The Experts below are selected from a list of 2796 Experts worldwide ranked by ideXlab platform
Beomsoo Kang - One of the best experts on this subject based on the ideXlab platform.
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loading path optimization of a hydroformed part using multilevel response surface method
The International Journal of Advanced Manufacturing Technology, 2014Co-Authors: S Ahmadi Y Brooghani, Khalil Khalili, S Eftekhari E Shahri, Beomsoo KangAbstract:In tube hydroforming, the loading path that is the relationship between Axial Feeding and internal fluid pressure is of important significance. Researchers have employed various optimization approaches to find an optimum loading path. In this research, a statistical method based on finite element analysis has been developed. An accurate FEA has been used to simulate the process and to find the response of the process to the loading. By performing an experimental test, the model is verified in comparison with the actual T part. The multilevel response surface method (MLRSM) has been used to model the responses from the finite element analysis. The behavior of the process can be predicted using the response surface methodology (RSM) model, and then, the obtained model is used to optimize the process. The optimum point in the RSM highly depends on the initial range of design variables. Thus, after finding the optimum point in each level, the ranges of variables are adjusted around the last optimum point. Then, the optimization process can be continued as a multilevel process. In the performed optimizations, the thickness variance has been considered as the objective function and the protrusion height as the constraint. The thickness variation based on the optimum loading path is highly improved, and it shows that multilevel RSM is very effective in improving the results.
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investigation on determination of loading path to enhance formability in tube hydroforming process using apdl
Journal of Materials Processing Technology, 2006Co-Authors: Seongchan Heo, J Kim, Beomsoo KangAbstract:Abstract During tube hydroforming (THF) process, failure modes such as buckling, necking and bursting may occur because Axial Feeding and internal pressure are imposed simultaneously. Therefore, the suitable loading condition in THF with regard to internal pressure and Axial Feeding should be designed to improve formability and to avoid failure modes on the final hydroformed product. This study deals with the procedure for the determination of the loading path in THF for improving the formability of the final product after the THF. The suitable loading path is based on the adaptive method using ANSYS parametric design language (APDL). This proposed procedure is demonstrated via a sub-frame model of an engine cradle module in an automobile to be able to satisfy the specifications required after hydroforming, such as excessive thickness thinning phenomena, and the results have been proved to be successful on its effectiveness and feasibility. Consequently, it is shown that the approach proposed in this study will provide a valuable method to satisfy the increasing practical demands for designing the process conditions in THF.
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analytical and numerical approach to prediction of forming limit in tube hydroforming
International Journal of Mechanical Sciences, 2005Co-Authors: Woo-jin Song, Beomsoo KangAbstract:Analytical and numerical analyses of forming limit in tube hydroforming under combined internal pressure and independent Axial Feeding are discussed in this paper. To predict the initiation of necking, Swift's criterion for diffuse plastic instability is adopted based on Hill's general theory for the uniqueness to the boundary value problem. In addition, in order to predict fracture initiation, Oyane's ductile fracture criterion is introduced and evaluated from the histories of stress and strain calculated by means of finite element analysis. From the comparison with a series of tube bulge tests, the prediction of the bursting failure based on the plastic instability and the ductile fracture criterion demonstrates to be reasonable so that these approaches can be extended to a wide range of practical tube hydroforming processes.
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A prediction of bursting failure in tube hydroforming process based on plastic instability
The International Journal of Advanced Manufacturing Technology, 2005Co-Authors: Jeong Kim, Sang-woo Kim, Hoon-jae Park, Beomsoo KangAbstract:Based on plastic instability, an analytical prediction of bursting failure on tube hydroforming processes under combined internal pressure and independent Axial Feeding is carried out. Bursting is an irrecoverable phenomenon due to local instability under excessive tensile stresses. In order to predict the bursting failure, three different classical necking criteria – diffuse necking criteria for a sheet, and a tube, and a local necking criterion for a sheet – are introduced. The incremental theory of plasticity for an anisotropic material is adopted and the hydroforming limit, as well as a diagram of bursting failure with respect to Axial Feeding and hydraulic pressure are presented. In addition, the influences of material properties such as anisotropy parameter, strain hardening exponent and strength coefficient on plastic instability and bursting pressure are investigated. As a result of the above approach, the hydroforming limit with respect to bursting failure is verified with experimental results.
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Analytical approach to bursting in tube hydroforming using diffuse plastic instability
International Journal of Mechanical Sciences, 2004Co-Authors: Jeong Kim, Sang-woo Kim, Woo-jin Song, Beomsoo KangAbstract:Analytical studies on onset of bursting failure in tube hydroforming under combined internal pressure and independent Axial Feeding are carried out. Bursting is irrecoverable phenomenon due to local instability under excessive tensile stress. In this paper, in order to predict the bursting failure diffuse plastic instability based on the Hill's quadratic plastic potential is introduced. The incremental theory of plasticity for anisotropic material is adopted and then the hydroforming limit and bursting failure diagram with respect to Axial Feeding and hydraulic pressure are presented. The influences of the plastic anisotropy on plastic instability, the limit stress and the bursting pressure are also investigated. Finally, the stress-based hydroforming limit diagram obtained from the above approach is verified with experimental results.
Shijian Yuan - One of the best experts on this subject based on the ideXlab platform.
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tube hydro forging a method to manufacture hollow component with varied cross section perimeters
Journal of Materials Processing Technology, 2017Co-Authors: Guannan Chu, Gang Chen, Yanli Lin, Shijian YuanAbstract:Abstract To overcome the problems in high pressure tube hydroforming (HPTH), such as too high forming pressure, thickness thinning and low productivity, a new forming technology was put forward, named as tube hydro-forging(THFG). In THFG, hollow components were formed by cross-section compression, overturned the traditional idea about conventional tube hydroforming in which the tube was expanded into the desired shape. Compared with HPTH, the role of the internal pressure was translated into the function of supporting and the tube sidewall was subjected to compression deformation throughout the process. These changes permit the THFG process with lots of advantages, such as low required internal pressure, avoiding thickness thinning or crack defect, no need for Axial Feeding, and so on. In this study, an analytical model based on a rigid, perfectly plastic material model was developed to investigate the possibility and the main influencing factors of the THFG. The analytical solution developed was compared with the experimental results. Experimental results validate that the tube can be formed into the desired shape by cross-section compression under a certain internal pressure supporting. Through the analytical model combining FEM simulation, the critical support pressure was given. The critical support pressure increases gradually as the deformation going on and has great dependence on the materials properties, however has no dependence on the tube thickness. It is also validated that the required pressure in the THFG is much lower than that needed in the traditional tube hydroforming.
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The deformation and microstructure of Ti-3Al-2.5V tubular component for non-uniform temperature hot gas forming
The International Journal of Advanced Manufacturing Technology, 2016Co-Authors: Gang Liu, Kai Wang, Zhiqiang Liu, Shijian YuanAbstract:In this paper, three 70 % expansion ratio Ti-3Al-2.5V tubular parts were formed by non-uniform temperature hot gas forming with different temperature distributions. The deformation behavior, thickness distribution, microstructure, and mechanical property of tubular parts were studied. The result shows that a suitable temperature difference between forming zone and transition zone is beneficial for Axial Feeding, which promote the thickness distribution uniform. The number of wrinkles in forming zone is affected by the temperature distribution. There are two wrinkles, one wrinkle, and three wrinkles when the temperature differences are 0, 50, and 15 °C, and the max thinning ratio is 24.9, 24.1, and 18 %, respectively. When the temperature difference is 15 °C, the microstructure and mechanical property is uniform.
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loading path and microstructure study of ti 3al 2 5v tubular components within hot gas forming at 800 c
The International Journal of Advanced Manufacturing Technology, 2016Co-Authors: Gang Liu, Kai Wang, Zhiqiang Liu, Shijian YuanAbstract:Hot tube gas forming is a forming technology, whose ultimate goal is forming a uniform cross-section blank tube into a complex shape die cavity with varying cross-sections without necking, wrinkling, or buckling by applying of Axial Feeding and internal pressure at elevated temperature. In this paper, the effects of Feeding speed and internal pressure on the quality of formed tubular components were studied by theoretical analysis, FEM simulation, and experiment. The microstructure evolutions at four typical positions were analyzed by electron back-scattered diffraction (EBSD). The mechanical properties of tubular component were tested by the uniAxial tensions and hardness tests. A good tubular component can be formed under a two-stage loading path at 800 °C, the Feeding speed is 0.1 mm/s and the internal pressure is 5 MPa during the first Feeding stage while the Feeding speed is 0.2 mm/s and the internal pressure is 7 MPa during the second Feeding stage. At the forming zone, the grains are significantly elongated along the hoop direction. Compared with the as-received tube, the tensile strength of parts reduces about 6 % along Axial direction.
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Effect of Feeding length on deforming behavior of Ti-3Al-2.5 V tubular components prepared by tube gas forming at elevated temperature
The International Journal of Advanced Manufacturing Technology, 2015Co-Authors: Gang Liu, Wang Dongjun, Shijian YuanAbstract:In order to investigate the deforming behavior of the tubular components with a large expansion ratio fabricated by tube gas forming technique, the Ti-3Al-2.5 V tubular components with 50 % expansion ratio were studied under the forming conditions of internal pressure and Axial Feeding at 800 °C. Through thickness measurements, EBSD and tensile tests, the effects of Axial Feeding on deforming behaviors, such as thickness distribution, microstructure, and mechanical properties of Ti-3Al-2.5 V tubular components, were investigated in details. The results showed that the average thinning ratio of the bulging area could be reduced significantly and the thickness distribution of the workpiece was more uniform with increasing of the Feeding. Feeding length influenced the microstructure and strength of components. When the Axial Feeding ratio (actual Feeding length/theoretical Feeding length) was 56 %, the component had even higher tensile strength than the original tube because of the grain refinement. If the Axial Feeding was excessive large, the grain size became adversely coarser, which in turn reduced the tensile strength. These investigations illustrated that tube gas forming under high pressure had potential for fabricating complicated shaped titanium alloy tubular components by reasonably designing and controlling the deforming process.
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optimization of loading path in hydroforming t shape using fuzzy control algorithm
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: B G Teng, Kai Li, Shijian YuanAbstract:The loading path is crucial to the quality of forming parts in the process of tube hydroforming, and thus the design and optimization of loading path is an important issue for tube hydroforming. Wrinkling is a catastrophic defect for thin-walled tube hydroforming. In order to avoid wrinkling, an adaptive simulation approach integrated with a fuzzy control algorithm is used to optimize the loading path of hydroforming a T-shaped tube. The tubular material used is stainless steel and has an outer diameter of 103 mm and the wall thickness of 1.5 mm. The controlled variables are the Axial Feeding, the counterpunch displacement, and the internal pressure. A code is developed to make the optimization automatically, which works together with LS-DYNA. Six evaluation functions are adopted for identifying geometrical shape and quality of T-shape. Failure indicators obtained from the simulation results are used as the input of the fuzzy control, and then process parameters are adjusted according to the expert experiences in the fuzzy controller. In this way, a reasonable loading path for producing a sound T-shape is obtained, and also a T-shaped product is successfully hydroformed by experiment. The result shows that the fuzzy control algorithm can provide an adequately reliable loading path for hydroforming T-shaped tubes.
Luen Chow Chan - One of the best experts on this subject based on the ideXlab platform.
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Analysis and reduction of wrinkling defects for tube-hydroforming magnesium alloy components at elevated temperatures
Materials & Design, 2019Co-Authors: Ting Fai Kong, Luen Chow ChanAbstract:Abstract Wrinkling defects commonly occur in tube hydroforming (THF) magnesium (Mg) alloy at elevated temperatures when the tube-end and Axial-Feeding regions of the workpiece are overheated. Most previously proposed methods for preventing such defects have been applied at room temperature and restricted by several limitations. Therefore, this paper presents a breakthrough in tool design through the appropriate control of temperature distribution of the Mg alloy AZ31B tubular material to minimise the wrinkling defects in THF at evaluated temperatures. The proposed cost-effective, simple and user-friendly collet-type device design was able to provide a non-isothermal condition for THF within an appropriate pre-heating time after die closing. An axisymmetric barrel-shaped component was taken as a prime example to demonstrate the methodology, in which various thermal potential differences between the Axial-Feeding and deformation regions were investigated using finite-element (FE) simulation so as to evaluate the wrinkling effects under various non-isothermal conditions. The results showed that the most satisfactory component could be obtained when the average temperatures of Axial-Feeding and deformation regions were around 240 and 330 °C, respectively. Subsequently, with the same approach, a wrinkle-free non-axisymmetric tubular bike-frame component was hydroformed successfully as a more realistic and practical application example.
Mohammad Bakhshi Jooybari - One of the best experts on this subject based on the ideXlab platform.
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Experimental and Numerical Study on Forming Limit Diagrams of 304 Stainless Steel Tubes in the Hydroforming Process
Journal of Materials Engineering and Performance, 2016Co-Authors: Mahdi Falahati Naghibi, Mahdi Gerdooei, Mohammad Bakhshi JooybariAbstract:Tearing as a factor that restricts formability of sheets and tubes is determined by forming limit diagram (FLD). The aim of the current study is to present a novel approach to achieve FLD of a metallic tube using hydroforming process. Here, for 304 stainless steel tubes, various loading conditions, namely free loading, bulging with Axial Feeding and bulging with closed end, were considered. Along with loading condition, die geometries with different corner radius and deformation width were studied on the strain path and plastic instability. The effects of process parameters on the strain path have been evaluated and simulated using ABAQUS/Explicit. Meshed tubes were bulged under controlled loading, and the FLD was drawn after measuring the major and minor strains close to the tearing location. Finally, the evaluation of the current method has been investigated by using the obtained FLD in the forming of an industrial part (i.e., the cam-shaped tube). The results revealed that the proposed approach has the capability to predict the formability of industrial components.
Yeong-maw Hwang - One of the best experts on this subject based on the ideXlab platform.
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Adaptive simulations in T-shape tube hydroforming with different outlet diameters
Proceedings of the Institution of Mechanical Engineers Part B: Journal of Engineering Manufacture, 2014Co-Authors: Yeong-maw Hwang, Kuo-hsing Wang, Nai-shin KangAbstract:A successful tube hydroforming process depends largely on the loading paths for controlling the relationship between the internal pressure, Axial Feeding and the counter punch. The objective of thi...
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Tube Hydroforming of Magnesium Alloys at Elevated Temperatures
Journal of Engineering Materials and Technology, 2010Co-Authors: Yeong-maw Hwang, Bing-jian ChenAbstract:In this paper, a hydraulic forming machine with the functions of Axial Feeding, counter punch, and internal pressurization is designed and developed. This self-designed forming machine has a capacity of 50 tons for Axial Feeding and counter punch, 70 MPa for internal pressurization, and 300°C for forming temperature. Using this testing machine, experiments of T-shape protrusion of magnesium alloy AZ61 tubes at elevated temperatures are carried out. A commercial finite element code DEFORM 3D is used to simulate the plastic deformation of the tube within the die during the T-shape protrusion process. Different kinds of loading paths for the pressurization profile and the strokes of the Axial Feeding and the counterpunch are scheduled for analyses and experiments of protrusion processes at 150°C and 250°C. The numerical thickness distributions and the flow line configurations of the formed product are compared with the experimental results to validate this finite element modeling. The thickness distribution of the formed product or the flowability of AZ61 tubes at 150°C and 250°C is discussed. The effects of the forming rate on tube flowability at 250°C are also investigated. Through the observation of the fiow line configurations of the tube material, adequate backward speeds of the counter punch relative to the Axial Feeding for preventing the material from accumulating at the die entrance region are verified. Finally, a sound product with a protrusion height of 49 mm is obtained.
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Forming limit diagrams of tubular materials by bulge tests
Journal of Materials Processing Technology, 2009Co-Authors: Yeong-maw Hwang, Han-chieh ChuangAbstract:This study uses bulge tests to establish the forming limit diagram (FLD) of tubular material AA6011. 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 corresponding to the strain paths with a constant strain ratio at the pole of the bulging tube are determined by FE simulations linked with a self-compiled subroutine and are used to control the internal pressure and Axial Feeding punch of the test machine. After bulge tests, the major and minor strains of the grids beside the bursting line on the tube surface are measured to construct the forming limit diagram of the tubes. Furthermore, Swift's diffused necking criterion and Hill's localized necking criterion associated with Hill's non-quadratic yield function are adopted to derive the critical principal strains at the onset of plastic instability. The critical major and minor strains are plotted to construct the forming limit curve (FLC). The effects of the exponent in the Hill's non-quadratic yield function and the normal anisotropy of the material on the yield locus and FLC are discussed. Tensile tests are used to determine the anisotropic values in different directions with respect to the tube axis and the K and n values of the flow stress of the tubular material. The analytical FLCs using the n values obtained by tensile tests and bulge tests are compared with the forming limits from the forming limit experiments.
