共查询到20条相似文献,搜索用时 15 毫秒
1.
A new piezolaminated sandwich type structure to be eventually used as a smart wall for active control of sound radiated by harmonically excited thin walled structures is proposed. The present study presents the equations of motion of the new adaptive sandwich structures in a sufficiently accurate model in a form readily for solution either in closed-form or by approximate methods. The theoretical natural frequencies are compared with an approximate evaluation and test results yielding a good correlation. It also yields the axial strains and the curvature of the composite beam leading to the calculation of equivalent mechanical loads produced by the piezoceramic actuator for inclusion in a finite element code. The numerical results are compared with experimental ones obtained during a test series on a cantilever sandwich beam equipped with piezoceramic sensors and actuators and constructed according to the new proposed concept. The influence of the input voltage on the performance of the new sandwich structure is investigated. The beam tip deflection induced by the piezoceramic actuators is measured and compared with numerical and finite element predictions to yield a very good match. Both the numerical and the experimental results show the applicability of the new proposed concept. 相似文献
2.
针对悬臂板挠度大、低频振动突出问题,对悬臂Kagome夹心板的振动主动控制进行研究。建立结构及压电作动器有限元模型;将独立模态空间控制与模态观测器相结合,提出悬臂Kagome夹心板的主动控制策略;针对突风载荷作用下夹心板基于独立模态空间的振动控制进行仿真,重点研究观测器极点对控制效果影响。结果表明,所提控制方法能显著提高悬臂Kagome夹心板结构的阻尼特性,观测器衰减系数越大控制效果越好;该夹心板在振动控制方面较传统板结构优势明显。 相似文献
3.
Moon-Young Choi Se-Um Kim Hogyeong Kim Kitae Kim Mohsin Hassan Saeed Srinivas Pagidi Jun-Hee Na 《Advanced Engineering Materials》2023,25(17):2300267
Elementary actuators performing branching or surface swelling are the primary units in the actuator integration system that is leveraged in works requiring a high versatility and complex motion. However, those primary actuator units often lack scalability or compatibility at assembly into a compact form due to the complexity of the structure and the actuation interference between adjacent units. Herein, it is shown that the phase-change actuator in a simple bilayer structure of a top active layer and a bottom constraint layer achieves 1D surface swelling, such that the closely packed 2D array system of this actuator is easily constructed. Upon resistive heating, the active layer inflates based on the phase change of microliquid droplets embedded in an elastomer body. The inflation along the lateral direction of the actuator is suppressed by controlling the thickness ratio between the active and the constraint layers. The actuation of individual units in the array system is performed independently using a switching device with a microcontroller for the parallel application of resistive heating. The application of 2D shape morphing of the actuator arrays in beam steering and shape displays is investigated. 相似文献
4.
Micro actuators are an irreplaceable part of motion control in miniaturized systems and are intended to have a high range of deformation, high accuracy, large force, and quick response. In this article, an analytical model for a hybrid thermopiezoelectric micro actuator is developed in which a double lead-zirconnate-titanate piezoceramic (PZT) beam structure consisting of two arms with different lengths are used. Governing differential equation of motion and electrical field are derived and solved. Out of parametric studies it was observed that, under application of temperature and voltage gradients, the deflection of the actuator shows different trends depending on the geometry of the micro actuator and also type of PZT material. 相似文献
5.
为了深入研究尺蠖型压电驱动器的性能,分析了尺蠖型压电直线驱动器的工作原理,研究了直线动子对驱动器性能的影响.通过实验方法分析了钳位机构调整前后对钳住稳定性的影响.采用驱动器输出单步位移的步距失稳系数和驱动电压与输出位移拟合曲线斜率和截距偏差率的方法评价尺蠖型压电直线驱动器的运动稳定性.经实验测试发现驱动器的步距失稳系数与驱动电压关系密切,当驱动电压较高时,驱动器具有较好的步距稳定性.驱动器的驱动电压与输出位移拟合曲线斜率和截距偏差率分别为1.8%和9.07%,说明所开发的驱动器具有很好的运动稳定性. 相似文献
6.
The span limits of two glass fiber-reinforced polymer (GFRP) bridge concepts involving GFRP-balsa sandwich plates are discussed. The sandwich plates were either used directly as slab bridges or as decks of a hybrid sandwich-steel girder bridges. In the latter case, the potential of the sandwich decks to replace reinforced concrete (RC) decks was also evaluated. Taking the limits of manufacturing into account (800 mm slab thickness), maximum bridge spans of approximately 19 m can be reached with FRP-balsa sandwich slab bridges, if a carbon-FRP (CFRP) arch is integrated into the balsa core. Above this limit, hybrid sandwich-steel girder bridges can be used up to spans of 30 m. RC deck replacement requires timber and steel plate inserts into the balsa core above the steel girders. GFRP-balsa sandwich slabs or decks exhibit full composite action between lower and upper face sheets. Stress concentrations occur at the joints between balsa core and timber inserts which however can effectively be reduced by changing from butt to scarf joints. 相似文献
7.
Aurelio L. Araújo Cristovao M. Mota Soares Carlos A. Mota Soares 《Applied Composite Materials》2010,17(5):529-542
In this paper we present a finite element model for the analysis of active sandwich laminated plates with a viscoelastic core
and laminated anisotropic face layers, as well as piezoelectric sensor and actuator layers. The model is formulated using
a mixed layerwise approach, by considering a higher order shear deformation theory (HSDT) to represent the displacement field
of the viscoelastic core and a first order shear deformation theory (FSDT) for the displacement field of the adjacent laminated
anisotropic face layers and exterior piezoelectric layers. The dynamic problem is solved in the frequency domain with viscoelastic
frequency dependent material properties for the core. Control laws are also implemented for the piezoelectric sensors and
actuators. The model behaviour in dynamics is assessed with the few solutions found in the literature, including experimental
data, and a laminated composite active sandwich application is proposed. In this numerical application, velocity feedback
control law is implemented for active control, using co-located piezoelectric patch sensors and actuators. 相似文献
8.
Won-Cheol Kim Jung-Hwan Kim Minho Lee Jang-Kyoo Shin Hyun-Seung Yang Yonezu H. 《IEEE sensors journal》2005,5(3):501-509
We developed a new active vision system using an artificial retina chip and the shape memory alloy actuator. A foveated CMOS retina chip for edge detection designed and fabricated for an image sensor of the developed system and the shape memory alloy actuator was used for mimicking the roles of the ocular muscles to track a desired target. Also, we proposed a new computational model that mimics the functional roles of our brain organs for generating the smooth pursuit eye movement. In our model, a neuromorphic model for the medial temporal cell generates motion energy, and the medial superior temporal cell is considered to generate an actuating signal so that the developed active vision system smoothly pursues the target with similar dynamics to the motion of our eyeball during the smooth pursuit. Experimental results show that the developed system successfully operates to follow the edge information of a moving object. 相似文献
9.
结构振动主动控制可以采用压电自感知执行器。空分复用解耦方法是实现压电自感知执行器的一种新方法,实质是采用几何方法解耦,即将压电片的一个完整电极分割为执行区和传感区以实现自感知。本文以悬臂梁为对象,以涡流位移计作为标准传感器,对两种电极分割方式的压电片的传感和执行效果进行了实验研究。通过测量压电梁的频率特性,证明了空分复用的压电陶瓷片同时兼有传感和执行两种功能。实验结果也表明传感区的敏感输出受到执行区激励电压的静电耦合的影响,利用悬臂梁存在反谐振点的特性,提出了一种定量测量静电耦合的方法,并测定了不同电极宽度、不同极间隙下的静电耦合系数。本文的工作为采用空分复用的压电自感知执行器进行振动主动控制奠定了基础。 相似文献
10.
为考察碱化剂抑制压水堆二回路结构材料腐蚀的情况,通过腐蚀失重法、电化学极化曲线、扫描电镜(SEM)以及小角XRD分析等方法研究了模拟压水堆二回路水化学环境中分别添加乙醇胺(ETA)和氨水(NH_3·H_2O)_2种碱化剂对A508Ⅲ钢和P22钢2种结构材料的腐蚀行为的影响。结果表明:2种结构材料腐蚀速率均在10~(-1)~10~(-2)mg/(dm~2·h)之间,但在ETA中腐蚀电流密度更小,腐蚀速率也更低。在2种结构材料表面形成的主要腐蚀产物均为Fe_3O_4,SEM观察到在ETA中生成的腐蚀产物较为致密。比较ETA与NH_3·H_2O的物化性能,可知在高温水(280℃)中ETA的挥发性能弱于NH_3·H_2O,因此添加ETA的溶液的pH值更高,pH值的不同决定了2种材料的溶液腐蚀行为的差异。综上所述,二回路结构材料在ETA环境中的耐蚀性能更好。 相似文献
11.
《IEEE transactions on magnetics》2009,45(7):3017-3024
12.
F. Ebrahimi A. Rastgoo 《International Journal of Mechanics and Materials in Design》2009,5(2):157-165
Nonlinear vibration analysis of thin circular pre-stressed functionally graded (FG) plate integrated with two uniformly distributed
piezoelectric actuator layers with an initial nonlinear large deformation are presented in this paper. Nonlinear governing
equations of motion are derived based on classical plate theory (CPT) with von-Karman type geometrical large nonlinear deformations.
A nonlinear static problem is solved first to determine the initial stress state and pre-vibration deformations of the plate
that is subjected to in-plane forces and applied actuator voltage. By adding an incremental dynamic state to the pre-vibration
state, the differential equations that govern the nonlinear vibration behavior of pre-stressed piezoelectrically actuated
circular FG plate are derived. An exact series expansion method is used to model the nonlinear electro-mechanical vibration
behavior of the structure. Control of the FG plate’s nonlinear deflections and natural frequencies using high control voltages
are studied and their nonlinear effects are evaluated. In a parametric study the emphasis is placed on investigating the effect
of varying the applied actuator voltage as well as gradient index of FG plate on the dynamic characteristics of the structure. 相似文献
13.
14.
15.
耐震时程法的典型表征在于随着时间的增加,地震强度逐渐增大。基于非线性最小二乘算法合成了基于我国抗震规范反应谱的三条耐震时程曲线。以两个5层和12层钢筋混凝土框架结构为例,分别对结构进行22条天然地震动下的增量动力分析和3条耐震时程曲线输入下的非线性分析,对比研究了结构在不同强度下的最大顶点位移、最大层间位移角、最大基底剪力和结构滞回耗能分析,比较了结构在大震时的最大层间位移角分布和最大楼层剪力分布。分析研究表明,耐震时程法能较好的预测结构的抗震响应,其分析结果离散性小,宏观上与多条天然地震动分析结果的中位值吻合较好。由于耐震时程法仅需进行一次时程分析便可获得结构不同强度下的抗震响应,计算效率高,计算精度较好,这为结构的抗震性能评估提供了一种新的有效方法。 相似文献
16.
The behaviour of structural glass fibre reinforced polymer (GFRP) composite sandwich slab was investigated under static point load. In this paper, the effects of dimensions aspect ratio, skin fibre orientations, overall thickness, boundary restraints, and boundary conditions on the static behaviour of the GFRP slab were presented. It was found that the ultimate load of the fibre composite sandwich slab is reducing with increasing panel dimension aspect ratio. The experimental results also showed that the fibre orientation of the skin has an effect on the failure mode and stiffness of the slab. As expected, the flexural stiffness of 18 mm thick slab is higher than the 15 mm thick slab. Finally, the restraint conditions did not affect much on the failure load and stiffness of the one-way and two-way slab systems. 相似文献
17.
A method for reducing vibration of a sandwich structure using the antiresonance technique is presented. It is found that with appropriate resonators, the motion of the sandwich structure due to disturbances with certain frequencies can be effectively suppressed. A simple two-degree-of-freedom system consisting of an absorbing mass connected by springs to a drive mass is introduced and used to interpret the vibration behavior of the sandwich structure with resonators. 相似文献
18.
为提高夹层结构的抑振特性,开展了基于主动温控变阻尼技术的夹层结构振动控制方法研究。基于高分子聚合材料在玻璃化转变区的高阻尼特性,提出了一种针对夹层结构高分子聚合芯材进行温度控制,增大其损耗因子以提高结构阻尼的技术途径。根据此技术途径设计了以聚氨酯改性环氧材料为芯材,中间铺设加热膜的温控夹层梁。开展了不同控制温度下夹层梁的振动响应试验研究并探讨了温度对夹层梁弯曲刚度的影响规律,试验结果表明,当将夹层梁温度控制在玻璃化转变温度(Tg)左侧附近时,夹层梁的振动响应可较常温状态下降低8.85 dB,证明了所提出的主动温控变阻尼技术具有良好的抑振效果。 相似文献
19.
20.
We present the mechanical and actuator design of an adaptive secondary mirror that matches the optical requirements of the active and adaptive corrections. Conceived for the particular implementation for the 6.5-m conversion of the multiple-mirror telescope, with small variations of the input parameters this study is suitable for applications for telescopes of the same class. We found that a three-layer structure, i.e., a thin deformable shell, a thick reference plate, and a third plate that acts as actuator support and heat sink, is able to provide the required mechanical stability and actuator density. We also found that a simple electromagnetic actuator can be used. This actuator, when optimized, will dissipate a typical power of a few tenths of watts. 相似文献