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1.
跨度大、薄且阻尼小的悬臂结构易受到外界复杂环境干扰,导致悬臂结构产生的振动很难在短时间内减小到零。以压电智能悬臂梁为研究对象,在随机激励环境、风变环境和温控环境下,开展智能结构的振动控制实验研究工作。基于极点配置控制和最小方差自校正控制的理论,实验研究多种激励环境下智能结构产生的振动得到有效控制的方法,对比多种激励环境下智能结构振动控制结果,分析多种激励环境下智能结构振动控制效果。实验结果表明多种激励环境下智能悬臂结构产生的振动在采用自适应控制后得到了更为有效的控制,这为柔性结构的动力学设计、寿命延长及减振降噪问题提供了更为有效的理论和技术支持。  相似文献   

2.
摘 要:由于智能结构的工作环境变化多端,各种性能参数会随着环境变化而变化,先前建好的模型不再适应设计好的控制律,本文应用压电双晶片的驱动传感一体化的特性,实现了智能悬臂梁的自适应控制研究。基于极点配置理论,采用了自校正PID控制方法在线实时设计了控制参数,解决了模型参数无法实时更新进而导致的控制精度低的问题。通过MATLAB的SIMULINK的数值仿真,得出了自校正PID控制方法在实现智能结构自适应振动控制中是可行的结论,并且通过搭建实验平台进行实验验证;利用压电双晶片的驱动传感特性,使智能悬臂梁的自由振动得到了有效控制。因此,基于自校正PID控制方法,采用压电双晶片对智能结构吸振减振提供了理论与实验的研究基础。  相似文献   

3.
将一致性控制方法和PID控制方法的基本思想相结合,提出了一种适用于压电智能结构振动控制的一致性PID(Consensus-PID,CPID)控制方法。该方法将系统输出偏差作为PID控制器的输入,PID控制器的输出及其在采样周期内的变化量作为一致性控制器的输入,致动器的输入电压为一致性控制器的输出。推导压电智能结构振动控制方程,以两边简支的压电智能梁为数值算例,建立动力学有限元模型,数值结果表明CPID控制方法能够有效控制压电智能结构的振动,当某些传感器失效时,对比集中式PID控制,系统在CPID控制下仍然能保持较好的控制效果。  相似文献   

4.
对表面粘贴压电元件的压电智能悬臂梁进行有限元建模和分析,获取了结构的动力响应数据。根据神经网络的非线性逼近能力,用动态递归神经网络对压电振动系统进行了系统辨识,建立了系统的预测模型。以此预测模型来代替传统广义预测控制算法中的受控自回归积分滑动平均模型,对压电智能悬臂梁进行振动主动控制的研究,并优化了控制系统参数。对一单输入单输出压电智能悬臂梁系统进行了仿真分析,控制效果良好,为智能算法在智能结构中应用有一定的指导意义。  相似文献   

5.
智能磁流变(MR)阻尼器半主动控制的研究   总被引:6,自引:0,他引:6  
提出了一种基于磁流变(MR)阻尼器的结构智能半主动控制方法。利用模糊神经网络辨识出能真正反映磁流变阻尼器动力特性的智能辨识模型,在此基础上提出一种基于最佳逼近Bang—Bang主动控制的智能半主动控制算法,从而使得MR阻尼器在每一控制瞬时始终处于最大耗能状态,有效地减小了结构在地震作用下的位移与加速度响应。算例仿真验证了所提方法的有效性与实用性。  相似文献   

6.
杨飏  欧进萍 《工程力学》2007,24(7):140-145
将电流变智能阻尼器与叠层橡胶隔震垫相结合,形成新型电流变智能隔震装置,对结构进行智能隔震控制。首先,进行了新型电流变智能隔震装置的设计,推导了转动电流变阻尼器控制力的计算公式,提出了电场强度和装置剪切变形之间的函数关系,实现了拟限位型和拟摩擦型的隔震装置模型;然后,针对电流变智能隔震控制的特点,提出了摩擦控制的判别规则并给出了计算公式,编制了相应的程序;最后,对应用电流变智能隔震装置的单自由度结构进行了数值分析,结果表明:两种类型的隔震装置对结构都有较好的控制效果,限制了隔震层变形的同时不增加隔震层的加速度,控制效果比较理想。  相似文献   

7.
基于设置在结构上的加速度传感器,导出了传声器与加速度传感器的关系,建立了主动结构声辐射控制模型,提出了以声控制指标为约束条件,设计主动结构鲁棒H∞控制器的方法,建立相应的以TMS320C30为核心的实验系统.实验取得了在指定频带上较好的降噪声效果,同以往的噪声主动控制相比,这种控制方法的传感器、作动器都设置在结构上,符合智能结构的发展趋势.  相似文献   

8.
加强企业内部财务管理与控制是企业深化改革、迎接WTO挑战以及公司治理的客观要求,必须采取有效措施,在财务组织结构、全面预算的硬约束机制、风险防范意识等方面,强化企业内部财务管理与控制。  相似文献   

9.
磁控形状记忆合金在结构振动控制中的应用研究   总被引:1,自引:0,他引:1  
磁控形状记忆合金(MSMA)是一种在磁场控制下可产生较大变形,且具有形状记忆功能的新型智能材料,利用其磁控特性可以制作智能作动器进行结构的振动控制。首先介绍了MSMA材料在磁场作用下的变形机理与磁控特性,在此基础上提出了两种可以应用于结构振动控制中的新型MSMA驱动器,并分析了其工作原理和设计方法,最后阐述了利用MSMA的逆特性制作MSMA自传感作动器的关键技术及解决方法,为其在土木工程领域的应用打下了良好的基础。  相似文献   

10.
智能PID控制器在光电经纬仪系统中的应用研究   总被引:6,自引:3,他引:3  
应用常规的 PID控制器难以解决复杂对象的控制问题 ,尝试将模糊控制和常规的 PID控制相结合 ,构成智能 PID控制器。介绍了智能 PID控制器的原理、结构、算法及其在光电经纬仪系统中的应用研究 ,并对实验结果加以分析。  相似文献   

11.
Kin-tak Lau   《Materials & Design》2002,23(8):741-749
Recently, the development of shape memory alloy (SMA) actuators, in the forms of wire, thin film and stent have been found increasingly in the fields of materials science and smart structures and engineering. The increase in attraction for using these materials is due to their many unique materials, mechanical, thermal and thermal-mechanical properties, which in turn, evolve their subsequent shape memory, pseudo-elasticity and super-elasticity properties. In this paper, a common type of SMA actuator, Nitinol wires, were embedded into advanced composite structures to modulate the structural dynamic responses, in terms of natural frequency and damping ratio by using its shape memory and pseudo-elastic properties. A simple theoretical model is introduced to estimate the natural frequency of the structures before and after actuating the embedded SMA wires. The damping ratios of different SMA composite beams were measured through experimental approaches. The natural frequencies changed slightly at a temperature above the austenite finish temperature of composite beams with embedded non-prestrained SMA wires. However, the increase of the natural frequencies of the beams with embedded prestrained SMA wires were found in both the theoretical prediction and experimental measurements. The damping ratios of SMA composite beams increased with increasing the temperature of the embedded wires with and without being pre-strained. Compressive and local failures of the beams with high wire content are a possible explanation.  相似文献   

12.
SMA混杂复合材料单层的被动阻尼   总被引:1,自引:0,他引:1  
任勇生  秦惠增 《工程力学》2002,19(2):160-164
由形状记忆合金纤维、普通纤维、基体构成的混杂复合材料是一类用途广泛的智能材料结构系统。阻尼性能研究是结构被动振动控制的一项重要研究内容。本文采用混杂复合材料阻尼预测的细观力学理论计算SMA纤维混杂复合材料单层的阻尼特性。首先计算包含普通纤维和基体材料的复合材料介质的阻尼性能,其次计算由横观各向同性介质和SMA纤维构成的混杂材料的阻尼性能。通过计算实例分析SMA纤维混杂复合材料单层的正轴阻尼特性及其偏轴阻尼的特性随SMA纤维体积含量、纤维铺设角等参数改变的规律。  相似文献   

13.
Shape memory alloy (SMA) is commercially available for a variety of actuator and damping materials. Recently, SMA wires have also become commercially available for the design of smart composite structures because SMA wires with a small diameter can be easily produced. In this work, two types of SMA-based composites are presented for investigating the vibration characteristics. First, laminated composite plates containing unidirectional fine SMA wires are fabricated. By measuring the vibration mode of a clamped cantilever, the influence of both SMA arrangement and temperature on the vibration characteristics is made clear. Next, laminated composite plates with embedded woven SMA layer are fabricated. The stiffness tuning capability is evaluated by impact vibration tests with different temperatures. It is found that the stiffness tuning capability may be improved by increasing the volume fraction of SMAs and by controlling accurately the internal stress according to the phase transformation temperature of SMAs from martensite to austenite. The theoretical prediction on the natural frequency considering the SMAs behavior and laminated structures is proposed and their results agree reasonably with experimental ones.  相似文献   

14.
Embedding Shape Memory Alloy (SMA) wires in composite structures enables controlling of their mechanical properties. The main aim of this study is to characterize experimentally the mechanical properties of two-layer smart composite structures which are made of one layer of carbon fibers epoxy laminate and one layer of epoxy embedded with SMA wires. A carbon/epoxy layer was first fabricated using vacuum infusion method. Then a SMA/epoxy layer was prepared separately and then laid over the completely cured carbon/epoxy layer using the hand lay-up process. The final structure is smart and has potential of being specifically bent under controlled thermal loading, due to the embedded pre-strained SMA wires. However the temperature was kept constant and there was no thermal excitation of the SMA wires in this experimental study. The configuration of the material constituents through the thickness of the structure renders the cross-section to be unsymmetrical. The specimens were tested in a specially developed unsymmetrical tensile testing machine. From the readings of force from the testing machine and strain gages, the tensile and shear stress–strain relations of the composite materials were obtained. The elastic and shear moduli and also Poisson’s ratio of the composite materials were defined and it was observed that, the effective moduli increased with increasing density of SMA wires in the layer. It is concluded that, due to the asymmetrical material variation, finding the mechanical properties via conventional testing machine is not accurate and a special testing machine is needed.  相似文献   

15.
使用模具并采用磁控溅射法在铁电陶瓷PZT基体上沉积具有条形分布结构的Ni Ti SMA薄膜。显微组织结构观察发现,以条形分布结构方式沉积的Ni Ti SMA薄膜晶化处理后具有等轴晶结构。比较所制备PZT/Ni-Ti SMA薄膜复合材料与纯PZT的介电常数及介电损耗发现,两者的介电损耗水平接近;复合材料的介电常数比纯PZT的提高约18%。Ni Ti SMA的沉积使基体中靠近薄膜区域的Zr/Ti物质的量比恰好落在准同型相界区内,致使所制备复合材料的介电性能优于纯PZT。  相似文献   

16.
采用有限元软件ABAQUS实现了埋入形状记忆合金(SMA)丝的复合材料圆柱壳壁板结构热振动特性分析.基于“ang-Rogers本构模型编写用户子程序(UMAT)模拟形状记忆合金材料的超弹性行为和形状记忆效应,并在不同温度和应力状态下验证了程序的正确性.基于此程序,计算了埋入SMA丝的复合材料圆柱壳壁板在温度和机械载荷作用下的一阶固有频率,分析了其热振动特性和屈曲特性.模拟结果表明:加热驱动SMA丝一般会提高结构的固有频率和屈曲临界,SMA丝的数量对结构的热振动和屈曲特性有显著影响。这些结论将对智能复合材料结构设计、抗热设计有一定的指导作用。  相似文献   

17.
Delamination of composite materials due to low velocity impacts is one of the major failure types of aerospace composite structures. The low velocity impact may not immediately induce any visible damage on the surface of structures whilst the stiffness and compressive strength of the structures can decrease dramatically.

Shape memory alloy (SMA) materials possess unique mechanical and thermal properties compared with conventional materials. Many studies have shown that shape memory alloy wires can absorb a lot of the energy during the impact due to their superelastic and hysteretic behaviour. The superelastic effect is due to reversible stress induced transformation from austenite to martensite. If a stress is applied to the alloy in the austenitic state, large deformation strains can be obtained and stress induced martensite is formed. Upon removal of the stress, the martensite reverts to its austenitic parent phase and the SMA undergoes a large hysteresis loop and a large recoverable strain is obtained. This large strain energy absorption capability can be used to improve the impact tolerance of composites. By embedding superelastic shape memory alloys into a composite structure, impact damage can be reduced quite significantly.

This article investigates the impact damage behaviour of carbon fiber/epoxy composite plates embedded with superelastic shape memory alloys wires. The results show that for low velocity impact, embedding SMA wires into composites increase the damage resistance of the composites when compared to conventional composites structures.  相似文献   


18.
In this paper, the results of an experimental analysis on the active buckling control behaviour of a laminated composite beam with embedded shape memory alloy (SMA) wires are presented. For the purpose of enhancing the critical buckling load, active buckling control was investigated through the use of the reaction time associated with the shape recovery force of SMA wires. An increased critical buckling load and altered deflection shape due to the effects of activation of embedded SMA wires are represented qualitatively and quantitatively on the load–deflection behaviour records. The results obtained from this active buckling control test confirm that the buckling resistance in a composite beam with embedded SMA wires can be increased by the use of an activation force of the embedded SMA wires. Based on our experimental analysis, a new formula for the behaviour control of active buckling in a laminated composite beam with embedded SMA wires is also suggested.  相似文献   

19.
In this paper, the thermal buckling and postbuckling behaviours of a composite beam with embedded shape memory alloy (SMA) wires are investigated analytically. For the purpose of enhancing the critical buckling temperature and reducing the lateral deflection for the thermal buckling, the characteristics of thermal buckling are investigated through the use of the shape recovery force associated with SMA wire actuators. The results of both thermal buckling and postbuckling behaviours present quantitatively how the shape recovery force affects the thermal buckling behaviour. The analytical results show that the shape recovery force reduces the thermal expansion of the composite laminated beam, which results in both an increment of the critical buckling temperature and also a reduction of the lateral deflection of postbuckling behaviours. A new formula is also proposed to describe the critical buckling temperature of the laminated composite beam with embedded SMA wire actuators.  相似文献   

20.
Shape memory alloy (SMA) in the form of wires or short fibers can be embedded into host materials to form SMA composites that can satisfy a wide variety of engineering requirements. The recovery action of SMA inclusions induced by elevated temperature can change the modal properties and hence the mechanical responses of entire composite structures. Due to the weak interface strength between the SMA wire and the matrix, interface debonding often occurs when the SMA composites act through an external force or through actuation temperature or combination of the two. Thus the function of SMAs inside the matrix cannot be fully utilized. To improve the properties and hence the functionality of SMA composites it is therefore very important to understand the stress transfers between SMA fibers and matrix and the distributions of internal stresses in the SMA composite. In this paper, a theoretical model incorporating Brinson’s constitutive law of SMA for the prediction of internal stresses is successfully developed for SMA composites, based on the principle of minimum complementary energy. A typical two-cylinder model consisting of a single SMA fiber surrounded by epoxy matrix is employed to analyze the stress distributions in the SMA fiber, the matrix, and at the interface, with important contributions of the thermo-mechanical effect and the shape memory effect. Assumed stress functions that satisfy equilibrium equations in the fiber and matrix respectively are utilized, as well as the principle of minimum complementary energy, to analyze the internal stress distributions during fiber pull-out and the thermal loading process. The entire range of axisymmetric states of stresses in the SMA fiber and matrix are developed. The results indicate substantial variation in stress distribution profiles for different activation and loading scenarios.  相似文献   

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