Piezoelectric Ceramic Actuators Research Articles

On-Demand MEMS Device Production System by Module-Based Microfactory

Many micro-scale devices have been developed by applying micro-electro-mechanical systems (MEMS) technology, but MEMS production facilities are large and costly, making it difficult to develop small numbers of trial devices. The novel on-demand MEMS device production system we developed applies two major concepts – that of the microfactory and the introduction of non-MEMS processes in microfabrication. These two concepts have made manufacturing more ecological, economical, agile, and flexible through downsizing, forming an automated production line by connecting standardized unit-processing cells, each of which has a desktop process, a part transfer robot, and a standardized connection interface. These enable any process cell to be connected in any sequence that the target product requires. Four unit-process cells were developed – the micropress cell for fabricating microstructures from thin sheet metal and the miniature aerosol deposition (AD) process cell for fabricating high-performance piezoelectric (PZT) ceramics actuators. The feasibility of the on-demand MEMS production system was demonstrated by the fabrication of a MEMS-like micromirror scanner, proving the potential of on-demand MEMS production in diversified small-lot production.

Influence of Interface Degradation on the Performance of Piezoelectric Actuators

An experimental and numerical study was performed to investigate the effects of interface debonding on the performance of piezoelectric (PZT) ceramic actuators for structural health monitoring (SHM) systems. Interface degradation of PZT actuators may occur over time during the in-service life of the structure compromising the performance and reliability of the SHM system. Energy losses and signal changes should be understood to guarantee the reliability of the SHM systems during the life-time of the structure. Here we present the first systematic study on the performance of PZT actuators with a partially degraded interface. The electro-mechanical coupling between PZT actuators and a hosting aluminium plate was found to vary with the interface debonding over a wide frequency range affecting the amplitude and phase of the actuator’s signal. A signal delay and an amplitude decrease were observed for: increasing debonding area, different debond shape, and location underneath the PZT actuators. Changes were found to be dependent on the actuation frequency with respect to the PZT resonance frequency. A spectral element-based code integrated with a coupled electro-mechanical field solver was used to verify the experimental results by simulating the propagation of ultrasonic Lamb waves in an aluminum plate with built-in PZT sensors/actuators.

Modeling Multilayer Piezoelectric Actuators in a Residual Temperature Field

Electromechanical field concentrations near the electrodes in multilayer piezoelectric ceramic actuators in a residual temperature field are examined. The problem is formulated by considering a representative unit in the real multilayer actuators. A singular integral equation, in which the unknown function is the electric potential ahead of the electrode tip, is derived. The solution of the integral equation gives the electroelastic fields near the electrode tip. The thermally induced electric field ahead of the electrode tip is found to be highly singular. On the other hand, the stresses and electric displacements are singular behind the electrode tip. Possible debonding and cracking between the electrodes and the piezoelectric medium is investigated by energy density theory.

A Piezoelectric Micropump Based on MEMS Fabrication

This paper presents a valve-less micropump which is actuated by a piezoelectric ceramic chip. We employ a microelectromechanical system process for the silicon substrate and anodic bonding for assembly of the Pyrex glass and silicon wafer. The reciprocating type micropump contains two nozzle/diffuser elements and a silicon membrane with an embedded piezoelectric ceramic actuator.

CrossRef Listing of Deleted DOIs

Multilayer piezoelectric ceramic displacement actuators are susceptible to cracking in the region near the edge of the internal electrode, which may cause system damage or failure. In this paper, the stress distribution of a multilayer piezoelectric composite is investigated in a working environment and the optimized geometrical configuration of the piezoelectric layer is obtained. The stress distribution in the structure and the stress concentration near the edge of the internal electrode, induced by non-uniform electric field distribution, are analyzed by moire interferometry experiment and finite element numerical simulation. Based on the above analysis, two optimized geometrical models are presented for the purpose of geometrical configuration selection, with which stress concentration can be reduced significantly while the feasibility of the machining process and the basic structural functions occurring in the conventional model are retained. The numerical results indicate that the maximum stress in the optimized models is effectively diminished compared to the conventional model. For instance, the peak value of the principal stress in the optimized model II is 93.1% smaller than that in the conventional model. It is proved that stress concentration can be effectively relaxed in the latter of the two optimized models and thus the probability of fracture damage can be decreased.

Application of Ag–ceramic composite electrodes to low firing piezoelectric multilayer ceramic actuators

Application of Ag–ceramic composite electrodes to low firing piezoelectric multilayer ceramic actuators

Study on Displacement Self-Sensing of Piezoelectric Actuator

This paper aims to make piezoelectric ceramic actuator self-sense its own displacement in the absence of independent sensor. It is derived from the basic piezoelectric equation that the free charge on the wafer of piezoelectric ceramic actuator contains displacement information. So a displacement self-sensing method based on integrate circuit is presented. Voltage driving circuit for the piezoelectric ceramic actuator and integrated circuit for gathering free charge are designed. Based on the proposed compound circuits, the actuator can sense its own displacement while actuation. It is convenient to adjust the circuit and easy to acquire sensitive signal by using this method, and the impedance mismatching problem met in bridge method is overcome. The experimental results show that piezoelectric self-sensing actuator can effectively measure its displacement signal under the conditions of different wave form of driving voltage and different driving voltage frequency.

Structural Vibration Control via R-L Shunted Active Fiber Composites

This article presents a successful extension of passive R-L shunt damping to piezoelectric ceramic elements working in direct 3-3 mode and a performance comparison to elements working in indirect 3-1 mode. A new circuit topology is implemented to synthesize the very large inductances required by the low inherent piezoelectric device capacitance at relatively low frequencies. This allows for efficient tuning of the R-L circuit to the structure resonance frequency to be damped. The vibration suppression performance of monolithic piezoelectric ceramic actuators and active fiber composites is compared in this study. For this purpose, different actuators are bonded on aluminum cantilever plates. An integrated FE model is implemented for the prediction of structure resonance frequencies, optimum values for electric components, and the resulting vibration suppression performance. The passive structure, bonded active patch, and shunted electrical network are analyzed within the same FE model. Active fiber composite patches working in the direct 3-3 mode show equivalent specific damping performance compared to conventional monolithic 3-1 actuated patches. Issues related to the sensitivity of R-L shunts to variations in environmental and operational conditions are discussed in this study. In short, monolithic actuators operating on the 3-1 piezoelectric effect seem to be the best for use in R-L shunting.

Design, Processing and Evaluation of Graded Piezoelectric Ceramic Bending Actuators

This paper introduces the development of two kinds of graded piezoceramic bending actuators. For designing the graded compositional profiles, classical lamination theory (CLT) is used to explore the optimal gradient that generates large electromechanical response. As the first model material, a laminated piezoceramic bimorph actuator was designed and fabricated with a graded compositional distribution of PZT and Pt, and its electric-induced bending characteristics were evaluated and compared with the analytical results by CLT. Furthermore, porosity-graded PZT ceramics were developed, which may be used as the preforms for the infiltration process to fabricate bending actuators with graded ceramic/metal and/or ceramic/polymer interfaces. The fabrication process and property evaluation of homogenously porous and porosity-graded PZT ceramics were introduced.

FATIGUE BEHAVIOR DEGRADATION DUE TO THE INTERLAMINAR CONDITIONS IN LIGHTWEIGHT PIEZOELECTRIC COMPOSITE ACTUATOR (LIPCA)

The advanced piezoelectric ceramic composite actuator, which is called LIPCA (LIghtweight Piezoelectric Composite Actuator), replaced the Al foil and stainless steel in THUNDER with the FRP and the optimization of the laminate configuration was performed to maximize the stress transfer and the fiber bridging effect. This study evaluated the fatigue characteristics in LIPCA under the resonance frequency, and the changes of its interlaminar phase were also evaluated. Beside, the residual stress distribution was estimated. In conclusions, firstly, comparing with the fatigue life of LIPCA without the artificial delamination (intact LIPCA), the fatigue life of LIPCA embedded by the artificial delamination was decreased up to 50%. Secondly, the micro void growth and the coalescence of epoxy were actively made at the interlaminar phase subject to the large tensile stress. Finally, it was known that the harmonic configuration between the compressive residuals stress and the tensile one was made. The requirement of the performance displacement increment was satisfied.

압전 복합재료 작동기 LIPCA와 단일 PZT의 보 진동 제어 성능 비교

본 논문에서는 기존에 개발한 압전 복합재료 작동기인 LIPCA가 동적 구조물의 작동기로 적용 가능한지를 평가하였다. 압전 세라믹 층, 탄소/에폭시 층 및 유리/에폭시 층으로 이루어진 LIPCA 작동기는 단일 PZT에 비하여 성능 및 내구성이 크다는 장점이 있다. 성능 평가를 위하여 정적 작동력 실험과 진동 제어 실험을 수행하였다. 알루미늄 보의 한 쪽 면에 LIPCA와 단일 PZT를 각각 보에 부착하고 반대쪽 면에는 변형률 게이지를 부착하였다. 먼저 정적 작동력 실험에서는 작동 전압에 따른 변형률 신호를 등가 작동 모멘트로 환산하여 크기를 비교함으로써 성능을 평가하였다. 진동 제어 실험에서는 스트레인 게이지의 변형률 신호를 PID 제어 알고리듬을 사용하여 보의 자유 진동을 억제하도록 제어 신호를 생성하였다. 진동 신호가 감쇠하는 정도를 나타내는 안정화 시간을 비교함으로써 성능을 평가하였다. 실험 결과 LIPCA가 정적 작동 뿐 아니라 자유 진동 제어에서도 단일 PZT보다 성능이 우수함을 확인하였다. The purpose of this paper is to evaluate potential application of Lightweight Piezo-composite Actuator (LIPCA) to suppress vibrations of structures. The LIPCA, consisting of a piezoelectric layer, a carbon/epoxy layer and glass/epoxy layers, has advantages in terms of high performance, durability and reliability, compared to the bare piezoelectric ceramic (PZT) actuator. We performed two kinds of experiments on static actuation and active vibration suppression to investigate the actuation performances of the LIPCA and the bare PZT. We attached the actuator on one side and a strain gage on the other side of an aluminum beam. In the static actuation test, we evaluated the performance by comparing equivalent actuation moments of the LIPCA and the bare PZT due to the applied voltage. In the active vibration control test, control signals were generated to suppress the vibration of the beam by the PID control algorithm based on the measured strain signals. The performances were estimated based on settling times of the strain responses. It can be concluded that the LIPCA has better actuation performances than the bare PZT in active control of free vibration as well as static actuation.

Design and Manufacturing of IDEAL with Stacked Ceramic Layers and Inter-Digitated Electrodes

This paper is concerned with the development of stacked ceramic thin actuation layer IDEAL (Inter-Digitated Electrode Actuation Layer) using d33 actuation mechanism of piezoelectric ceramic. Most of the thin piezoelectric actuators are operated with d31 actuation mechanism. Many kinds of piezoelectric ceramic actuators are strived now to improve the actuation performance. One of efforts to improve performance of piezoceramic actuators is the research trying to develop an actuator using the piezoelectric coefficient d33. The piezoelectric coefficient d33 is almost twice larger than piezoelectric coefficient d31. Therefore, the induced strain of PZT thin layer with d33 actuation mechanism is bigger than that with d31 actuation mechanism. The AFC and LaRC-MFC used d33 actuation mechanism with surface interdigitated electrode to enhance its actuation performance. But their actuation mechanism is not perfect d33 actuation mechanism since the interdigitated electrodes are placed at the surface of the actuation layer. In this research, the stacked ceramic thin actuation layer with imbedded inter-digitated electrodes is designed and manufactured. The actuation strain of stacked ceramic thin actuation layer is measured and compared with the actuation strain of the LaRC-MFC. The comparison shows that the developed stacked ceramic thin actuation layer can produce 10% more actuation strain than LaRC-MFC at relatively high electric field.

Analysis of piezoelectric ceramic multilayer actuators based on an electro-mechanical coupled meshless method

This paper presents an efficient meshless method for analyzing cracked piezoelectric structures subjected to mechanical and electrical loading. In this method, an element free Galerkin (EFG) formulation, an enriched basic function and some special shape functions that contain discontinuous derivatives are employed. Based on the moving least squares (MLS) interpolation approach, the EFG method is one of the promising methods for dealing with problems involving progressive crack growth. Since the method is meshless and no element connectivity data are needed, the burdensome remeshing procedure required in the conventional finite element method (FEM) is avoided. The numerical results show that the proposed method can yield an accurate near-tip stress field in an infinite piezoelectric plate containing an interior hole. In another example studying a ceramic multilayer actuator, the proposed model was found to be accurate in the simulation of stress and electric field concentrations arround the abrupt end of an internal electrode.

DISPLACEMENT COMPOUNDING CONTROL OF PIEZOELECTRIC MICRO-MOTION WORKTABLE

A compounding control method with feedforward compensation and feedback control is presented in order to balance the accuracy and stability, improve the performance of piezoelectric ceramic actuator, and then to get high positioning accuracy for micro-motion worktable drived by piezoelectric ceramic actuator. Feedforward compensation is feedforward control based hysteresis model of piezoelectric ceramic actuator and is realized through self-learning algorithm, the aim of which is to compensate piezoelectric hysteresis and improve tracking ability to reference displacement signal. Feedback control is PID control, which eliminates the residual error of feedforward compensation and the error caused by uncertainty of model. Moreover, traditional PID control is improved to be variable-coefficient integrals and weighted differential PID to decrease the integral saturation and differential sensitivity to disturbance. This compounding control method is validated by experiments and compared with other control strategies, such as open loop control, feedforward control and PID control. The results demonstrate that the motion worktable under compound control has better performance than other control strategies.

Characterization and modelling of 3D piezoelectric ceramic structures with ATILA software

In this paper, the correspondence between ATILA-simulated and measured values of two piezoelectric ceramic structures, bulk and RAINBOW actuators, was determined. Modelling was started by creating a 2D wire model of the structures, after which a 3D model was created and simulation parameters were introduced (electric potentials, polarizations and boundary conditions). Harmonic type analysis was used in the simulations. The results obtained from the simulations contained information about displacements in the z-axis direction. Displacements of the measured structures behaved nonlinearly as a function of the electric field. Accordingly, effective piezoelectric coefficients (i.e. d 31, d 33) calculated from the electric field and the displacement also changed nonlinearly. However, the displacement results acquired from simulations are linear, since the ATILA program uses a linear approach for in the calculation. This causes the modelling results to differ from the measurement results, especially when large voltages are used. The problem was solved by modifying the constant parameters used in the simulations. In the study reported here, relative permittivity K 33, piezoelectric coefficient d 33 and approximated piezoelectric coefficient d 31 were used to obtain more accurate modelling results corresponding to the measurement results. The differences in the z-axis displacements between the modelling (using the original material parameters) and measurement results obtained with bulk and RAINBOW actuators were 6.5–17.7% and 6.0–27.9%, respectively. With modified material parameters, the differences were 1.1–1.6% and 3.1–8.5%, respectively.

Dynamic Topology Optimization of Compliant Mechanisms and Piezoceramic Actuators

A topology optimization method is developed to design a piezoelectric ceramic actuator together with a compliant mechanism coupling structure for dynamic applications. The objective is to maximize the mechanical efficiency with a constraint on the capacitance of the piezoceramic actuator. Examples are presented to demonstrate the effect of considering dynamic behavior compared to static behavior and the effect of sizing the piezoceramic actuator on the optimal topology and the capacitance of the actuator element. Comparison studies are also presented to illustrate the effect of damping, external spring stiffness, and driving frequency. The optimal topology of the compliant mechanism is shown to be dependent on the driving frequency, the external spring stiffness, and whether the piezoelectric actuator element is considered design or nondesign. At high driving frequencies, it was found that the dynamically optimized structure is very near resonance.

Structural vibration control using an active resonator absorber: modeling and controlimplementation

A new dynamic vibration absorber referred to as an active resonator absorber (ARA) isproposed; we explore its practical implementation using piezoelectric ceramic (PZT)inertial actuators. The ARA is a passive absorber with an additional dynamic feedbackcompensator within the PZT actuator. Without any controller, it becomes a passivevibration absorber due to internal damping and elasticity properties of the piezoelectricmaterials; hence, it is inherently fail-safe. For active operation, the compensatorparameters are designed such that a resonance condition is intentionally createdwithin the absorber subsection to mimic the vibratory energy from the system ofconcern to which it is attached. The resonance condition can be created through theappropriate design of the compensator and implemented through adjusting theexternal electrical voltage applied to the PZT actuator. Although PZT materialsinherently possess nonlinear characteristics (e.g., hysteresis), an equivalent linearizedmodel is developed for the actuator subsystem. An experimental set-up is thenconstructed to validate the proposed linearized model and estimate the actuatorparameters using a nonlinear least squares algorithm. Because the parameters of thePZT actuators (i.e. stiffness, damping, and effective mass) are approximate, thecompensator designs based on these parameters would result in partial vibrationsuppression when utilized in real applications. An auto-tuning method is used toeffectively tune the compensator parameters to improve the vibration suppressionquality. The effectiveness and stability of the proposed auto-tuning scheme whenimplemented on a single-degree-of-freedom primary system are demonstrated.

Closed-loop-controlled vortex shedding and vibration of a flexibly supported square cylinder under different schemes

Different schemes were experimentally investigated of the closed-loop control of vortex shedding from a spring-supported square cylinder in cross flow. The control action was implemented through the perturbation of one cylinder surface, which was generated by three piezoelectric ceramic actuators, embedded underneath the surface and controlled by a proportional-integral-derivative controller. Three control schemes were investigated using different feedback signals, including the turbulent flow signal measured by a hot wire, flow-induced structural oscillation signal obtained by a laser vibrometer, and a combination of both signals. An investigation was conducted at the resonance condition, when the vortex-shedding frequency coincided with the natural frequency of the fluid-structure system. The flow and structural vibration were measured using particle image velocimetry, laser-induced fluorescence flow visualization, a laser Doppler anemometer, and a laser vibrometer. It was observed that the control scheme based on the feedback of both flow and structural oscillation led to the almost complete destruction of the Kármán vortex street and a reduction in the structural vibration, vortex shedding strength, and drag coefficient by 82%, 65%, and 35%, respectively, outperforming by far an open-loop control as well as the other two closed-loop schemes.

On the directional decoupling characteristics of active stiffeners for shape control oftwo-dimensional structures

A substantial amount of research exists concerning shape control of two-dimensional opticalmirror structures with attached piezoelectric ceramic sheet actuators. Researchers haveinvestigated the optimal placement, size, and electrode pattern of the piezoceramicactuators for maximizing the system performance. In many situations, the performancecould be further improved with tailoring of the actuator configuration. For example, it wasfound that to avoid ‘exciting’ higher order deformation modes (the wrinkling effect) intwo-dimensional structures, the ideal actuator would be one that is directionally decoupled,i.e., only actuates in one direction when controlling certain deformation modes ofinterest. The active stiffener (AS) concept has been proposed to realize such aneffect, where a stiffener is inserted between a host structure and the piezoelectricceramic actuator patch. The objective of the research presented in this paperis to develop a local analysis of the AS actuator to gain good insight into itscharacteristics and determine parameters that can best achieve the decoupling actions.Using a three-dimensional finite element model, analyses of a single active stiffenerattached to rigid and flexible host structures are presented. The effects of variousmaterial and system parameters on the bending moments applied to the hoststructure are illustrated. It is shown that, with proper design, the active stiffener cansignificantly reduce the bending moment (active authority) in a selected direction whilemaintaining sufficient authority in the orthogonal direction. The results of thisinvestigation should provide valuable guidelines for the design of effective ASactuators.

Thermal deformation compensation of a composite beam using piezoelectric actuators

Maintaining the surface shape of precision structures such as spacecraft antennareflectors has been a challenging task. Surface errors are often introduced by thermaldistortions due to temperature differences. This paper presents numerical andexperimental results of active compensation of thermal deformation of a compositebeam using piezoelectric ceramic actuators. To generate thermal distortion of thecomposite beam, two film heaters are bonded to only one side of the beam usingthermally conductive materials. To correct thermal deformation caused by the filmheaters, PZT (lead zirconate titanate), a type of a piezoelectric ceramic material,is used in the form of patches as actuators. These PZT patches are bonded onthe other side of the beam. First, finite-element analyses are conducted withconsideration of the coupled effects of structural, electric and thermal fields onthe composite beam. These analyses include static coupled field modeling of thebeam deformation with PZT actuation, transient modeling of the beam underthermal loading, and static coupled field modeling of the composite beam withthermal distortion and simultaneous PZT actuation to correct this distortion.Then, experiments are conducted to study the thermal effect, the PZT actuationeffect and active thermal distortion compensation using PZT actuators with aproportional, integral and derivative feedback controller. Finite-element modeling andexperimental results agree well and demonstrate that the proposed method canactively perform structural shape control in the presence of thermal distortion.