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Hu J.,Shijiazhuang University | Hu J.,University of Science and Technology Beijing | Fu S.,Haier | Huo Y.,Tianjin Long March Launch Vehicle Manufacturing Co. | And 2 more authors.
Journal of Rare Earths | Year: 2016

Effect of impurity phase (α-Fe phase and La-rich phase) on corrosion resistance and magnetic entropy change of LaFe11.3Co0.4Si1.3C0.15 compound was studied using scanning electron microscopy, potentiodynamic polarization, electrochemical impedance spectroscopy techniques and magnetism testing. With the decrease of impurity phase, the corrosion resistance of LaFe11.3Co0.4Si1.3C0.15 compound was first enhanced and then slightly impaired. Corrosion resistance could be significantly improved by the decrease of α-Fe phase. However, the matrix phase was corroded if the La-rich phase as anode was too few. This caused the corrosion resistance to decrease slightly. After immersing the sample in distilled water for 15 d, -ΔSmax of the samples annealed for 3, 12 h, 3 and 7 d decreased about 50%, 41%, 16% and 17%, respectively. © 2016 The Chinese Society of Rare Earths.

Zhang X.,Harbin Institute of Technology | Yu H.P.,Harbin Institute of Technology | Su H.,Tianjin Long March Launch Vehicle Manufacturing Co. | Li C.F.,Harbin Institute of Technology
International Journal of Advanced Manufacturing Technology | Year: 2015

Evaluation on mechanical properties of a riveted structure with electromagnetic riveting was performed experimentally in this work. The effect of rivet tail dimension on mechanical properties and microstructure evolution were investigated by controlling deformation. The possibility of substituting a riveted structure for a bolted structure was explored by the contrast analysis. Results showed that dislocation slip in the adiabatic shear band was a main deformation mechanism of rivet tail. The rivet tail dimension mainly determined pull-out strength and failure mode of the riveted structure, and the optimal height of rivet tail was 5∼6 mm for this riveted structure. The maximum bearing loads of shear tests and pull-out tests were 23.3 and 35.0 kN, respectively. Both shear strength and pull-out strength of riveted structures exceeded that of bolted structures, where the bolt has similar tensile-loading capacity as the rivet shaft. In contrast to the bolted structure, the load-to-weight ratio values of the riveted structure for shear test and pull-out test were improved by 22.64 and 66.10 %, respectively. © 2015 Springer-Verlag London

Li J.G.,Tianjin Long March Launch Vehicle Manufacturing Co. | Zhang J.G.,China Aerospace Science and Technology Corporation | Liu J.P.,China Aerospace Science and Technology Corporation | Zhao R.F.,Tianjin Long March Launch Vehicle Manufacturing Co. | And 4 more authors.
Advanced Materials Research | Year: 2014

Viscous pressure forming(VPF) is a new developed sheet soft-punch forming process in 1900s. The basic principle and characteristics of VPF are described. The applications of VPF technologies of nickel-based super-alloy corrugated thin-walled part, asymmetrical thin-wall part with variable diameter, super-alloy thin-walled part with variable diameters, corrugated thin-walled part with larger diameter and small section are presented. The results show that VPF is suitable for the forming of parts with high strength, low plasticity, super thin-wall and complex shaped. © (2014) Trans Tech Publications, Switzerland.

Hao Z.,Beihang University | Jia Y.H.,Beihang University | Zhong R.,Beihang University | Wang L.,Tianjin Long March Launch Vehicle Manufacturing Co.
Chinese Control Conference, CCC | Year: 2016

This paper presents an end-satellite attitude and tether shimmy combined control method under the condition of a free companion flight status between the end-satellite and the space target in the process of tether-tugging. Firstly, a dynamic model for tether-tugging system is established, and the adaptive control sliding mode controller and high-order sliding mode observer are adopted in each channel controller of the model; finally, simulation results prove that the control method designed in this paper can effectively inhibit the swing tether and eliminate the end-satellite attitude coupled motion caused by tether installation point bias, and the control method presents good performance, which has widely application prospects in this space mission. © 2016 TCCT.

Yuan B.,Tianjin University of Technology and Education | Fang W.,Tianjin University of Technology and Education | Li J.,Tianjin Long March Launch Vehicle Manufacturing Co. | Cai Y.,Tianjin University of Technology and Education | And 2 more authors.
Engineering Analysis with Boundary Elements | Year: 2016

Viscous pressure forming (VPF) is a kind of sheet flexible-die forming process which uses a semisolid, flowable and viscous material as the pressure-transmitting medium. Unlike the conventional rigid die punching or hydroforming process, there are strong nonlinear features between the sheet metal and viscous medium in VPF. In this paper, a numerical analysis method for coupling sheet metal deformation and bulk deformation of viscous medium is presented. A static explicit approach based on the Updated Lagrangian (U.L.) formulation is adopted. The elastoplastic deformation of sheet metal is analyzed with finite element method (FEM), and the visco-elastoplastic bulk deformation of viscous medium is analyzed with the element-free Galerkin method (EFGM), which can eliminate mesh distortion unavoidable during the deformation of viscous medium in FEM. The contact and friction between the sheet metal and viscous medium are treated by the penalty function method. An FEM-EFGM program for coupled deformation between sheet metal and viscous medium is developed, called CDSB-FEM-EFGM for short. Several numerical examples of coupled deformation between viscous mediums with different viscosities and sheet metal are presented to demonstrate the effectiveness of the proposed method. Compared the numerical simulation results with experimental measurements, the validity of the CDSB-FEM-EFGM program is obtained. © 2016 Published by Elsevier Ltd.

Qin T.,China Communications Construction Company Ltd. | Ma H.,China Communications Construction Company Ltd. | Chen T.,China Communications Construction Company Ltd. | Tang C.,China Communications Construction Company Ltd. | And 2 more authors.
Jianzhu Cailiao Xuebao/Journal of Building Materials | Year: 2016

To solve the problem that the dry film thickness of the concrete coatings was difficult to be tested nondestructively, ultrasonic coating thickness gauge was adopted to measure the dry film thickness of coating on the surface of concrete in different strength grades. Uncertainty evaluation and quality judgment of the measurement results were conducted. The results show that the degree of reliability of the measurement results could be found by the uncertainty evaluation, which is the important basis for quality judgment whether the measurement result satisfies the requirements or not. The higher the strength grade of concrete is, the smaller the uncertainty of the dry film thickness of concrete coatings is, and vice versa. © 2016, Tongji University. All right reserved.

Yuan B.,Tianjin University of Technology and Education | Fang W.,Tianjin University of Technology and Education | Li J.,Tianjin Long March Launch Vehicle Manufacturing Co. | Qu Z.,Tianjin University of Technology and Education | And 2 more authors.
International Journal of Advanced Manufacturing Technology | Year: 2015

The properties of pressure-transmitting medium have a great effect on the formability of sheet metal in sheet flexible-die forming, such as rubber-pad forming and viscous pressure forming (VPF). In this study, viscous pressure bulging (VPB) experiments were used to investigate the effects of viscosity on Al1060 sheet. At the same dome height, the configurations of bulging specimen varied with three different viscosity viscous mediums (1#, 550,000 g/mol; 2#, 700,000 g/mol; and 3#, 900,000 g/mol). The thickness strain distributions of specimen formed by a higher viscosity medium had a relatively uniform distribution. In order to further study the effects of viscosity on VPB, a CDSB-FEM-EFGM program was used to analyze viscous pressure bulging process. The configuration, stress, strain, and wall thickness distributions of bulging specimen were obtained. The numerical analysis results had a good agreement with the experimental ones, which also showed that properties of the viscous medium had a great effect on the formed specimen. The formability of sheet metal can be further improved through increasing the viscosity of viscous medium. © 2015 Springer-Verlag London

Zhou W.,Beihang University | Chen W.,Beihang University | Liu H.,Beijing Institute of Technology | Li X.,Tianjin Long March Launch Vehicle Manufacturing Co.
Mechanism and Machine Theory | Year: 2015

In this paper, a new forward kinematic algorithm based on dual quaternion for a six-degree-of-freedom (DOF) general Stewart Platform is proposed. The algorithm is established after taking into account the pose parameters of joints and the D-H parameters of each branch chain, which yields a precise mathematic model with a total of 174 geometric parameters. The validity of the algorithm is tested using an inverse kinematic algorithm of a general serial manipulator. The forward kinematic algorithms for the 6-6R and 6-2RP3R mechanisms can be expressed by a unified mathematic model. The proposed algorithm can solve the difficult problem of forward kinematics for the unsolved 6-6R parallel manipulator and can also be applied to error analysis, error synthesis, kinematic calibration, stiffness analysis and the accurate kinematic simulation by analysing the effect of geometric parameters on the platform. © 2015 Elsevier Ltd. All rights reserved.

Yin Y.,Beihang University | Guo L.,Beihang University | Han N.,Beihang University | Zheng J.,China Aerospace Science and Technology Corporation | Zhang P.,Tianjin Long March Launch Vehicle Manufacturing Co.
ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE) | Year: 2015

High speed machining is widely used in manufacturing. For its high cutting speed, high feeding rate, and high machining accuracy, its requirements for cutting trajectory in high speed machining are so strict that only continuous and smooth trajectories with even cutting loads can lead to high machining efficiency and accuracy. The traditional row or ring machining trajectory fails to meet these requirements. In order to acquire the continuous and smooth machining trajectories, and to avoid load mutation in the machining process, some researchers developed a curvilinear cutting trajectory generating method based on partial differential equation. This trajectory, however, is still made up from free form curve segment, and unable to completely eliminate the effects on smoothness by line segment interpolation, which has a very adverse effect on the efficiency, tool life and machining accuracy. A new strategy to generate a continuous and smooth cavity cutting trajectories in high speed machining is introduced in this article. The new trajectory determines the necessity-nodes from outside (the boundary) to inside in the way of spiral cutting. It starts from the cavity center with spiral expanding, and each cutting loop adopts end connection between straight line and the tangent arc, meeting continuous first-order constraint satisfaction. The smooth trajectory reduces the amplitude and directing mutation of cutting force, thus effectively avoids the impact on the machining efficiency and machining accuracy by speeding down in the corner. The strategy also, by controlling the row space, ensures that there is no cutting residual. Copyright © 2015 by ASME.

Cheng J.,Harbin Engineering University | Cheng J.,University of Québec | Chen D.,Harbin Engineering University | Rene L.,University of Québec | And 2 more authors.
Chinese Control Conference, CCC | Year: 2014

For long-time operation applications based on single-axis rotation inertial navigation system (SRINS), the estimation and compensation of gyroscope's constant drift along the rotational axis in comprehensive calibration is the most important problem. In this paper, a novel comprehensive calibration method for SRINS is presented. During this process, SRINS is operating in the outer level damping mode. Kalman filter has been designed based on the SRINS model with the damping network. The velocity and position provided by differential GPS (DGPS) are introduced as reference information for the estimation of rotational axis gyroscope drift. For stationary scenario, the observability degree of system states are given by an observability analysis based on singular value decomposition. The validity of this method is confirmed by simulations. The influence of linear accelerated motion on the estimation of drift is obtained. © 2014 TCCT, CAA.

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