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Geometrically exact nonlinear analysis of pre-twisted composite rotor blades

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Chinese Journal of Aeronautics 2018年第2期31卷 300-309页

作者： Li'na SHANG pinqi xia Dewey H.HODGES College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Guggenheim School of Aerospace Engineering Georgia Institute of Technology

Modeling of pre-twisted composite rotor blades is very complicated not only because of the geometric non-linearity, but also because of the cross-sectional warping and the transverse shear deformation caused by the anisotropic material properties. In this paper, the geometrically exact nonlinear modeling of a generalized Timoshenko beam with arbitrary cross-sectional shape,generally anisotropic material behavior and large deflections has been presented based on Hodges＇ method. The concept of decomposition of rotation tensor was used to express the strain in the beam. The variational asymptotic method was used to determine the arbitrary warping of the beam cross section. The generalized Timoshenko strain energy was derived from the equilibrium equations and the second-order asymptotically correct strain energy. The geometrically exact nonlinear equations of motion were established by Hamilton＇s principle. The established modeling was used for the static and dynamic analysis of pre-twisted composite rotor blades, and the analytical results were validated based on experimental data. The influences of the transverse shear deformation on the pre-twisted composite rotor blade were investigated. The results indicate that the influences of the transverse shear deformation on the static deformation and the natural frequencies of the pre-twisted composite rotor blade are related to the length to chord ratio of the blade.

关键词： Geometrically exact Nonlinear Pre-twisted composite blade Transverse shear deformation Variational asymptotic Warping

Control of dynamic stall of helicopter rotor blades

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Science China(Technological Sciences) 2013年第2期56卷 171-180页

作者： WANG Rong xia pinqi National Key Laboratory of Helicopter Rotor Aeromechanics Nanjing University of Aeronautics and Astronautics

An effective method for delaying the dynamic stall of helicopter retreating blade by using the trailing edge flap has been established in this paper.The aerodynamic loads of blade section are calculated by using the Leishman-Beddoes unsteady two-dimensional dynamic stall model and the aerodynamic loads of the trailing edge flap section are calculated by using the Hariharan-Leishman unsteady two-dimensional subsonic model.The analytical model for dynamic stall of elastic blade with the stiff trailing edge flap has been established.Adopting the aeroelastic analytical method and the Galerkin's method combined with numerical integration,the aeroelastic responses of rotor system in high-speed and high-load forward flight are solved.The mechanism for control of dynamic stall of retreating blade by using trailing edge flap has been presented.The numerical results indicate that the reasonably controlled swing of trailing edge flap can delay the dynamic stall of retreating blade under the same flight conditions.

关键词：直升机旋翼失速控制叶片空气动力载荷后缘襟翼动态失速计算结果弹性分析

Finite element corotational formulation for geometric nonlinear analysis of thin shells with large rotation and small strain

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Science China(Technological Sciences) 2012年第11期55卷 3142-3152页

作者： YANG JinSong xia pinqi College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Based on the consistent symmetrizable equilibrated(CSE) corotational formulation,a linear triangular flat thin shell element with 3 nodes and 18° of freedom,constructed by combination of the optimal membrane element and discrete Kirchhoff triangle(DKT) bending plate element,was extended to the geometric nonlinear analysis of thin shells with large rotation and small strain.Through derivation of the consistent tangent stiffness matrix and internal force vector,the corotational nonlinear finite element equations were established.The nonlinear equations were solved by using the Newton-Raphson iteration algorithm combined with an automatic load controlled technology.Three typical case studies,i.e.,the slit annular thin plate,top opened hemispherical shell and cylindrical shell,validated the accuracy of the formulation established in this paper.

关键词：几何非线性分析有限元方程小应变薄壳转动旋制非线性方程基尔霍夫

Energy conserving and decaying algorithms for corotational finite element nonlinear dynamic responses of thin shells

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Science China(Technological Sciences) 2012年第1期55卷 3311-3321页

作者： YANG JinSong xia pinqi College of Aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China

On the basis of the finite element corotational formulation for geometric nonlinear static analysis of thin shells with large rotation and small strain established before and from the generalized-α time integration algorithm, the energy conserving and decaying algorithms for corotational formulation nonlinear dynamic response analysis of thin shells are established in this paper. Responses are solved by means of a predictor-corrector procedure. In the case of ignoring the structural damping, the conserving or decaying total energy of structure and the controllable numerical damping for high frequency responses can ensure the numerical stability of the algorithm. The inertial parts are linearly interpolated directly in the fixed global coordinate system by using the element nodal displacement in the global coordinate system for obtaining the constant mass matrix, while the elastic parts adopt the corotational formulation. Hence, the whole formulation obtained in this paper is element independent. Through three typical numerical examples, the performances of the algorithm in this paper were compared with those of the classical Newmak and HHT-α algorithms to indicate that the algorithm in this paper could accurately solve nonlinear dynamic responses of thin shells with large displacements and large rotations.

关键词：非线性动力响应积分算法有限元薄壳能源节约腐烂非线性静力分析数值稳定性

Adaptive Control of Helicopter Ground Resonance with Magnetorheological Damper

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Chinese Journal of Aeronautics 2007年第6期20卷 501-510页

作者： Wang Wei xia pinqi College of Aerospace Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

The methodology for adaptive control of helicopter ground resonance with magnetorheological （MR） damper is presented. The adaptive inverse control method is used to control the output damping force of MR damper and the range of the damping force is given. Through the adaptive inverse control, the damping force of MR damper is fit to a desired damping force. With the background of applying MR damper to control of helicopter ground resonance, a model of loss force and an adaptive arithmetic for stabilization of the coupled rotor/fuselage system are presented. The simulation shows that the controller presented in this paper can stabilize the rotor/fuselage coupling system quickly and control the helicopter ground resonance effectively.

关键词： ground resonance adaptive control magnetorheological damper

Aeroelastic stability of wing/pylon/rotor coupled system for tiltrotor aircraft in forward flight

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Science China(Technological Sciences) 2011年第10期54卷 2708-2715页

作者： YANG ChaoMin xia pinqi Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and Astronautics Nanjing 210016 China

An analytical model for aeroelastic stability of the wing/pylon/rotor coupled system with elastic bending-twist coupling wing for tiltrotor aircraft in forward flight has been established in this paper. The investigation is focused on the effectiveness of the wing elastic bending-twist couplings provided by composite wing beam on the aeroelastic stability for the wing/pylon/rotor coupled system. By introducing the different wing elastic bending-twist couplings into the Boeing’s test model, the aeroelastic stability of the Boeing’s test model with different wing elastic bending-twist couplings has been analyzed. The numerical re-sults indicate that the negative wing beamwise bending-twist elastic coupling (the wing upward beamwise bending engenders the nose-down torsion of the wing section) can saliently enhance the stability of the wing beamwise bending modal. The posi-tive wing chordwise bending-twist elastic coupling (the wing forward chordwise bending engenders the nose-down torsion of the wing section) has a great benefit for increasing the stability of the wing chordwise bending modal.

关键词：气弹稳定性倾转旋翼飞机耦合系统气动弹性稳定性转子吊架飞行弯扭耦合

A wake bending unsteady dynamic inflow model of tiltrotor in conversion flight of tiltrotor aircraft

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Science China(Technological Sciences) 2009年第11期52卷 3188-3197页

作者： YUE HaiLong xia pinqi Laboratory of Rotorcraft Aeromechanics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

The aerodynamics, dynamic responses and aeroelasticity of tiltrotor aircraft in the tilting of rotor i.e. in conversion flight are extraordinarily complicated. The traditional quasi-steady assumption model can not reflect the unsteady aerodynamic problems in the tilting of rotor. The CFD method based on the vortex theory can get better results, but it consumes a lot of computing resources. In this paper, a wake bending dynamic inflow model of tilting rotor was established firstly based on the Peters-He dynamic inflow model used in helicopter. Then combining with the ONERA unsteady aerodynamic model, a wake bending unsteady dynamic inflow model of tilting rotor in conversion flight of tiltrotor aircraft was established. The wake bending unsteady dynamic inflow model of tilting rotor was verified by using the experimental data of an isolated rotor model in large angle pitching up maneuver and was used to calculate the dynamic responses of tilting rotor in conversion flight of a tiltrotor aircraft model. The calculated results were analyzed to be physically reasonable.

关键词： tiltrotor dynamic inflow wake bending unsteady aerodynamics

采用压电叠层作动器的弹性梁振动主动控制实验研究

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航空学报 2014年第1期35卷 171-178页

作者：宋来收夏品奇南京航空航天大学航空宇航学院江苏南京210016

结构响应主动控制系统中常用的惯性作动器由于附加质量大、工作频带窄和响应速度慢等缺点,降低了控制系统的性能。压电作动器具有质量轻、工作频带宽和响应速度快等优点,作为高效执行元件能有效地提高控制系统的性能。本文采用压电叠层... 详细信息

结构响应主动控制系统中常用的惯性作动器由于附加质量大、工作频带窄和响应速度慢等缺点,降低了控制系统的性能。压电作动器具有质量轻、工作频带宽和响应速度快等优点,作为高效执行元件能有效地提高控制系统的性能。本文采用压电叠层作动器驱动自由-自由弹性梁模型,以观测点的加速度响应为控制目标,采用频域谐波稳态控制策略进行了自由梁结构谐波振动响应主动控制实验研究。实验结果表明,本文建立的采用压电叠层作动器的结构响应主动控制系统能有效地控制弹性梁结构的振动水平,并具有快速跟踪外激励变化的自适应控制能力。

关键词：弹性梁压电叠层作动器谐波振动自适应振动控制实验研究

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无减摆器旋翼桨叶气弹稳定性分析

南京航空航天大学学报 2012年第5期44卷 700-705页

作者：夏品奇周景良南京航空航天大学直升机旋翼动力学国家级重点实验室南京210016

无减摆器旋翼具有桨毂结构简单、桨毂气动阻力小、桨毂维护简便等优点,但取消了桨毂减摆器后必须确保桨叶在摆振方向有足够的阻尼以保证桨叶的摆振稳定性。基于气弹耦合的方法是实现无减摆器旋翼桨叶摆振稳定性的一个有效方法。建立了... 详细信息

无减摆器旋翼具有桨毂结构简单、桨毂气动阻力小、桨毂维护简便等优点,但取消了桨毂减摆器后必须确保桨叶在摆振方向有足够的阻尼以保证桨叶的摆振稳定性。基于气弹耦合的方法是实现无减摆器旋翼桨叶摆振稳定性的一个有效方法。建立了无减摆器无铰式旋翼桨叶带有预锥角、下垂角、后掠角和预扭角等结构参数的非线性气弹动力学模型,利用伽辽金方法把桨叶偏微分运动方程简化为非线性常微分平衡方程和关于平衡位置的小扰动运动方程,分析了桨叶的气弹稳定性并进行了参数影响分析。数值结果表明,合理的桨叶结构参数和气弹耦合可确保无减摆器旋翼桨叶在摆振方向的气弹稳定性。

关键词：无减摆器旋翼无铰式桨叶气弹耦合气弹稳定