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采用压电机敏元件进行结构振动控制Ⅲ:控制系统设计与实验研究 总被引:5,自引:0,他引:5
采用作者在上篇导出的压电耦合体动力学模型,给出了压电主动阻尼控制系统的设计方法;导出了压电耦合梁系统的作动方程和检测方程的显式表达式。以此为基础,以简单梁为对象,对压电检测器和作动器的性能、粘结层的影响、压电主动阻尼控制及压电主、被动阻尼双控制进行了实验研究 相似文献
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大型天线必须保持非常精确的形状。由于载荷变化及各种随机干扰,为了保持精确的形状,这类结构宜采用主动控制。针对智能抛物面天线结构,建立了对天线反射面的最佳吻合抛物面的RMS精度和作动器能耗为综合目标的多目标优化模型。优化模型以结构强度和作动器性能作为约束条件,模型转化为二次规划问题进行求解,实现智能抛物面天线的准静态最优控制。算例表明,可以用较少的作动器,实现大型天线结构的精密控制。 相似文献
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提出了将智能材料粘贴在叶片表面或嵌入叶片内部形成新结构的概念。本文将智能材料作为传感器和作动器,通过机电耦合抑制叶片的振动;利用有限元软件 Algor 分析在气动力作用下叶片的应力、应变;基于压电陶瓷第一压电方程,将风电叶片简化成柔性悬臂梁,建立了压电智能悬臂梁状态空间的动力学模型;针对此系统利用最优控制理论进行主动振动控制,设计了在系统低阶模态空间的振动控制器。最后通过计算机仿真得出:系统振动幅度缩小了约20%,振动时间减少了约80%,从而说明了此主动振动控制方法的有效性和可行性,对防止叶片这一弹性体发生颤振也起到一定的作用。 相似文献
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压电作动器可以把电能转换成机械能,在结构主动振动控制中具有应用背景. 由于压电作动器的布局对振动控制效果影响很大,因此作动器布局优化一直是结构控制研究的关键之一. 为了提高压电结构控制能量的利用效率,本文提出了以提高结构可控性为目标的压电作动器的拓扑优化方法. 基于经典层合板理论对压电结构进行了有限元建模,并采用模态叠加法将动力控制方程映射到模态空间,推导了基于控制矩阵奇异值的可控性指标. 优化模型中,选取可控性指标指数形式为目标函数,将设计变量定义为作动器单元的相对密度,并基于人工密度惩罚模型构造了压电系数惩罚模型,给出了基于控制矩阵奇异值的可控性指标关于设计变量的灵敏度分析方法. 优化问题采用基于梯度的数学规划法求解. 数值算例验证了灵敏度分析方法和优化模型的有效性,并讨论了主要因素对优化结果的影响. 相似文献
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压电作动器可以把电能转换成机械能,在结构主动振动控制中具有应用背景.由于压电作动器的布局对振动控制效果影响很大,因此作动器布局优化一直是结构控制研究的关键之一.为了提高压电结构控制能量的利用效率,本文提出了以提高结构可控性为目标的压电作动器的拓扑优化方法.基于经典层合板理论对压电结构进行了有限元建模,并采用模态叠加法将动力控制方程映射到模态空间,推导了基于控制矩阵奇异值的可控性指标.优化模型中,选取可控性指标指数形式为目标函数,将设计变量定义为作动器单元的相对密度,并基于人工密度惩罚模型构造了压电系数惩罚模型,给出了基于控制矩阵奇异值的可控性指标关于设计变量的灵敏度分析方法.优化问题采用基于梯度的数学规划法求解.数值算例验证了灵敏度分析方法和优化模型的有效性,并讨论了主要因素对优化结果的影响. 相似文献
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As tensegrity research is moving away from static structures toward active structures it is becoming critical that new actuation strategies and comprehensive active structures theories are developed to fully exploit the properties of tensegrity structures. In this paper a new general tensegrity paradigm is presented that incorporates a concept referred to as clustered actuation. Clustered actuation exploits the existence of cable elements in a tensegrity structure by allowing cables to be run over frictionless pulleys or through frictionless loops at the nodes. This actuation strategy is a scalable solution that can be utilized for active structures that incorporate many active elements and can reduce the number of actuators necessary for complex shape changes. Clustered actuation also has secondary benefits, specifically reducing the force requirements of actuators in dynamic structures, reducing the number of pre-stress modes to potentially one global mode and relieving element size limitations that occur with embedded actuation. Newly formulated clustered equilibrium equations are developed using energy methods and are shown to be a generalization of the classic tensegrity governing equations. Pre-stress analysis, mechanism analysis and stability of clustered structures are discussed. Lastly, examples compare the mechanics of a clustered structure to an equivalent classic structure and the utility of clustering is highlighted by allowing for actuation throughout a class 1 (no bar-to-bar connections) tensegrity while not embedding the actuators into the structure. 相似文献
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Exact mesh shape design of large cable-network antenna reflectors with flexible ring truss supports 总被引:3,自引:0,他引:3
An exact-designed mesh shape with favorable surface accuracy is of practical significance to the performance of large cable-network antenna reflectors. In this study, a novel design approach that could guide the generation of exact spatial parabolic mesh configurations of such reflector was proposed. By incorporating the traditional force density method with the standard finite element method, this proposed approach had taken the deformation effects of flexible ring truss supports into consideration, and searched for the desired mesh shapes that can satisfy the requirement that all the free nodes are exactly located on the objective paraboloid. Compared with the conventional design method,a remarkable improvement of surface accuracy in the obtained mesh shapes had been demonstrated by numerical examples. The present work would provide a helpful technical reference for the mesh shape design of such cable-network antenna reflector in engineering practice. 相似文献
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针对大型周边桁架式索网天线由拉索拉压模量不同引起的本构非线性和结构大变形引起的几何非线性问题,给出了基于参变量变分原理的几何非线性有限元方法. 首先针对含预应力索单元拉压模量不同分段描述的本构关系,通过引入参变量,导出了基于参变量及其互补方程的统一描述形式,避免了传统算法需要根据当前变形对索单元张紧/松弛状态的预测,提高了算法收敛性. 然后利用拉格朗日应变描述索网天线结构大变形问题,结合几何非线性有限元法,建立了基于参变量的非线性平衡方程和线性互补方程;并给出了牛顿-拉斐逊迭代法与莱姆算法相结合的求解算法. 数值算例验证了本文提出的算法比传统算法具有更稳定的收敛性和更高的求解精度,特别适合于大型索网天线结构的高精度变形分析和预测. 相似文献
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针对大型周边桁架式索网天线由拉索拉压模量不同引起的本构非线性和结构大变形引起的几何非线性问题,给出了基于参变量变分原理的几何非线性有限元方法. 首先针对含预应力索单元拉压模量不同分段描述的本构关系,通过引入参变量,导出了基于参变量及其互补方程的统一描述形式,避免了传统算法需要根据当前变形对索单元张紧/松弛状态的预测,提高了算法收敛性. 然后利用拉格朗日应变描述索网天线结构大变形问题,结合几何非线性有限元法,建立了基于参变量的非线性平衡方程和线性互补方程;并给出了牛顿-拉斐逊迭代法与莱姆算法相结合的求解算法. 数值算例验证了本文提出的算法比传统算法具有更稳定的收敛性和更高的求解精度,特别适合于大型索网天线结构的高精度变形分析和预测. 相似文献
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This paper studies the wave based active vibration control of a membrane antenna structure. The membrane antenna structure studied in this paper has a great prospect in aerospace engineering. First, the dynamic model of the membrane antenna structure is established based on the finite element method. Then, based on the hypothesis of modal excitation mechanism, a wave-based controller is designed using the wave attenuation method. This method does not depend on the wave transfer function of the structure, so it can be applied to structures with complex shapes and boundaries. At last, the validity of the presented controller is verified through numerical simulations. Simulation results indicate that the dynamic behavior of the membrane antenna structure shows obvious wave characteristics; the presented controller can suppress the vibration of the structure effectively through holding back the formation of standing waves, and better control effect can be obtained when the actuators are placed near to the excitation point. 相似文献
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确定大跨径悬索桥主缆成桥线形的虚拟梁法 总被引:12,自引:1,他引:11
精确计算悬索桥主缆索形是悬索桥设计和实现施工开环控制的关键。本文通过柔计算的虚拟梁法,导出了确定大跨径悬索桥主缆成桥线形的非线性方程组,建立了索型迭代的计算流程。 相似文献