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Shi X.,Nanjing University of Aeronautics and Astronautics | Lu S.,Nanjing University of Aeronautics and Astronautics | Zhang W.,Xian Aircraft Industry Ltd.
Zhongguo Jixie Gongcheng/China Mechanical Engineering

USP forming on AA2024-T351 sheet was studied. Improvement of the surface integrity of treated AA2024-T351 and the relations among several parameters (micro hardness, residual stress distribution, surface topography, surface roughness and full width half maximum(FWHM)) and different USP process parameters were analyzed. The research shows that micro hardness of treated material is improved obviously(about 20%) with influenced area of 300μm depth down. Residual compressive stress is introduced, which is higher and gradient distribution, depth of residual compressive stress field is about 500~650μm, and the maximum point is located at the 200 μm layer below the surface. There are many furrows on the surface of workpices at the sametime, the roughness of surface increases slightly, the half-width of X-ray diffraction of sample is increased, the 125 μm layer below the surface, which shows the cold work hardening is occurred and crystal dislocation density is considerably increased. The experiments show that the improvement of micro hardness and induced residual compressive stress by ultrasonic shot peening forming make great positive influence on the fatigue life, wear resistance and corrosion resistance of AA2024-T351. Source

Xiao Z.,Xian University of Science and Technology | Liu X.,Xian Aircraft Industry Ltd. | Hou Y.,Xian University of Science and Technology
Proceedings - 2012 International Conference on Computer Science and Service System, CSSS 2012

The programs having syntax errors submitted to some programming examination automatic scoring system would be only given zero point, the result is not coincided with the habit of artificial test paper marking. In order to solve this problem, an automatic grading algorithm which based on the theory of compiler theory is provided. The algorithm gave a method which combined dynamic marking and static marking, and the static marking achieved with matched key knowledge points. According to the experiment, the algorithm has accuracy of remarking and some valuable domains of application. © 2012 IEEE. Source

Jia Z.,Northwestern Polytechnical University | Zeng W.,Northwestern Polytechnical University | Zhang Y.,Northwestern Polytechnical University | Shi C.,Xian Aircraft Industry Ltd. | And 2 more authors.
Journal of Alloys and Compounds

Abstract The oxidation of titanium alloy at elevated temperature severely limits its property and service life. It is a common and urgent issue to assess the mechanical property of oxidized titanium component without destroying its structural integrity. In this work, the color changes and tensile properties of oxidized Ti-6A1-2Mo-1.5Cr-2Zr-2Sn-2Nb alloy with initial basket-weave microstructure were investigated in the temperature range of 100-1000 C. It was found that the oxidized specimens exhibited brilliant and regular color changes. X-ray diffraction (XRD) analysis indicated that the color changes were mainly attributed to the mixing of colored titanium oxides in the oxidation layer (such as yellow TiO, white TiO2 and blue Ti2O3). It was also found that mechanical properties were significant influenced by the oxidation treatment. The specimens oxidized below 600 C exhibited excellent strength and plasticity due to its fine basket-weave microstructure and dense oxidation layer. In the temperature range from 600 to 800 C, the strength slightly decreased while the plasticity rose a little. The change of mechanical properties during the temperature range was mainly determined by the microstructure change. Eventually, both strength and plasticity decreased sharply when the temperature was over 800 C, which was mainly caused by the thick oxidation layer with porous and loose microstructure. The fracture mode of tensile specimens also changed from ductile fracture (below 800 C) to transgranular cleavage fracture (over 800 C). On the basis of experiments, a corresponding relation between the color changes and tensile properties was established. The royal blue should be regard as critical color between the acceptable and unacceptable tensile properties of the oxidized titanium alloy. © 2015 Elsevier B.V. All rights reserved. Source

Wang Y.-J.,Northwestern Polytechnical University | Sun B.-L.,Northwestern Polytechnical University | Zhang W.,Xian Aircraft Industry Ltd. | Gao G.-Q.,Xian Aircraft Industry Ltd. | Qiao M.-J.,Xian Aircraft Industry Ltd.
Hangkong Dongli Xuebao/Journal of Aerospace Power

According to the characteristics of shot peening process, a three-dimensional finite element model was established by using ABAQUS finite element software to simulate the residual stress field. Based on this model, the effects of shot parameters such as velocity, diameter and shot number on residual stress field of Al-Li alloy were studied respectively. Then the distributions of the residual stress field of single shot model, uniform array shots model and random shot model were compared. Furthermore, the residual stress distribution in Al-Li alloy specimen thickness direction was measured by using X-ray residual stress analyzer and electrolytic polishing method. The depth of residual stress layer is 0.24 mm. The maximum residual stress occurs at the depth of 0.08 mm. It verifies the validity of the finite element model. ©, 2015, BUAA Press. All right reserved. Source

Feng T.,Xian Aircraft Industry Ltd. | Wang Z.,Xian Aircraft Industry Ltd. | Meng J.,Xian Aircraft Industry Ltd.
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics

With the development of the information technology, the advance manufacture technology and the material technology, the airplane manufacturing is facing the technology revolution. The digital collaborate manufacturing is one of the key technologies in airplane manufacturing. In this paper, the application ways and the existent problems of the model based definition (MBD) in the digital collaborate manufacturing are discussed, and some thoughts that how to use the MBD dataset in the airplane manufacture are proposed. Source

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