotube LLC from a nondeformed continuously cast billets produced by MZ Dniprostal LLC have been studied. Characteristic genetic and morphological signs of defects were revealed which makes it possible to reliably classify them, identify cause of defect formation and recommend measures to eliminate them. Defects on the outer and inner surfaces of tubes are of metallurgical origin and associated with quality of initial continuously cast billets (a consequence of violation of the smelting and continuous casting technology). Defects on the inner surface of tubes were caused on defects in the axial zone of original billets (unacceptable porosity, looseness, chemical inhomogeneity, liquation stripes and cracks, etc.) and are classified as steel-smelting films and bulges. It was found that displacement of the thermal center of crystallization (a feature of the machines for continuous steel casting of curvilinear type) had an additional negative effect on quality of the inner surface of the studied tubes. Defects on the outer surface of tubes are tears of burning in places of accumulation of low-melting inclusions and their eutectics, as well as steel-smelting scabs on rolled dirt and gas bubbles. Likelihood of formation of scabs on outer surface of the studied tubes over rolled crust introversions is not excluded. The study results will allow manufacturers to reliably classify defects, promptly reject tubes with unacceptable defects of metallurgical origin and minimize supply of low-quality products to consumers. These results will later be included in the classifier of defects in tubes manufactured on the TPA 30-102 unit from nondeformed continuously cast billets. The results of the study of natural signs of defects of metallurgical origin in the tube surface will be useful for elaboration of measures aimed at improvement of the technology of manufacturing initial tube billets. Keywords: tube surface defects, continuously cast billets, microstructure, rolled contamination, low-melting inclusions, eutectic, gas bubbles, decarburization, liquation.

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10

Mitsui, Satoshi, Taisuke Miyagawa, Hajime Yasui e Shoichiro Yoshihara. "Warm Bulge Forming of Small Diameter A1100 Aluminium Tube". Materials Science Forum 920 (aprile 2018): 149–54. http://dx.doi.org/10.4028/www.scientific.net/msf.920.149.

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In recent years, the small diameter aluminium tube has been widely utilized for chemical instruments and medical devices. These instruments are should be minimized since the usage of the small diameter tubes has been extremely increased. However, the deformation characteristics could not be scaled down similarly to the material dimensions due to the size effect. Thus, tube bulge forming is necessary to clarified the deformation characteristics of the small diameter tubes. In this paper, the formability of the warm tube bulge forming by using the small diameter A1100 aluminium tube with 2.0 mm outer diameter and 0.2 mm thickness has been investigated. As the results, the effect of the different temperature and the different internal pressure on the tube bulge forming of the small diameter A1100 aluminium tubes was clarified. Furthermore, it was confirmed that the variation of the internal pressure loading rate affected the deformation characteristics of the tubes.

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11

Yoshimura, Hidenori, Kana Nakahara e Masaaki Otsu. "Local One-Sided Rubber Bulging Test to Measure Various Strain Paths of Metal Tube". Metals 11, n. 5 (2 maggio 2021): 751. http://dx.doi.org/10.3390/met11050751.

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We proposed a local one-sided rubber bulging method of metal tubes to evaluate various strain paths at an aimed portion and measured the forming limit strains of metal tubes at the place of the occurrence of necking under biaxial deformation. Using this method, since rubber is used to give pressure from the inner side of the tube, no sealing mechanisms were necessary unlike during hydraulic pressure bulging. An opening was prepared in front of the die to locally bulge a tube at only the evaluation portion. To change the restriction conditions of the bulged region for biaxial deformation at the opening, a round or square cutout, or a slit was introduced. The test was conducted using a universal compression test machine and simple dies rather than a dedicated machine. Considering the experimental results, it was confirmed that the strain path was varied by changing the position and size of slits and cutouts. Using either a cutout or a slit, the strain path in the side of the metal tubes can be either equi-biaxial tension or simple tension, respectively. Additionally, by changing the size of the cuts or slits, the strain path can be varied.

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12

Słowiński, Jakub, Dawid Surmik, Piotr Duda e Michał Zatoń. "Assessment of serpulid-hydroid association through the Jurassic: A case study from the Polish Basin". PLOS ONE 15, n. 12 (9 dicembre 2020): e0242924. http://dx.doi.org/10.1371/journal.pone.0242924.

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The coexistence of sessile, tube-dwelling polychaetes (serpulids) and hydroids, has been investigated. Serpulid tubes bearing traces after hydroids are derived from different stratigraphic intervals spanning the Middle and Upper Jurassic, the rocks of which represent the diverse paleoenvironments of the Polish Basin. Although fossil colonial hydroids classified under the species Protulophila gestroi are a commonly occurring symbiont of these polychaetes during the Late Cretaceous and Cenozoic, they seem to be significantly less frequent during the Jurassic and limited to specific paleoenvironments. The hydroids described here are represented by traces after a thin stolonal network with elongated polyp chambers that open to the outer polychaete tube’s surface with small, more or less subcircular apertures. Small chimney-like bulges around openings are an effect of the incorporation of the organism by in vivo embedment (bioclaustration) within the outer layers of the calcareous tube of the serpulid host. Considering the rich collection of well-preserved serpulid tubes (>3000 specimens), the frequency of bioclaustrated hydroids is very low, with an infestation percentage of only 0.6% (20 cases). It has been noticed that only specimens of the genus Propomatoceros from the Upper Bajocian, Lower Bathonian, Middle Bathonian, and Callovian have been found infested. However, the majority of bioclaustrated hydroids (17 cases) have been recorded in the Middle Bathonian serpulid species Propomatoceros lumbricalis coming from a single sampled site. Representatives of other genera are not affected, which is congruent with previous reports indicating that Protulophila gestroi was strongly selective in the choice of its host. A presumably commensal relationship is compared with the recent symbiosis between the hydroids of the genus Proboscidactyla and certain genera of sabellid polychaetes.

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13

Ragab, A. R., S. A. Khorshid e R. M. Takla. "Limit Strains for Thin-Walled Tubes With Initial Thickness Inhomogeneity". Journal of Engineering Materials and Technology 107, n. 4 (1 ottobre 1985): 293–97. http://dx.doi.org/10.1115/1.3225822.

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Limiting strains during tube bulging have been investigated for long tubes subjected to an internal pressure together with an external axial force. A strain instability criterion which takes into consideration the inevitable geometrical defects in the tube wall is developed. The results revealed that small eccentricities produce a substantial decrease in the amount of deformation sustained by the tube at instability conditions. Moreover, the sensitivity to such defects increases for tubes made of low strain-hardening materials. The developed strain instability criterion has been subjected to an experimental verification where commercially pure aluminium tubes have been bulged to fracture. Experimental results are found to be in good agreement with theory, thus justifying the validity of this instability criterion and the resulting limit strains.

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14

Al-Qahwaji, Tahseen T. Othman, e Ahmad Ameen Hussain. "Numerical Study of Tube Hydroforming Process Using Conical Dies". Tikrit Journal of Engineering Sciences 28, n. 4 (1 novembre 2021): 25–36. http://dx.doi.org/10.25130/tjes.28.4.3.

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In this paper the effect of die angle, fluid pressure and axial force on loading paths were studied. In order to reduce the cost and time for the experimental work, ANSYS program is used for implementing the Finite Element Method (FEM), to get optimized loading paths to form a tube using double – cones shape die. Three double die angles θ (116˚ 126˚, 136˚), with three different values of tube outer diametres (40, 45, 50) mm were used. The tube length L_o and thickness t_o for all samples were 80 mm and 2 mm respectively. The most important results and conclusions that have been reached that had the highest wall thinning percentage of 26.8% with less corner filling is at tube diameter 40 mm and cone angle of (116^°) at forming pressure of 43 MPa with axial feeding 10 mm. However, the lowest wall thinning percentage was 6.9% with best corner filling at diameter 50 mm and cone were angle of (136^°) and forming pressure of 30 MPa with axial feeding 4.5 mm. Two wrinkles constituted during the initial stages of forming the tube with initial diameter of 40 mm where the ratio d⁄(t=20) (thick-walled tubes) for all die angles, while only one wrinkle is formed at the center for tubes diameter 45 and 50 mm (thin-walled tubes) . The difference in the location and number of wrinkles at the first stage of formation depends on the loading paths that has been chosen for each process, which was at the diameter 45 and 50 mm towards thin-wall cylinder deformation mode was uniaxial tension. The maximum wall thinning percentage was at the bulge apex for tube diameter 40 mm. But, the maximum wall thinning for tubes of diameters 45 and 50 mm was found at the two sides of the bulge apex .

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15

Tuema, Eric Velaski, e Olusegun Ilegbusi. "Unsteady Integrodifferential Equation of Fluid-Structure Interaction in Constricted Collapsible Tube Model of Diseased Human Coronary Artery". International Journal of Differential Equations 2012 (2012): 1–21. http://dx.doi.org/10.1155/2012/376350.

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Unsteady flow in a collapsible tube is analyzed to simulate a diseased human coronary artery. The novelty of the approach is that the set of equations governing the fluid-structure interaction is reduced to a single integrodifferential equation in the transient state. The equation is then solved using the finite difference method to obtain the flow characteristics and compliant wall behavior. Three control parameters are investigated, namely, Reynolds number, inlet transmural pressure, and the wall thickness. The predicted wall deflection is quite large at low Reynolds numbers, suggesting possible approach to breakdown in equilibrium. The transmural pressure increases with wall deflection and bulges appear at the ends of the membrane indicating critical stage of stability, consistent with previous studies. Increase in wall thickness reduces the wall deflection and ultimately results in its collapse which may indicate another breakdown in equilibrium. An increase in internal pressure is required to maintain membrane stability.

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16

Maeno, Tomoyoshi, Kenichiro Mori e Kouji Fujimoto. "Development of the Hot Gas Bulging Process for Aluminium Alloy Tube Using Resistance Heating". Key Engineering Materials 410-411 (marzo 2009): 315–23. http://dx.doi.org/10.4028/www.scientific.net/kem.410-411.315.

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A hot gas bulging process of an aluminium alloy tube using resistance heating, set into a forming machine, was developed. The tube was rapidly heated by the electrifying to increase the formability and to decrease the flow stress. The tube was bulged by thermally expanding the air sealed in the tube without control of internal pressure during the forming. Hot gas bulging of an aluminium alloy tube without and with axial feeding was performed. The effects of the initial internal pressure and the current on the expansion ratio of the tube were examined. The decrease in temperature around the contact with the electrode was prevented by inserting a stainless steel ring having low thermal conductivity and high heat generation between the copper electrode and tube, and thus the bulging length was increased. It was found that the hot gas bulging is effective in heightening the formability of the aluminium alloy tubes.

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17

Lei, Pan, Lian Fa Yang e Yu Xian Zhang. "Investigation on the Formability of Tube in Hydroforming with Radical Crushing under Simple Loading Paths". Advanced Materials Research 291-294 (luglio 2011): 595–600. http://dx.doi.org/10.4028/www.scientific.net/amr.291-294.595.

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Tube hydroforming with radial crushing (THFRC) process is particularly applicable to the tube which is difficult to shape due to lack of axial feeding. In this paper, the formability of the circular tube expanded into a triangle cross-section under the simple loading paths is explored by using the numerical simulation. The effect of the forming mode and the loading paths on bulged profile, wall-thickness distribution and the potential fracture location of the bulged tube are analyzed. The results showed that constraint conditions at tube ends have small influence on the bulged profile and wall-thickness distribution. Moreover, the larger the peak value of the internal pressure is, the better material filling ability and higher accurate the tube bulged profile are. Furthermore, the higher forming accuracy, the better material filling ability and wall-thickness distribution are gained in THFRC than those in free hydro-bulging (FHB) process, and they can be obtained under constant than linear pressure loading paths. Finally, the potential fracture location of the bulged tube in THFRC process is quite different from that in FHB process.

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18

Yi, Hyae Kyung, Jung Hwan Lee, Young Seon Lee e Young Hoon Moon. "Warm Hydroformability and Mechanical Properties of Pre- and Post- Heat Treated Al6061 Tubes". Advanced Materials Research 29-30 (novembre 2007): 87–90. http://dx.doi.org/10.4028/www.scientific.net/amr.29-30.87.

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Warm hydroformability and mechanical properties of pre- and post- heat treated Al6061 tubes were investigated in this study. For the investigation, as-extruded, fully annealed and T6- treated Al 6061 seamless tubes were prepared. To evaluate the hydroformability, uni-axial tensile test and free bulge test were performed at room temperature and 200ÓC. Also mechanical properties of hydroformed part at various pre- and post-heat treatments were evaluated by tensile test. The tensile test specimens were obtained from hexagonal shaped tube hydroformed at 200ÓC forming temperature. As a result, hydroformability of fully annealed tube is 25% higher than that of extruded tube. The tensile strength and elongation were more than 330MPa and 12%, respectively, when hydroformed part was T6 treated after warm hydroforming. However, hydroformed part using T6 pre treated tube represents low elongation, 8%. Therefore, the T6 treatment after hydroforming for as-extruded tube is proved to be the most cost-effective among various processing conditions.

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Lin, Pao Chun, Toru Takeuchi, Ryota Matsui e Ben Sitler. "Seismic Design of Buckling-Restrained Brace in Preventing Local Buckling Failure". Key Engineering Materials 763 (febbraio 2018): 875–83. http://dx.doi.org/10.4028/www.scientific.net/kem.763.875.

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When a buckling-restrained brace (BRB) is composed of a flat steel core encased in a rectangular steel tube with infill mortar, the flat steel core develops high-mode buckling waves within the spaces occupied by compressible debonding layers when BRB is in compression. The wave crests and troughs collide with mortar and then acting outward forces on restrainer. The steel tube wall may bulge out if the restrainer is too weak to sustain the outward forces and the BRB may lose its compression carrying capability. The outward force can be estimated according to steel core high-mode buckling wavelength and the debonding layer thickness. The restrainer capacity in resisting outward forces can be estimated by using the upper bound theory in plastic analysis. The results of 39 BRB tests were compared in order to evaluate the effectiveness of steel tube capacity estimation methods. 24 BRBs exhibiting local bulging failure suggested that the steel tube capacity can be estimated by assuming the bulged wall as a wedge shape with five of its boundary developing flexural strength. The proposed estimation is conservative and can be adopted for BRB design in preventing local bulging failure for severe seismic services.

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Połomski, Zbigniew. "Polyamide tube bulge forming process". Mechanik, n. 8-9 (settembre 2015): 620–21. http://dx.doi.org/10.17814/mechanik.2015.8-9.495.

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Kesvarakul, Ramil, Suwat Jiratheranat e Bhadpiroon Sresomroeng. "Determination of Forming Limit Curves of Steel Pipes for Hydroformability Evaluation". Advanced Materials Research 622-623 (dicembre 2012): 484–88. http://dx.doi.org/10.4028/www.scientific.net/amr.622-623.484.

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The aims of this research are to establish the forming limit curve (FLC) of tubular material low carbon steels commonly used in Thai industry, verify these FLCs with real part forming experiments and compare these experimentally obtained FLCs against analytical ones available in FEA software database. A self-designed bulge forming apparatus of fixed bulge length and a hydraulic test machine with axial feeding are used to carry out the bulge tests. Loading paths resulting to linear strain paths at the apex of the bulging tube are determined by FE simulations in conjunction with a self-compiled subroutine. These loading paths are used to control the internal pressure and axial feeding punch of the test machine. In this work a common low carbon steel tubing grade STKM 11A, with 28.6 mm outer diameter and 1.2 mm thick is studied. Circular grids are electro chemically etched onto the surface of tube samples. Subsequently, the tube samples are bulge-formed. The forming process is stopped when a burst is observed on the forming sample. After conducting the bulge tests, major and minor strains of the grids located beside the bursting line on the tube surface are measured to construct the forming limit curve (FLC) of the tubes. The forming limit curves determined for these tubular materials are put to test in formability evaluations of test parts forming in real experiment. It was found that the tool geometry can keep the strain ratio constant is not dependent on the thickness but only on OD of the tube, as in equations L=OD and rd=(15xOD)/25.4. The experimen-tal FLDs have predicted failures in forming process consistently with the real experiments. The ex-perimentally obtained forming limit curves (determined following STKM 11A) differ from empiri-cal one (from FEA software) and analytical one by about 0.02339 and 0.15736 true strain respec-tively at FLD0, the corresponding plane strain values.

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Khalfallah, Ali, Temim Zribi e Hedi Belhadj Salah. "Application of Tube Hydroforming in Square Cross-Section Die for Inverse Identification Method Validation". Key Engineering Materials 554-557 (giugno 2013): 966–73. http://dx.doi.org/10.4028/www.scientific.net/kem.554-557.966.

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Abstract (sommario):

Tube hydroforming processes are an excellent way for manufacturing reduced weight parts with complex shapes in widespread fields. Accurate numerical simulation of tube hydroforming process is particularly based on precise material parameters deduced from experimental tests. The free bulge test is widely employed for the parameter identification of tubular material behavior models by means of analytical [1] and numerical methods [2]. In this context, an inverse identification methodology using free bulge tests was developed. These tests were carried out by means of a new home-designed and manufactured bulge forming machine. The objective of this work is the validation of the inverse identification method using tube hydroforming in square cross-section die. The analysis of this particular hydroforming process with respect to material parameters is performed. For this purpose, circular section tubes made of low carbon steel S235 and aluminum alloy AA6063-O are hydroformed against square-cross sectional die using our bulge forming machine. Afterwards, FE model is constructed to simulate square-sectional hydroformed parts. The influence of some parameters, such as strain hardening exponent, anisotropy parameter and friction coefficient, on numerical square cross-sectional hydroformed part thickness is analyzed. It permits to assess the sensitivity of the thickness relative to used material parameters in the FE model. In order to validate the inverse identification procedure for both materials, experimental thicknesses along the profile of cross-sectional hydroformed parts are measured and compared with the corresponding numerical thicknesses predicted by FE model. It is proven after analyzing the obtained results that the chosen response, i.e. thickness distribution along the profile of the tube hydroforming against the square cross-section die, used for the validation is sensitive to the identified material properties. Particularly, it is demonstrated for low carbon steel S235 that numerical thickness is in good agreement with experimental data. However, for aluminum alloy AA6063-O, a discrepancy between experimental and predicted thicknesses is noticed. Anyway, it is demonstrated that inverse identification approach leads to sufficiently accurate parameters used for numerical tube hydroforming simulations. Furthermore, it seems that Hill48’s yield criterion is more suitable for describing steels plastic behavior than aluminum alloys for tube hydroforming processes. Concerning aluminum alloy, certainly the choice of appropriate yield criterion is of paramount importance on the prediction of tubular plastic behavior in tube hydroforming. Consequently, it is shown that the use of simple tube hydroforming in square-section die is suitable for the validation of FE model which is identified by inverse method using free bulge test.

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Nishi, Eijiroh, Hirokazu Abe, Katsuhiko Tanaka, Naoto Jimi e Elena K. Kupriyanova. "A new species of the Spirobranchus kraussii complex, S. akitsushima (Annelida, Polychaeta, Serpulidae), from the rocky intertidal zone of Japan". ZooKeys 1100 (12 maggio 2022): 1–28. http://dx.doi.org/10.3897/zookeys.1100.79569.

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A new species of Spirobranchus (Annelida: Serpulidae) is described based on specimens collected at the coastal Shonan area of Sagami Bay and the adjacent areas of Honshu, Japan. Spirobranchus akitsushimasp. nov. forms large aggregations in the intertidal rocky zone of warm-temperate Japanese shores. This species was referred to as Pomatoleios kraussii (Baird, 1864) until the monotypic genus Pomatoleios was synonymized with Spirobranchus. This new species is formally described based on morphologically distinct Japanese specimens with supporting DNA sequence data. The calcareous opercular endplate of Spirobranchus akitsushimasp. nov. lacks a distinct talon, but some specimens have a slight rounded swelling on the endplate underside, while in other species of the S. kraussii complex a talon is present, usually extended, and with bulges. We examined sub-fossil tube aggregations of the new species and suggest that such aggregation stranded ashore is a good indicator of vertical land movements (uplift and subsidence) resulting from past events, such as earthquakes, in Honshu, Japan.

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24

Phadke, M. V. "Prevention of stomal complications". Journal of Clinical Oncology 27, n. 15_suppl (20 maggio 2009): e20745-e20745. http://dx.doi.org/10.1200/jco.2009.27.15_suppl.e20745.

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e20745 Background: Ileostomy/Colostomy operations are associated with a high rate of infections and complications resulting in increased morbidity, mortality and litigation. Pathogenesis of each complication and role of Nature was observed. Technique of stomal maturation was modified. Surgeon must maintain control over the stoma at all times. Primary maturation of stoma is unnecessary and potentially harmful. Opening stomal lumen in O.R. is unscientific and allows bacteria to contaminate stomal and main wounds. Methods: Concept was evolved by serendipity in April 1986. Since then it has been used on all patients requiring an Ileostomy or Colostomy. Bacterial migration is prevented by keeping the lumen obstructed. Iatrogenic obstruction of small/large intestine has no deleterious effect on post-operative course. Obstructed bowel is brought out of opening at proposed site of stoma. Mesenteric corner of obstructed stoma is always above the skin. Anti-mesenteric surface is pulled out till the anti-mesenteric corner becomes the apex of a conical stoma. Serosa is sutured to a round opening in the rectus sheath. Stoma is covered by an appliance with a transparent pouch. Peristalsis starts in about 48–72 hours. When obstructed stoma bulges, it is opened with electrocautery as a minor bedside procedure. Diet is started. Peristalsis pushes mucosal cuff which protrudes, everts and auto-grafts over angiogenesis. This is based on Delayed-Primary (DP) wound healing. Mucosal cuff comes in contact with dermis of skin opening at stomal site completing Self-Maturation (SM). During SM, mucosal tube separates from serosal tube. Peristalsis continues to exert its effect on serosal tube but not on mucosal tube. Lumen of stoma remains concentric. Results: 65 Colostomies and 15 Ileostomies were performed using DPSM technique. Infection and complications were prevented. Minor complications were handled easily. Patient satisfaction was excellent. Conclusions: Primary maturation of stoma is unnecessary and potentially harmful and should be replaced by DPSM. It can be performed in all types of stoma construction, end or loop, temporary or permanent. It prevents infection and complications in all patients. No significant financial relationships to disclose.

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25

Sokolowski, T., K. Gerke, M. Ahmetoglu e T. Altan. "Evaluation of tube formability and material characteristics: hydraulic bulge testing of tubes". Journal of Materials Processing Technology 98, n. 1 (gennaio 2000): 34–40. http://dx.doi.org/10.1016/s0924-0136(99)00303-9.

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26

Hwang, Yeong-Maw, e Yi-Kai Lin. "Evaluation of Flow Stresses of Tubular Materials Considering Anisotropic Effects by Hydraulic Bulge Tests". Journal of Engineering Materials and Technology 129, n. 3 (26 dicembre 2006): 414–21. http://dx.doi.org/10.1115/1.2744406.

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Abstract (sommario):

This paper aims to evaluate the stress-strain characteristics of tubular materials considering their anisotropic effects by hydraulic bulge tests and a proposed analytical model. In this analytical model, Hill’s orthogonal anisotropic theory was adopted for deriving the effective stresses and effective strains under a biaxial stress state. Annealed AA6011 aluminum tubes and SUS409 stainless-steel tubes were used for the bulge test. The tube thickness at the pole, bulge height, and the internal forming pressure were measured simultaneously during the bulge test. The effective stress-effective strain relations could be determined by those measured values and this proposed analytical model. The flow stress curves of the tubular materials obtained by this approach were compared with those obtained by the tensile test with consideration of the anisotropic effect. The finite element method was also adopted to conduct the simulations of hydraulic bulge forming with the flow stress curves obtained by the bulge tests and tensile tests. The analytical forming pressures versus bulge heights were compared with the experimental results to validate the approach proposed in this paper.

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27

Lee, Young Seon, Jung Hwan Lee, M. Y. Lee, Young Hoon Moon e T. Ishikawa. "Formability of Al6061 Extruded Tube in Warm Hydroforming". Key Engineering Materials 340-341 (giugno 2007): 599–604. http://dx.doi.org/10.4028/www.scientific.net/kem.340-341.599.

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Abstract (sommario):

Formability of tube in elevated temperature is essential data to design the warm hydroforming process parameters, such as tube diameter, forming temperature and die geometries. Since the quantitative data of forming limit can be used to predict the failure on forming process, formability data available on the FE analysis is one of the very important information for the optimum design. In this study, the effect of heat treatment conditions and deformation temperature on the formability was investigated for the warm hydroforming of Al6061 tube. Full annealing and T6-treatment are applied for the heat treatment of Al6061 tubes. To evaluate the hydroformability, uni-axial tensile test and bulge test were performed at temperature ranges between room temperature and 300oC. The measured flow stresses were used as input parameters for the simulation of warm hydroforming process. The damage value and strain variation during hydroforming are analysed by FEM. A forming limit based on the ductile fracture criteria has been proposed by combining the results of experimental and FE analysis for the estimation of formability and optimization of warm hydroforming process.

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28

Elyasi, Majid, Hassan Khanlari e Mohammad Bakhshi-Jooybari. "Numerical and Experimental Study of the Effect Pressure Path in Tube Hydroforming Process". Key Engineering Materials 473 (marzo 2011): 579–86. http://dx.doi.org/10.4028/www.scientific.net/kem.473.579.

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Abstract (sommario):

In this paper, the effect of pressure path on thickness distribution and product geometry in the tube hydroforming process is studied by finite element simulation and experimental approach. In simulations and experiments, low carbon stainless steel (SS316L) seamless tubes were used. The obtained results indicated that with increasing of the initial pressure, the bulge value of the part increases and the wrinkling value decreases. In addition, if the initial pressure is highly decreased, then bursting may occur.

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29

Talebi-Anaraki, Ali, Tomoyoshi Maeno, Yuta Matsubara, Ryohei Ikeda e Ken-ichiro Mori. "Integration of Hot Tube Gas Forming and Die Quenching of Ultra-High Strength Steel Hollow Parts Using Low Pressure Sealed-Air". Materials 15, n. 4 (10 febbraio 2022): 1322. http://dx.doi.org/10.3390/ma15041322.

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Abstract (sommario):

A low pressure sealed-air hot tube gas forming process of ultra-high strength steel tubes was developed not only to change the cross-section of the hollow products by bulging but also to increase the strength of components. Gas-formed components are typically formed by a controlled-gas pressure with extremely high internal pressure, which leads to affected production costs and safety. Moreover, compressing the gas with high pressure requires high energy during its preparation. Therefore, to simplify the internal pressure controlling system and improve the safety factor in gas forming processes, the sealed-air tubes are formed with a quite low initial pressure. The pressure of the sealed air increased with increasing temperature of the air inside the resistance-heated tube, and the bulging deformation was controlled only by axial feeding. The effects of the initial pressure and heating temperature on the bulging deformation and quenchability of the tubes, and the effect of the starting time of axial feeding on the bulging behavior were examined. Consequently, ultra-high strength steel bulged parts were produced even in low initial internal pressure and with the rapid heating of the tubes.

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30

Zhang, Jianzhong, Shusheng Gao, Wei Xiong, Liyou Ye, Huaxun Liu, Wenqing Zhu, Ying Mu e Wente Niu. "Physical and Numerical Simulation of Tight Gas Flow at the Microscale". Energies 16, n. 16 (11 agosto 2023): 5937. http://dx.doi.org/10.3390/en16165937.

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Abstract (sommario):

The porous media in tight reservoirs are mainly composed of micro- and nanopores, gas seepage through which is complex, making it difficult to study. Physical simulation using micron tubes is an intuitive and effective method to study the seepage mechanism of tight gas. The lattice Boltzmann method (LBM) is the most effective method for the tight gas seepage simulation, and it has been widely used. Microscale gas seepage simulation experiments and LBM simulations of micron tubes with different inner diameters were performed. The results showed that in micron tubes, the gas flow increases nonlinearly with an increasing pressure gradient. Influenced by compression and rarefaction effects, the degree of the nonlinearity of pressure distribution in series micron tubes increases with inlet pressure. The existence of a connecting channel between parallel micron tubes breaks the linear distribution of pressure in the original micron tubes, and the gas forms a raised relative high-pressure area at the connection of the two micron tubes; the wider the channel, the greater the bulge. The average gas flow rate in the whole micron tube increases with the channel width, and the seepage capacity increases instead of decreases. The diameter change of one micron tube has no effect on the gas flow in the other micron tube. Although the two micron tubes are connected, they are still relatively independent individuals. These research results lay a foundation for the correct understanding of the characteristics and laws of tight gas seepage in the pores of reservoirs at the micro- and nanoscales, and they have important theoretical significance for the study of seepage mechanisms in tight gas reservoirs.

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31

Yang, Lian Fa, Pan Lei e Chen Guo. "The Influence of Friction on Forming Accuracy of Tubular Parts by Hydroforming with Radial Crushing". Advanced Materials Research 328-330 (settembre 2011): 1386–90. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.1386.

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Abstract (sommario):

Forming accuracy is one of the important indicators to evaluate the forming quality of a tubular part by tube hydroforming. However, shape asymmetry on cross-section of tubular part produced by hydroforming with radial crushing (THFRC) inevitably appears due to the friction between the die and the part. In this paper, a circular tube is formed into a square cross-section one by THFRC under the various loading paths and the influence of friction on the forming accuracy of cross-section of the bulged parts is analyzed by using numerical simulation. The results show that the larger the tube is expended to, the lower the forming accuracy is under the identical coefficients of friction (COF); the larger the COF value is, the lower the forming accuracy is under a constant maximum hydraulic pressure. In a word, a reasonable loading path and a low COF value can observably improve the forming accuracy of the bulged tube.

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32

Maeno, Tomoyoshi, Kenichiro Mori e Chihiro Unou. "Optimisation of Condition in Hot Gas Bulging of Aluminium Alloy Tube Using Resistance Heating Set into Dies". Key Engineering Materials 473 (marzo 2011): 69–74. http://dx.doi.org/10.4028/www.scientific.net/kem.473.69.

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Abstract (sommario):

A hot gas bulging process of an aluminium alloy tube using resistance heating set into a die was developed. In the developed process, the tube was heated during the forming, and thus the drop in temperature was prevented. The control of the hot gas bulging was simplified by sealing air in the tube. The tube was bulged by thermal expansion of the air sealed in the tube without control of internal pressure during the forming. Hot gas bulging of an aluminium alloy tube without and with the axial feeding was performed. The deformation behaviour of the tube in the die was observed by a heatproof glass plate inserted in the die. The timing of the axial feeding, the feeding velocity and the amount of the axial feeding were optimised.

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33

MORI, Takao, Koji AKIMARU, Koji SUZUKI e Akihide YOSHITAKE. "Effect of Tube Length on Deformation Behavior for Free Bulged Electric Resistance Welded Tubes". Proceedings of the 1992 Annual Meeting of JSME/MMD 2000 (2000): 737–38. http://dx.doi.org/10.1299/jsmezairiki.2000.0_737.

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34

Loh-Mousavi, M., Kenichiro Mori, K. Hayashi e M. Bakhshi. "Improvement of Filling of Die Corners in Box-Shaped Tube Hydroforming by Control of Wrinkling". Key Engineering Materials 344 (luglio 2007): 461–67. http://dx.doi.org/10.4028/www.scientific.net/kem.344.461.

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Abstract (sommario):

The filling of the die corner in hydroforming of a tube with a box die was improved by controlling wrinkling under oscillation of internal pressure. In this process, a small wrinkle occurs near the die corner in the former stage, and then the wrinkle is eliminated in the latter stage because the flat bulge appears in the former stage due to the oscillation of internal pressure. A hydroforming process of steel tubes with a box die was performed in both three dimensional finite element simulation and experiment. The filling of the die corner for the mean linear pressure was not sufficient due to large wrinkles appearing in the former stage, whereas bursting occurs for the peak linear pressure due to round bulging. On the other hand, the uniformity of wall thickness of the formed tube was improved by the pulsating pressure.

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35

Elyasi, Majid, Hassan Khanlari e Mohammad Bakhshi-Jooybari. "Investigation of Load Path Effect on Thickness Distribution and Product Geometry in the Bulge Hydroforming Process". Applied Mechanics and Materials 110-116 (ottobre 2011): 1477–82. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.1477.

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Abstract (sommario):

In this paper, the effect of load path on thickness distribution and product geometry in the tube hydroforming process is studied by finite element simulation and experimental approach. The pressure path was obtained by using finite element simulation and its validation with experiments. In simulations and experiments, low carbon stainless steel (SS316L) seamless tubes were used. The obtained results indicated that if pressure reaches to maximum faster, bulge value and thinning of the part will be more and wrinkling value will be less.

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36

Chen, Xian Feng, Zhong Qi Yu e Shu Hui Li. "Study on the Formability and its Geometric Factors of Seamed Tube Hydroforming". Advanced Materials Research 314-316 (agosto 2011): 733–37. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.733.

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Forming limit curve (FLC) is an important tool for assessing formability of steel metal. It is commonly obtained from experiment, theoretical calculation and finite element method (FEM) simulation. In this study, the FLC of a seamed tube hydroforming is established by combining the failure criterion of strain increment ratio and FEM simulation. The numerical method is verified by tube bulge tests. Then the sensitivity studies are carried out to evaluate the effect of the geometrical features of seamed tube on its formability by numerical approach. Results show that the changes of the formability with the geometrical features of a seamed tube.

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37

Smith, Warren R. "Wave–structure interactions for the distensible tube wave energy converter". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 472, n. 2192 (agosto 2016): 20160160. http://dx.doi.org/10.1098/rspa.2016.0160.

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Abstract (sommario):

A comprehensive linear mathematical model is constructed to address the open problem of the radiated wave for the distensible tube wave energy converter. This device, full of sea water and located just below the surface of the sea, undergoes a complex interaction with the waves running along its length. The result is a bulge wave in the tube which, providing certain criteria are met, grows in amplitude and captures the wave energy through the power take-off mechanism. Successful optimization of the device means capturing the energy from a much larger width of the sea waves (capture width). To achieve this, the complex interaction between the incident gravity waves, radiated waves and bulge waves is investigated. The new results establish the dependence of the capture width on absorption of the incident wave, energy loss owing to work done on the tube, imperfect tuning and the radiated wave. The new results reveal also that the wave–structure interactions govern the amplitude, phase, attenuation and wavenumber of the transient bulge wave. These predictions compare well with experimental observations.

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38

Reddy, Pathapalli Venkateshwar, B. Veerabhadra Reddy, Perumalla Janaki Ramulu e U. Pranavi. "Comparison of Constitutive Models for Predicting the Formability of SS 304 by Tubular Hydroforming Process". International Journal of Manufacturing, Materials, and Mechanical Engineering 12, n. 1 (gennaio 2022): 1–11. http://dx.doi.org/10.4018/ijmmme.293227.

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Abstract (sommario):

Finite Element (FE) simulation of sheet/tube forming precision depends mainly on the accuracy of the constitutive modeling. The present paper aim is to compare the constitutive models to fit the stress-strain curves. The accurate deformation behavior of the SS 304 tubes depends on the constitutive modeling of hardening behavior. Deformation data of the tensile specimens cut from tubular sample were collected by conducting Uniaxial tensile tests (UTT) at three different rolling directions. Five constitutive relationships were then recognized by fitting the true stress and strain data with the constitutive models of Hollomon, Power, Krupowsky, Voce and Ghosh, and the fitting accuracy were analyzed and compared. Effects of hardening models on Forming Limit Curves (FLC), pressure loading and bulge height of the hydroformed tube were then studied. The obtained FLC from the simulations were compared with experimental FLC to predict the accuracy of the hardening models.

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39

Alaswad, Abed, Abdul Ghani Olabi e Khaled Y. Benyounis. "Employment of Finite Element Modelling and Design of Experiments to Investigate the Geometrical Factors in T-Type Bi-Layered Tube Hydroforming". Key Engineering Materials 473 (marzo 2011): 775–82. http://dx.doi.org/10.4028/www.scientific.net/kem.473.775.

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Abstract (sommario):

In the last years many researchers were concentrating to develop and design new unconventional metal forming processes. Among such new technologies, tube hydroforming was proved as one of the most promising. Geometry of the tube and die were found to have significant effects on the hydroformed part. In this work, Response surface method was used based on data provided by Finite element modeling to construct a model for the bulge height as a function of geometrical factors for T-type bi-layered tube hydroforming. Interaction effects were analyzed and discussed.

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40

Ni, Yanbin, Xiancheng Liu, Yahui Chen e Ruyue Liu. "Cyclic Behaviors of Geopolymeric Recycled Brick Aggregate Concrete-Filled Steel Tubular Column". Applied Sciences 13, n. 3 (17 gennaio 2023): 1235. http://dx.doi.org/10.3390/app13031235.

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Incorporating geopolymeric recycled brick aggregate concrete into steel tubes provides a promising solution to reduce environmental impact of construction and demolition waste. In this paper, geopolymeric recycled brick aggregate concrete-filled steel tubular column (GRBACFST) was developed to improve the environmental sustainability of composite column. Considering the replacement ratio of recycled brick aggregate (RBA), the thickness of the steel tube, type of cementitious materials and the axial compression ratio as the variation parameters, experimental research was performed to explore the cyclic behavior of GRBACFST columns, including the failure mode, bearing capacity, hysteresis curve, ductility and degradation characteristics. Results demonstrated that the failure of GRBACFST columns occurred in the region at column bottom, with the bulge of steel tube and crush of geopolymeric recycled brick aggregate concrete. The proposed GRBACFST columns exhibited favorable hysteretic behaviors with desired bearing capacity, excellent ductility, and energy dissipation behavior, which were enhanced by the increased thickness of the steel tube. The bearing capacity and ductility were reduced with the increase of axial compression ratio, while enhanced with thicker steel tube. Moreover, the degradation of stiffness and strength was more obvious under larger axial compression ratio. The increase of replacement ratio of RBA caused a significant reduction of bearing capacity, while it had few effect on the hysteretic index. It was concluded that the hysteretic behavior of proposed GRBACFST column was not sensitive to the types of cementitious material and geopolymers could serve as an eco-friendly binder for concrete.

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41

Kim, Tae-Joon, e Nak-Soo Kim. "Determination of Material Properties of Tube using Inverse Engineering and Analytic Method in Tube Bulge Test". Transactions of the Korean Society of Mechanical Engineers A 27, n. 9 (1 settembre 2003): 1508–16. http://dx.doi.org/10.3795/ksme-a.2003.27.9.1508.

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42

Djavanrood, F., e M. Gheisary. "Fracture and springback on Double Bulge Tube Hydro-Forming". American Journal of Applied Sciences 5, n. 8 (1 agosto 2008): 1041–46. http://dx.doi.org/10.3844/ajassp.2008.1041.1046.

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43

Djavanrood, F., M. Gheisary e H. Zoghi-shal. "Analytical and Numerical Analysis of Free Bulge Tube Hydroforming". American Journal of Applied Sciences 5, n. 8 (1 agosto 2008): 972–79. http://dx.doi.org/10.3844/ajassp.2008.972.979.

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44

LIN, Yanli, Zhubin HE e Shijian YUAN. "THE FACTORS AFFECTING THE PROFILE OF MIDDLE BULGE REGION DURING TUBE BULGE TEST". ACTA METALLURGICA SINICA 46, n. 6 (15 luglio 2010): 729–35. http://dx.doi.org/10.3724/sp.j.1037.2010.00729.

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45

Larin, Sergey N., e Andrey A. Pasynkov. "Formation of bulges on hollow cylindrical products made of non-ferrous difficult-to-deform alloys". MATEC Web of Conferences 329 (2020): 02004. http://dx.doi.org/10.1051/matecconf/202032902004.

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Abstract (sommario):

Formation of thickened elements on the edge parts of hollow cylindrical products, which serve as the elements of fuel lines of various power plants, can be applied to ensure a significant quality of their welding connection. The article deals with the formation of such thickening elements on tubes made of special non-ferrous alloys. Due to the mechanical features of these materials, these processes were investigated under narrow temperature and speed conditions causing short-term creep of the material. To analyze these operations, mathematical models have been created that describe power modes. Quantitative rules of the influence of the geometric parameters of the process on the pressure during the upsetting have been obtained. The materials obtained during the analysis can be used to create similar technologies.

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46

Seyedkashi, S. M. H., Golam Hosein Liaghat, Hassan Moslemi Naeini e M. Hoseinpour Gollo. "Study of Forming Parameters in Hydroforming of a Thin-Walled ASTM C11000 Copper Tube". Advanced Materials Research 83-86 (dicembre 2009): 133–42. http://dx.doi.org/10.4028/www.scientific.net/amr.83-86.133.

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Abstract (sommario):

Tube hydroforming technology is still considered a new technique growing fast in automotive and aircraft industries. Many researches on all aspects of this process are still required. Contact friction is one of the most effective parameters on tube wall thinning. To successfully fulfill the process without any common defects, it is very important to determine the proper internal pressure and axial feeding loading paths. In this paper, the effect of lubrication on tube wall thinning on ASTM C11000 copper alloy is discussed as well as the effect of internal pressure and axial feeding. An axisymmetric bulged tube is investigated using theoretical, numerical and experimental methods. Improved linear and non-linear pressure and feeding loading paths are applied and the predicted results are experimentally proved. It is observed that non-linear pressure application gives smoother results. Also proper lubrication plays an important role in success of the process.

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47

Mohamed, Mohamed, Ali Abd El-Aty, Abdel Aziz Hegazy e Nader Farahat. "Theoretical Investigations and Simulation of the Hydroforming Processes Performed on C1010 Low Carbon Steel Tubes". Applied Mechanics and Materials 799-800 (ottobre 2015): 443–47. http://dx.doi.org/10.4028/www.scientific.net/amm.799-800.443.

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Abstract (sommario):

This research aims at analyzing and optimizing the hydroforming process parameters to achieve a sound bulged tube without failure. Theoretical constitutive model is formulated to build up a working diagram including process window, which is used to optimise the process parameters and predict the formability and the failure of the tube accurately. The model is validated using the published experimental and analytical results of previous research works for 37% bulging ration of low carbon steel (C1010). The model gave a very good agreement with the published data.

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48

Liu, Xiao Feng, Lian Fa Yang e Yu Xian Zhang. "An Approach for Analysis of Bulged Profile and Thickness Distribution of Tube in Free Hydro-Bulging Process". Advanced Materials Research 499 (aprile 2012): 127–31. http://dx.doi.org/10.4028/www.scientific.net/amr.499.127.

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Abstract (sommario):

Tubular components are widely used in the areas of automotive and aerospace industries due to their excellent properties. A mathematical model considering the bulged region as a parabola curve is proposed to examine the plastic deformation behavior of a thin-walled tube during the free hydro-bulged process. The finite element simulations of the free hydro-bulging process are carried out to verify the approach indirectly. The results indicate that the model is accurate and acceptable to figure out the circumferential radius, wall thickness and axial radius of the bulged profile.

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49

Zhang, Qing. "ANALYSIS AND NUMERIC SIMULATION OF THIN TUBE BULGE FORMING LIMIT". Chinese Journal of Mechanical Engineering 40, n. 03 (2004): 137. http://dx.doi.org/10.3901/jme.2004.03.137.

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50

Li, W. S., J. Zou, K. Y. Lee e X. F. Li. "Asymmetric trapped modes in a tube waveguide with a bulge". Acta Mechanica 229, n. 3 (16 ottobre 2017): 1123–36. http://dx.doi.org/10.1007/s00707-017-1999-9.

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