【作者】 孙伟；

【导师】 胡海岩；

【作者基本信息】 南京航空航天大学 ， 一般力学与力学基础， 2005， 博士

【摘要】 近年来,基于磁流变阻尼器的振动半主动控制技术取得重要进展,并被应用于土木结构、车辆悬架的振动控制。由于该技术稳定性好、成本低、重量轻、能耗小,从而引起了航空科技界的关注。本学位论文尝试通过磁流变阻尼器来实时调节机翼与操纵面之间的扭转刚度和阻尼,进而改善整个机翼系统的颤振特性。本文的主要学术贡献如下: (1) 提出了多级磁流变阻尼器的概念,其特点是通过改变磁场作用面积来改变阻尼力矩的大小,从而实现了阻尼力矩的分级调节。设计了适用于机翼操纵面结构的多级磁流变阻尼器。基于流变力学建立了多级磁流变阻尼器的输出力矩理论模型,推导了磁场作用面积和输出力矩的函数关系。针对不同激励频率、激励位移和磁场作用面积,通过试验获得了该阻尼器的特性,基于实验数据建立了描述阻尼器动态特性的 BP 神经网络模型。 (2) 针对带有操纵面的三自由度翼段,基于 Theodorsen 非定常气动力模型建立了其气动弹性方程,研究了气动弹性系统的颤振机理。分析了机翼结构的频率比,阻尼比等参数与颤振临界速度和颤振频率之间的关系;探讨了结构参数对颤振形态的影响,从理论上证明通过提高操纵面的转动阻尼比可提高气动弹性系统的颤振临界速度。 (3) 针对上述三自由度翼段设计了抑制操纵面颤振的半主动控制算法。包括常阻尼控制、开关控制、输出反馈次最优控制以及输出反馈次最优关控制。根据机翼模型、非定常气动力模型和磁流变阻尼器建立了气动弹性系统仿真模型,并结合半主动控制算法进行了不同空气速度下的数值仿真分析。仿真结果表明,气动弹性系统模型的颤振临界速度可提高 53.85%。 (4) 基于结构力学、Theodorsen 非定常气动力模型和片条理论建立了大展弦比平直机翼的气动弹性方程。研究了大展弦比平直机翼的颤振机理,分析了大展弦比平直机翼的结构参数对颤振临界速度和颤振形态的影响。从理论上阐述了使用磁流变阻尼器来提高颤振临界速度的可行性。研究了带有多个磁流变阻尼器的大展弦比平直机翼的半主动控制算法,并进行了数值仿真分析。结果表明,半主动控制可以将大展弦比平直机翼的颤振临界速度提高 17.24%。 (5) 设计并实现了带有多级磁流变阻尼器的三自由度翼段模型实验系统,构建了数据采集处理系统、计算机控制系统和阻尼器伺服电源系统,开发了计算机半主动控制软件,并在风洞中进行了三自由度机翼气动弹性系统的半主动控制实验。在不同风速条件下,对颤振半主动控制算法进行了验证,并比较了不同半主动控制算法的控制效果。实验结果表明,半主动控制可以有效地提高气动弹性系统的颤振临界速度,最多可达到 26%。风洞实验与理论分析、数值仿更多还原

【Abstract】 Recent years have witnessed considerable attention paid to the semi-active control for structural vibration, especially the semi-active control based on MR (Magneto-Rheological) dampers. Such a kind of technique features simple mechanism, low energy requirement, high robustness and flexible control algorism. It is quite natural, hence, to develop the proper semi-active control based on MR dampers to suppress the flutter of aeroelastic systems in aerospace engineering. The primary objective of this study is to develop the semi-active flutter control for airfoil systems. The study starts with the new concept of stepped MR damper, of which the restoring torque can be adjusted by changing the area of magnetic field or the number of powered coil sets inside, in Chapter 2. Then, the chapter outlines the design procedure of a novel rotational MR damper of shear mode for the semi-active flutter control of the airfoil with aileron. Chapter 3 presents the simplified mathematical model for the stepped MR damper and the theoretical analysis based on the theory of rheology so as to establish the relation between the number of powered coils and the restoring torque for the design of the MR damper. To provide a more accurate model for the control simulation, the dissertation gives the relation between the restoring torque and the relative angular velocity of the MR damper through the use of experimental modeling based on a BP neural network. Chapter 4 focuses on the semi-active flutter control for an aeroelastic system of three degrees of freedom, including a two-dimensional airfoil section with a control surface and a stepped MR damper installed on the aileron rotation axis. The numerical simulations based on the Theodoson’s aerodynamic load showed that the MR damper was able to increase not only the structure damping, but also the critical flutter speed by at most 53.85% when one of the four semi-active control strategies proposed was put into use. Chapter 5 deals with the semi-active flutter control of a high-aspect-ratio (HAR) wing-aileron system through the use of multiple MR dampers mounted on the hinge axis along span-wise. The chapter presents how to establish the dynamic equation of the wing-aileron section of unit span subject to Theodorsen’s aerodynamic load, and how to reach the aerodynamic equation of the whole system through the use of the strip theory. The numerical simulations showed that the semi-active control strategies based on multiple MR dampers worked well for suppressing the flutter of an entire HAR wing with aileron and increased the flutter critical speed by 17.24%. Chapter 6 presents a wind tunnel test of the aeroelastic system under semi-active flutter control to testify the theoretical and numerical results. In the study, the test rig includes the airfoil section with an aileron and a stepped MR damper installed, the measurement system, the signal processing system and the semi-active controller with amplification circuit for the stepped MR damper. The control system increased the flutter critical speed by at most 26% using various control straties under different air flow speed. The experimental results got an agreement with the simulation results, demonstrating a profound increase in the critical flutter speed of the whole aeroelastic system in the wind tunnel test.更多还原