Cao Z.,Shanghai JiaoTong University |
Wang F.,Shanghai JiaoTong University |
Wan Q.,AVIC Jiangxi Hongdu Aviation Industry Group Co. |
Zhang Z.,Shanghai JiaoTong University |
And 2 more authors.
Materials and Design | Year: 2015
Flow forming is a plastic deformation process to produce thin-walled and high-precision cylindrical components. In this study, the hot flow forming of Mg-8.5Al-0.5Zn-0.2Mn (AZ80) alloy tubes was conducted innovatively. The effects of processing parameters including flow forming temperature, spindle speed, feed ratio and thickness reduction on the microstructures and mechanical properties of AZ80 alloy tubes were investigated. The results show that a more unanimous and raised grain size appeared with deforming temperature from 300 to 420. °C. The variation of spindle speed and feed ratio had a slight influence on the microstructure, but an obvious influence on the tensile properties, particularly the elongation. With increasing the thickness reduction, the grain size decreased while the micro-hardness increased significantly. The electron backscatter diffraction (EBSD) results show that the c-axes of most grains are approximately parallel to the radial direction. And likewise, they have a slight deflection towards the axial direction. Furthermore, ultimate tensile strength (UTS) of 308. MPa and elongation of 9.8% were obtained when the hot flow forming was carried out under a temperature of 420. °C, a spindle speed of 400. rev/min, a feed ratio of 0.1. mm/rev and a thickness reduction of 45%. © 2014 Elsevier Ltd.
Tian W.,Beihang University |
Li S.,Beihang University |
Du N.,Nanchang Hangkong University |
Chen S.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Wu Q.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd
Corrosion Science | Year: 2015
Effects of applied potential on stable pitting corrosion of 304 stainless steel were studied by potentiostatic polarization and three-dimensional video microscope. The results showed that pit mouth morphologies and three-dimensional structures were dependent on potential. Higher potentials resulted in more open pits. Pit volume, depth, and width increased with potential. The ratio of pit depth to width continuously changed with time and potential. The pitting current density of a single pit increased with potential, indicating that an ohmic potential drop presented between the pit internal surface and the bulk solution, but stable propagation was still controlled by corrosion products diffusion. © 2015 Elsevier Ltd.
Hu X.,Nanchang University |
Chen W.,Avic Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Yu X.,Nanchang University |
Li Y.,Nanchang University |
And 2 more authors.
Journal of Alloys and Compounds | Year: 2014
The effects of displacement rate and reflow duration on the shear strengths of the Cu/Sn37Pb/Cu soldered joints as well as the interfacial microstructure were investigated after reflowing. The samples were reflowed at 300 C for different durations (5 min, 15 min and 30 min) and then shear tested with different displacement rates ranging from 2.5 × 10-3 to 5 × 10-2 mm s-1. The intermetallic compounds (IMCs), including Cu6Sn5 and Cu3Sn phases were observed between Sn37Pb solder and Cu substrate, and their thicknesses increased with increasing reflow duration up to 30 min. The single lap shear test results indicated that the shear forces of the joints increased with increasing displacement rate, but decreased with increasing reflow duration. Failure mechanisms of soldered joints in different displacement rate regimes were investigated based on the fractography analysis. After reflowing for 5 and 15 min, the fractures of the Sn37Pb soldered joints mainly occurred inside the bulk solder irrespective of the displacement rate. While some broken Cu 6Sn5 particles could be observed at the bottom of dimples in solder bulk as the high displacement rates were adopted (such as 1 × 10-2 and 5 × 10-2 mm s-1). In case of reflow duration of 30 min, as the low displacement rates (such as 2.5 × 10-3 and 5 × 10-3 mm s-1) were adopted, the fracture patterns of soldered joints were similar to that of soldered joints reflowed for 5 and 15 min. In contrast, little solder and many IMCs were detected on the fracture surface under high displacement rates condition (such as 1 × 10-2 and 5 × 10-2 mm s-1), which indicated that the fracture mainly occurred in the interior of Cu-Sn IMC layer. The displacement rate sensitivities of the soldered joints reflowed for different durations were also investigated, and it is found that the displacement rate sensitivity decreased with increasing reflow duration due to the increased interfacial IMC layer thickness. © 2014 Elsevier B.V. All rights reserved.
Xu X.F.,Nanchang Hangkong University |
Zhang J.G.,China Aerospace Science and Technology Corporation |
Liu C.F.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Wang G.C.,Nanchang Hangkong University |
Yun Z.H.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd
Journal of Materials Engineering and Performance | Year: 2014
The effect of stepped tensile deformation at 850, 900, 950 °C on the elongation, microstructure, and mechanical characteristics of titanium alloy has been investigated. The stepped uniaxial tension (stepped-UT) was composed of the following three steps in sequence: constant speed tension, clearance stage, and maximum m superplasticity tension (MaxmSPT). Results showed that the maximum elongation of TC6 alloy between 850 and 950 °C through the Stepped-UT was 2053%, in which the first engineering strain of constant speed tension was 2.0, the following clearance time was 15 min, and the MaxmSPT was finally carried on until failure. And the optimal elongations obtained by the MaxmSPT and constant speed tensile method were 1347 and 753.9% at 850 °C, respectively. The true stress-strain curves showed the strain rate sensitivity index m of the alloy in the stepped-UT was higher than the one in the single step of the MaxmSPT. Moreover, the microstructure of TC6 alloys in the stepped superplastic deformation was observed and the grain refinement was found. The grain refinement and true stress-strain curves of TC6 alloys were all affected by preplanned engineering strain and temperatures. The results also showed the joint action of the dynamic recrystallization and static or meta-dynamic recrystallization refined the grains, improved the structure property, and induced the plasticity enhancement. © The Author(s). This article is published with open access at Springerlink.com.
Zou W.-D.,Nanchang Hangkong University |
Huang C.-H.,Nanchang Hangkong University |
Zheng Q.,AVIC Jiangxi Hongdu Aviation Industry Group Co. |
Xu Z.-J.,AVIC Jiangxi Hongdu Aviation Industry Group Co. |
Dong N.,AVIC Jiangxi Hongdu Aviation Industry Group Co.
Guangxue Jingmi Gongcheng/Optics and Precision Engineering | Year: 2011
Scanning White-light Interferometry (SWLI) was proposed to measure the complex microscopic surface topography of a dimple fracture of 30CrMnSiA alloy. The Linnik structure was adopted in the system and the 3D image of the dimple fracture was rebuilt by the cosine Fourier analysis algorithm. Experiments show that the longitudinal measuring accuracy is better than 5 nm for a scan range of 120 μm. The cosine Fourier analysis offers strong abilities of phase extraction and noise suppression, and an ideal 3D reconstruction image of the dimple fracture is obtained. The obtained surface data were tested for fractal dimension by a slit island method. At incised height from 40% to 70%, the fractal dimension values range from 1.6304 to 1.6432 with an average of 1.6417 and the standard deviation of 0.0120, which indicates that the dimple fracture of 30CrMnSiA has a typical fractal character. In conclusion, the SWLI is an effective way to measure the microscopic 3-D fracture surface topography, and it is characterized by high longitudinal precision, long dynamic measuring range and high reconstruction efficiency.
Hu X.,Nanchang University |
Chen W.,Avic Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Wu B.,Nanchang University
Materials Science and Engineering A | Year: 2012
Cu 6Sn 5 fiber reinforced Sn in situ composites with a nominal composition Sn-1Cu (wt%) were produced by specially controlled directional solidification using a laboratory-scale Bridgman furnace equipped with a liquid metal cooling (LMC) device. The microstructure of as-produced composites was characterized by using optical microscopy (OM), electron microscopy (SEM) and microanalysis (EDX). The tensile strength and plasticity at room temperature were examined by tensile tests. The microstructure observation showed that the microstructure consisted of Β-Sn matrix and fiber-like Cu 6Sn 5 intermetallics compounds (IMCs). For a constant temperature gradient (12Kmm -1), it was found that the spacing between Cu 6Sn 5 fibers and diameter of single crystalline Cu 6Sn 5 fiber were mainly controlled by the solidification rate (V), and both of them decreased with increasing solidification rate. The strength was dominated by the Cu 6Sn 5 fiber alignment, such as the spacing and diameter. Thus the tensile tests results have been correlated to fiber spacing (λ) and diameter (d), since fiber growth has prevailed along all obtained Sn-1Cu samples. It was found that the ultimate tensile strength (UTS) and yield tensile stress (YS) initially increased with increasing solidification rate which ranged from 5 to 60μms -1, and decreased with further increasing solidification rate, such as 100μms -1. In contrast, the elongation (EL) decreased with increasing solidification rate due to the increased amount Cu 6Sn 5 IMC quantity. © 2012 Elsevier B.V.
Shen W.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Peng Z.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Li B.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Ye B.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2016
Most airplane landing gear retracts during airplane's flight. The landing gear is mainly subjected to aerodynamic load, flight overload and inertial load that change with flight speed and landing gear rotation angle. How to apply load on the ground to simulate the real situation that happens in the air becomes a key technology in the reliability test. This paper calculates a certain airplane's nose gear retraction actuating cylinder load in the retracting process and proposes an equivalent method. The dynamic simulation result agrees well with measurement statistical curve. This equivalent method applying to the landing gear retraction mechanism reliability test is simple and effective. © 2016, Press of Chinese Journal of Aeronautics. All right reserved.
Xiong Y.,Jiangxi Science and Technology Normal University |
Wang H.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd |
Li Y.,Jiangxi Science and Technology Normal University
Lecture Notes in Electrical Engineering | Year: 2014
People's increasing demand formobile multimedia business, mobile communication must integrate the Internet to offer high-speed and high-quality mobile multimedia communication business. In the process of integration, the multimedia technology that has maturely developed in the Internet will play a very important role. This paper introduces the concepts and features of the multimedia technology. Through the research on the application of the four key technologies in multimedia technology in the field of mobile communication and detailed analysis of the advantages of 4G network and the impact that it has on the multimedia technology in the mobile communication field, prospect the development of themultimedia technology in the mobile communication. © Springer-Verlag Berlin Heidelberg 2014.
Fang Z.,China Three Gorges University |
Xiang B.,AVIC Jiangxi Hongdu Aviation Industry Group Corporation Ltd. |
Xiao H.,China Three Gorges University |
He K.,China Three Gorges University |
Liu J.,China Shipbuilding Industry Corporation 710 Institute
Jixie Gongcheng Xuebao/Journal of Mechanical Engineering | Year: 2013
In order to reduce the swing of underwater device and the tension fluctuation of wire rope, taken the recovery drum and anti-sway drum as actuating mechanism, the control strategy of unilateral anti-sway and rope tension is presented for underwater device. The dynamic model of steel cable is established by discrete beam finite elements and the relative nodal displacements method. The winding contact model between wire rope and drum is also introduced. Taken self-developed launch and recovery device as research object, combined technology of virtual prototype and control, the study of kinematics, kinetic and control strategy is carried out in the process of recovering underwater device. The dynamics simulation model is established in software RecurDyn, and the collaborative simulation model of mechanical system and control is built for launch and recovery device, which the algorithm is designed to control unilateral anti-sway and tension in software RecurDyn library Colink. The kinetic and collaborative simulation is studied, which provides the theoretical basis and data references about improving the stability and safety, reducing dynamic load, optimizing overall structure, guiding conceptual design for launch and recovery and underwater device. ©2013 Journal of Mechanical Engineering.
Wu X.-B.,Tongji University |
Liao J.,AVIC Jiangxi Hongdu Aviation Industry Group Co. |
Wang Z.-C.,Tongji University
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015
Water wave optimization (WWO) is a novel evolutionary algorithm borrowing ideas from shallow water wave models for global optimization problems. This paper presents a first study on WWO for a combinatorial optimization problem — the traveling salesman problem (TSP). We adapt the operators in the originalWWOso as to effectively exploring in a discrete solution space. The results of simulation experiments on a set of test instances from TSPLIB show that the proposed WWO algorithm is not only applicable and efficient for TSP, but also has significant performance advantage in comparison with two other methods, genetic algorithm (GA) and biogeography-based optimization (BBO). © Springer International Publishing Switzerland 2015.