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Xu M.,Beihang University | Xu M.,Chinese Helicopter Research and Development Institute | Bai J.,Beihang University | Lv M.,Chinese Helicopter Research and Development Institute | And 3 more authors.
Key Engineering Materials | Year: 2017

In this paper, experimental and finite element methods are integrated to carry out the research about residual strength of composite laminate structure with central and edge notch. First, the specimens with central and edge notch and the fixtures used in compression tests were designed and manufactured, and the tensile and compression residual strengths with different notch size were measured. Then, finite element analysis model of specimens with central and edge notch were established to predict the residual strength based on the average stress criterion and Hoffman criterion, the effect of the notch size on the residual strength is evaluated, the results were compared and found that the average stress model has higher prediction accuracy and notch size has a significant influence on the residual strength of composite laminate structure with central and edge notch. © 2017 Trans Tech Publications, Switzerland.


Zhang M.,Beihang University | Meng Q.,Beihang University | Hu W.,Beihang University | Shi S.,Chinese Helicopter Research and Development Institute | And 2 more authors.
International Journal of Fatigue | Year: 2010

According to the law of thermodynamics, a new damage evolution equation is advanced in the present study to predict the fatigue life of the Pitch-Change-Link component. As its premise, the fatigue life prediction method for smooth specimens under the repeated loading with constant strain amplitude is constructed. In addition, based on the theory of conservative integral, the closed form relation for notched specimens between the maximum stress and fatigue life is derived, by reference to which the material parameters in damage evolution equation are obtained with fatigue experiment data of standard specimens. The damage mechanics-finite element method operates with APDL language code on the ANSYS platform. Finally, the mean fatigue crack initiation life of Pitch-Change-Link is predicted with the newly proposed method, that is damage mechanics-finite element method. What's most important, the calculated results comply with the experimental data. © 2010 Elsevier Ltd. All rights reserved.


Zhao P.,Beihang University | Liu Z.,Beihang University | Cheng W.,Chinese Helicopter Research and Development Institute
Advances in Intelligent and Soft Computing | Year: 2012

Mean-shift based tracking technique is successfully used in target tracking. However, classic Mean-shift based tracking algorithm uses fixed kernel-bandwidth, which limits the performance when the target's orientation and scale change. In this article, we firstly outlines the basic concepts of Mean Shift Algorithm, and Mean Shift algorithm for target tracking in the visual tracking and its application in visual tracking. Then an improved adaptive kernel-based object tracking is proposed, which extends 2-dimentional mean shift to 4-dimentional, meanwhile combine s multiple scale and orientation theory into tracking algorithm. A multi-kernel method is also brought forward to improve the tracking Accuracy. Finally, experimental results validate that the new algorithm can adapt to the changes of orientation and scale of the target effectively. © 2012 Springer-Verlag GmbH Berlin Heidelberg.


Ren Y.,Beihang University | Ren Y.,Inner Mongolia University of Science and Technology | Liu Z.,Beihang University | Cheng W.,Chinese Helicopter Research and Development Institute | Zhou R.,Beihang University
Advances in Intelligent and Soft Computing | Year: 2012

Friction torque is the main factor that influences dynamic response performance of high precise servo systems. To compensate for the friction torque, a compound control strategy based on backstepping and acceleration feedback with friction observer is proposed. In this control strategy, the backstepping controller with integral element was used for the position loop; the acceleration feedback controller with friction observer was introduced to compensate for friction torque. The simulation results show that dynamic friction torque is inhibited more effectively, and the robustness of system for the exterior disturbance is also improved simultaneously. © 2012 Springer-Verlag GmbH Berlin Heidelberg.


Chen Y.,Nanjing University of Aeronautics and Astronautics | Chen Y.,Chinese Helicopter Research and Development Institute | Gao L.,Huazhong University of Science and Technology | Wang C.,Commercial Aircraft Corporation of China | And 2 more authors.
Zhongguo Jixie Gongcheng/China Mechanical Engineering | Year: 2010

In order to improve helicopter collaborative design, a method of regionalization design in context for DMU was proposed and the system frame for implementation of the method was designed. Based on the characteristics of helicopter development, the expression model of DMU regionalization based on hierarchical tree of axis aligned bounding box (AABB) was proposed to search the DMU region; the relationship graphic of model link (RGML) was proposed to express the relationship of model link (RML) in DMU, and the impacts of correlative models in context can be analyzed effectively. The method was used to develop some helicopters, the accuracy rate of models search and the efficiency of models loading from whole helicopter DMU are improved, and the cycle of sub-system optimization and part change is shortened.


Huang X.,Jiujiang Vocational and Technical College | Wang W.,Chinese Helicopter Research and Development Institute | Jiang W.,Chinese Helicopter Research and Development Institute
Jixie Qiangdu/Journal of Mechanical Strength | Year: 2012

Rotor system is the core component of the helicopter, flexible blade with the spherical thrust bearing connected to provide the wielding, shimmy and pitch degrees of freedom, the stiffness characteristics is one of the main mechanical properties. Test the spherical thrust bearing compression, torsion and bending stiffness characteristics by twisting the screw to drive the semi-circular fixture. These results indicated that the test method is distinctive and general. It can accurately determine whether the spherical thrust bearing is qualified and provide a test before installing for different type of spherical thrust bearings.


Liu S.,Nanjing University of Aeronautics and Astronautics | Yang W.,Nanjing University of Aeronautics and Astronautics | Dong L.,Nanjing University of Aeronautics and Astronautics | Wu Q.,Chinese Helicopter Research and Development Institute | Wu Y.,Chinese Helicopter Research and Development Institute
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics | Year: 2014

The performance of helicopters can be significantly influenced by rotor speed variation. A performance analysis model is built to exam the influences of rotating speed, airspeed, take-off weight and flight altitude on the optimal rotating speed of a specific helicopter with a variable speed rotor. The Peters-He generalized dynamic inflow model and full aircraft trim model are introduced. The result shows 30% reduction in main rotor power is observed through rotor rotating speed reduction for the maximum take-off weight. For lower take-off weights or altitudes, the reductions in rotor speed and power savings are more apparent. The optimal rotating speed can cause a 20.5% increase in endurance and 8.5% in range by thoroughly consuming 400 kg of fuel. Setting thick airfoil at the inner side of blade can increase blade stiffness, which leads to some increments in required power when speeding up, but has little effect on the performance at middle and low speed, and no effect on endurance. ©, 2014, Nanjing University of Aeronautics an Astronautics. All right reserved.


Yang J.,Nanjing University of Aeronautics and Astronautics | Zhang L.,Nanjing University of Aeronautics and Astronautics | Zhou S.,Chinese Helicopter Research and Development Institute | Fang Y.,Chinese Helicopter Research and Development Institute | Huang W.,Chinese Helicopter Research and Development Institute
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2010

To improve the efficiency of the geometric modeling of composite plies in helicopter rotor blades, a method is presented. First, the typical types of the blade plies are summarized systematically. A parametric composite ply representation scheme is proposed. Designers can specify the ply by an intelligent wizard, which contains a program for converting the user-specified parameters of each ply into a ply design table. Then, according to the blade profile and the ply design table, a geometric model of the ply is constructed by duplicating the current-ply-covered region from the last ply surface and offsetting it by a thickness of the ply. The geometric modeling process of the whole blade can be automatically completed layer by layer in this way. Experimental results demonstrate that the proposed method can complete the geometric modeling of composite blade plies efficiently.


Yang J.,Nanjing University of Aeronautics and Astronautics | Zhang L.,Nanjing University of Aeronautics and Astronautics | Zhou S.,Chinese Helicopter Research and Development Institute
Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica | Year: 2013

A composite rotor blade structure optimization design approach based on parametric module definition is presented to improve design efficiency for engineering application. By taking a C-spar composite rotor blade as the research object, both the profile and the overall structure optimization models are built based on parametric module definition. By using the results of the profile optimization, the initial values of the overall structure optimization model are obtained. Then, the overall structure optimization is implemented to obtain the best blade structure. A case study is performed. The results demonstrate that the proposed method can complete the structure design of composite rotor blades efficiently.


Yu Z.,Nanjing University of Aeronautics and Astronautics | Dong L.,Nanjing University of Aeronautics and Astronautics | Deng J.,Chinese Helicopter Research and Development Institute | Yang W.,Nanjing University of Aeronautics and Astronautics
Nanjing Hangkong Hangtian Daxue Xuebao/Journal of Nanjing University of Aeronautics and Astronautics | Year: 2011

Aeroelastic model is developed using large deflection theory. Based on the two-dimensional cross-section analysis and one-dimensional nonlinear beam analysis, the strain energy in the composite rotor blade is deduced. The generalized strains are expressed by the variables describing the elastic motion of a reference line along the axis of the rotor blade, and all the nonlinear terms are included in the formulation. The kinetic energy and aerodynamic force are also incorporated. To verify the correctness of the analysis result, a special-shaped blade mode test is conducted. Correlations between the analysis results and the experimental data from Princeton beam test and Minguet's composite beam experiments also show that this method is valid for large deflection analysis of composite rotor blades. Aeroelastic analysis of helicopter rotor and influence study of blade sweep are implemented.

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