Piezoelectric Composite Actuators: Modelling of the Static and Dynamic Behaviour

Studies on muscle mimicking piezo-composite actuators have been increased during the last two decade due to the possibility of various applications for compact lightweight actuators of small unmanned aircraft and biomimetic robots. Piezoelectric materials have been used in a variety of application ranging from shape control of structure, active vibration control of structure to noise suppression due to compact size and good frequency response. The conventional poly-crystal piezoelectric ceramic materials, however, have rather low actuating strains and displacement. In this paper, design and fabrication methods of actuator with single crystal piezoelectric material were investigated to increase actuation strain and displacement.

The present article reports the feasibility of the electrical energy generation from ambient low-frequency vibration using a piezoelectric material mounted on a bimorph cantilever beam actuator. A corresponding higher-order analytical model is developed using MATLAB in conjunction with finite element method under low-frequency with both damped and undamped conditions. An alternate model is also developed to check the material and dimensional viability of both piezoelectric materials (mainly focussed to PVDF and PZT) and the base material. Also, Genetic Algorithm is implemented to find the optimum dimensions which can produce the higher values of voltage at low-frequency frequencies (≤ 100 Hz). The delamination constraints are employed to avoid inter-laminar stresses and to increase the fracture toughness. The delamination has been done using a Teflon sheet sandwiched in between base plates and the piezo material is stuck to the base plate using adhesives. The analytical model is tested for both homogenous and isotropic material characteristics of the base material and extended to investigate the effect of the different geometrical parameters (base plate dimensions, piezo layer dimensions and placement, delamination thickness and placement, excitation frequency) on the model responses of the bimorph cantilever beam. It has been observed that when the base material characteristics are homogenous, the efficiency of the model remains higher when compared to the condition when it is of isotropic material. The necessary convergence behaviour of the current numerical model has been established and checked for the accuracy by comparing with available published results. Finally, using the results obtained from the model, a prototype is fabricated for the experimental validation via a suitable circuit considering Glass fibre and Aluminium as the bimorph material.

The piezoelectric actuating device that consist of piezoelectric material is known for large power density with simple structure. It can generate large force than the conventional actuator and it has also wide bandwidth with fast response in a compact size. To control the piezoelectric actuator, we need analog signal conditioning circuit as well as digital microcontrollers. Conventional microcontrollers are not equipped with analog part and need digital to analog converters in addition to the embedded analog to digital converters, which makes the system bulky compared with the small size of the piezoelectric devices. To overcome these weaknesses, we are developing single-chip controller that can handle analog and digital signals simultaneously using mixed signal FPGA technology. We used the Smart Fusion FPGA device that integrates ARM®Cortex-M3, analog interface and FPGA fabric in a single chip and offering full customization. It gives more flexibility than traditional fixed-function microcontrollers with the excessive cost of soft processor cores on traditional FPGAs. In this paper we introduce the design of a single chip controller using mixed signal FPGA, Smart Fusion device. To demonstrate its performance, we implemented a PID controller and PWM generator in the FPGA fabric. PWM generator and PID controller showed the effective regulation of a simple 1st order plant.

Polymer piezoelectric materials polyvinylidene fluoride (PVDF) and its copolymers P(VDF-TRFE) and P(VDF-HFP) are typical organic polymer materials with piezoelectric properties. Currently, these materials attract great attention in academic and application area for their good mechanical properties, corrosion resistance, biocompatibility and easy processing. However, compared with the traditional inorganic piezoelectric ceramic materials, the piezoelectric constant of polymer piezoelectric materials is still relatively low, so improving the piezoelectric properties of such polymer piezoelectric materials has become one of the research hotspots at home and abroad. In this paper, the methods of improving the piezoelectric properties by combining PVDF and its copolymers with different functional materials at national and international levels in recent years are summarized, and the advantages and disadvantages of different types of fillers doped with different polymer piezoelectric materials and their development trends are prospected.

Recently, most research has focused on energy recovery and storage. One of the materials allowing the recovery of dissipated energy is the piezoelectric material. Piezoelectric (PE) materials are functional materials, which fulfill this role in both directions, transforming electrical energy into mechanical and vice versa. In this paper, we are interested in recovering the vibratory energy, otherwise dissipated via conventional shock absorbers, in suspension systems by using piezoelectric materials and reuse it. We propose a physical model integrating a piezoelectric actuator in the vehicle suspension system. This energy is used for the operation of accessories (windows, mirrors …). The idea is to integrate renewable energy sources to optimize the performance of the vehicle. We proposed a multi-physic model of the system under a software used to this type of modeling (LMS.AMESim). The simulation results of the system and its various sub-systems are presented for studying the piezo-actuator response in order to reduce consumption and increase energy performance in a vehicle.

Piezoelectric distributed actuators are exhaustively utilized in control of the structural deformation/vibration. These actuators are also used in the form of smart composite of which active fiber composite (AFC) and macro-fiber composite (MFC) are the most popular smart composites. In the present work, few shortcomings of MFC/AFC actuator in its structural applications are identified and those are alleviated through the proposition of a short piezoelectric fiber-reinforced composite (SPFRC) actuator. The SPFRC is composed of equally spaced coaxial short piezoelectric fibers embedded within the polymer matrix. Every fiber is poled along its length that yields maximum piezoelectric stress/strain within the composite along the same direction in effect of co-directional applied electric field. This piezoelectric effect quantified by the coefficient (e11) is the main parameter in its use as an actuator with a special arrangement of electrodes in microscale. The SPFRC is designed with an objective of improved magnitude of major effective coefficient (e11), and it is performed through a continuum micro-mechanics finite element analysis of its effective electro-elastic properties. The actuation-capability of SPFRC actuator according to its present design is verified by analyzing the geometrically nonlinear electro-elastic deformations of a simply supported smart beam. The micro-mechanics analysis reveals a significant magnitude of e11 of SPFRC although it is lesser than the case of continuous fibers within the similar composite. However, the analysis of smart beam reveals better actuation-capability of the smart composite actuator when short fibers are used instead of continuous fibers retaining the same applied voltage and electrodes.

A novel characterization method of piezoelectric composite material based on particle swarm optimization algorithm

Piezoelectric materials, capable of 0.1% strains, have been extensively used in sensor and actuator applications. Ferroelectric materials, a subset of the piezoelectric class, are capable of strains an order of magnitude larger. For a ferroelectric material with tetragonal crystal structure, large strains can be achieved through 90 degree domain switching between a and c domains. Bulk barium titanate has been shown to produce strains of 0.9% through such domain switching under combined electromechanical loading. Lead titanate has a larger c/a ratio and would be expected to produce 6% strains, though it is prone to brittle fracture. By examining the solid solution lead barium titanate, larger strains can be achieved while maintaining mechanical integrity. The work presented here covers the development of multiple sol-gel processes for producing powder and highly oriented thin film lead barium titanate, and a detailed discussion of their parametric optimization towards low temperature crystallization. Finally, results of early efforts toward integrating these films into useful structures and devices are discussed, including sol-gel synthesis of highly oriented conductive oxide electrodes. Thin film barium lead oxide and lanthanum nickelate electrodes were produced using sol-gel processing. (100)-oriented lanthanum nickelate electrodes were produced on a wide variety of amorphous and crystalline substrates, and subsequently deposited PBT showed excellent (100/001)-orientation regardless of substrate. The ability to produce highly oriented ferroelectric films on oxide electrodes deposited directly on Si promises to improve fatigue characteristics and greatly facilitate efforts to integrate ferroelectric thin films into MEMS process.

Piezoelectric functional materials have been extensively studied and employed in numerous devices. With the rapid development of modern industries, such as power plants, aerospace, automotive, renewable energy and material processing industries, the high temperature piezoelectric materials that can work in extreme environments are in great demand. Piezoelectric materials including piezoelectric single crystals, ceramics and films, are at the heart of electromechanical actuation and sensing devices. A variety of applications where piezoelectric actuators and sensors operate at elevated temperatures (T 200℃) would be extremely desired. The actuators need to work efficiently with high strokes, torques, and forces while operating under relatively harsh conditions. These include high-temperature fans and turbines, motors for valves or natural gas industries, kiln automation, and actuators for automotive engines such as fuel injectors and cooling system elements. Yet, the majority of industrial actuator applications are at or below the 250℃ temperature limit. In addition to the increase in operational temperatures of piezoelectric motors and actuators, a future area of interest is high-temperature MEMS research, which can be used for high-temperature valving. On the other hand, the piezoelectric sensors have been widely used for structural health monitoring applications. This is due to their wide bandwidth, versatility, simplicity, high rigidity, high stability, high reproducibility, fast response time, wide operating temperature range, insensitivity to electric and magnetic fields, the capacity for miniaturization and minimal dependence on moving parts and low power consumption, and wide piezoelectric materials and mechanisms selections, which will greatly benefit the sensing applications. In addition to the temperature usage range, the piezoelectric sensors must withstand the harsh environments encountered in space, engine, power plants, and also need to possess high sensitivity, resistivity, reliability, stability and robustness. In order to use the piezoelectric materials for a specific high temperature application, many aspects need to be considered together with piezoelectric properties, such as phase transition, thermal aging, thermal expansion, chemical stability, electrical resistivity, and the stability of properties at elevated temperature. In this paper, ferroelectric materials with high Curie point, including perovskite-type ferroelectrics, bismuth layer structured ferroelectrics, tungsten-bronze structured ferroelectrics, together with non-ferroelectric piezoelectric single crystals, are surveyed. The crystal structure characteristics, high temperature piezoelectric properties, and recent research progress are discussed. A series of high temperature piezoelectric devices and their applications are reviewed, including high temperature piezoelectric detectors, sensors, transducers, actuators, etc. Finally, recent important research topics, the future development of high temperature piezoelectric materials and the potential new applications are summarized.

A meter-scale piezoelectrically active composite re ector has been developed and tested. The active re ector consists of a spherically curved, graphite face sheet, aluminum honeycomb core composite panel augmented with a network of distributed piezoelectric composite actuators. The piezoelectric actuator system may be used for controlling the structural dynamic response of the re ector, or for correcting low-order, thermally-induced quasistatic distortions of the panel. In this study, thermally-induced surface deformations of 1 to 5 microns were deliberately introduced onto the re ector, then measured using a speckle holography system. The re ector surface gure was subsequently corrected to a tolerance of 100 nm using a lattice of 90 piezoelectric composite actuators distributed across the re ector’s back face sheet. Initial experimental investigations consisted of open-loop gure control to determine in uence functions and control authority for each individuallyaddressable actuator, followed by a closed-loop gure control implementation. This paper will describe the design, construction, and testing of the active composite re ector system under thermal loads, and subsequent correction of thermal deformations via distributed piezoelectric actuation.

Energy is a paramount factor because society uses it in distinct forms as a part of conservation of energy savings on the cost of living is successfully brought. Investigation of different piezoelectric forms of energy and its characteristics are very important to develop piezoelectricity energy nowadays because it is most easily obtained, cost effective, and good frequency response by its nature. A Composite material is a combination of two materials with distinct physical and chemical properties which is combined to form single material which is specialized to perform a certain jobs such to make the substance stronger, lighter and more resistance to electricity. Investigation study of complex ceramic oxides such as PZT , BZT, quartz , roschelle salt , lithium neobate, topaz, tourmaline etc piezoelectric materials are attracted for the researchers and scientists around the world due their extensive investigational study of various engineering applications in the field of sensors, transducers, Micro Electro Mechanical System(MEMS), actuator, etc In the present work, brief investigation study of Lead Zirconate Titanate-PZT composite preparation which is the synthetic piezoelectric form of material and polymerization of quartz, which is a natural form of material ,experimentation has been carried out to understand the material characteristical behavior of two predominant piezoelectric materials through Hydrothermal technique. In this work the hydrothermal method have been deployed to obtain pure form of Lead Zirconate Titanate ceramic composite materials because it has various add on advantages such as low reaction temperature, three dimensional substrate availability, automatic alignment or polarization during the process. The powder synthesis of PZT is performed by hydrothermal process. The polymerization method of PZT and quartz powder with PVDF based polymer is performed by employing solvent intercalation method with 2% of weight of PZT and Quartz powder. The PVDF polymer has been selected for polymerization because of non toxic in nature, flexible easily to process the films. This method has been investigated systematically within a wide range of experimental trial conditions to achieve reasonable piezoelectric ideal performance and brief characterization study of both the thin film materials of PZT and quartz was performed based on the interest of research.

Barium hexaferrite and strontium titanate are well established permanent magnet and piezoelectric materials which are technologically and scientifically attractive due to their potential for various applications in the field of magnetic electronics functional materials. However, the material properties for both require a careful control of grain structure as well as microstructure design to meet a specific application. In this work, we report some results of materials characterization especially particles and grains which were promoted during mechanical milling of a BaFe12O19/SrTiO3 composite system. These are including mean particle size characterization by Particle Size Analyzer and mean grain size determination by means of line broadenning analysis employing a step scanning counting in XRD apparatus for composite powders at various milling time up to 60 hours. It was found that the particle size of composite powders initially increased due to laminated layers formation of a composite and then decreased to an asymptotic value of ~8 ?m as the milling time extended even to a relatively longer time. However, based on results of line broadening analysis the mean grain size of the particles was found in the nanometer scale. We thus believed that mechanical blending and milling of mixture components for the composite materials has promoted heterogeneous nucleation and only after successive sintering at 1100 oC the milled powder transformed into particles of nanograin. In thireport, microstructure as well as magnetic properties for the composite is also briefly discussed.

Overall properties of piezoelectric composites with spring-type imperfect interfaces using the mechanics of structure genome

Using piezoelectric elements to harvest energy from ambient vibrations has been of great interest over the past few years. Due to the relatively low power output of piezoelectric materials, there are many study to improve the energy harvesting efficiencies. This paper is study the efficiencies of the output energy considering the cantilever piezoelectric bimorph using aluminum vibration beam. when the length of vibration beam and the piezoelectric body becomes same and the maximum output power comes out. DC voltage was increased as the beam thickness and vibration frequency was increased. The vibration beam was able to achieve very large energy value.

Active vibration control of a smart FG (functionally graded) cylindrical shell conveying fluid in thermal environment is studied theoretically by using a laminated piezoelectric actuator. Velocity feedback control law is implemented to activate the piezoelectric actuator. Considering the electric-thermo-fluid-structure interaction effect, a nonlinear dynamic model of the smart fluid-conveying FG cylindrical shell is developed based on Hamilton’s principle and von-Karman type geometrical nonlinear relationship. The inviscid, incompressible, isentropic and irrotational fluid is coupled into governing equations using the linearized potential theory. The Galerkin’s method is used to obtain the nonlinear governing equations of motion of the coupled system. The multiple time scales approach is applied to solve the resulting governing equations for analysing the nonlinear dynamic characteristics of the coupled system. The influence of fluid flow velocity, feedback control gains of piezoelectric voltage, external excitation and material properties of FGM on the frequency-response curves of system are investigated. The results indicate that the piezoelectric voltage is an effective controlling parameter for vibration control of the system, and the flow velocity can effect significantly the vibration amplitude and nonlinearity of the coupled system.