【作者】 王新杰；

【导师】 邓宗全；

【作者基本信息】 哈尔滨工业大学 ， 机械设计及理论， 2011， 博士

【摘要】 回转壳结构在航空、航天、民用和国防工业领域有着广泛的应用,其形状控制和振动控制一直是系统设计和工程应用中的重点和难点。利用智能材料来实施有效的主动激励,是目前对回转壳进行主动控制所采取的一种重要方法。但由电、磁信号激发的智能材料,需要复杂的激发装置和连接导线,易引起电磁噪音干扰,而新型的智能材料镧改性锆钛酸铅(PLZT)陶瓷,可将光能转化为机械能,无电磁噪声干扰,适于在太空环境下实施非接触激励及远程控制。因此,本文在对PLZT陶瓷光致伸缩特性研究的基础上,对光电层合回转壳结构的主动控制问题展开研究,旨在为光电类智能结构的工程应用提供理论依据。对多能场耦合下PLZT的光致伸缩效应进行研究,揭示了冷光源(LED-UV)照射下的光致伸缩机理;基于PLZT陶瓷等效电学模型,研究了光照强度、PLZT陶瓷长宽比及PLZT陶瓷厚度参数对光致应变的影响,建立了PLZT陶瓷在光照阶段的光致伸缩数学模型,并通过光致伸缩静态实验验证了该数学模型的正确性;对光照停止阶段的残余应变进行研究,给出了残余应变的表达形式及黑暗时间常数与光照时间常数的关系。对PLZT陶瓷基光致伸缩作动器的构型及激励特性进行研究。分析了0-1极化式、0-3极化式、双晶片式及多片组合式四种构型下光致伸缩作动器产生光致形变的特点;在确定与被控结构体层合方式的基础上,推导了不同构型下光致伸缩作动器所产生的激励力与力矩;对光致伸缩作动器的激励策略进行了研究,提出了单个光源ON/OFF激励与两个光源双面ON/OFF激励两种激励策略;分析了不同构型光致伸缩作动器的适用性,最后确定0-1极化式光致伸缩作动器作为回转薄壳结构主动控制的作动器构型。从弹性薄壳的Love方程出发,推导出光电层合开口圆柱壳、开口薄球壳和抛物薄壳三种典型回转薄壳结构的控制方程;为将光电层合薄壳结构的控制方程由物理空间转换到模态空间,从而实现模态解耦,采用membrane理论对自由边界条件下的开口薄球壳和抛物薄壳的模态振型函数进行推导;利用模态展开方法推导出光电层合开口圆柱壳、开口薄球壳及抛物薄壳的模态控制方程,并给出了相对应的模态控制因子表达式,利用模态控制因子对这三种光电层合回转薄壳结构进行了模态控制分析,为光致伸缩作动器在薄壳结构上的空间布局提供理论依据。为实现对光电层合回转薄壳结构的闭环控制,对光电层合回转薄壳结构的主动控制策略进行了研究。在对光电层合智能结构主动控制特性分析的基础上,给出了适合光电层合回转薄壳结构的光源激励策略;提出了基于速度比例反馈的定光强控制和变光强控制两种算法;将光源激励策略与控制算法相结合形成适合光电层合回转薄壳结构的主动控制策略,利用Newmark-β法对闭环控制下光电层合回转薄壳的模态控制方程进行数值分析;以光电层合抛物薄壳为实例,对一阶和二阶模态进行了主动振动控制仿真,仿真分析结果表明,定光强控制效果要优于变光强控制效果,且在同一种控制算法下,作动器的布局会对控制效果产生影响。为验证相关理论分析的正确性及主动控制策略的有效性,以光电层合树脂抛物薄壳结构为实例,开展了主动控制实验研究。搭建了实验平台,对两种自由边界实现方式下的抛物壳进行了固有频率测试与分析;对光电层合抛物薄壳进行了主动激励特性实验、电极短接开关控制实验及主动振动控制实验;实验结果证明,光致伸缩作动器对抛物薄壳可产生主动控制力,可抑制抛物薄壳的低阶模态振动,从而验证了本文所提出的光电层合回转薄壳结构主动控制策略的有效性。更多还原

【Abstract】 The thin shell of revolution is widely used in the aviation, aerospace, civilian and national defense industries. The shape control and vibration control of thin revolution shell structure has always been difficult and important item of the system design and engineering application. By using smart materials to give effective actuation for the purpose of achieving vibration suppression has been a favored way. The smart material activated by electric or magnetic signals can induce electromagnetic noise because of complex accessorial devices and connecting wires.The new smart material, lanthanum modified lead zirconate titanate (PLZT), can transform the light energy to the mechanical energy without electromagnetic noise. PLZT is suitable for the non-contact actuation and remote control in the space environment. In this paper, based on the research of the photostrictive characteristics of PLZT ceramics, the active vibration control of the photostrictive laminated thin shell of revolution is studied, which can provide the theoretical base for engineering applications of photostrictive laminated smart structure.The photostrictive effect of PLZT with multi-energy field coupling is researched in this paper. Photostrictive mechanism with LED-UV illumination is revealed here.Based on the equivalent electrical model of the PLZT ceramics, the effect of the light intensity, aspect ratio and the thickness of the PLZT ceramics on the photostrictive strain are researched. And the new photostrictive mathematic model of PLZT ceramics with illumination is established. The mathematic model is validated through the photostrictive static experiments. Residual strain light off is studied; the expression of the residual strain and the relationship of the darkness time constant and the illumination time constant are presented.The configuration and actuation characteristic of photostrictive actuator made of PLZT are studied, and photodeformation characteristic of 0-1 polarized, 0-3 polarized, bimorph and multi-patch combination configuration is analyzed respectively. Based on the laminated method with controlled structure, actuation force and moment of different configurations are deduced. Actuator’s actuation strategies are investigated and two actuation strategies, ON/OFF actuation with a single light source and double side ON/OFF actuation with two light sources, are presented. The applicability of photostrictive actuators are analyzed, the 0-1 polarized photostrictive actuator is chosen for active control of thin revolution shell.Governing equations of photostrictive laminated open cylindrical shell, open spherical thin shell and paraboloidal thin shell are presented based on the Love equations of elastic shell. In order to transform the governing equation of photostrictive laminated thin revolution shell from physical space into mode space which can achieve modes decoupling, mode shape functions of open spherical thin shell and paraboloidal thin shell with free boundary conditions are obtained using membrane theory. Modal control equations of photostrictive laminated these three shells are deduced using modal expansion method, and corresponding modal control factor expressions are given. Using the modal control factor, modal control analysis of the photostrictive laminated these three thin shells of revolution are implemented, which can provide the theory for actuator configuration.In order to realize the closed-loop control of the photostrictive laminated thin shell, research on the active vibration control scheme of the photostrictive laminated thin shell is carried out. Based on the active control characteristic analysis for the photostrictive laminated smart structure, suitable illumination scheme for the photostrictive laminated thin shell structure is presented, together with the constant light intensity control and the variable light intensity control algorithm based on velocity proportional feedback. Active control scheme for the photostrictive laminated thin shell structure is obtained through combining the illumination scheme and the control algorithm. Dynamic numerical analysis of the modal control equation of the photostrictive laminated thin shells under the closed-loop control is carried out using Newmark-βmethod. Taking the photostrictive laminated paraboloidal thin shell for example, active vibration control simulation analysis for the 1st and 2nd mode is carried out. Simulation results show that the constant light intensity control is better than the variable light intensity control, and the control effect is affected by the actuator configuration under the same control algorithm.In order to verify the correctness of the theory analysis and the effectivity of the active control scheme, active vibration control experiment is carried out by taking the photostrictive laminated paraboloidal thin shell for an instance. The experiment platform is set up. Natural frequency testing and analysis of the paraboloidal thin shell with two kinds of free boundary conditions are carried out. Actuation characteristic experiment, ON/OFF control experiment and active control experiment for the photostrictive laminated paraboloidal thin shell are carried out. Test results show that photostrictive actuator can give active control force to the paraboloidal shell and restrain the low order mode vibration of the photostrictive laminated paraboloidal shell. Thus the active vibration control scheme for the photostrictive laminated thin shell of revolution is effective.更多还原