Papers by Keyword: Tube

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Authors: Xiao Feng Liu, Lian Fa Yang, Yu Xian Zhang
Abstract: 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.
Authors: Satoshi Takaoka, Hiroshi Horikawa, Jyunji Kobayashi, Kenichi Shimizu
Authors: David Bryan
Abstract: ATI 425® Alloy, nominal composition Ti-4.0Al-2.5V-1.5Fe-0.25O, is a new alpha/beta Ti alloy of significant commercial interest as a viable replacement for Ti-6Al-4V, CP-Ti, and other titanium alloys in a variety of aerospace applications. ATI 425® Alloy offers properties comparable to Ti-6Al-4V alloy with significant improvements in formability, both at room and elevated temperatures. The reasons for the improved formability, particularly at low temperatures, are not well understood. The development of a thorough understanding is complicated by the wide array of phases, microstructures, and deformation paths available via thermomechanical processing in alpha/beta titanium alloys. In this paper, theories of strengthening and dislocation mobility in titanium and HCP metals will be reviewed and applied to better understand why ATI 425® Alloy offers a unique combination of strength and formability not obtainable by conventional alpha/beta titanium alloys. Subsequently, the application of the improved formability to a range of product forms including sheet, tubing, and forgings will be discussed.
Authors: Kyung Young Jhang, Hyun Mook Kim, Kyung Ill Jung, Hyung Keun Ahn
Authors: Zhong Tang Wang, Guang Xia Qi, Fang Wang, Shi Hong Zhang
Abstract: ] Theoretical calculation formula of punch force during tube extrusion has been proposed by means of slab method. On the basis of theoretical and experimental study, it is found that theoretical results of extrusion force given by the calculating formula approached to that of the experiment, and the relative errors are less than 20%. It is also found that the extrusion force is closely related to deformation temperature, lubricant and the ratio of extrusion. The calculating formula of extrusion force is given by considering the factors which are the conical angle of die, and the friction coefficient between the deformation zone and the extrusion container, and the friction coefficient between the undeformed zone and the mandrel. Key Words: Tube, Extrusion, Force, Physical model
Authors: Ji Yeon Park, Dae Jong Kim, Weon Ju Kim
Abstract: SiCf/SiC composites are one of the candidates for high temperature structural applications because of their high strength and corrosion resistance under severe conditions and stability under neutron irradiation [1~3]. A silicon carbide fuel cladding for the light water cooled reactors (LWRs) may allow a number of advances, including: the increased safety margins under transients and accident scenarios, such as loss of coolant accident; the improved resource utilization via a higher burn-up beyond the present limit of 62 GWd/MTU; and improved waste management [3~5]. Some components of SiCf/SiC composite will be applied as tubular geometry for the high-temperature core parts. The proposed design of an advanced LWR fuel cladding, referred to as Triplex, consists of three layers: an inner SiC monolith, a central SiCf/SiC composite, and an outer dense SiC evrionmental barrier coating. The inner SiC layer provides the strength and hermeticity to contain fission products. The SiCf/SiC composite layer fabricated by the CVI process provides a pseudo-ductile failure mode. The outer SiC thin coating layer protects against corrosion [5]. The chemical vapor deposition (CVD) technique is an effective approach for the fabrication of SiCf/SiC composite and coated SiC monolith [6]. To increase the homogeneity of the microstructure and the deposition rate of a SiC tube, the process parameters should be optimized and modified.
Authors: Carl T.F. Ross, Marcus Engelhardt, Andrew P.F. Little
Abstract: This paper describes an experimental and an analytical and numerical investigation into the buckling behaviour of cylindrical composite tubes under external hydrostatic pressure. The investigations concentrated on fibre reinforced plastic tube specimens made from a mixture of three carbon and two E-glass fibre layers. The lay-up was 0°/90°/0°/90°/0; the carbon fibres were laid lengthwise (0°) and the E-glass fibres circumferentially (90°). The theoretical investigations were carried out using a simple solution for isotropic materials, namely a well-known formula by “von Mises” and also by finite element analyses using ANSYS. The experimental investigations showed that the composite specimens behaved similarly to isotropic materials tested by various other researchers. The specimens failed by the common modes associated with this study, namely due to elastic buckling, inelastic buckling and axisymmetric yield failure. Furthermore it was discovered that the specimens failed at changes of the composite lay-up due to the manufacturing process of these specimens. These changes seem to be the weak points of the specimens. For the theoretical investigations two different types of material properties were used to analyse the composite. These were calculated properties derived from the properties of the single layers given by the manufacturer and experimentally obtained properties. Two different approaches were chosen for the investigation of the theoretical buckling pressure, a program called “MisesNP”, based on a well-known formula by von Mises for single layer isotropic materials, and two finite element analyses using the famous computer package called “ANSYS”. This latter analyses simulated the composite with a single layer orthotropic element (Shell93) and also with a multi layer element (Shell99). It was found out that the results obtained with ANSYS predicted questionable buckling pressures that could not be reproduced logically. Nevertheless this report provides Design Charts for all approaches and material types. These Design Charts allow the possibility of obtaining a ‘plastic knockdown factor’. The theoretical buckling pressures obtained using MisesNP or ANSYS can then be divided by the plastic knockdown factor, to give predicted buckling pressures. This method can be used for the design of full-scale vessels.
Authors: Togay Ozbakkloglu
Abstract: This paper reports on the development and testing of a new concrete-filled fiber reinforced polymer (FRP) tube (CFFT) system. The CFFT system was designed to enhance the effectiveness of rectangular FRP tubes in confining concrete. The technique used in the development of the CFFT system involved the incorporation of an internal FRP panel as an integral part of the CFFT. The performance of the system was investigated experimentally through axial compression tests of six unique CFFTs. The results of the experimental study indicate that the new CFFT system presented in this paper offer significantly improved performance over conventional CFFTs with similar material and geometric properties. Examination of the test results have led to a number of significant conclusions in regards to confinement effectiveness of each new CFFT system. These results are presented and a discussion is provided on the parameters that influenced the compressive behavior of the new CFFT system.
Authors: M. Avalle, Giovanni Belingardi, A. Gugliotta, R. Vadori
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