考虑大变形的刚-柔耦合旋转智能结构动力学分析

基于Hamilton原理对带端部质量的刚柔耦合旋转智能结构建立了耦合的非线性动力学模型．根据一阶近似耦合（FOAC）模型理论,通过有限元方法,得到了系统的有限维模型．模型中考虑了轴向、横向位移和转动角度的非线性几何效应,以及压电材料和结构的大变形及离心刚化效应．在有限元模型的基础上,建立了3种实际系统模型方程,分别是无压电层的结构,有压电层开环状态和闭环状态．最后基于简化模型的仿真结果显示出有端部质量和没有端部质量的差异,智能结构梁在闭环和开环的差异,高速旋转梁的离心作用及结构外加电载荷的动力响应．     

智能复合材料结构振动控制力学模型

介绍了在航空，航天等高技术在领域中柔性结构振动衰减控制９０年代初期新兴的智能复合材料结构技术及应用发展前景，对一个具有应用背景的双压电片复合材料层合板帆板结构的振动衰减控制系统人出了数学模型，导出了压电传感器／激振器的输出／输入方程，进行了最优控制算法数值仿真，结果表明，其控制效果是显著的。     

埋入式光纤模式功率调制传感原理及实验研究——航天smart结构

对 Smart材料 /结构中的光纤传感原理进行了探讨 ,并进行了实验研究。这种新研制的传感器工作原理是基于模式功率调制。远场光强将反映结构内的变形场 ,亦即光纤受到外界加载或扰动后所产生的变形。最后提出了应用多模光纤在编织复合材料 Smart结构中进行远场光强测量的方案 ,建立了实验装置 ,给出了实验结果并进行了讨论。     

复合材料层板构件气弹振动控制实验研究

飞机局部复合材料构件存在着因涡流作用诱发的弹性振动问题。本文首先研究了表面粘贴型压电元件对复合材料构件的传感和驱动原理;针对结构待控模态的要求,采用了D-准则优化确定同位压电传感/驱动器在构件中的布置方案;应用自适应振动前馈控制原理和方法,构造了闭环控制系统;分别利用正弦和方波信号激发气动声场,对玻纤/环氧圆筒构件进行激振和振动控制实验;结果表明：构件主要待控模态的振动得到了有效抑制,但也出现了高阶模态被激发的问题,导致结构辐射噪声上升。     

A review of development and implementation of an active nonlinear vibration absorber

Summary We present an account of an implementation of an active nonlinear vibration absorber that we have developed. The control technique exploits the saturation phenomenon that is known to occur in quadratically-coupled multi-degree-of-freedom systems subjected to primary excitation and possessing a two-to-one internal resonance. The technique is based on introducing an absorber and coupling it with the structure through a sensor and an actuator, where the feedback and control signals are quadratic. First, we consider the case of controlling the vibrations of a single-degree-of-freedom system. We develop the equations governing the response of the closed-loop system and use the method of multiple scales to obtain an approximate solution. We investigate the performance of the control strategy by studying its steady-state and transient characteristics. Additionally, we compare the performance of the quadratic absorber with that of a linear absorber. Then, we present theoretical and experimental results that demonstrate the versatility of the technique. We design an electronic circuit to emulate the absorber and use a variety of sensors and actuators to implement the active control strategy. First, we use a motor and a potentiometer to control the vibration of a rigid beam. We develop a plant model that includes Coulomb friction and demonstrate that the closed-loop system exhibits the saturation phenomenon. Second, we extend the strategy to multi-degree-of-freedom systems. We use PZT ceramics and strain gages to suppress vibrations of flexible steel beams when subjected to single- and simultaneous two-mode excitations. Third, we employ Terfenol-D, a nonlinear actuator, and accelerometers to control the vibrations of flexible beams. In all instances, the technique is successful in reducing the response amplitude of the structures. Received 3 May 1999; accepted for publication 3 June 1999     

New Nanophase Separated Intelligent Amphiphilic Conetworks and Gels

Amphiphilic conetworks (APCN) are new materials composed of covalently bonded otherwise immiscible hydrophilic and hydrophobic polymer chains. The amphiphilic nature of these new crosslinked polymers is indicated by their swelling ability in both hydrophilic and hydrophobic solvents. Special synthetic techniques have been developed for the preparation of these new unique materials, such as poly(2-hydroxyethyl methacrylate)-l-polyisobutylene (PHEMA-l-PIB), poly(methacrylic acid)-l-polyisobutylene (PMAA-l-PIB) and poly(N,N-dimethylaminoethyl methacrylate)-l-polyisobutylene (PDMAEMA-l-PIB) (-l- stands for linked by). Due to their unique architecture, macrophase separation of the immiscible components is prevented by the chemical bonding in the conetworks. As a results, phase separation leads to nanodomains with usually 2-20 nm domain sizes as shown by AFM measurements. The nanophase separated morphology may also lead to smart temperature responsive gels with high mechanical stability, such as in the case of poly(N,N-dimethylaminoethyl methacrylate)-l-polyisobutylene APCNs as discovered during these studies. In another approach, poly(2-hydroxyethyl methacrylate)-l-polyisobutylene and poly(methacrylic acid)-l-polyisobutylene APCNs were prepared by a special two-step process. The new PMAA-l-PIB polyelectrolyte APCNs possess smart (intelligent) reversible pH-responsive properties in aqueous media. These unique conetwork structures and properties of these new emerging materials may lead to numerous new potential applications, such as smart materialk products, sustained drug release matrices, biomaterials, nanohybrids, nanotemplates etc.     

智能手机光学检测技术用于检测水体中污染物的研究

数字图像比色法(Digital Image Colorimetry,DIC)作为一种传感器方法具有简易、灵敏、成本低廉的优点,广泛应用于环境监测、化学及生物化学等领域。以LED面光源作为数字图像比色法的光源对六价铬水样进行了检测,显色反应后的溶液通过手机免费软件获取R(红)、G(绿)、B(蓝)颜色值。由于RGB模型为非均匀的颜色参数,故把R、G、B值转化为不同的数学模型,并比较各种数学模型所得出的标准曲线的线性相关性,其中灰度吸光度模型的线性相关系数最高(R~2=0.999 2)。检测方法的线性范围为0.02～1.0mg/L,检出限为0.006mg/L,加标回收率为96.5%～107%,方法具有简便快捷、灵敏度高,适用于快速现场检测。     

“Smart” Stimuli-responsive Injectable Gels for Bone Tissue Engineering Application

Bone grafting, as the current gold-standard for large scaled bone damage of various causes, has faced challenges from both the source and appliance. Emerging new tissue engineering substitutes are demonstrating more options and possibilities, with their improved biocompatibility, accessibility, and customizable function. Amongst them, injectable gels (IGs) are a class of gel material displaying astonishing non-invasive properties and surgical viability. While possessing responsiveness toward specific stimuli, they change their physical form in vivo, thus serving as wonderful biomaterials and drug delivery systems. In this review, the mechanics of stimuli-responsive IGs developed during the past decade are illustrated. Two branches of crosslinked gels – co-valent and non-covalent crosslinked IGs and their composition and customization are introduced. In conclusion, the present trend in bone tissue engineering research is summarized and made an outlook for future. It is hoped that this comprehensive review can provide a proper reference for the development of new IGs.     

An investigation on multilayer shape memory polymers under finite bending through nonlinear thermo-visco-hyperelasticity

This study presents a semi-analytical solution to describe the behavior of shape memory polymers(SMPs) based on the nonlinear thermo-visco-hyperelasticity which originates from the concepts of internal state variables and rational thermodynamics. This method is developed for the finite bending of multilayers in a dual-shape memory effect(SME) cycle. The layer number and layering order are investigated for two different SMPs and a hyperelastic material. In addition to the semi-analytical solution...     

Nanotechnology for Smart Polymer Optical Devices

Within the last decade the use of nano-structured polymers for biochips, biosensors and novel nano-optical devices gained world-wide attention due to a number of key-developments. The most fascinating example is microelectronics, where smaller means more cost efficiency, more circuits per chip, faster, and less heat to dissipate. Many intriguing new phenomena occur at nanometer dimensions including quantum size effects, Coulomb blockade, plasmon wave guides and electron tunnelling. Defined multilayer nano-assemblies enable to construct three-dimensional devices based on Plasmon and nano-optic resonance. Decisive for these types of devices and sensors is the ultra-precise nanometric assembly. Manufacturing of opto-nano-devices thus requires the development of a completely new set of ultra-precise techniques to deposit, arrange, and couple nano-polymer layers. These nano-layers are the most essential key elements of novel nano-optical-devices. Smart-responsive nano-polymer gels as transducer and building blocks for nano-devices open novel routes to photonic nano-optical sensors and chips. Optical effects based on ‘resonance enhanced absorption (REA)’ in combination with nano-layers of smart-stimulus-response polymers allow the construction of a new type of sensor device. The article will focus on up-to-date lithographic techniques of nanolayers, continue to smart-nanolayer polymers, describe the REA effect and lead to a functional REA-polymer-sensor.