Statistical Algorithm for Damage Detection of Concrete Beams Based on Piezoelectric Smart Aggregate

The functional piezoelectric ceramic smart aggregate(SA) sensors and actuators,based on piezoelectric ceramic materials such as lead zirconium titanate(PZT),were embedded into the reinforced concrete beams with three-point bending under static loading for purposes of damage detection.The SA actuators generated the desired sine sweep excitation signals online and the SA sensors received and detected real-time signals before and after damage.The wavelet analysis and statistical characteristics about damage signals were used as a signal processing and analysis tool to extract the optimal damage information and establish a statistical damage detection algorithm.The damage index-based wavelet analysis and damage probability-based probability and statistics were proposed by PZT wavebased theory and active health monitoring technology.The results showed that the existence of cracks inside largely attenuated the amplitude of active monitoring signal after the damage of beam and the attenuation was related to the severity degree of damage.The innovative statistical algorithm of damage pattern detection based PZT-SA can effectively determine damage probability and damage degree,and provide a prediction for the critical damage location of reinforced concrete structures.The developed method can be utilized for the structural health comprehensive monitoring and damage detection on line of various large-scale concrete structures.

Nonlinear active control of damaged piezoelectric smart laminated plates and damage detection

Considering mass and stiffness of piezoelectric layers and damage effects of composite layers, nonlinear dynamic equations of damaged piezoelectric smart laminated plates are derived. The derivation is based on the Hamilton＇s principle, the higher- order shear deformation plate theory, von Karman type geometrically nonlinear straindisplacement relations, and the strain energy equivalence theory. A negative velocity feedback control algorithm coupling the direct and converse piezoelectric effects is used to realize the active control and damage detection with a closed control loop. Simply supported rectangular laminated plates with immovable edges are used in numerical computation. Influence of the piezoelectric layers＇ location on the vibration control is in- vestigated. In addition, effects of the degree and location of damage on the sensor output voltage are discussed. A method for damage detection is introduced.

Control Effects and Material Parameters of Piezoelectric Smart Moment Controllers

The control using piezoelectric smart moment (PSM) controllers for seismically excited structures was studied.The radical principle of PSM controller was introduced firstly and then the different formulae of control shear force for different structures were derived with the stiffness ratio of columns taken into consideration.With the active control algorithm based on the theory of modern optimal control,this study proposes a simulative computation on the frame structure and mill structure respectively,and the results indicate that the installation of this smart controller with proper parameters can significantly reduce seismic responses of different structures. The optimal parameters of the damper can be identified through a parameter study.

A refined finite element method for bending analysis of laminated plates integrated with piezoelectric fiber-reinforced composite actuators

This research presents a finite element formulation based on four-variable refined plate theory for bending analysis of cross-ply and angle-ply laminated composite plates integrated with a piezoelectric fiber-reinforced composite actuator under electromechanical loading. The four-variable refined plate theory is a simple and efficient higher-order shear deformation theory, which predicts parabolic variation of transverse shear stresses across the plate thickness and satisfies zero traction conditions on the plate free surfaces. The weak form of governing equations is derived using the principle of minimum potential energy, and a 4-node non-conforming rectangular plate element with 8 degrees of freedom per node is introduced for discretizing the domain. Several benchmark problems are solved by the developed MATLAB code and the obtained results are compared with those from exact and other numerical solutions, showing good agreement.

Modeling and optimal vibration control of conical shell with piezoelectric actuators

In this paper numerical simulations of active vibration control for conical shell structure with dis-tributed piezoelectric actuators is presented.The dynamic equations of conical shell structure are derivedusing the finite element model (FEM) based on Mindlin's plate theory.The results of modal calculationswith FEM model are accurate enough for engineering applications in comparison with experiment results.The Electromechanical influence of distributed piezoelectric actuators is treated as a boundary conditionfor estimating the control force.The independent modal space control (IMSC) method is adopted and theoptimal linear quadratic state feedback control is implemented so that the best control performance withthe least control cost can be achieved.Optimal control effects are compared with controlled responses withother non-optimal control parameters.Numerical simulation results are given to demonstrate the effective-ness of the control scheme.

A Multivariate Variational Principle for Piezoelectric Efect Problems

The mechanical electric coupling effect of piezoelectric materials and devices is discussed and a brief review on the evolution of the technique is presented.On such basis,as a first step toward the formulation of finite elements for analysis of piezoelectric devices,a multivariate variation principle is presented.As has been revealed by the present work,an important particularization thereof is the Allik Hughes functional.

Optimal Control of a Beam with Discontinuously Distributed Piezoelectric Sensors and Actuators

因为它的轻重量，宽带，和能适应的性质，聪明的材料广泛地在灵活结构的活跃颤动控制(AVC ) 被使用了。基于一一阶砍变丑理论由联合电、机械的操作， 4 节点有为概括排水量的自由的 24 度和自由的一电的潜在的度的四边的压电的合成元素每压电的层被导出。有不连续地分布式的压电的传感器和致动器的一根横梁的动态特征被介绍。一个线性二次的管理者(LQR ) 反馈控制器被设计用高度在州的空间压制横梁的颤动精确直接(HPD ) 集成方法。

多工况车辆荷载下嵌入式压电传感路面结构动态响应分析

嵌入式智能装置与路面结构在车辆荷载作用下的动态响应对其服役性能和使用寿命意义突出。为此,采用1/4车辆振动模型,构建车辆动荷载作用下的嵌入式压电系统-路面结构有限元模型。基于足尺加速加载试验路段实测应变数据和文献振动数据,对有限元模型的响应结果进行了验证;进一步考虑了不同车辆轴载、车速和路面平整度等工况下,嵌入式路面结构的动态响应变化和压电系统的电压峰值输出。结果表明,路面结构的竖向加速度峰值、嵌入式压电系统的输出峰值随着车辆荷载的增加而增加,线性度良好;超载带来的横向应变峰值变化和竖向应变拉压交替峰峰值变化,需重点考虑;行驶速度对路面的振动和应变响应影响明显,均不为单调变化;随着路面等级从A级降为C级,路面各结构层平均竖向加速度从-10×10^(-3) g增加到-39×10^(-3) g,其中深度200 mm以内的三向振动增幅最为明显。该研究为嵌入式压电系统的实际应用和布置优化提供了支撑,也为智能道路的长期服役性能分析提供了依据。

基于压电导纳的叠堆型压电智能骨料工作性能试验研究

叠堆型压电智能骨料是一种以压电叠堆为核心元件制备的新型换能器。相比于传统的智能骨料,它有着更优异的力电耦合性能,可有效提高结构损伤诊断的精度和可靠性,在结构健康监测领域有重要的应用前景。但是,目前主要侧重于器件的设计和理论建模,基于压电导纳的器件工作性能还需进一步评估。设计了温度敏感性试验,分析了器件的谐振频率在温度梯度下的变化规律;开展了28 d的浸水试验,绘制了器件谐振频率随浸水天数的变化曲线;制备了三个200 mm×200 mm×200 mm土体试件,并将器件嵌入到土体试件中开展含水率的监测试验,通过分析不同含水率下的量化指标对土体含水状态进行监测。研究结果表明:叠堆型压电智能骨料的谐振频率随温度的升高而线性下降;在28 d浸水过程中,谐振频率的最大偏移率不超过10%,稳定性良好;基于导纳信号计算得到的量化指标均随土体试件含水率的升高而增大,可有效监测土体含水率的变化。

Smart结构——用压电材料抑制结构振动研究之一

指出了Ｓｍａｒｔ材料及结构在航天技术发展中的重要作用，并从常用的Ｓｍａｒｔ材料－压电材料的本构方程出发，着重探讨了由压电驱动器组成的ＲＣ电路和ＬＲＣ电路在抑制结构振动中的应用；最后通过实验验证了ＲＣ电路的振动抑制性能；为航天Ｓｍａｒｔ结构的深入研究做必要的准备。

高强钢管超高性能混凝土柱地震损伤监测

在带肋高强钢管超高性能混凝土柱(UHPCFHSST)内埋设压电智能骨料,钢管外壁粘贴压电陶瓷片,采用主动波动法对UHPCFHSST在往复加载过程中柱端的损伤情况进行监测,通过小波包分析方法对监测数据进行分析,探究循环往复荷载作用下管内核心混凝土损伤和管壁界面剥离损伤过程。结果表明,损伤状态下信号的到达时间比健康状态下的到达时间更晚,且信号的幅值更低。核心混凝土和界面剥离损伤指数随加载等级和加载循环次数的增加而增大,界面剥离损伤先于核心混凝土内部损伤产生。损伤监测结果与试件的滞回曲线、骨架曲线的承载力变化趋势具有较好的一致性。研究结果表明,利用压电智能骨料和压电陶瓷传感器能对管内核心混凝土和管壁届面剥离的损伤过程进行有效监测。

直升机ACF智能旋翼压电叠堆输出特性仿真分析

压电叠堆是ACF智能旋翼中后缘襟翼的致动元件,其输出性能的好坏直接影响后缘襟翼的偏转效率。基于COMSOL Multiphysics有限元平台,对全电极和叉指电极两种构型的压电叠堆进行了参数化建模,对叠堆自由位移和阻塞力两种典型输出特性进行了仿真分析,并利用理论进行了校验。结果表明,基于参数化建模的压电叠堆有限元模型具有良好的准确性,其计算结果与理论模型计算结果基本保持一致;两种构型压电叠堆的输出特性随激励电压的变化都是趋于线性的;相同激励电压下,同横截面积的叉指电极型压电叠堆的自由位移小于全电极型,减小比例与各陶瓷层活性区面积的缩减比例一致,而两种构型叠堆的阻塞力大小相当,叉指电极的尺寸缩进不会使得阻塞力明显降低。

Hamiltonian parametric element and semi-analytical solution for smart laminated plates

Based on the Hellinger-Reissner （H-R） mixed variational principle for piezoelectric material, a unified 4-node Hamiltonian isoparametric element of anisotropy piezoelectric material is established. A new semi-analytical solution for the natural vibration of smart laminated plates and the transient response of the laminated cantilever with piezoelectric patch is presented. The major steps of mathematical model are as follows： the piezoelectric layer and host layer of laminated plate are considered as unattached three-dimensional bodies and discretized by the Hamiltonian isoparametric elements. The control equation of whole structure is derived by considering the compatibility of generalized displacements and generalized stresses on the interface between layers. There is no restriction for the side-face geometrical boundaries, the thickness and the number of layers of plate by the use of the present isoparametric element. Present method has wide application area.

PZT Based Smart Aggregate for Unified Health Monitoring of RC Structures

The most familiar civil engineering structure is reinforced concrete (RC) structure. Performance of structure undergoes changes during their service life with time. Thus, it is of great concern to monitor the health of RC structure. Structural health monitoring (SHM) is the art of detecting the changes in structure that influences its performance. Various techniques to monitor the health of structure are broadly studied worldwide. PZT based smart aggregate can play an effective role as an advanced tool in the development of structural health monitoring. This research work contributes for proposing a more generous Non-Destructive Evaluation (NDE) technique for structural health monitoring by using smart materials. If performance of a structure deviates from the design parameters with time, appropriate and effective maintenance is required. Considering the relevant need of RC structures, a more sensitive and cost-effective approach by using Electro-Mechanical Impedance (EMI) technique has been proposed for implementation in real-life situations. In general, surface bonded PZT transducer is used for SHM. Since PZT transducers are of very small dimension and brittle in nature, for consistent characteristics, they should be protected from severe environmental condition and other external interruptions. For this reason, PZT transducer is embedded in structure at the time of construction and manufacturing of the embedded transducer is simple. The proposed EMI technique assesses the health of RC structures more rationally by embedding PZT transducer in the structure, whose health is to be monitored over the user specified preset frequency range. The conductance and susceptance signatures are acquired by using LCR meter. At any future point of time, when it is desired to assess the health of structure, the conductance and susceptance signatures are acquired and further utilized for damage detection and quantification. The Root Mean Square Deviation (RMSD) is used to specify damage severity.

Simple Efficient Smart Finite Elements for the Analysis of Smart Composite Beams

This paper is concerned with the development of new simple 4-noded locking-alleviated smart finite elements for modeling the smart composite beams.The exact solutions for the static responses of the overall smart composite beams are also derived for authenticating the new smart finite elements.The overall smart composite beam is composed of a laminated substrate conventional composite beam,and a piezoelectric layer attached at the top surface of the substrate beam.The piezoelectric layer acts as the actuator layer of the smart beam.Alternate finite element models of the beams,based on an“equivalent single layer high order shear deformation theory”,and a“layer-wise high order shear deformation theory”,are also derived for the purpose of investigating the required number of elements across the thickness of the overall smart composite beams.Several cross-ply substrate beams are considered for presenting the results.The responses computed by the present new“smart finite element model”excellently match with those obtained by the exact solutions.The new smart finite elements developed here reveal that the development of finite element models of smart composite beams does not require the use of conventional first order or high order or layer-wise shear deformation theories of beams.Instead,the use of the presently developed locking-free 4-node elements based on conventional linear piezo-elasticity is sufficient.

Experimental Investigation on Sensitivity of Smart Aggregate Embedded in Reinforced Concrete Beam

Electromechanical impedance (EMI) based lead zirconate titanate (PZT) is an effective sensor to ensure the safety of structure. In civil engineering community, Reinforced Concrete (RC) structure is one of the most familiar engineering structures. Hence, it is very important to monitor the health of structure. In this paper, a new approach of structural health monitoring using embedded PZT in host structure is proposed. There are several issues while embedding PZT inside RC structure which are examined during study. This paper presents two experimental studies on lab sized concrete beams. First implementation was carried out with different methods of embedment of PZT and its sensitivity study when the host structure was subjected to damage. The second implementation was verified in terms of conductance sensitivity of embedded Smart Aggregate (SMAG) in varying orientation i.e. horizontal (0?) and vertical (90?) after embedding in RC beam. The electrical conductance and susceptance signatures of different embedded PZT transducers were measured and damage index was calculated by using Root Mean Square Deviation Method.

一种基于防震锤的新型压电复合能量收集方法

为了解决智能电网环境下输电线有害振动与工况检测传感器的供电及续航问题,该文设计了一种压电式振动与磁场复合能量收集的防震锤。防震锤的主压电梁收集输电线振动能量,副压电梁通过安装磁铁收集输电线电流产生的变化磁场能量,摆脱了传统收集磁场能量时线圈的使用。对收集器进行有限元仿真分析与实验测试。结果表明,收集器工作频带更宽,比传统的单梁输出高54%,主压电悬臂梁最大输出功率可达到874μW,副压电梁最大功率可达到683μW。

高温退火处理对ZnO压电涂层结构和性能的影响

ZnO是目前压电螺栓传感器的主要涂层材料,具备优异的压电性能,表现出优异的声-电信号转换性能,但目前对其高温结构及性能稳定性研究较少。本工作利用射频磁控溅射法在(100)_(Si)和工业用钛合金螺栓上制备出可产生超声纵波的ZnO压电涂层,并对其进行不同温度和不同时长的退火处理,用扫描电子显微镜、原子力显微镜、X射线衍射和自建的WHU-US100声信号测量设备研究高温退火处理对涂层结构及性能的影响。结果表明,Si/ZnO涂层在600℃以下的退火处理不会对涂层表面微观形貌产生影响,涂层截面形貌呈现柱状晶结构,且随着温度的升高,柱状晶有合并的趋势;涂层表面粗糙度变化幅度为±4 nm;不同的退火温度对涂层的晶体结构未产生明显的影响。螺栓/ZnO涂层在500℃及以下温度的退火处理后涂层表面完整,600℃退火处理后的螺栓涂层完全脱落,超声检测表明涂层在500℃以下退火后保持稳定;在300℃下,经过长时间的退火处理后,螺栓样品可正常激发出超声波,涂层结构未被破坏,表明该ZnO涂层可以在300℃的温度范围内长期服役。

Active vibration control of piezoelectric bonded smart structures using PID algorithm

Thin-walled structures are sensitive to vibrate under even very small disturbances. In order to design a suitable controller for vibration suppression of thin-walled smart structures, an electro-mechanically coupled finite element（FE） model of smart structures is developed based on first-order shear deformation（FOSD） hypothesis. Considering the vibrations generated by various disturbances, which include free and forced vibrations, a PID control is implemented to damp both the free and forced vibrations. Additionally, an LQR optimal control is applied for comparison.The implemented control strategies are validated by a piezoelectric layered smart plate under various excitations.

Piezoelectric fbers for fexible and wearable electronics

Flexible and wearable electronics represent paramount technologies ofering revolutionized solutions for medical diagnosis and therapy,nerve and organ interfaces,fabric computation,robot-in-medicine and metaverse.Being ubiquitous in everyday life,piezoelectric materials and devices play a vital role in fexible and wearable electronics with their intriguing functionalities,including energy harvesting,sensing and actuation,personal health care and communications.As a new emerging fexible and wearable technology,fber-shaped piezoelectric devices ofer unique advantages over conventional thin-flm counterparts.In this review,we survey the recent scientifc and technological breakthroughs in thermally drawn piezoelectric fbers and fber-enabled intelligent fabrics.We highlight the fber materials,fber architecture,fabrication,device integration as well as functions that deliver higher forms of unique applications across smart sensing,health care,space security,actuation and energy domains.We conclude with a critical analysis of existing challenges and opportunities that will be important for the continued progress of this feld.