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Xu C.T.,Harbin Institute of Technology | Xu C.T.,University Of Science And Technology Liaoning | Li J.G.,Harbin Institute of Technology | Ding J.,Harbin Institute of Technology | And 2 more authors.
Proceedings - 2013 IEEE International Symposium on Assembly and Manufacturing, ISAM 2013 | Year: 2013

The androgynous peripheral driving mechanism is a flexible series multi-body system, of which assembly precision is primarily dependent on worker's experience. In order to improve the assembly efficiency and reduce the assembly cost, a system used to predict the synchronous accuracy for guide assembly is developed based on Matlab-GUI. This system consists of three modules, i.e., data management module, accuracy prediction module and animated simulation module. Each module is briefly investigated in this paper. By predicting the driving mechanism, the theoretical data have been compared with the experimental data. And the synchronous errors of the simulation and animation are also shown on the interface. The results indicate that the predicted values are within the permitted deviation range and agree well with changes of the synchronous errors. Moreover, the prediction system is also of good reliability and stability which can be used to guide the workers for assembly. © 2013 IEEE.

Li J.,Harbin Institute of Technology | Xu C.,Harbin Institute of Technology | Xu C.,University Of Science And Technology Liaoning | Yao Y.,Harbin Institute of Technology | And 2 more authors.
Precision Engineering | Year: 2015

Wire sheave drives are used as transmission elements in docking mechanisms for their excellent flexibility, light weight and high intensity performance. The synchronous accuracy of sheave drives is vital to the docking of spacecraft and is achieved mainly by manual assembly. Due to the lack of further research in this aspect, assembly workers have to operate it for several cycles, which leads to lower assembly efficiency and quality. This paper takes two sheaves of serial drives as a typical example and establishes a prediction model for their synchronous accuracy based on the classic sheave equation. Then the prediction model is modified because of large error between the predicted values and the experiment results. The modified model captures the dominant trends under various operating conditions, and the predicted values also agree well with the experiment results. Thus, the modified model can be used to predict synchronous accuracy of wire sheave drives, to analyze the effect of dominating parameters and to test whether the preset parameters imposed on rope is appropriate or not. This lays a foundation for the study of serial drives and for further improving assembly efficiency and quality of docking mechanisms. © 2014 Elsevier Inc.

Xu C.T.,Harbin Institute of Technology | Xu C.T.,University Of Science And Technology Liaoning | Li J.G.,Harbin Institute of Technology | Yao Y.X.,Harbin Institute of Technology | And 3 more authors.
Mechanics of Time-Dependent Materials | Year: 2015

From three aspects of the stress, temperature, and time, rope creep research is often carried out based on its own ontology without various operation conditions. Thus, it is difficult to accurately reflect its creep behavior in real working conditions. The rope creep, caused by the preload for a long time, will affect the assembly and working synchronous accuracy of sheave drives in the assembly of docking mechanisms. However, it is quite difficult to analyze the rope creep behavior only with simple creep phenomenon, and the experiments still play an important role in obtaining uncertain creep information. In this paper, to study the rope creep behavior of sheave drives in assembling the docking mechanisms, a creep constitutive model is built based on the experimental creep data by the modified Norton–Bailey equation. Also, the rope creep strain laws, affected by the operating conditions, are analyzed. This lays a foundation for improving the assembly efficiency and precision compensation of the serial sheave drives. Experiments validated the effectiveness of the model. © 2015, Springer Science+Business Media Dordrecht.

Li P.,Shanghai JiaoTong University | Xu Z.,Shanghai JiaoTong University | Yu C.,Shanghai JiaoTong University | Yu C.,Shanghai Key Laboratory of Materials Laser Processing and Modification | And 4 more authors.
Acta Metallurgica Sinica (English Letters) | Year: 2012

The 2219 aluminum alloy under refllling friction stir welding (RF-FSW) was investi- gated. The micrographs showed that the bead could be divided into six zones, and the grain size and shape were greatly different in these zones. According to the mi- crostructure analysis, the weld nugget zone and the shoulder stirring zone consisted of equiaxed grains, while the grains in the heat affected zone were seriously coars- ened. It was obvious that bending deformation occurred in the thermo-mechanically affected zone. According to the microhardness analysis, the lowest hardness of the weld was at the thermo-mechanically affected zone, and the microhardness increased with the retraction of the stir-pin. The tensile strength and elongation of the bead were 70% and 80% of the base metal, respectively. The tensile strength was slightly different for the stable stage and the retraction stage, while the elongation decreased in the retraction stage. The mechanical properties and microstructure responded to different retraction speed were analyzed, and it showed that the elongation decreased with increasing retraction speed.

Yao Z.,Harbin Institute of Technology | Hu B.,Harbin Institute of Technology | Shen Q.,Harbin Institute of Technology | Niu A.,Harbin Institute of Technology | And 3 more authors.
Surface and Coatings Technology | Year: 2014

It is of great significance for the research of thermal control coatings on Ti alloys due to their wide applications in aerospace and satellites and many other fields. In this work, black thermal control coatings were prepared on Ti-6Al-4V alloy by plasma electrolytic oxidation (PEO) technique. The coatings were characterized by SEM, EDS and XRD, respectively. The thermal control properties (solar absorbance, αS and emissivity, ε) were investigated by ultraviolet-visible-near infrared spectrophotometer instrument and solar absorption reflectometer. Meantime, the thermal shock properties of the coated samples were investigated as well. The results show that the ceramic coatings are black and porous and the elements such as Fe, Co and Ni and W from the electrolyte incorporate into the coating and exist in the form of an amorphous state. The coatings are of high emissivity and high absorbance character, which are influenced by the doping of Na2WO4 and the PEO time. Increasing the concentration of Na2WO4, αS increases firstly and then remains constant while ε increases gradually. Extending PEO time, both αS and ε increase. The annealing treatment reduces the solar absorbance greatly, but does not influence the emissivity apparently, which may be due to the improvement of the crystallization of the coating. When the dosage of Na2WO4 is 7.5g/L and the reaction time is 25min, the best coating is obtained with αS and ε of 0.93 and 0.88, respectively. This work not only provides an effective method to prepare thermal control coating for Ti alloys as the engineering materials, but also expands the application range of PEO technique in the fields of functional coatings. © 2014 Elsevier B.V.

Li J.,Harbin Institute of Technology | Du J.,Harbin Institute of Technology | Yao Y.,Harbin Institute of Technology | Hao Z.,Changchun University of Technology | Liu X.,Shanghai Aerospace Equipments Manufacture
Journal Wuhan University of Technology, Materials Science Edition | Year: 2014

An attempt was made to investigate the machinability of SiCp/Al composites based on the experimental study using mill-grinding processing method. The experiments were carried out on a high-speed CNC machining center using integrated abrasive cutting tool. The effects of combined machining parameters, e g, cutting speed (vs), feed rate (vf), and depth of cut (ap), with the same change of material removal rate (MRR) on the mill-grinding force and surface roughness (Ra) were investigated. The formation mechanism of typical machined surface defects was analyzed by SEM. The experimental results reveal that with the same change of material removal rate, lower mill-grinding force values can be gained by increasing depth of cut and feed rate simultaneously at higher cutting speed. With the same change of MRR value, lower surface roughness values can be gained by increasing the feed rate at higher cutting speed, rather than just increasing the depth of cut, or increasing the feed rate and depth of cut simultaneously. The machined surface of SiCp/Al composites reveals typical defects which can influence surface integrity. © 2014, Wuhan University of Technology and Springer-Verlag Berlin Heidelberg.

Li J.-Z.,Dalian University of Technology | Zhang Y.-S.,Shanghai Aerospace Equipments Manufacture | Luan J.-J.,Wuxi Micro Research Co. | Yu Z.-Y.,Dalian University of Technology
Dalian Ligong Daxue Xuebao/Journal of Dalian University of Technology | Year: 2012

The diameter of micro-hole varies proportionally with the length of electrode when a micro-hole with high aspect ratio is drilled by micro-electrical discharge machining (EDM) even under the same machining conditions. To explain this phenomenon, the theory of classic Bernoulli-Euler rod is used to study the relationship between the reaction force during micro-hole drilling by micro-EDM and the deflection of electrode under three reaction force conditions. Theoretical values are very close to experimental results. It is clarified that the bending of an electrode increases with an increase of the electrode length, resulting in different diameters of micro-holes using the same diameter of electrode but in different lengths.

Shen Z.,Tianjin University | Yang X.,Tianjin University | Yang S.,Tianjin University | Zhang Z.,Tianjin University | Yin Y.,Shanghai Aerospace Equipments Manufacture
Materials and Design | Year: 2014

Friction spot welding (FSpW) is a relatively new solid state joining technology developed by GKSS. In the present study, FSpW was applied to join the 6061-T4 aluminum alloy sheet with 2. mm thickness. The microstructure of the weld can be classified into four regions, which are stir zone (SZ), thermo-mechanically affected zone (TMAZ), heat affected zone (HAZ) and the base material (BM), respectively. Meanwhile, defects such as bonding ligament, hook and voids are found in the weld, which are associated to the material flow. The hardness profile of the weld exhibits a W-shaped appearance and the minimum hardness is measured at the boundary of TMAZ and SZ. Both the tensile/shear strength and cross-tension strength reach the maximum of 7117.0. N and 4555.4. N at the welding condition of the rotational speed of 1500. rpm and duration time of 4. s. Compared to cross-tension strength, the tensile/shear strength were stable with the variation of processing parameters. Three different fracture modes are observed under tensile/shear loading, which are plug type fracture, shear fracture and plug-shear fracture. There are also there different fracture modes under cross-tension loading, which are plug type fracture (on the upper sheet), nugget debonding and plug type fracture (on the lower sheet). © 2013 Elsevier Ltd.

Wang M.-B.,China Jiliang University | Li D.-S.,China Jiliang University | Hu J.-C.,China Jiliang University | Yang Y.,Shanghai Aerospace Equipments Manufacture | And 2 more authors.
Jiliang Xuebao/Acta Metrologica Sinica | Year: 2016

In order to solve the problems of fixture spatial attitude on calibration device of cryogenic liquid level sensor, an error identification based on the principle of multilateral method is proposed. Based on the high-precision distance measurement of laser tracker, using the principle of multilateral method to calibrate the track of the calibration device, a virtual coordinate system is created which uses the gravity opposite direction as Z-axis direction, and because two positions always being the same in rigid body, the redundant data of six errors are obtained, so the error identification of calibration device is finished. Simulation results show that the method is feasibility, combinating genetic algorithm and trust region method with Guass-Newton can effectively avoid non-convergence problem which were caused by unknown initial data. © 2016, Acta Metrologica Sinica Press. All right reserved.

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