Showing papers by "Yueming Li published in 2012"
TL;DR: In this article, a study on vibration and acoustic radiation characters of an isotropic rectangular thin plate under thermal environments is presented, which is assumed that thermal loads caused by thermal environments just change the structure stress state.
Abstract: A study on vibration and acoustic radiation characters of an isotropic rectangular thin plate under thermal environments is presented in this paper. It is assumed that thermal loads caused by thermal environments just change the structure stress state. Thermal stresses induced by uniform temperature rise of the plate are determined with the thermo-elastic theory. Then the stress state is used in the following dynamic analysis as a pre-stressed factor. It is observed that thermal loads influence the natural frequencies evidently, especially the fundamental natural frequency. The order of mode shapes stays the same. Dynamic response peaks float to lower frequency range with the increment of structure temperature. Acoustic radiation efficiency of the plate subjected to thermal loads decreases in the mid-frequency band. For validation, numerical simulations are also carried out. It can be found that the combined approach of finite element method (FEM) and boundary element method (BEM) is more appropriate for radiation problems.
58 citations
TL;DR: A robust gain-scheduling control-law design method for active flutter suppression based on the proposed linear parametervarying model is investigated and simulation results show that the linear parameter-varying gain- scheduled controller can effectively suppress flutter over a range of airspeeds.
Abstract: The design of classic active flutter controllers has often been based on low-fidelity and low-accuracy linear aerodynamic models. Most of these models were usually treated as a linear time-invariant system, without considering time-varying parameters, such as the Mach number, the angle of attack, the Reynolds numbers, etc. A high-fidelity reduced-order model based on the proper orthogonal decomposition adaptation algorithm is used to develop a new general linear parameter-varying aeroservoelastic model with aerodynamic nonlinearity. A robust gain-scheduling control-law design method for active flutter suppression based on the proposed linear parametervarying model is investigated. The proposed design method is demonstrated with the Goland wing aeroelastic model. The simulation results show that the linear parameter-varying gain-scheduled controller can effectively suppress flutter over a range of airspeeds, and the flutter boundary in the transonic regime is simultaneously increased by nearly 20% to 30%.
40 citations
TL;DR: In this paper, a support vector machine (SVM) based reduced-order model was proposed to predict the limit cycle oscillation generated by the nonlinear unsteady aerodynamics.
Abstract: It is not easy for the system identification-based reduced-order model (ROM) and even eigenmode based reduced-order model to predict the limit cycle oscillation generated by the nonlinear unsteady aerodynamics. Most of these traditional ROMs are sensitive to the flow parameter variation. In order to deal with this problem, a support vector machine- (SVM-) based ROM was investigated and the general construction framework was proposed. The two-DOF aeroelastic system for the NACA 64A010 airfoil in transonic flow was then demonstrated for the new SVM-based ROM. The simulation results show that the new ROM can capture the LCO behavior of the nonlinear aeroelastic system with good accuracy and high efficiency. The robustness and computational efficiency of the SVM-based ROM would provide a promising tool for real-time flight simulation including nonlinear aeroelastic effects.
31 citations
01 Jan 2012
TL;DR: In this article, the structural topology optimization to minimize the radiated acoustic power in a thermal environment for the first time was carried out, where the thermal stress induced by the thermal environment which can reduce the stiffness of the structure, thus changing its radiation property and optimal design.
Abstract: This paper carries out the structural topology optimization to minimize the radiated acoustic power in a thermal environment for the first time. The stress induced by the thermal environment which can reduce the stiffness of the structure, thus changing its radiation property and optimal design. An approach to investigate this effect is presented through studying a baffled bi-material plate. The plate is excited by a harmonic load and subjected to a uniform temperature rise. The thermal stress is first evaluated and considered as pre-stress in the structural dynamic analysis. With the dynamic response, the acoustic power can be obtained using Rayleigh integral. Sensitivity analysis with respect to the design variables is calculated according to the material interpolation model. Some typical cases are studied; the thermal environment is below the critical buckling temperature and the driving frequency is lower than the plate’s second natural frequency. Numerical results show that the natural frequencies decrease with the increase of the temperature and the structure tends to resonance; thus the radiated sound power level becomes higher and the pattern of the optimal topology resembles that of the associated mode shape more closely. The sound power level of the optimal plate becomes lower than that of the initial plate, especially for the higher temperature cases. During the optimization process, the critical buckling temperature increases and the structure is always in pre-buckling.
3 citations