分段阻尼隔振系统的动力学特性分析

针对传统线性隔振器在降低共振峰值的同时会牺牲隔振性能的矛盾,设计了一种含分段阻尼的隔振器.首先,采用移动凸轮变阻尼装置,通过凸轮廓线的设计使系统的垂向阻尼系数的受振动位移大小控制并呈现分段线性特征,分析了该装置的阻尼特性.然后将分段阻尼装置应用于隔振器中,建立了含分段阻尼的积极隔振系统模型及其动力学方程,通过能量等效原理求出了分段阻尼系统的等效线性阻尼系数,求解了简谐力激励下系统响应的理论解,并用四阶龙格-库塔法数值仿真验证了理论解的正确性.最后研究了分段阻尼隔振系统的动态特性,分析了主要参数对幅频响应特性与力传递率特性的影响.结果表明,通过合理的参数选择,分段阻尼隔振器可兼顾无阻尼隔振器与线性阻尼隔振器的优点,既能有效降低系统的共振峰值,又能保证高频区域的优秀隔振性能,为新型非线性隔振器的设计提供了理论依据.     

Integrated design optimization of base-isolated concrete buildings under spectrum loading

Base isolation has become a practical control strategy for protecting structures against seismic hazards. Most previous studies on the optimum design of base-isolated structures have been focused on the design optimization of either the base isolation or the superstructure. It is necessary to simultaneously optimize both the base isolation and the superstructure as a whole to seek the most cost-efficient design for such structures. This paper presents an effective numerical optimization technique for the seismic design of base-isolated concrete building structures under spectrum loading. Attempts have been made to automate the integrated spectrum analysis and design optimization procedure and to minimize the total cost of the base-isolated building subject to design performance criteria in terms of the interstory drifts of the superstructure and the lateral displacement of the isolation system. In the optimal design problem formulation, the cost of the superstructure can be expressed in terms of concrete member sizes while assuming all these members to be linearly elastic under earthquake actions. However, the isolation system is assumed to behave nonlinearly, and its cost can be related to the effective horizontal stiffness of each isolator. Using the principle of virtual work, the lateral drift responses of concrete base-isolated buildings can be explicitly formulated and the integrated optimization problem can be solved by the optimality criteria method. The technique is capable of achieving the optimal balance between the costs of the superstructure and the isolation system while the design performance criteria can be simultaneously satisfied. One practical building example with and without base isolation is used to illustrate the effectiveness of the optimal design technique.     

Seismic analysis of base isolated buildings

Summary  This paper presents a survey of the numerical simulation of base isolation systems for the vibration control of buildings and their equipment, primarilly against earthquakes. Base isolation has received much attention in the recent twenty years and many buildings have been protected using this technology. The article focusses mainly on the different numerical methods used in the analysis of base isolated buildings. The conventional form of solving the equations of motion governing the seismic response of building structures with nonlinear base isolation consists of using monolithic step by step integration methods. As an efficient alternative static condensation and block iterative schemes can be applied. The particularities of the equations of motion of buildings equiped with various base isolation systems are described. The linear theory of base isolated buildings is then presented. After this, numerical solution techniques for the analysis of the seismic response of buildings with isolation systems are developed in detail in the paper. Finally, numerical results for elastic and inelastic structures are described. A complete set of references coverning a wide range of studies is included.     

基于结构抗震复合控制的哈密顿H∞ 控制器设计

针对制约结构抗震复合控制在工程中应用的执行器输出饱和问题,设计了一种基于哈密顿模型的H∞输出饱和控制器。首先对用多自由度描述的建筑物模型和隔震装置建立了哈密顿模型,然后根据地震波的有界特性,将地震波视为有界扰动,据此设计H∞控制器。为了保证在执行器输出饱和情况下该H∞控制器仍能保证稳定,在确定最大椭球体的基础上利用LMI方法计算得到了干扰抑制水平常数下限。以业界常用三层楼模型为例对此控制器进行了仿真实验,结果表明该控制器在执行器存在输出饱和情况下,可以较好地抑制地震对建筑物的影响,且优于现有被动控制方案。     

试验台测控仪器隔振装置振动传递特性分析

试验台精密测控仪器在工作过程中会受到振动设备的干扰,从而对其正常工作产生影响,因此需要采用隔振装置进行振动保护.本文以双层隔振装置为研究对象,结合有限元法和阻抗综合法建立了多点多维柔性动力学模型,分析了不同仪器质量、系统结构型式和隔振器参数对隔振装置振动传递特性的影响,结果表明所设计的双层隔振装置可以满足使用需求,增加上台面厚度和减小隔振器刚度可显著提高隔振效率.     

Best performing parameters of linear and non-linear seismic base-isolator systems obtained by the power flow analysis

In this paper the problem of finding the best performing base isolator parameters of a seismic excited structure is treated. The structural and earthquake parameters and the isolator type are considered assigned. The approach here proposed is based on the minimization of the power flow transmitted by the isolator to the structure. The power flow is a statistical measure of the power transmitted to the structure during an earthquake. The earthquake is idealized as a filtered stochastic process. This approach considers the structure–isolator–excitation system as a super-structure in which the structure, the isolator and the excitation filter are the sub-structures. It guarantees a very good global behaviour of the structure, both in terms of relative displacements and in terms of accelerations. The isolator types considered in this work are the linear, the yielding and the friction ones.     

反压气流温度及传热对隔离段激波串的影响

隔离段出口反压,气流温度和传热都影响激波串的位置,长度和隔离段的性能.采用实验方法和数值方法对均匀来流情况下具有不同隔离段长度的超燃冲压发动机燃烧室内流动进行了研究.分析了隔离段的下游反压前传模式和反压对隔离段激波串的影响;用数值方法研究了温度和传热对激波串及隔离段性能的影响.结果表明:隔离段越长,激波承受能力越强,极限反压越大;对超音速气流加入热量能够增加附面层厚度,减小气流马赫数.降低隔离段的抗反压能力;高温气流产生的激波串长度相对较长,因此需要更长的隔离段来防止发动机不启动.     

仿猫类落地姿态的准零刚度隔振器

对设备加装隔振装置是保证其高效工作的重要方法之一.本文从仿生学的角度,根据猫科动物落地时优秀的抗冲击能力,通过观察其落地动作姿态,利用非线性补偿原理,以空气弹簧作为正刚度结构,设计出一种具有非对称刚度特性的高静低动刚度隔振器.以其为研究对象,建立了动力学模型,利用特定的方法对非对称刚度系统进行分析求解,并与数值结果和有限元仿真结果进行对比.结果表明,在较低阻尼以及较高激励幅值下,还会出现倍周期响应甚至混沌响应.同时,通过将本文设计的隔振结构和单一空气弹簧的隔振性能对比,可以得到隔振效果明显优于单一空气弹簧的结论,从而验证了所设计隔振结构的有效性和可行性.     

Efficient predictive vibration control of a building‐like structure

This paper presents the design of a model predictive controller (MPC) based on Laguerre functions for vibration control. The controller is tested in a building‐like structure consisting on a three‐story building with a passive vibration absorber. The structure is connected to an electromagnetic shaker, which excites the support of the superstructure, providing forces with a wide range of excitation frequencies, including some resonance frequencies of the structure. The overall controller is a hybrid vibration absorber conformed of (i) an active absorber, that is a predictive vibration control scheme, synthesised to actively attenuate the vibratory system response via (ii) a passive absorber, known as a tuned mass damper (TMD), located over the third story building to reduce the vibrations caused by harmonic forces acting on the base of the structure. The proposed predictive control strategy proves to be effective and efficient, improving system's performance with guaranteed stability and feasibility. Experimental and numerical results are included to illustrate the overall system performance.     

自动气象站系统防雷关键技术设计与实现

现代精密电子测量仪器大都采用大规模集成电路构成,电路的耐压比较低,很容易受到电磁脉冲的冲击,致使测量数据出错或者仪器损坏;文中重点介绍了自动气象站系统在原理设计和设备制造时如何引入防雷关键技术,包括信号电路、通信接口采用光电隔离技术;电源系统采用双电池交叉充电、供电方法; PCB布线注意高低压线路间的距离;电气线路屏蔽以及器件选型等技术;DZZ1-2型自动气象站系统是分布式积木结构,各模块之间采用了物理隔离技术,其防雷效果良好,在广泛的应用中经受了考验;实践表明,采取物理隔离方法进行自动气象站的设计是防御雷击的最有效办法.     

低频大幅隔振器设计及实验

为了突破传统隔振器刚度和承载能力之间的矛盾,需要隔振器具有高的静态刚度,低动态刚度的特性.如今的准零刚度隔振器技术可以实现低频微幅隔振,但是对于大幅振动,隔振效果并不明显甚至失效,因此突破宽幅隔振成为隔振领域亟待解决的问题.为此,我们利用多稳态折纸通过并联装配的方式,构造具有宽幅零刚度区间的折纸型隔振器,以解决传统隔振器振动抑制幅值较低的问题.本文建立了宽零刚度隔振器模型,提出宽幅零刚度的设计方法,并通过动力学分析分析了模型的隔振效果.最后搭建试验样机,验证了理论的正确性.这种设计打破了传统准零刚度隔振器单点准零的设计准则,能够在一个大幅范围内保证稳定性,同时实现零刚度,极大拓宽了隔振器的适用范围.这种设计理念能够被用在新隔振材料设计和航空、船舶等大幅低频动态环境中.     

舰船概念设计中振动预报方法

以带有双层隔振装置的舰船模型为对象,利用MSC Nastran的有限元分析方法以及试验手段,对其隔振性能进行研究.将船体与双层隔振装置作为一个系统,建立三维有限元振动分析模型;以降低船体结构振动能量为目标,对发动机激励作用下的双层隔振装置与船体的振动特性进行分析;通过有限元分析方法和试验两方面的研究与对比,为舰船的减振降噪的初期概念设计提供快速预报方法.     

高压放电紫外传感器与检测装置研究

采用光电倍增管(PMT)研制了一种基于紫外光功率法的电力设备放电检测装置.围绕着"日盲"区紫外检测,进行了传感器系统设计,分析了其响应特性.介绍了系统整体结构、系统信号处理模块的软硬件设计,采用数字积分方法实现了紫外光功率测量.使用新装置进行了火花放电和针板放电模拟检测试验,验证了该仪器能够准确检测放电紫外辐射,线性反应放电的强弱,可获得设备放电能量依据.研制的装置工作稳定可靠,灵敏度高,抗干扰能力强,线性度好.     

双向地震激励下隔震结构抗倾覆特性的数值分析

为研究叠层橡胶支座隔震建筑的抗倾覆性能,建立隔震结构在双向地震激励下倾覆力矩时域响应动力分析模型.在对该模型进行简化的基础上,利用结构设计反应谱探讨结构高宽比和结构基本周期等因素对隔震结构抗倾覆力矩与倾覆力矩比值的影响.给出多层和小高层隔震结构在双向地震作用下的抗倾覆安全因数随地震烈度、场地土类别的变化规律.利用本课题...     

Numerical simulation of structure response outfitted with a tuned liquid damper

An integrated fluid–structure numerical model has been developed to simulate the response of a single degree of freedom (SDOF) structure outfitted with a Tuned Liquid Damper (TLD). The structure is exposed to random external excitations. A non-linear, two-dimensional, flow model has been developed using the finite-difference method. Unlike most existing flow models, the present model does not include any linearization assumptions; it rather solves the entire nonlinear, moving boundary, flow problem under conditions leading to large interfacial deformations. The free surface has been reconstructed using the volume of fluid method and the donor–acceptor algorithm. The Duhamel integral method has been used to determine the response of the structure. The effectiveness and accuracy of the flow model has been validated using a set of benchmark problems and experimental data. The numerical results of this model have been compared with results of an equivalent TMD model. The present fluid–structure model can be used as a valuable tool for performance evaluation and design of more effective tuned liquid dampers.     

基于材料与结构一体化的车辆吸能结构碰撞仿真

从车辆耐撞结构和吸能材料两方面入手,基于材料与结构一体化思想,利用数值仿真技术研究某高速动车被动安全性问题.设计5种适用于高速动车的吸能结构,分别为普通双层吸能管结构,3种端部带有不同薄弱环节的双层吸能管结构和泡沫铝材料夹心双层吸能管结构;利用PAMCRASH软件,分别将5种不同吸能结构安装到整车上进行相同编组对撞试验仿真;针对碰撞仿真结果评价车辆的整体被动安全性,并通过各工况结果的对比分析找出最优吸能装置.结果表明:泡沫铝夹心吸能装置在加速度和逃生空间评价指标中表现最好,在以后的吸能结构设计中可适当采用.     

基于MR的船用减振抗冲隔离器试验研究

提出了一种新型的船用减振抗冲隔离器系统。此隔离器由钢丝绳弹簧和磁流变(MR)阻尼器并联组成,应用MR阻尼器的高阻尼和阻尼可控性使该隔离器的力学性质可控,进而实现协调解决船舶设备的低频减振和高频抗冲击问题。在对隔离器抗冲减振性能的研究中,分别采用了数值试验和模型试验方法,并进行了对比分析。研究结果表明:隔离器系统对振动和冲击响应有较好的控制作用,尤其体现在抑制系统共振和控制系统的低频振动上。     

隔振对象重量变化对准零刚度隔振器隔振性能的影响

本文主要研究隔振对象重量变化对一类准零刚度隔振器隔振性能的影响,并给出了新的研究结果.文中使用欧拉屈曲梁构建负刚度调节结构并设计了隔振系统的平衡位置可调机构.假设系统有轻微的过载和超载,推导了系统的动力学方程并进行求解,定义了非线性隔振系统的力传递率及位移传递率来评价系统的隔振性能.对线性隔振系统,超载会让隔振频率略微降低,共振放大峰略微增大.对于准零刚度隔振系统,力传递率和线性系统类似,但是对于位移传递率,过载会导致系统固有频率和共振放大峰均升高,反而不利于隔振.研究结果可以对此类隔振系统的使用场合以及对过载和轻载的选择有工程指导意义.     

仿生隔振器设计方法研究进展

基于仿生学的思想,通过模仿生物系统的结构几何构成特性,创新优化隔振模型是当今隔振领域的热门问题.本文基于仿生灵感来源的不同,对现有的仿生隔振器进行了系统的分类,并对不同设计原理的仿生隔振器恢复力本构与隔振性能做了详细的阐述和对比,旨在通过隔振器隔振频带的横向对比厘清几何构型与可调参数的影响,以此厘清隔振器几何设计和隔振性能的关系.并且,本文展望了未来仿生隔振器的发展前景和研究方向.     

FDTD analysis of photoconducting antennas for millimeter‐wave generation

In this paper, a hybrid numerical technique is presented for modeling a photoconducting antenna structure designed for optoelectronic generation of millimeter waves. The technique interfaces the solid‐state device model with the three‐dimensional (3D) finite‐difference time‐domain (FDTD) method to achieve the active antenna modeling effectiveness and efficiency. The FDTD algorithm is applied to simulate the passive part of the antenna structure, whereas the numerical device simulation is employed to model the photoconductor that is illuminated by lasers. Physical performance of the photoconductor and response of the antenna are analyzed. Numerical results show good correlation with the experimental result and consequently demonstrate the feasibility of the full‐wave modeling. © 2000 John Wiley & Sons, Inc. Int J RF and Microwave CAE 10: 213–220, 2000.