LINEAR ACTIVE STRUCTURES AND MODES (Ⅱ)--DISCRETE SYSTEMS AND BEAMS

The basic concepts about the active structures and some attributes of the modes were presented in paper "Liner Active Structures and Modes ( Ⅰ ) ". The characteristics of the active discrete systems and active beams were discussed, especially, the stability of the active structures and the orthogonality of the eigenvectors. The notes about modes were portrayed by a model of a seven-storeyed building with sensors and actuators. The concept of the adjoint active structure was extended from the discrete systems to the beams that were the representations of the continuous structures. Two types of beams with different placements of the measuring and actuating systems were discussed in detail. One is the beam with the discrete sensors and actuators, and the other is the beam with distributed sensor and actuator function. The orthogonality conditions were derived with the modal shapes of the active beam and its adjoint active beam. An example shows that the variation of eigenvalues with feedback amplitude for the homo-configuration and non-homo-configuration active structures.     

LINEAR ACTIVE STRUCTURES AND MODES (Ⅱ) —DISCRETE SYSTEMS AND BEAMS

IntroductionThestudiedobjectintheclassicstructuredynamicsisthepassivestructureswhicharechangedintoactivestructurewhencontroldevicesorsmartmaterialsareintroducedintoandthecontrolfunctionisapplied .Anactivestructureisgenerallycalledactivesystem .Asforthedefinitionofactivestructure ,itistheconceptofworthydiscussion[1].Thedefinitionshouldbebecomingrigorouswiththestudyontheactivestructuraldynamics.Withincertaincategoryofactivestructuresinpaper (Ⅰ ) [2 ],someattributesaboutthemodesoflinearactivest…     

LINEAR ACTIVE STRUCTURES AND MODES (Ⅰ)--BASIC CONCEPTS AND PROPERTIES

Some basic concepts about the active structures were firstly explained, and the main subjects to study in the field of active structure dynamics were synthesized. For the linear active structures, the annotations on the modes were done in detail. The physical meanings of the right and left eigenvectors were explained. The right eigenvectors are the modal shapes and the modal responses of an active structure depend on the left ones. The adjoint structure of an active structure was defined and the reciprocity theorem was interpreted. For two active structures, which are adjoint to each other and with the reciprocal gain-matrices, the right and left eigenvector are reciprocal. The relationship between an active structure and the corresponding passive structure is expressed with the transfer functions, which is employed to resolve the estimation problems.     

水下圆柱壳体固有频率的近似计算分析

水下发射导弹在出、入水以及水下运行过程中,由于流体、水动力以及运动速度的影响,产生附加质量和轴向荷载作用,影响结构振动频率.本文针对水下高速运动结构,给出了流体影响、轴向荷载分别作用以及二者同时作用下,结构频率的固有频率计算方法;并从理论分析、数值模拟和实验研究三个方面对水下的结构的固有频率进行了分析和研究.近似计算表明计算结果具有较好的一致性,而且由于流体和轴向荷载的影响,结构的固有频率有明显下降的趋势,而且对低阶频率影响较大.     

强度参量双界限凸集模型及双调数值解法

采用非传统概率方法—凸集方法来考虑地震动强度的不确定性。提出了一个能直接关联反应地震动强度因素的双界限凸集模型 ,介绍了在该模型下求得最不利侧移响应和地震激励的双调数值解法。最后通过实际算例 ,验证了该模型算法的实用性。     

非线性动力学系统的辨识：时频滤波与骨架曲线

利用非平稳信号的时频分析方法研究了一类非线性系统的频率特性和阻尼特性随运动形态的变化规律,得到了能简洁、直观地反映系统基本非线性动力学特性的广义骨架线性系统（简称GSLS）和骨架曲线。在此基础上,利用时频滤波方法根据系统非平稳响应信号对非线性系统进行辨识。该项工作为非线性系统反问题的研究提供了一条新的途径。     

Convex-model analysis of the seismic response

I.IntroductionThemaximumresponseofastructureisoftenusedasthebasisfordesigning.Drenick(l968,l97o),Shinozuka(l97O)andmanyotherauthorshaveusedthemaximumresponsetoseismicexcitationasadesigncriterion.Theresponse-spectrumtheoryinseismicdesignisalsobasedonthemax…     

The hybrid control of vibration of thin plate with active constrained damping layer

This paper concerns in the active and passive hybrid control of vibration of the thin plate with Local Active Constrained damping Layer (LACL). The governing equations of system are formulated based on the constitutive equations of elastic, viscoelastic, piezoelectric materials. Galerkin method and GHM method are employed to transform partial differential equations into ordinary ones with a lower dimension. LQR method of classical control theory is used in simulating calculation. Numeral results show that the active and passive hybrid control manner obtained in this paper is a better one for vibration control of the plate. Project supported by the National Science Foundation of China (19632001) and the Research Foundation of Xian Jiaotong University     

随机调幅Rattling系统建模

本文研究了一个随机调幅Ｒａｔｌｉｎｇ系统·代替常用的数值分析方法,采用非高斯截断技术,导出一个由三维平均映射描述的离散的随机模型·实测指出该模型能揭示浑沌随机性质,故更适于用以模拟齿轮箱噪声源     

线性主动结构及模态（I）——基本概念及属性

阐明了主动结构的若干基本概念，归纳了主动结构动力学的主要问题．对线性主动结构的模态做了注释，注释包括：右和左特征向量的物理意义，右特征向量为振型，左特征向量表征响应的模态分量；伴随结构及互易定理，两个互为伴随主动结构，且有对偶反馈增益矩阵，左和右特征向量互易；主动结构与被动结构的关联用传递函数表示，可用于主动结构的估计问题．