Papers by Author: He Yang

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Authors: Wen Ting Tang, Li Jin, Jin Zhang, He Yang
Abstract: In-plane bending is an advanced plastic processing technology which controls the uneven compressing plastic deformation of strip metal harmoniously and forces the strip metal to produce in-plane bending and to form an open circle. In-plane bending is divided into incremental and continuous process according to the loading manner. While much attention has been paid to the continuous in-plane bending techniques and achievements have been made at home and abroad, only limited experimental investigation has so for been done on incremental in-plane bending by overseas scholars. In this paper, a 3D finite element simulation based on the rigid-plastic principle is performed for incremental in-plane bending of pure aluminum sheet with width of 25 ~ 27.5 mm, thickness of 1.5 ~ 3 mm. Influences of technical parameters such as punch inclined angle αp, punch indentation s, thickness of strip t0, width of strip w0 and strip pitch p on the strip bending radius Rin are studied. The achievement of this study enriches the uneven deformation theory. It lays a theoretical foundation for generalization and industrialization of incremental in-plane bending and offers a new idea to the research and development of the advanced plastic processing technologies.
Authors: Hong Wei Li, He Yang
Abstract: This study developed a new polycrystal plasticity model by deducing a set of linear controlling equations with respect to the controlling equation of rate dependent crystal plasticity (RDCP). It was proved numerically efficient and stable by means of the comparison with experiment and an implicit model. The model was then applied to describe earing in deep drawing process. Remarkable effects of rate sensitivity coefficient of the material, drawing speed and dies clearance on earing were found.
Authors: Zhi Chao Sun, He Yang
Abstract: Isothermal local loading forming is an advanced technology for large-scale complex integral component forming, but the process is with coupling effects of multi-fields and multi-factors due to the local loading mode and high temperature condition, thus makes deformation mechanism extremely complicated and some forming defects may occur. Based on DEFORM3D software, relative FE models for the isothermal local loading forming of large-scale complex integral components of TA15 titanium alloy have been established, and key technologies for modeling have been dealt with properly. Then taking a representative large-scale complex integral component as object the froming process, the typical deformation behavior and metal flow were investigated. And typical forming defects which may occur during the process and causes for them are discussed.
Authors: Wen Ting Tang, Chao Li Tang, Lei Huang, He Yang
Abstract: Incremental in-plane bending is a flexible and laborsaving manufacturing technology for short production runs in a variety of sizes and shapes. But the technology parameters are interactive intimately and it is hard to forecast and control the bending radius accurately. Based on the features of incremental in-plane bending and the advantage of expert system dealing with problems, an expert system of incremental in-plane bending by designing knowledge base of representation of creation regulation, reasoning system based on rules and search mechanism and explaining system based on prefabricating text has been researched and developed in this paper. The system, making use of ADO technology, Access database and Visual Basic, develops knowledge base, database and reasoning system. Based on client / server model, the system realizes a seamless link between Visual Basic and Matlab by using ActiveX. The system can perform functions of bending radius forecasting and forming program evaluating and optimizing. It has a friendly interface and it is easy to operate and convenient for maintenance.
Authors: Zhi Chao Sun, He Yang, Lan Yun Li
Abstract: Guide rolls play an important role in controlling both the ring circularity and the stability of cold ring rolling process. However, it is difficult to predict and control the motion of the guide rolls due to the complexity of process associated with the coupled effects of multi-factors. In this paper, a reasonable controlling model of the guide rolls is proposed, and the functional relationship between the motion track of the guide rolls and their setup parameters and process ones is established, by which the guide rolls motion track can be determined. On this basis, a 3D-FE simulation model for cold ring rolling is developed under the ABAQUS software environment and the effects of the initial position and motion track of the guide rolls on the forming stability, ring circularity, rolling force, and oscillating are investigated. Taking the forming stability and ring circularity as objects, the optimum initial position and motion track of the guide rolls are obtained.
Authors: Yu Li Liu, Gang Yao Zhao, Jin Zhang, He Yang
Abstract: In rotary-draw bending process of thin-walled rectangular tube, cross-sectional distortion is an unwanted byproduct, which is closely related to geometry parameters. To study the effects of geometry parameters on cross-sectional distortion, a 3-D finite-elements model was built under the ABAQUS/Explicit environment, and its reliability was validated by experiments. Then, simulation and analysis of the influence laws of geometrical parameters on cross-sectional deformation degree were carried out. The results show that increases with the increase of b/h and decreases with the increase of R/h when b/h>1. However, R/h has little influence on δh when b/h≤1. And the influence of b on δh is larger than that of h, and the effect of h on δh is larger than that of R.
Authors: Jun Qing Guo, He Yang, Ping Liu, Shu Guo Jia, Li Ming Bi
Abstract: The DPCC(deformation processed Cu-based in-situ composite) behaved better combined performance. In this paper, Cu-10Fe-1.5Ag and Cu-10Fe-1.5Ag-0.1Zr in-situ composites were prepared using different forming processes and annealing techniques. The microstructure evolution was explored by SEM during the plastic deformation. It was found that Fe fibers were produced during drawing process and changed from trees dendrite to fiber structure in the form of flake. The effect of Zr on thermal stability of composite was analyzed also. It was shown that the adding of Zr element was helpful to increase the thermal stability of Cu-Fe composite by multi elements compound.
Authors: Yu Li Liu, He Yang, Tao Gao
Abstract: A blade with a damper platform, with excellent anti-vibration characteristic and high efficiency, has become one of the most important types of blades being developed in the aeronautical engines. During the precision forging process of this blade, the friction between dies and workpiece has important effects on metal flow, deformation defects, load and energy etc. So researching the effects of friction conditions on the forging process of blade with a damper platform has been a crucial problem urgent to be resolved. In this paper, the precision forging process of titanium alloy blade with a damper platform under different friction conditions has been simulated and analyzed based on the DEFORM-3D software platform. The obtained results reveal the influence laws of friction on temperature field and load-stroke curves, and provide a significant basis for determining technological parameters of the blade forging process.
Authors: Shan Tian, Yu Li Liu, Gang Yao Zhao, He Yang
Abstract: The rotary-draw bending process of thin-walled rectangular tube is a complex process with large deformation, large displacement and finite strain which makes the defects, such as wrinkling, distortion and crack be easily produced. To study the complex plastic deformation characteristics of thin-walled rectangular 3A21 aluminum tube during rotary-draw bending, the distributions of tangential, circumferential and normal strain have been studied by experiment using grid method. The results show that the maximum value of three-direction strain appears in the ridges of rectangular tube and tangential strain is the maximum principal strain. The value of maximum tangential tensile strain is lager than the maximum tangential compressive strain; it is the reason why crake is prone to occur during rotary-draw bending. The strain distribution curve along bending direction is not completely symmetrical with middle cross-section. With the increase of bending angle, three-direction strain of tube also increases and circumferential strain increases relatively smaller.
Authors: Heng Li, He Yang, Yu Li Tian, Kai Peng Shi
Abstract: The larger bending velocity is needed in practice to improve efficiency of tube bending, however, whether it has undesired effects on bending behavior has not been identified and clarified. In this study, taking thin-walled 6061-T4 Al-alloy tube of Φ50.8×0.889×101.6mm (out diameter D×wall thickness t×bending radius R) as the objective, the physical experiments are carried out to explore the influence rules of the bending velocity on tube bending in terms of major defects such as wall thinning, wrinkling and springback. The results show that: 1) both higher and lower bending velocities result in excessive wall thinning and wrinkling. 2) springback angle increases with increasing of bending velocity.
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