Key Laboratory of Dynamics and Control of Flight Vehicle

Beijing, China

Key Laboratory of Dynamics and Control of Flight Vehicle

Beijing, China
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Liu C.,Key Laboratory of Dynamics and Control of Flight Vehicle | Tian Q.,Key Laboratory of Dynamics and Control of Flight Vehicle | Hu H.,Key Laboratory of Dynamics and Control of Flight Vehicle | Garcia-Vallejo D.,University of Seville
Nonlinear Dynamics | Year: 2012

The Absolute-Coordinate-Based (ACB) method that combines the Natural Coordinate Formulation (NCF) describing rigid bodies and the Absolute Nodal Coordinate Formulation (ANCF) describing flexible bodies has been widely used to study the dynamics of rigid-flexible multibody system since it exhibits many good features, such as the constancy of the mass matrix of the derived dynamic equation, and the easy description and great simplification of the constraint conditions. In order to achieve these good features, both NCF and ANCF take the vectors, rather than rotational coordinates, to describe the rotation and deformation of the rigid-flexible bodies. In this study, the physical meaning of the components of the generalized force vector corresponding to the vector coordinates is revealed on the basis of both ANCF and NCF. Some new and simple formulations of imposing moments and evaluating joint reaction forces for rigid-flexible multibody system are proposed by making full use of the physical meaning of vector coordinates and Lagrange multipliers. All the proposed formulations are defined in the global frame so as to avoid the coordinate transformation. Hence, it can be directly applicable to various types of finite elements of ANCF, including the slope deficient elements. Finally, several typical and practical examples are used to verify the effectiveness of the proposed formulations. © 2011 Springer Science+Business Media B.V.


Tian Q.,Key Laboratory of Dynamics and Control of Flight Vehicle | Sun Y.,Key Laboratory of Dynamics and Control of Flight Vehicle | Liu C.,Key Laboratory of Dynamics and Control of Flight Vehicle | Hu H.,Key Laboratory of Dynamics and Control of Flight Vehicle | Flores P.,University of Minho
Computers and Structures | Year: 2013

A new methodology is proposed for the dynamic analysis of rigid-flexible multibody systems with ElastoHydroDynamic (EHD) lubricated cylindrical joints. The EHD lubricated cylindrical joint is formulated by the Natural Coordinate Formulation (NCF) and the 20-node hexahedral elements of Absolute Nodal Coordinate Formulation (ANCF), with the lubricant pressure determined through the resolution of the Reynolds' equation employing the finite difference method. The main outcomes are validated with those obtained by using the commercial software ADINA. It is shown that the bearing flexibility plays a significant role in the system responses, extends the lubricant distribution space and, consequently, reduces the lubricant pressure. © 2012 Elsevier Ltd. All rights reserved.


Li Y.,Key Laboratory of Dynamics and Control of Flight Vehicle | Li Y.,Tsinghua University | Song J.,Tsinghua University | Yang J.,Beihang University
Renewable and Sustainable Energy Reviews | Year: 2015

To address the demand for vehicles using fuel cell energy with high-performance electrodes, this paper discusses the energy storage model, nano-scale characterization technology, nanoenergy system and the structural design for fuel cell graphene electrodes while giving special attention to three characteristics: electrode conversion efficiency, specific power and cost. The structural stability model, evolutionary mechanism and the construction process of graphene electrodes of fuel cell technology are introduced. By analyzing electron and ion transmission and characterizing the electrode structure, energy system, surface and interface property at the nano-scale level, this paper reveals the intrinsic link between how an energy system is structured and performs. It combines the system model with the application of high-performance electrodes to highlight the compatibility between graphene and the electrode. By addressing progress in the applicability of renewable energy and the sustainability of energy technology during recent years, this paper provides scientific and experimental support for the practicality of fuel cell energy while also addressing bottleneck issues such as conversion efficiency, specific power and the cost of electrodes. © 2014 Elsevier Ltd. All rights reserved.


Liu X.N.,Key Laboratory of Dynamics and Control of Flight Vehicle | Liu X.N.,University of Arkansas at Little Rock | Huang G.L.,University of Arkansas at Little Rock | Hu G.K.,Key Laboratory of Dynamics and Control of Flight Vehicle
Journal of the Mechanics and Physics of Solids | Year: 2012

In continuum mechanics, the non-centrosymmetric micropolar theory is usually used to capture the chirality inherent in materials. However, when reduced to a two dimensional (2D) isotropic problem, the resulting model becomes non-chiral. Therefore, influence of the chiral effect cannot be properly characterized by existing theories for 2D chiral solids. To circumvent this difficulty, based on reinterpretation of isotropic tensors in the 2D case, we propose a continuum theory to model the chiral effect for 2D isotropic chiral solids. A single material parameter related to chirality is introduced to characterize the coupling between the bulk deformation and the internal rotation, which is a fundamental feature of 2D chiral solids. Coherently, the proposed continuum theory is applied for the homogenization of a triangular chiral lattice, from which the effective material constants of the lattice are analytically determined. The unique behavior in the chiral lattice is demonstrated through the analyses of a static tension problem and a plane wave propagation problem. The results, which cannot be predicted by the non-chiral model, are verified by the exact solution of the discrete model. © 2012 Elsevier Ltd.


Liu A.,Key Laboratory of Dynamics and Control of Flight Vehicle | Zhou X.,Key Laboratory of Dynamics and Control of Flight Vehicle | Huang G.,University of Arkansas at Little Rock | Hu G.,Key Laboratory of Dynamics and Control of Flight Vehicle
Journal of the Acoustical Society of America | Year: 2012

The resonant tunneling effects that could result in complete transmission of evanescent waves are examined in acoustic metamaterials of anisotropic effective mass. The tunneling conditions are first derived for the metamaterials composed of classical mass-in-mass structures. It is found that the tunneling transmission occurs when the total length of metamaterials is an integral number of half-wavelengths of the periodic Bloch wave. Due to the local resonance of building units of metamaterials, the Bloch waves are spatially modulated within the periodic structures, leading to the resonant tunneling occurring in the low-frequency region. The metamaterial slab lens with anisotropic effective mass is designed by which the physics of resonant tunneling and the features for evanescent field manipulations are examined. The designed lens interacts with evanescent waves in the way of the propagating wavenumber weakly dependent on the spatial frequency of evanescent waves. Full-wave simulations validate the imaging performance of the proposed lens with the spatial resolution beyond the diffraction limit. © 2012 Acoustical Society of America.


Chang Z.,Key Laboratory of Dynamics and Control of Flight Vehicle | Liu X.,Key Laboratory of Dynamics and Control of Flight Vehicle | Hu G.,Key Laboratory of Dynamics and Control of Flight Vehicle | Hu J.,Beijing Institute of Technology
Journal of the Acoustical Society of America | Year: 2012

Elastic ray theory is a high frequency asymptotic approximation of solution of elastodynamic equation, and is widely used in seismology. In this paper, the form invariance under a general spatial mapping and high frequency wave control have been examined by transformation method. It is showed that with the constraint of major and minor symmetry of the transformed elastic tensor, the eikonal equation keeps its form under a general mapping, however, the transport equation loses its form except for conformal mapping. Therefore, the elastic ray path can be controlled in an exact manner by a transformation method, whereas energy distribution along the ray is only approximately controlled. An elastic rotator based on ray tracing method is also provided to illustrate the method and to access the approximation. © 2012 Acoustical Society of America.


Guo J.,Key Laboratory of Dynamics and Control of Flight Vehicle
IET Conference Publications | Year: 2012

In order to improve the efficiency of parameter adjustment in aerodynamic configuration design of flight vehicle, the influences of the main configuration parameters on the aerodynamic coefficients, dynamic coefficients and dynamic characteristic parameters are analyzed based on the integrated design concept and parameter sensitization analysis method. A new idea of aerodynamic optimization taking the dynamic characteristic parameters as the objectives is proposed, and the major configuration parameters are optimized based on the idea and immune clonal selection algorithm.


Shen Z.,Key Laboratory of Dynamics and Control of Flight Vehicle | Tian Q.,Key Laboratory of Dynamics and Control of Flight Vehicle | Liu X.,Key Laboratory of Dynamics and Control of Flight Vehicle | Hu G.,Key Laboratory of Dynamics and Control of Flight Vehicle
Aerospace Science and Technology | Year: 2013

A coupled thermal-structural analysis based on the Euler-Bernoulli beam model is conducted within a framework of Absolute Nodal Coordinate Formulation. The absorbed heat flux on the beam surface depends on actual deformation and motion of the beam, therefore the coupled transient heat conduction equation and structural dynamics equation are established and solved interactively by the generalized-α scheme. Thermally induced vibrations for a thin-walled tubular boom subjected to a sudden heating in order to simulate spacecraft's exit from eclipse, and structure dynamics of a rotating flexible manipulator in a thermal environment are examined in details. With the coupled thermal-structural analysis, the thermal flutter can be well predicted for a cantilever beam moving from eclipse with large incident angles of solar radiation, and the proposed model is also able to characterize the coupled thermal-structural dynamics when a flexible beam is subjected to a large rotation. The developed model can be served as a basic unit for analyzing thermal-mechanical coupling response of large flexible space structures based on the Absolute Nodal Coordinate Formulation. © 2013 Elsevier Masson SAS. All rights reserved.


Ma S.,Key Laboratory of Dynamics and Control of Flight Vehicle | Zhao Z.,Key Laboratory of Dynamics and Control of Flight Vehicle | Wang X.,Key Laboratory of Dynamics and Control of Flight Vehicle
Journal of Strain Analysis for Engineering Design | Year: 2012

By using the 8-node-quadrangular isoparametric element to discretize the speckle image, a 8-node-quadrangular mesh-based digital image correlation method is proposed. The model of 8-node-quadrangular mesh digital image correlation and its solving scheme based on the Newton-Raphson iteration have been constructed. The method is realized and then verified with speckle images produced by numerical simulations and real experiments. The results show that the 8-node-quadrangular mesh digital image correlation has a similar accuracy on a simple deformation measurement (translation, rotation and constant strain deformation) compared with mesh digital image correlation using the simple 4-node-quadrangular element. But for a heterogeneous deformation field measurement, the 8-node-quadrangular mesh digital image correlation has a higher accuracy because the 8-node isoparametric element used has the second-order interpolation accuracy, which is higher than that in 4-node-quadrangular mesh digital image correlation and in the conventional subset-based digital image correlation. Moreover, the 8-node-quadrangular mesh digital image correlation has the advantage for the measurement of a specimen with circular edges; the 8-node-quadrangular mesh digital image correlation can measure the displacement of all points close, even on, the curve edges because the 8-node-quadrangular isoparametric element is able to be mapped onto an element with second-order curved edges. © IMechE 2012.


Zhou X.,Key Laboratory of Dynamics and Control of Flight Vehicle | Hu G.,Key Laboratory of Dynamics and Control of Flight Vehicle
Applied Physics Letters | Year: 2011

A metamaterial slab of anisotropic mass with one diagonal component being infinity and the other being zero is demonstrated to behave as a superlens for acoustic imaging beyond the diffraction limit. The underlying mechanism for extraordinary transmission of evanescent waves is attributed to the zero mass effect. Microstructure design for such anisotropic lens is also presented. In contrast to the anisotropic superlens based on Fabry-Pérot resonant mechanism, the proposed lens operates without the limitation on lens thickness, thus more flexible in practical applications. Numerical modeling is performed to validate the proposed ideas. © 2011 American Institute of Physics.

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