Abstract: The purposes of this paper are to weld dissimilar aluminum alloys joints, AA1050 and AA6061, and to find Young’s modulus on the welded zone along the thickness. Dissimilar aluminum alloys plates are friction stir welded in the butt configuration by using an adapted milling machine. Young’s modulus of components is found out by applied a reverse method and the out-of-plane displacement is measured by Electronic Speckle Pattern Interferometry. The out-of-plane displacement of the welded cantilever beam is subjected to a concentrated load. The results reveal that Young’s modulus in the welded zone is the deeper the smaller.
Abstract: Stainless steel tubes are widely used in various fields, such as electrode tubes, probe tubes, electronic parts, painless injection needles, and micro-nozzles etc. In this study, a self-developed prototype dieless drawing machine is used to explore the formability of the dieless drawing process of SUS304 stainless steel tubes. The critical process parameters of the forming temperature, drawing velocity, the drawing accelerations and area reduction are investigated. A commercial finite element code of DEFORM 3D is used to simulate the temperature, stress, strain distributions and drawing velocity limit in the dieless drawing process of the stainless steel tubes. The maximum area reduction obtained can reach 50% and the better forming temperatures are between 1000°C and 1100 °C.
Abstract: A bipolar plate is one the most crucial and costliest of the various components of a proton exchange membrane fuel cell (PEMFC). It is important to reduce the cost of bipolar plate, not only in terms of material, but also in terms of the manufacturing process, to allow the commercialization of PEMFC’s. The performance of PEMFC’s is also of importance. Metallic bipolar plates have been the subject of much attention recently, because of their low material cost, formability and excellent thermal and mechanical prosperities. Therefore, this study uses a rubber pad forming process for stainless 316L steel to fabricate a bipolar plate with serpentine channels. A computational fluid dynamics (CFD) analysis is performed, in order to determine the influence of channel geometries, such as channel width, channel height and rib width, on the flow distribution of the reactant. Using the CFD results, finite element analysis models are then constructed and the formability of the micro-flow channel is studied. Finality, experiments are conducted to determine the channel height and thickness distribution of the bipolar plate. The numerical results are verified by the experimental results.
Abstract: With the rapid development of mechanical manufacturing technology and numerous demands of different technique products and the applied industry, commercial products trend miniature and precision. In order to satisfy the demands of miniature and precision components, the precision forming technology which takes advantages of high mass production, low costs and stable quality is proposed. This paper develops the precision flange forming die for sheet metal. In the paper, the SUS304 stainless steel was adopted to enhance the structural rigidity. The hollow flange sheet is manufactured by precision forming processes. The forming height, the sheet thickness and the other geometry parameters are considered and the technologies of hole-flanging forming, pressing and forging are applied in this study. The CAE (Computer-Aid Engineering) simulation tool is adopted as a reference to analyze the feasibility of the proposed forming processes. Both simulated and manufactured results show that the proposed precision forming technique can be a reliable process for the production of precision hollow flange sheet.
Abstract: In this study, the finite element software ANSYS was used to analyze the mechanical behavior of local sharp-notched circular tubes under cyclic bending. The local sharp-notched depths include: 0.2, 0.4, 0.6, 0.8 and 1.0 mm, and the local sharp-notched directions include: 0, 30, 60 and 90 degrees. According to the experimental result, the notch depth has no influence on the moment-curvature relationship. But the notch depth increases, the unsymmetrical phenomenon of the ovalization-curvature relationship becomes more obvious and the speed of ovalization accelerates. In addition, the ovalization-curvature relationship becomes symmetrical when the direction angle increases. The ANSYS analysis was compared with the experimental finding. Although some differences between the experimental and simulated results, but both trends were very similar.
Abstract: New finite element homogenization model with nonaffine constitutive equation of rubber is developed to study the deformation behavior of silica-filled rubber under monotonic and cyclic deformation. The obtained results clarified the effect of the volume fraction of the silica coupling agent and the networklike structure connecting the silica particles on essential physical enhancement mechanisms of deformation resistance and hysteresis loss for silica-filled rubber. The finding suggests that the material characteristics of silica-filled rubber are much more controllable than those of carbon-black-filled rubber.
Abstract: The generalized stacking fault (GSF) energy surfaces of (110), (101), (121), (001), and(100) planes in -Sn are analyzed using first-principles density functional theory calculations. Fromthe minimum energy paths (MEPs) on the GSF energy surfaces analyzed, energetically preferableslip paths of 13 nonequivalent slip systems in -Sn are investigated. It is found that the MEP of(110)/2, (101), (101)/2, (121), and (121)/2 deviates from the straight linepath and takes a curve line path. The results indicate that perfect dislocations on these five slip systemsdissociate into partial dislocations as in cubic and hexagonal crystals.
Abstract: The effect of directional grain structure and strain rate on the impact properties and dislocation substructure of 6061-T6 aluminum alloy is studied. Impact tests are performed at strain rates ranging from 1x103 to 5x103s-1 using a split Hopkinson pressure bar system. Cylindrical specimens are prepared from the rolled plates in longitudinal direction, transverse direction and through-thickness direction, respectively. The results show that the flow stress is strongly dependent on the strain rate and displays complex variations with grain structure direction. The flow stress increases with increasing strain rate. For all tested strain rates, the flow stress is the highest in the transverse specimen, followed by the through-thickness specimen and longitudinal specimen. However, at the strain rate of 5x103s-1, the flow stress in longitudinal specimen is higher than that in through-thickness specimen due to the change of dislocation multiplication rate. The plastic flow occurs within the deformation regions, and becomes more pronounced at high strain rates, especially for the longitudinal specimen. Dislocation density increases markedly with increasing strain rate. Strengthening effect is the highest in the transverse specimen, followed by the longitudinal specimen and through-thickness specimen.
Abstract: Abstract. This contribution presents the investigation of energy absorption mechanism of metal tubes and composite-wrapped metal tubes subjected to a diametric deformation via an expansion process. In the experiments, the expansion of the tubes was performed under quasi-static loading using a conical-cylindrical expansion die. The experimental results are repeatable and thus reliable. An extensive finite element analyses and experimental investigation were carried out in parallel. Both two-dimensional and three-dimensional finite element models were created based on the actual experimental geometrical and material parameters. Results from the finite element analyses correlate rather well with the experimental data. Glass fibre-wrapped metal tubes showed an increased steady-state reaction force which in turn reflects better specific energy absorption capacity for every layer of composite wrapped as compared to bare metal tubes.