部分覆盖压电约束层阻尼板的建模与控制特性分析

仅考虑逆压电效应,由压电材料的本构关系求出了约束层的膜内力。采用速度反馈控制策略,并结合约束层的膜内力和薄板控制方程,导出了压电约束层阻尼矩形板在频域内的整合一阶常微分矩阵方程。在此基础上,结合精细元法和叠加原理提出了一种分析部分覆盖压电约束层阻尼层合板振动和阻尼特性的半解析方法。通过与文献值的比较,证明了方法的有效性。还讨论了结构和控制参数对部分覆盖压电约束层阻尼层合板动力学特性的影响。     

压电结构的有限元分析方法

提出了一种新的压电结构有限元分析方法，即压电薄板立体单元法。利用哈密顿原理推导出压电结构的变分方程，建立了智能结构的有限元动力方程。并以具有压电薄层的层合板为例进行了研究，证明了本文所用方法简单、正确     

基于压电悬臂梁的驱动器与传感器性能分析的精确解析模型

三层压电梁结构在电场作用下发生变形后会产生诱发电势,进而改变材料整体电势分布,本文考虑此变形和电势耦合效应,基于欧拉-伯努利梁变形理论,推导出能够准确预测压电智能悬臂梁传感器与驱动器性能的解析表达式。考虑压电梁结构弯曲变形后产生的电场影响,建立了三层压电梁结构的控制方程;建立了压电梁作为驱动器时端部输出位移、驱动力矩与输入电压之间联系的解析表达式,以及作为传感器时输出电压与端部作用力之间联系的解析表达式。通过与ANSYS有限元模拟结果以及传统的驱动器和传感器性能表达式的对比,验证了所推导的解析表达式的准确性。     

压电层合板智能结构分析

本文详细推导了具有压电材料的层合板智能结构的有限元方程的一般形式，最后用算例验证该模型的有效性。     

基于多变量MIC神经PID智能板的主动控制

智能压电材料由于它的正逆压电效应,故在噪声及振动的主动振控制中应用越来越多,基于薄板理论并且利用有限元的方法对压电板进行离散化,推导出智能压电板的有限元动力学方程,并且应用多变量MIC网络神经PID算法,对其进行控制,利用MATLAB编程分几种情形进行数字仿真,对响应曲线进行分析,仿真结果表明该方法能有效抑制层合板的振动,达到对智能层合板的主动控制,特别是模型失配时仍然有较好的控制,很好地解决了这类智能板模型易变的控制问题,相对一般的控制方法具有较强适应性。     

基于离散层模型的多层压电板变形问题的数值解

研究了由压电材料组成的层合板在力场、电场、温度场及湿度场综合作用下的相互耦合效应.从弹性理论、压电理论、热传导理论和湿度传播理论的基本方程出发,导出了具有力电热湿耦合作用的材料体系的状态方程,进而对得到的微分方程组应用加权余量法进行弱化,得到弱形式的方程组,建立了均匀材料体系的解析模型并进一步拓展为离散层模型,用来解决压电层合板变形问题.最后通过算例计算了施加外部载荷于简支压电层合板的变形情况并同现有的精确解进行了对比,以表明模型的有效性.     

基于压电材料反射声压最小的主动吸声方法

提出一种基于反射声功率最小的吸声方法。将压电材料作为主动吸声的主体材料,借鉴主动吸声的原理进行吸声,将压电陶瓷晶片粘贴在很薄的简支平板上,通过布置于简支平板正前方的两个麦克风传感器检测出入射声波与反射声波。根据检测出的反射声波,将其与加在压电陶瓷上电压而引起简支平板振动而引起的声压表示为总的反射声压。在反射声压平方和最小的条件下,求得加在压电陶瓷上的电压,从而达到吸声的效果。并将单片压电陶瓷晶片反射声压平方和的理论和多片压电陶瓷晶片反射声压平方和的理论分别进行设计。对压电陶瓷晶片数量为一片、三片、五片几种情况,分别进行数值计算与试验,结果表明,该方法能起到很好的主动吸声效果,且压电陶瓷晶片数量为三片时效果就很好,更多的压电陶瓷晶片没有使吸声效果明显的增加。     

弹性机构振动主动控制中压电作动器/传感器的优化配置

讨论了高速弹性机构构件上压电作动器和传感器粘贴位置优化配置的方法。基于机构弹性动力学控制方程，对系统模态作动力系数矩阵，作奇异值分解和振动响应观测信号，作小波变换，获得了作动器和传感器不同分布情况下作动力和观测信号的能量表达式，提出了判定作动器／传感器最优配置的可控性指标和可观性指标。最后，对弹性连杆机构进行数值仿真，确定了机构构件上压电作动器和传感器的最优配置。     

柔性压电智能反射面的静态形状控制

建立了柔性压电智能反射面系统的有限元模型和优化控制模型,给出了结构力学建模和形状控制方法以及相应的优化算法。首先,将蜂窝夹层结构的压电智能反射面等效为多层复合板;基于Kirchhoff假设和经典层合板理论,根据虚功原理推导了柔性压电智能反射面的有限元方程;采用蜂窝等效理论计算了反射面蜂窝夹芯等效弹性模量,有限元模型中的单元为四节点四边形压电板单元,每个作动器单元中引入额外的电势自由度。然后,根据建立的有限元方程,推导了反射面变形均方根误差与作动器控制电压的关系式;以均方根误差最小为优化目标,建立了柔性压电智能发射面的静态形状控制优化模型;采用Lagrange乘子法处理了压电作动器工作电压的限制。最后,用提出的方法分析已有模型并验证建模方法。以600mm口径的平面柔性智能反射面为例,验证了采用压电陶瓷贴片对反射面静态形状控制的可行性及优化算法有效性。仿真结果表明:通过控制压电陶瓷贴片作动器,可以使反射面的静态形状误差减小97%以上,而且作动器的控制电压均在极限电压范围内。     

Hamilton体系下压电材料层合板特征值灵敏度分析

在Hamilton体系下,基于区间B(B-spline wavelet on the interval)-样条小波有限元法研究压电材料特征值的灵敏度分析问题,推导压电材料特征值响应灵敏度系数的控制方程.利用二分法求得压电材料层合板前4阶特征值对材料密度的灵敏度系数,并与有限差分法所得结果相比较,证明所提方法的可靠性.结...     

采用压电陶瓷元件进行智能板振动控制

将分布的压电传感器／驱动器运用于智能板结构的主动减振控制中,分布的压电传感器能感知结构的局部应变状态,并通过控制回路反馈给驱动元件,构成闭环控制。建立了智能板闭环控制的分析模型,揭示在应变率反馈下,主动控制的机理是增加了结构的阻尼。用两对压电陶瓷元件仿真了柔性板的闭环控制,获得了令人满意的结果。     

压电板自适应独立模态控制初探

提出用分布式压电片组建模态传感器及作动器实现准独立模态控制的方法,为 结构的自适应控制提供了物质基础。结合自适应控制技术进一步进行了基于这种独 立模态控制策略的自适应振动控制实验研究,在压电板上取得了理想的控制效果。     

The deflection of a simply supported plate induced by piezoelectric actuators

The coupling effects between the mechanical and electric properties of piezoelectric materials have drawn significant attention for their potential applications as sensors and actuators. In this investigation, two piezoelectric actuators are symmetrically embedded in a simply supported plate. Electric voltages with the same amplitude and opposite sign are applied to the two symmetric piezoelectric actuators, resulting in the bending effect on the plate. The bending moment is derived by using the theories of elasticity and piezoelectricity. The analytical solution of the flexural displacement of a simply supported plate subjected to the bending moment is solved by using the plate theory. The analytical solution is compared with the finite element solution to show the validation of present approach. The effects of the size and location of the piezoelectric actuators on the response of a plate are presented through a parametric study.     

PIEZOELECTRIC ACTUATOR AND SENSOR MODELS FOR AN INFLATED TOROIDAL SHELL

Due to their low mass and conformability, actuators and sensors made of active materials can be used in the vibration control of inflatable structures. In this study, we model piezoelectric patches attached to an inflated toroidal shell as actuators and sensors. Using Sanders' shell theory in the presence of initial stresses, the generalised forces due to the piezoelectric actuators are derived for the inflated toroidal shell assuming quasi-static conditions. The derivations are given for both unimorph and bimorph configurations. Effects of the mass and stiffness of the patches are incorporated in the equations of motion. Thereafter, a sensor equation is presented. Within linear shell theory, the methodology is quite general in nature and can be applied easily to other types of shells and membranes. To demonstrate this, we specialise the actuator and sensor equations for a circular cylinder. Using the formulations for the inflated toroidal shell, the modal forces and modal sensing constants are calculated for different sizes and locations of the piezoelectric patches. Along with this, controllability and observability indices are calculated to quantify the performance of the actuators and sensors. A study of the stiffness and mass effects of the piezoelectric patches is performed using frequency response function.     

Nonlinear free and forced vibration of simply supported shear deformable laminated plates with piezoelectric actuators

This paper deals with the nonlinear vibration and dynamic response of simply supported shear deformable cross-ply laminated plates with piezoelectric actuators subjected to mechanical, electrical and thermal loads. The material properties are assumed to be independent of the temperature and electric field. Theoretical formulations are based on the higher order shear deformation plate theory and general von Kármán-type equation, which includes thermo-piezoelectric effects. Due to the bending and stretching coupling effects, a nonlinear static problem is first solved to determine the pre-vibration deformation caused by temperature field and control voltage. By adding an incremental dynamic state to the pre-vibration state, the equations of motion are solved by an improved perturbation technique to determine nonlinear frequencies and dynamic responses of hybrid laminated plates. The numerical illustrations concern nonlinear vibration characteristics of unsymmetric cross-ply laminated plates. The results presented show the effects of temperature rise, applied voltage and stacking sequence on the nonlinear vibration and dynamic response of the plates.     

综合模态H2范数下致动器/传感器的优化配置

致动器/传感器的优化配置问题是智能柔性结构振动主动控制中的关键技术问题,基于模态空间H_2范数研究了智能柔性梁系统中压电致动器/传感器的优化配置问题。根据Rayleigh-Ritz理论建立了系统的动力学方程并得到其状态空间表达式。提出了一种衡量系统能控/能观性并考虑模态权重的综合模态H_2范数准则,采用改进遗传算法研究系统中并置致动器/传感器的优化配置问题,得到了系统多个模态、综合模态H_2范数最优的致动器/传感器布局结果。实验结果表明,利用优化结果进行致动器/传感器的布局,系统单个模态和综合模态均具有较好的检测和控制效果,被控模态具有较好的能控/能观性,所提出的优化准则和优化方法是可行的。     

基于特征模型的压电悬臂板振动控制

航天器上悬臂板型挠性附件在扰动作用下将引起包括弯曲和扭转模态的振动,这将影响系统的稳定性和控制精度,尤其是在平衡点附近低频模态频率上的小幅值残余振动很难快速抑制。为了快速抑制压电智能挠性悬臂板系统,包括弯曲和扭转模态的振动,提出采用基于特征模型的非线性黄金分割自适应控制,组合非线性切换逻辑积分阻尼器算法。首先,优化配置压电传感器和驱动器实现了悬臂板的弯曲和扭转模态在检测和驱动上的解耦;其次,设计并建立压电挠性悬臂板试验平台,进行试验模态辨识并获得了悬臂板系统弯曲和扭转振动的模态频率和频响特性;最后,进行压电智能悬臂板的弯曲和扭转振动模态主动振动几种方法试验的比较研究。试验结果表明,采用的控制方法能够快速地抑制压电智能挠性悬臂板的振动。     

压电智能悬臂梁的压电片位置、尺寸及控制融合优化设计

对压电智能悬臂梁振动控制中的压电片的位置、尺寸及其控制参数进行研究.在对压电片和基板的耦合特性进行分析的基础上,建立智能悬臂梁的压电传感、致动方程及基于闭环控制系统的状态方程,并以系统的存留能量作为目标函数,建立压电智能悬臂梁压电片的位置、尺寸和控制参数的优化模型及一阶灵敏度分析表达式,并采用移动渐进线法(Method of moving asymptotes,MMA)对模型进行求解.采用Simulink对优化结果的动态响应特性进行仿真分析,仿真结果表明,采用提出的优化模型及算法对悬臂梁压电片的位置、尺寸和控制参数进行优化是合理的.     

Float characteristics of a squeeze-film air bearing for a linear motion guide using ultrasonic vibration

The float characteristics of a square squeeze-film air bearing using piezoelectric actuators as a vibrator are discussed. In this type of bearing, piezoelectric actuators are adhered to a flat bearing plate and vibrate the bearing plate at ultrasonic resonant frequency. The influence of various design parameters on the float characteristics of the proposed bearing, such as the vibration frequency, input voltage to the piezoelectric actuator, and imposed load were investigated theoretically and experimentally. Our proposed squeeze-film air bearing was found to be quiet, because this type of bearing uses ultrasonic vibration to generate the squeeze-film. An average film thickness of 5 μm could support an imposed load of 10 N.     

Thermally induced vibration control of cylindrical shell using piezoelectric sensor and actuator

Shell type components and structures are very common in many mechanical and structural systems. Modeling and analysis of adaptive piezothermoelastic shell laminates represent a high level of sophistication and complexity. In this paper a finite element model is developed for the active control of thermally induced vibration of laminated composite shells with piezoelectric sensors and actuators. The present model takes into account the mass, stiffness and thermal expansion of the piezoelectric patches. A C_o continuous nine-node degenerated shell element is implemented to model the structure. The piezoelectric sensing layer senses the structural vibration and a suitable voltage applied in the piezoelectric actuator layer suppresses the oscillation. Actuator and sensor are coupled together with a control algorithm so as to actively control the dynamic response of the structure in a close loop. Numerical results are generated for a cylindrical shell and it is observed that thermally induced vibration of a laminated cylindrical shell can be suppressed through the application of piezoelectric sensor and actuator. Effects of variation in control gain and piezoelectric layer area coverage (PAC) have been studied. Higher control gain is more effective in damping out the vibration. Although the damping is enhanced by increase in PAC, increase beyond a certain level may not be useful in view of smaller efficacy and increased weight.