跨声速风洞模型试验中时变宽频振动自适应模糊控制研究

In wind tunnel trials, due to the effect of airflow, the vibration of the aircraft model with tail support has the characteristic of lowers frequency and large amplitude, which may lead to the dangerous occurance and inaccurate data in experiment. In order to suppress the time-varying and wide-frequency vibration, it is the effective solution to develop the smart vibration reduction technology with wide regulating range of stiffness and damping, good adaptivity and fast response. Therefore, a magnetorheological elastomer （MRE） vibration mitigating device and adaptive fuzzy control strategy is proposed in this project. Based on the results of modal analysis for the aircraft model with tail support system in theory and experiments, MRE absorber with the sleeve structure is designed, and optimization methods of the structure and parameters are investigated to obtain the wider adjustment range of the stiffness and damping. On the basis of the designed MRE absorber, the adaptive fuzzy control strategy is proposed to deal with the time-varying vibration with amplitude and frequency in two dimensions. Meanwhile, the time-delay compensator is also employed to eliminate the phase difference between controlled output and response, and to improve the vibration attenuation effect. Finally, the broadband wide and time-varying vibration suppression experiments of model vibration system are implemented to verify the effectiveness of the proposed method in transonic wind tunnel. This study is not only a bold attempt of applying the intelligent material to wind transonic wind tunnel vibration system, but also a multi-disciplinary crossed research of precision machinery, intelligent control and vibration theory. Moreover, it is also applicable for the system with the signal analysis and vibration mitigation problem, which can be considered as a flexible support or a cantilever beam structure. Therefore, this research has the important academic value and the good prospect of engineering application.

在风洞试验中，飞机尾撑模型由于刚度低，在气流脉动载荷的作用下，极易产生低频大幅度振动，直接影响风洞试验的安全性和数据的准确性。针对模型振动的宽频时变性，研发可控刚度阻尼范围宽、自适应性能好、响应速度快的智能减振方法是解决问题的关键。本项目提出用磁流变弹性体半主动减振和自适应模糊控制相结合的思想，通过对模型的振动模态分析，设计一款新型套筒式变刚度变阻尼磁流变弹性体减振器，并对其结构进行优化。在此基础上制定自适应模糊控制算法应对二维振动频率和幅度的变化，同时对实时控制中的延时进行控制补偿，提高振动抑制效果。最后通过跨声速风洞实时控制试验对所提出的方法进行验证。该研究不仅是智能材料在风洞模型振动控制的大胆尝试，也是精密机械、智能控制和振动理论的多学科交叉，项目研究成果可以应用推广于柔性支杆或悬臂梁结构的振动信号分析与控制，具有重要的学术价值和工程应用前景。

风洞试验中飞机尾撑模型在气动载荷作用下的时变、宽频、多向振动直接影响风洞试验的安全性和数据的准确性。现有的被动减振方法存在结构参数固定，难以适应时变宽频振动的抑制要求，主动减振方法存在能耗高、成本高、输出位移小、高频易失稳及对多向振动抑制结构复杂等问题。本项目基于磁流变材料在磁场下模量等力学性能可调控，从而改变尾撑系统的刚度与阻尼比等参数来抑制振动原理，提出磁流变智能减振新方法，具有器件响应快、功耗低、失效免疫性等优点，项目围绕磁流变减振原理、器件设计、优化方法及智能控制策略与控制实现等开展系统性的研究：（1）在分析了尾撑模型的振动特性（主导模态）的基础上，分别从应力分布、风场影响及振幅等应用需求提出等值段磁流变弹性体（MRE）约束阻尼结构、根部剪切-压缩MRE结构和磁流变液（MRF）环形挤压减振结构三种方案，根据剪切变形理论与有限元理论推导磁流变智能减振系统的动力学方程，分析了减振机理并确定影响尾撑模型振动响应的参数。（2）针对减振器设计中磁控刚度与磁控阻尼比调控范围相互制约等问题，基于磁路基尔霍夫定律，从参数化扫描、相关性分析、磁路设计和多目标优化等几方面开展减振器结构设计与优化，实现器件最大磁控磁场为285mT时系统功耗仅7.3W。（3）通过风洞试验（随机宽频）对尾撑模型磁流变减振系统开展不同风速、攻角下的系统的磁控变刚度变阻尼性能测试与分析，减振系统实现在0-3A电流下，刚度引起的共振频率变化5Hz，阻尼最大调节范围达18.3倍。（4）设计ON-OFF 与模糊控制算法，对系统在 0.8米×0.6米风洞中进行减振控制试验验证。实现系统在风速20m/s-60m/s，攻角 0°-15°范围内，与原模型相比所设计的系统一阶共振峰降低75%，模型质心处的振动加速度均方根衰减66%。MRE减振结构在在小振幅值下用具有更优的减振效果，MRF阻尼器更适合大幅值下的振动抑制。该研究不仅是智能材料在风洞模型振动控制的大胆尝试，也是精密机械、智能控制和振动理论的多学科交叉，项目研究成果可以应用推广于各种飞行器风洞试验、柔性支撑或悬臂梁结构的振动特性分析与减振控制，具有重要的学术价值和工程应用前景。