动力吸振器中库仑阻尼对吸振性能的影响

研究了动力吸振器中库仑阻尼(干摩擦)对吸振性能的影响。给出了库仑摩擦模型,在考虑了吸振器中的库仑阻尼的情况下,分析了库仑阻尼引起的主振动系统与附加质量块的2种相对运动状态(滑移和粘滞)以及它们存在和转换的条件,讨论了因库仑阻尼引起的吸振器自由度冻结现象;用Simulink仿真工具对非线性吸振器进行了数值仿真,研究了谐波和白噪声激励下库仑阻尼对吸振器吸振性能的影响以及库仑阻尼与线性阻尼的等效问题。结果显示:弱激励条件下,非线性吸振器减弱吸振效果,强激励条件下增强吸振效果。     

摩擦板式电流变阻尼器在抑制转子突加不平衡响应中的应用

设计了用于转子振动控制的摩擦板式电流变阻尼器,建立了电流变阻尼器－转子系统的分析模型,根据文献「７」中建立的突加不平衡模型,理论分析了电流变阻尼器抑制转子系统突加不平衡响应,计算分析结果发现：随着外加电压的升高,电流变阻尼器能有效地抑制突加不平衡响应。     

Adaptive tuning of elasto-plastic damper

Hysteretic dampers are frequency independent, and thereby potentially effective for several structural vibration modes, provided that the inherent amplitude dependence can be controlled. An adaptive tuning procedure is proposed, aiming at elimination of the amplitude dependence by adjusting the damper parameter(s) with respect to the magnitude of the damper motion. The procedure is demonstrated in terms of the bilinear elasto-plastic damper model, and optimality corresponds to maximum modal damping. A parametric solution for the damping ratio is obtained by a two-component system reduction technique, and maximization leads to an amplitude dependent expression for the optimal yield level. The amplitude is predicted from the most recent extremum of the damper response, and simultaneously used to adjust the yield level. Numerical examples demonstrate that the adaptive tuning procedure succeeds in controlling the amplitude dependence, resulting in equal damping for the first vibration modes.     

基于磁流变液的回转式阻尼器设计与有限元分析

根据磁流变液在磁场作用下可进行固-液转换的特点,设计了一种回转式阻尼器,并建立了相应的阻尼器力矩模型,又利用ANSYS 9.0软件对其磁场分布进行了仿真.总结了设计磁流变阻尼器应注意的问题,为磁流变液阻尼器的结构设计和制作提供了相应的理论依据.     

Design and mechanical characteristics analysis of a new viscous damper for piping system

In this paper, the design of a new viscous damper is presented and its mechanical characteristics are investigated experimentally. The motion equation of a system consisting of a drop machine and the damper is set up. By numerically simulating this equation, the curve of the damper cavity generatrix is obtained on the assumption that the resisting force is constant. Then the new damper with big capacity and high-energy dissipation rate is designed. Drop tests using this damper and a Pro225-damper bought in the market are performed, respectively. On one hand, the experimental resisting forces of the new damper approximate constants, which illustrates that the simulation is viable. On the other hand, some advantages of the new damper over the Pro225-damper are found.     

斜拉索基于最优控制力的振动控制

采用Spencer的MR模型对斜拉索和MR阻尼器组成的系统进行了动力分析.基于最优控制力将主动控制算法(线性最优控制算法、特征结构配置法)与施加电压的切换方法(剪切优化控制法、基于阻尼器出力和速度法)有机结合,并考察了MR阻尼器安装位置、斜拉索基频及激励荷载大小等各种因素对MR阻尼器制振效果的影响.研究结果表明:MR阻尼器对斜拉索半主动控制的减振效果优于最优的被动控制,并优于最优的粘性油阻尼器.     

用含苯甲酸甲氧基苯酯的聚硅氧烷组成均相电流变液及其智能阻尼特性的研究

在合成并表征含苯甲酸甲氧基苯酯的侧链液晶聚硅氧烷高分子的基础上,制备了均相电流变(ER)液及其智能阻尼器.测试了ER液及其智能阻尼器在室温下的性能.结果表明,用含苯甲酸甲氧基苯酯的侧链液晶聚硅氧烷能组成在室温下表现出较强ER活性的均相ER液,它在外加电场E=2.2kV/mm,剪切速率为300s-1时,剪切应力达到1550Pa;增加E和振动频率,均相ER液智能阻尼器的阻尼力均增加,阻尼效果提高.     

起落架磁流变减摆器模糊PID控制算法的研究

为了减小飞机机轮的摆振,提高飞机乘坐的舒适性和驾驶的安全性,将磁流变控制技术应用于飞机起落架减摆器,实现减摆器阻尼力的实时智能控制。针对磁流变减摆器,建立了飞机起落架摆振的半主动控制非线性动力学模型,设计了模糊PID控制算法,并使用Matlab/Simulink建立了半主动控制仿真模型。通过调节流过磁感线圈的电流大小改变磁流变减摆器的阻尼力,从而减小机轮摆动实现半主动控制。通过动力学仿真,在给定速度下分别对比未安装减摆器、被动控制下以及半主动控制下机轮摆角、侧向位移、侧滑角随时间变化的曲线,结果表明了模糊PID控制算法的正确性和可行性,该控制策略可以较好的抑制机轮的摆振,同时也表明模糊PID控制算法具有良好的可控性,减摆效果也明显优于传统的被动控制。     

滑动轴承挤压油膜阻尼器的试验研究

本文对滑动轴承挤压油膜阻尼器的关键技术问题进行了大量的试验研究,结合理论分析,设计出结构简单合理、性能可靠的阻尼器。并提出了适合于工程设计的结构参数。     

Nonlinear dynamic analysis of a hybrid squeeze-film damper-mounted rigid rotor lubricated with couple stress fluid and active control

The hybrid squeeze-film damper bearing with active control is proposed in this paper and the lubricating with couple stress fluid is also taken into consideration. The pressure distribution and the dynamics of a rigid rotor supported by such bearing are studied. A PD (proportional-plus-derivative) controller is used to stabilize the rotor-bearing system. Numerical results show that, due to the nonlinear factors of oil film force, the trajectory of the rotor demonstrates a complex dynamics with rotational speed ratio s. Poincaré maps, bifurcation diagrams, and power spectra are used to analyze the behavior of the rotor trajectory in the horizontal and vertical directions under different operating conditions. The maximum Lyapunov exponent and fractal dimension concepts are used to determine if the system is in a state of chaotic motion. Numerical results show that the maximum Lyapunov exponent of this system is positive and the dimension of the rotor trajectory is fractal at the non-dimensional speed ratio s = 3.0, which indicate that the rotor trajectory is chaotic under such operation condition. In order to avoid the nonsynchronous chaotic vibrations, an increased proportional gain is applied to control this system. It is shown that the rotor trajectory will leave chaotic motion to periodic motion in the steady state under control action. Besides, the rotor dynamic responses of the system will be more stable by using couple stress fluid.