Feng K.,Jiangsu University |
Xu J.,Beijing Aeronautical Science and Technology Research Institute
Journal of Engineering Mechanics | Year: 2017
A semianalytical method hybridizing hierarchical theory and finite-strip method (FSM) is developed to analyze buckling behavior of composite laminate shells in this paper. The Legendre orthogonal polynomial series are chosen as the hierarchical shape functions for the shell strips. The critical buckling loads and modes of cylinder shells with various radiuses subjected to axial loads are calculated by the proposed hierarchical finite-strip method (HFSM). The efficiency of HFSM is noted as the method combines the advantages of both hierarchical theory and FSM. The convergence and precision of HFSM are also demonstrated by several numerical examples. © 2016 American Society of Civil Engineers.
Wang J.,Beijing Aeronautical Science and Technology Research Institute
Nonlinear Dynamics | Year: 2017
The paper designs new 2- and 3-stage Radau IIA algorithms to integrate the dynamic responses of flexible multibody system with holonomic constraints. The total translation, the incremental rotation and associated velocities are selected as unknowns to avoid the linearization of angular acceleration which makes it possible to parameterize the finite rotation by using the Wiener–Milenković parameters. The new algorithms release the heavy computational burden through the simplified Newton iterations and are stabilized by the preferable h-scaling technique. Contributions of the paper include: (1) For 2-stage algorithm, the resulting block triangular equations are solved efficiently by an inner iteration scheme. (2) For 3-stage algorithm, the full-size linear system is decoupled into a real and a complex subsystems which reduces the size of the system dramatically. (3) A new scheme is designed to predict the truncation error from the associated deferred correction equations without overestimation. Finally, numerical simulations show the 2- and 3-stage Radau IIA algorithms have excellent stability and convergence properties and behavior in a computationally efficient manner. © 2017 Springer Science+Business Media Dordrecht
Wang Z.-X.,Shanghai JiaoTong University |
Wang Z.-X.,Beijing Aeronautical Science and Technology Research Institute |
Xu J.,Beijing Aeronautical Science and Technology Research Institute |
Qiao P.,Shanghai JiaoTong University |
Qiao P.,Washington State University
Composite Structures | Year: 2014
A nonlinear analysis is presented for impact response of carbon nanotube-reinforced composite (CNTRC) structures under thermal conditions. Two plate configurations (i.e., single-layer and sandwich plates) are considered, and the nanotube reinforcement is either uniformly-distributed or functionally-graded in the plate thickness direction. The material properties of nanotube reinforced composites are estimated using micromechanical models. The equations of motion are based on a higher-order shear deformation theory with a von Kármán-type of kinematic nonlinearity, and the thermal effects are included by considering the nanotube reinforced composites as temperature-dependent. The equations of motion are solved with a two-step perturbation technique, and the initial stresses caused by either the thermal or in-plane edge loads as in-plane boundary conditions are introduced. The influences of material property gradient, volume fraction distribution, temperature change, initial stress, initial velocity of the impactor, and core-to-face sheet thickness ratio on impact response of plate structures are discussed. The analysis presented can help better understand the nonlinear impact response of functionally-graded materials and facilitate design and optimization of nanocomposite structures against impact and under thermal and other environments. © 2013 Elsevier Ltd.
Shen H.-S.,Shanghai JiaoTong University |
Wang Z.-X.,Beijing Aeronautical Science and Technology Research Institute
International Journal of Mechanical Sciences | Year: 2014
This paper deals with the large amplitude vibration, nonlinear bending and thermal postbuckling of functionally graded material (FGM) beams resting on an elastic foundation in thermal environments. Two kinds of micromechanics models, namely, Voigt model and Mori-Tanaka model, are considered. The motion equations are based on a higher order shear deformation beam theory that includes beam-foundation interaction. The thermal effects are also included and the material properties of FGMs are assumed to be temperature-dependent. The numerical illustrations concern the nonlinear vibration, nonlinear bending and thermal postbuckling of FGM beams resting on Pasternak elastic foundations under different thermal environmental conditions. It is found that the FGM beam with intermediate material properties does not necessarily have intermediate nonlinear frequencies. The thermal postbuckling path of simply supported FGM beams is no longer of the bifurcation type for both uniform and non-uniform temperature fields. © 2014 Elsevier Ltd.
Tao R.,Beijing Institute of Technology |
Gao Z.,Beijing Aeronautical Science and Technology Research Institute |
Wang Y.,Beijing Institute of Technology
IEEE Transactions on Aerospace and Electronic Systems | Year: 2012
Based on the analysis of the side peaks in passive radar using digital video broadcasting-terrestrial (DVB-T) signal, two methods for the side peaks interference suppression are presented: the side peaks identification (SPI) method and the side peaks elimination-intersection (SPE-I) method. The SPI method identifies the side peaks by their positions and amplitudes relative to the main peaks. The SPE-I method eliminates the intra-symbol side peaks and the inter-symbol side peaks by preprocessing the reference signal respectively, and obtains the main peaks from the intersection of the peak positions in the two cross-ambiguity function (CAF) diagrams. The SPI method can identify the side peaks without the power loss and may lose the main peaks masked by the side peaks. The SPE-I method can eliminate the side peaks and detect the main peaks masked by the side peaks at the expense of the power loss. Combination of the SPI method and the SPE-I method can overcome their disadvantages. The proposed methods can avoid the false alarms of the side peaks and improve the target detection performance. © 1965-2011 IEEE.
Zhou Y.,Dublin Institute of Technology |
Jerrams S.,Dublin Institute of Technology |
Chen L.,Beijing Aeronautical Science and Technology Research Institute
Materials and Design | Year: 2013
For materials in modern machines, fatigue strength is probably the most critical physical property that needs to be understood. In particular, the high dynamic loading experienced by machine parts necessitates understanding fatigue properties in life limiting components. However, rubber fatigue is imperfectly understood and even less is known about fatigue resistance in adaptive or smart elastomers. Preliminary research into the equi-biaxial fatigue behaviour of magnetorheological elastomers (MREs) is described here. Test samples were fabricated by incorporating carbonyl iron particles, typically of 6-7μm in diameter, in room temperature vulcanised (RTV) silicone rubber. Physical testing was conducted using a bubble inflation testing system and test samples were fatigued at stress amplitudes between 0.75MPa and 1.4MPa under engineering stress control. S-N (Wöhler) curves of stress amplitude (σa=S) versus cycles to failure (N) are presented. Stress-strain behaviour throughout the fatigue process is also described. For a stress amplitude of 0.75MPa and zero minimum stress, stress softening was observed for the entire test, though it was particularly pronounced in the first 100 cycles of testing. A limiting value of complex modulus (E*), observed previously in dynamic testing of conventional elastomers, was determined in these tests. © 2013 Elsevier Ltd.
Li J.,Yu Da University |
Wang D.,Beijing Aeronautical Science and Technology Research Institute |
Peterson G.P.,Georgia Institute of Technology
Applied Thermal Engineering | Year: 2010
A thorough experimental investigation was carried out on a copper-water compact loop heat pipe (LHP) with a unique flat, square evaporator with dimension of 30 mm (L)×30 mm (W)×15 mm (H) and a connecting tube having an inner diameter of 5 mm. Using a carefully designed experimental system, the startup process of the LHP when subjected to different heat loads was studied and the possible mechanisms behind the observed phenomena were explored. Two main modes, boiling trigger startup and evaporation trigger startup, were proposed to explain the varying startup behavior for different heat loads. In addition, an expression was developed to describe the radius of the receding meniscus inside the wick, to balance the increased pressure drop along the LHP with increasing heat loads. Finally, insight into how the compact LHP can transfer heat loads of more than 600 W (with a heat flux in excess of 100 W/cm2) with no occurrence of evaporator dry-out was provided. © 2009 Elsevier Ltd. All rights reserved.
Wang J.,Beijing Aeronautical Science and Technology Research Institute
Multibody System Dynamics | Year: 2015
The paper develops a new type of geometrically exact beam element featuring large displacements and rotations together with small warping. The dimension reduction approach based on variational asymptotic method has been explored, and a linear two-dimensional finite element procedure has been implemented to predict the cross-sectional stiffness and recover the cross-sectional strain fields of the beam. The total and incremental variables mixed formula of governing equations of motion is presented, in which the Wiener–Milenković parameters are selected to vectorize the finite rotation. The dynamic problem of geometrically exact beam has been solved by the implicit Radau IIA algorithms, the time histories of large translations and rotations with small three-dimensional warping have been integrated. Numerical simulations have been performed and the results have been compared to those of commercial software LS-DYNA. It can be concluded that the current modeling approach features high accuracy and that the new geometrically exact beam with warping is robust enough to predict large deformations with small strain. © 2015 Springer Science+Business Media Dordrecht
Yang B.,Beijing Aeronautical Science and Technology Research Institute
Chinese Journal of Aeronautics | Year: 2013
The potential hazard resulting from uncontained turbine engine rotor blade failure has always been the long-term concern of each aero engine manufacturer, and to fully contain the failed blades under critical operating conditions is also one of the most important considerations to meet the rotor integrity requirements. Usually, there are many factors involving the engine containment capability which need to be reviewed during the engine design phases, such as case thickness, rotor support structure, blade weight and shape, etc. However, the premier method to demonstrate the engine containment capability is the fan blade-off test and margin of safety (MS) analysis. Based on a concrete engine model, this paper aims to explain the key points of aero engine containment requirements in FAR Part 33, and introduces the implementation of MS analysis and fan blade-off test in the engine airworthiness certification. Through the introduction, it would be greatly helpful to the industrial community to evaluate the engine containment capability and prepare the final test demonstration in engine certification procedure. © 2013 CSAA & BUAA. Production and hosting by Elsevier Ltd. All rights reserved.
Qi G.J.,Beijing Aeronautical Science and Technology Research Institute
Journal of Composite Materials | Year: 2011
Three-dimensional quartz fiber-reinforced silicon nitride composites were prepared by perhydropolysilazane (PHPS) infiltration and pyrolysis method, and the microstructures and interfacial reaction mechanisms were investigated by Fourier transform infrared spectrometer, solid-state 29Si MAS NMR spectrometer, field emission scanning electron microscope, and high-resolution transmission electron microscope (HRTEM). Strong interfacial adhesion was observed for the composites due to the formation of silicon oxynitrides in the fiber/matrix interfaces. HRTEM images of the composites after thermal treatment at 1873K showed a-cristobalite, α-Si3N4, and amorphous silicon oxynitrides, corresponding to crystallized quartz fibers, crystallized silicon nitride matrix, and noncrystalline interfacial phases. The interfacial reactions resulted from the silicon hydroxyl groups on the surfaces of quartz fibers and the active radicals in PHPS during infiltration and high-temperature pyrolysis. © The Author(s) 2010.