NiTi SMAs的感知驱动特性及在振动控制中的应用

对ＮｉＴｉＳＭＡｓ的感知驱动特性进行了系统的理论分析与实验研究;将不同状态的ＮＩＴｉ ＳＭＡｓ复合于结构中,配以信息处理单元,使结构智能化;实验结果表明这种智能化结构可有效改变自身的动态特性,从而更好的自适应环境。     

载重绳索参数激励横向振动的减振策略

论述了一种抑制载重绳索参数激励横向振动的简便方法. 假设绳索底端的质量受到一个垂直简谐激励并忽略载重绳索高阶振型的影响, 载重绳索的运动方程可以用一个带有立方非线性项的Mathieu方程来描述. 根据Mathieu方程的有关理论, 在载重绳索系统中, 当索端质量垂直振动的频率接近绳索横向振动固有频率2倍时, 一旦索端质量垂直振动的幅度超过某个临界数值时, 绳索将产生参数共振. 为了避免这种现象, 建议在索端质量上加装一个减振器以削减索端质量的垂直振动, 进而抑制绳索的横向振动. 实验验证了该减振方案的有效性.     

Parametrically excited oscillation of stay cable and its control in cable-stayed bridges

ＩＮＴＲＯＤＵＣＴＩＯＮＣａｂｌｅ ｓｔａｙｅｄｂｒｉｄｇｅｓａｒｅｗｉｄｅｌｙａｐｐｌｉｅｄｉｎｍｏｄｅｒｎｂｒｉｄｇｅｓｔｒｕｃｔｕｒａｌｓｙｓｔｅｍ .Ｔｈｅｌａｒｇｅｓｔｓｐａｎｏｆｃａｂｌｅ ｓｔａｙｅｄｂｒｉｄｇｅｉｓｃｌｏｓｅｔｏ 1 0 0 0ｍｗｈｅｎｍａｎｙｎｅｗｍａｔｅｒｉａｌｓａｎｄｔｅｃｈｎｏｌｏｇｉｅｓａｒｅａｐｐｌｉｅｄ.Ｔｈｅｓｔａｙｃａｂｌｅｓａｒｅｉｍｐｏｒｔａｎｔｂｒｉｄｇｅｓｔｒｕｃｔｕｒｅｃｏｍｐｏｎｅｎｔｓｍｏｓｔｐｒｏｎｅｔｏｅｘｈｉｂｉｔｈｉｇｈａｍｐｌｉｔｕ…     

高层建筑风振反应被动控制

本文采用矩阵传递法分析了调频质量阻尼器(TMD)被动控制高层建筑风振反应,导出了结构顶层位移、加速度和基底剪力频域内统计特征公式。最后通过实例的结果说明,经过控制后能显著地降低风振反应。     

Parametrically excited oscillation of stay cable and its control in cable-stayed bridges

This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical, calculation. It is noted that parametrically excited oscillation of a stay cable with certain, sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the, first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress, the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced. Project supported by National Natural Science Foundation of China (No. 59978044)     

Pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer

This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonlinear two degrees of freedom system subject to excitation from a road profile. The active control is composed of fuzzy and disturbance controls, and the active control force is constructed by actuating a pneumatic actuator. A phase lead-lag compensator is inserted to counter the performance degradation due to the delay of the pneumatic actuator. The experimental result indicates that the proposed active suspension improves much the vibration suppression of the car model.     

Pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer

This paper presents the construction of a pneumatic active suspension system for a one-wheel car model using fuzzy reasoning and a disturbance observer. The one-wheel car model can be approximately described as a nonlinear two degrees of freedom system subject to excitation from a road profile. The active control is composed of fuzzy and disturbance controls, and the active control force is constructed by actuating a pneumatic actuator. A phase lead-lag compensator is inserted to counter the performance degradation due to the delay of the pneumatic actuator. The experimental result indicates that the proposed active suspension improves much the vibration suppression of the car model.     

Proportional-integral-derivative control of nonlinear half-car electro-hydraulic suspension systems

This paper presents the development of a proportional-integral-derivative (PID)-based control method for application to active vehicle suspension systems (AVSS). This method uses an inner PID hydraulic actuator force control loop, in combination with an outer PID suspension travel control loop, to control a nonlinear half-car AVSS. Robustness to model uncertainty in the form of variation in suspension damping is tested, comparing performance of the AVSS with a passive vehicle suspension system (PVSS), with similar model parameters. Spectral analysis of suspension system model output data, obtained by performing a road input disturbance frequency sweep, provides frequency response plots for both nonlinear vehicle suspension systems and time domain vehicle responses to a sinusoidal road input disturbance on a smooth road. The results show the greater robustness of the AVSS over the PVSS to parametric uncertainty in the frequency and time domains.     

基于MATLAB的电磁振动仿真分析

针对振动摩擦焊接机在焊接过程中的外激振力幅值确定较为困难的问题,对振动摩擦焊接机中的电磁振动原理、电磁力计算、电磁力仿真分析等方面进行研究,对静态进程模式下正余弦信号与电磁力之间关系进行归纳,提出一种基于MATLAB的电磁振动仿真分析方法。结合电磁振动学和牛顿运动学方法综合建立简化的电磁力理论推导,借用MATLAB分析正弦和余弦对电磁力的影响规律,利用振动摩擦焊接试验台对所建立的电磁力理论推导方法进行实验验证。研究结果表明,当输入正弦信号,时间为0.002 5s时,电磁力最大值为400N;当输入余弦信号,时间为0.002 6s时,电磁力最大值为556.080 0N,从而为振动摩擦焊接机的外激振力及其频率确定提供了依据。     

摩托车车架的振动特性分析与研究

课题基于UG软件对某两轮摩托车车架进行了几何建模,并经适当简化导入ANSYS软件进行自由振动(free vibration)分析与调和振动(harmonic vibration)分析。根据分析结果可以看出受迫振动的振幅表现与自然频率的共振现象,产生明显大振幅的低频率为20 Hz和50 Hz,此频率可视为路况所产生的频率,调和振动分析的共振与自由振动相吻合。比较车架不同位置,把手是最容易被振动的部位。     

Active suspension control of a one-wheel car model using single input rule modules fuzzy reasoning and a disturbance observer

INTRODUCTION Research and development of active suspensionsystems for car models are increasing much in recentyears because the active suspension systems offergood riding comfort to passengers of high speedground transportation. Investigation of linear activesuspension systems has been mainly developed basedon optimal control theory assuming that the car modelis described by a linear or approximately linear sys-tem (Hác, 1986; Hrovat, 1993; Yoshimura and Su-gimoto, 1990). However,…     

大型水轮发电机组不对称运行时的参、强联合共振研究

对某大型水轮发电机转子轴系在发生两相线间突然短路时由电磁力矩引起的扭振进行了研究,探讨了由参数激励、强迫激励以及二者联合作用下轴系扭振共振的规律．首先应用有限元法求得了轴系扭振的前五阶固有频率及振型,接着求得了考虑多磁极（凸极）和振动偏心双重影响下的气隙磁场能量,进而求得了电磁力矩的表达式．应用电机耦联系统的能量法,建立了轴系扭振共振时的一阶近似方程,并对稳态解进行了幅频特性分析,最后计算了轮系的动态应力．研究结果表明,两相线间突然短路时电磁转矩很大,并且其中的100Hz成分与轴系扭振的第二阶固有频率101．182Hz很接近,极剔］起共振,造成破坏,必须设法避免．     

电磁阻尼对低速电机转子横向非线性振动的影响

对交流电机转子横振时电磁阻尼及考虑电磁阻尼时转子横振进行了研究.首先应用磁场理论求得了电机三相不对称运行时电磁阻尼力,并对三相对称时的电磁阻尼进行了计算.接着用拉格朗日-麦克斯韦方程求得了转子横向振动的方程,画出了三相对称时转子强迫振动的幅频曲线,并与实验进行了对照,实验结果与理论结果吻合的很好.     

土木工程结构减震控制技术的研究动态

对土木工程结构减震控制方法进行了综述.阐述了结构控制发展历程、结构控制原理、结构控制方法(被动控制、主动控制、半主动控制、混合控制和智能控制)与应用研究概况,指出结构控制中存在的问题及解决办法,介绍了结构控制研究的热点benchmark问题.     

Effects of mechanical vibration on root development of Actinidia chinensis plantlet

The root development of Actinidia chinensis plantlets was studied in exposure to environmental stress of mechanical vibration at respectively 1 Hz, 2 Hz, 3 Hz, 4 Hz and 5 Hz. The plantlets exposed to vibration stimuli at all those frequencies have a larger total number and a larger total length of roots and a smaller permeability of root plasma-membrane, compared with those cultivated in an environment without vibration stress. Vibration at respectively 1 Hz, 2 Hz, 3 Hz and 4 Hz enhances root activity and the 3 Hz vibration is the most favorable. There is an obvious negative correlation between root activity and permeability of root plasma-membrane. The effects may be explained by the likelihood that mechanical vibration at an appropriate frequency facilitates roots’ absorbing water and minerals which are indispensable to inducing and synthesizing in roots some active substances favorable to growth. Nevertheless, overstress damages the integrity of root plasm-membrane, increases the permeability, and results in the disability of protecting root cells.     

拱桥柔性吊索索力振动频率法测试

通过对拉索索力振动法测试计算公式简化分析,引入振动法测试的索力系数,只要在桥梁施工过程中通过压力传感器法或张拉千斤顶法确定各条吊索的索力系数,则振动频率法测试索力的公式变成了仅与拉索振动频率有关,对提高利用振动频率法测索力精度意义很大,尤其是精确测试短索的索力。     

Experimental Study on External Low Frequency Vibration Influence on SPM

The influence of external low frequency (0-100 Hz) vibration on the tip-sample interaction in SPM is the main concern of this paper. A concept, vibration rejection ratio (VRR) proposed by Thompson et al, was investigated theoretically and experimentally. A concise theoretical background was introduced, a vibration stimulating and measuring system for SPM was built up, and an experimental research of the influence on SPM VRR was carried out with different SPM probes, samples, tip pre-loads and open/close loops of tip-sample interaction. It was proved both in theory and experiment that SPM VRR had correlations with the spring constant, the air damping constant, the effective mass of the cantilever, the contact spring constant and the contact damping constant between tip and sample. SPM's vibration rejecting ability can be improved by longer cantilever probe, softer sample surface, greater tip pre-load, and close-loop control for tip-sample interaction. More attention should be paid to a proper combination of the above parameters.     

基于滑模控制的悬臂梁振动控制实验研究

文章首先介绍了滑模面和控制函数的选取,然后用Matlab／Simulink建立基于滑模控制的仿真模型,通过实时仿真系统dSPACE实现仿真模型与实验硬件装置的连接。采用压电陶瓷传感器采集悬臂梁振动位移,控制器输出经压电陶瓷驱动器对悬臂梁进行振动控制,控制目标是获得短的调节时间,并减小滑模控制常有的抖振．实验结果表明,设计的滑模控制器对悬臂梁的振动具有很好的抑制作用．     

Aircraft Landing Gear Control with Multi-Objective Optimization Using Generalized Cell Mapping

This paper presents a numerical algorithm tuning aircraft landing gear control system with three objectives,including reducing relative vibration, reducing hydraulic strut force and controlling energy consumption. Sliding mode control is applied to the vibration control of a simplified landing gear model with uncertainty. A two-stage generalized cell mapping algorithm is applied to search the Pareto set with gradient-free scheme. Drop test simulations over uneven runway show that the vibration and force interaction can be considerably reduced, and the Pareto optimum form a tight range in time domain.     

液压机座减振行为研究

研制了具有油孔的金属液压减振器 ,它由油缸和油缸底部的弹簧组成 .考虑液体的动力学和连续条件 ,建立了液压减振器力学模型和动力学方程 ,研究了液体的动力刚度和液压机座的传递能力 .计算结果表明 ,所提出的液压机座具有优良的减振性能 .本文对于液压机座减振器的分析方法可应用于减振器的设计 ,并且所设计的金属液压减振机座可应用于实际减振工程中