The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Wenwu Cao - One of the best experts on this subject based on the ideXlab platform.
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dielectric elastic and piezoelectric properties of single domain pb zn1 3nb2 3 o3 6 5 pbtio3 single crystal with 3m symmetry measured using one sample
Scripta Materialia, 2021Co-Authors: Yang Xiang, Chuanwen Chen, Liguo Tang, Lei Qin, Hongmei Zhu, Wenwu CaoAbstract:Abstract In order to use finite element simulation to design Electromechanical Devices, self-consistent full tensor material properties are needed. The IEEE resonance technique usually requires more than 5 different geometry samples to complete the full tensor characterization, but the poling degree will depend on the sample geometry in relaxor-base ferroelectric single crystals. Hence, it is very difficult to obtain self-consistent full tensor properties using multiple samples. In this study, we used only one sample to determine the whole set of materials properties for single domain PZN–6.5%PT single crystals by combining the ultrasonic pulse-echo (UPE) method and the resonance ultrasonic spectroscopy (RUS) for the elastic and piezoelectric coefficients and the impedance analyzer for dielectric measurements. Comparison with other reported results show the advantage of our methodology and such self-consistent date set would facilitate fundamental studies on domain engineering technique as well as device design optimization using finite element software.
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relaxor based ferroelectric single crystals growth domain engineering characterization and applications
Progress in Materials Science, 2014Co-Authors: Enwei Sun, Wenwu CaoAbstract:Abstract In the past decade, domain engineered relaxor-PT ferroelectric single crystals, including (1 − x )Pb(Mg 1/3 Nb 2/3 )O 3 – x PbTiO 3 (PMN–PT), (1 − x )Pb(Zn 1/3 Nb 2/3 )O 3 – x PbTiO 3 (PZN–PT) and (1 − x − y )Pb(In 1/2 Nb 1/2 )O 3 – y Pb(Mg 1/3 Nb 2/3 )O 3 – x PbTiO 3 (PIN–PMN–PT), with compositions near the morphotropic phase boundary (MPB) have triggered a revolution in Electromechanical Devices owing to their giant piezoelectric properties and ultra-high Electromechanical coupling factors. Compared to traditional PbZr 1− x Ti x O 3 (PZT) ceramics, the piezoelectric coefficient d 33 is increased by a factor of 5 and the Electromechanical coupling factor k 33 is increased from 90%. Many emerging rich physical phenomena, such as charged domain walls, multi-phase coexistence, and domain pattern symmetries, have posed challenging fundamental questions for scientists. The superior Electromechanical properties of these domain engineered single crystals have prompted the design of a new generation Electromechanical Devices, including sensors, transducers, actuators and other Electromechanical Devices, with greatly improved performance. It took less than 7 years from the discovery of larger size PMN–PT single crystals to the commercial production of the high-end ultrasonic imaging probe “PureWave”. The speed of development is unprecedented, and the research collaboration between academia and industrial engineers on this topic is truly intriguing. It is also exciting to see that these relaxor-PT single crystals are being used to replace traditional PZT piezoceramics in many new fields outside of medical imaging. The new ternary PIN–PMN–PT single crystals, particularly the ones with Mn-doping, have laid a solid foundation for innovations in high power acoustic projectors and ultrasonic motors, hinting another revolution in underwater SONARs and miniature actuation Devices. This article intends to provide a comprehensive review on the development of relaxor-PT single crystals, spanning material discovery, crystal growth techniques, domain engineering concept, and full-matrix property characterization all the way to device innovations. It outlines a truly encouraging story in materials science in the modern era. All key references are provided and 30 complete sets of material parameters for different types of relaxor-PT single crystals are listed in Appendix A . It is the intension of this review article to serve as a resource for those who are interested in basic research and practical applications of these relaxor-PT single crystals. In addition, possible mechanisms of giant piezoelectric properties in these domain-engineered relaxor-PT systems will be discussed based on contributions from polarization rotation and charged domain walls.
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large size lead free na k nb ta o3 piezoelectric single crystal growth and full tensor properties
CrystEngComm, 2013Co-Authors: Limei Zheng, Xiaoqing Huo, Rui Wang, Junjun Wang, Wenhua Jiang, Wenwu CaoAbstract:Environmental friendly piezoelectric single crystal, Ta-modified (K,Na)NbO3 with the size of 12 × 11 × 11 mm3, has been successfully grown using the top seeded solution growth technique. This orthorhombic phase (K,Na)(Nb,Ta)O3 single crystal is the largest size to date in KNN-based crystals with homogeneous composition. The large size allowed us to apply the domain engineering technique to further enhance its piezoelectric properties. In addition, a self-consistent complete set of elastic, dielectric and piezoelectric constants for the [001]c poled domain engineered crystal has been measured, which is urgently needed for theoretical studies and simulation designs of Electromechanical Devices using this lead-free piezoelectric material. The Electromechanical coupling factors are very high (k33 = 0.827, kt = 0.646) and the dielectric loss tangent is as low as 0.004 for this lead-free piezoelectric crystal. Such excellent properties make this crystal an excellent candidate to replace lead-containing piezoelectric materials in Electromechanical Devices.
Timothy E. Long - One of the best experts on this subject based on the ideXlab platform.
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Advances in Polymeric Materials for Electromechanical Devices
Macromolecular rapid communications, 2018Co-Authors: B. Tyler White, Timothy E. LongAbstract:Electroactive polymers (EAP) provide lightweight and cost-effective materials that enable the next generation of Electromechanical Devices. Commercial polymers have historically dominated research in EAP Devices due to their availability. However, several drawbacks of these materials have limited their commercial applications, necessitating new materials for the commercial success of future EAP Devices. This review highlights recent advances in novel EAPs for ionic polymer-metal composites (IPMC) and dielectric elastomer actuators (DEA). Ion-containing block copolymers and charged segmented condensation polymers demonstrate suitable Electromechanical properties competitive with Nafion-based IPMCs. In addition, swelling ionic polymer membranes with free ionic liquid enhances ionic conductivity and promotes Electromechanical actuation. Synthetic approaches to increasing permittivity in dielectric elastomers are also explored as a method of producing more efficient DEAs. Incorporating polar functional groups into siloxane and acrylic elastomers through grafting or blending provides high-dielectric elastomers for use in DEAs with low driving voltages.
Stephane Evoy - One of the best experts on this subject based on the ideXlab platform.
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A review of piezoelectric polymers as functional materials for Electromechanical transducers
Smart Materials and Structures, 2014Co-Authors: Khaled S Ramadan, Dan Sameoto, Stephane EvoyAbstract:Polymer based MEMS and microfluidic Devices have the advantages of mechanical flexibility, lower fabrication cost and faster processing over silicon based ones. Also, many polymer materials are considered biocompatible and can be used in biological applications. A valuable class of polymers for microfabricated Devices is piezoelectric functional polymers. In addition to the normal advantages of polymers, piezoelectric polymers can be directly used as an active material in different transduction applications. This paper gives an overview of piezoelectric polymers based on their operating principle. This includes three main categories: bulk piezoelectric polymers, piezocomposites and voided charged polymers. State-of-the-art piezopolymers of each category are presented with a focus on fabrication techniques and material properties. A comparison between the different piezoelectric polymers and common inorganic piezoelectric materials (PZT, ZnO, AlN and PMN-PT) is also provided in terms of piezoelectric properties. The use of piezopolymers in different Electromechanical Devices is also presented. This includes tactile sensors, energy harvesters, acoustic transducers and inertial sensors.
Philip T. Krein - One of the best experts on this subject based on the ideXlab platform.
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a dual primal finite element tearing and interconnecting method combined with tree cotree splitting for modeling Electromechanical Devices
International Journal of Numerical Modelling-electronic Networks Devices and Fields, 2013Co-Authors: Wang Yao, Jianming Jin, Philip T. KreinAbstract:The dual-primal finite-element tearing and interconnecting (FETI-DP) method is combined with the tree-cotree splitting (TCS) method to expand the capability and improve the efficiency of the finite-element analysis of Electromechanical Devices. With the FETI-DP method, an original large-scale problem is decomposed into smaller subdomain problems and parallel computing schemes are then employed to reduce the computation time significantly. The TCS method is adopted to deal with the low-frequency breakdown problem, which often accompanies the finite-element analysis of Electromechanical problems. On the basis of the computed magnetic field values, the force is computed with the use of the Maxwell stress tensor method. The proposed technique is applied to solve both high-contrast magnetostatic problems and eddy-current problems. Results are compared with both measurement data and brute-force finite-element calculations without domain decomposition. Comprehensive tests are conducted to investigate the parallel efficiency and numerical scalability. The results show that the proposed method can achieve a good parallel efficiency and an excellent numerical scalability with respect to the number of subdomains and the size of the problem. Copyright © 2012 John Wiley & Sons, Ltd.
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A Time-Harmonic Three-Dimensional Vector Boundary Element Model for Electromechanical Devices
IEEE Transactions on Energy Conversion, 2010Co-Authors: Tim C. O'connell, Philip T. KreinAbstract:In present practice, the most effective way to solve the large electromagnetic (EM) boundary value problems typical in Electromechanical device analysis has been with the finite element method (FEM). The sparse, symmetric, and banded structure of FEM system matrices reduces the memory requirements and facilitates several fast and efficient solution algorithms. An alternative, boundary element methods (BEM), is more computationally intensive. Recently, however, fast and efficient solver codes have been developed for BEM solutions of EM scattering problems. These, if effectively implemented in Electromechanical device models, can make BEM a more feasible alternative for this purpose than previously. To generate a deeper understanding of this alternative formulation in the context of electromechanics problems, a time-harmonic 3-D vector BEM model for Electromechanical Devices is presented that is formulated in terms of the field variables and is capable of modeling multiple separated homogeneous regions with or without eddy currents. Extensions to electric machine modeling are given, and the model is assessed using experimental data.
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Force Calculation in 3-D Magnetic Equivalent Circuit Networks With a Maxwell Stress Tensor
IEEE Transactions on Energy Conversion, 2009Co-Authors: Marco Amrhein, Philip T. KreinAbstract:Magnetic equivalent circuit (MEC) models are increasingly valuable for analysis and design of Electromechanical Devices, particularly electrical machines, because of their moderate computational effort and reasonable accuracy. Force and torque calculations in prior MEC implementations are almost exclusively based on the virtual work method (VWM) adapted to the specific device model. But VWM does not easily extend to a general MEC modeling approach. In this paper, the more direct Maxwell stress tensor (MST) method is applied to a general 3-D MEC modeling framework. MST theory and implementation are presented. Its application is discussed with the example of an electromagnet. Results are compared to both measurements and analytical and finite-element models.
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3-D Magnetic Equivalent Circuit Framework for Modeling Electromechanical Devices
IEEE Transactions on Energy Conversion, 2009Co-Authors: Marco Amrhein, Philip T. KreinAbstract:Magnetic equivalent circuits (MECs) are becoming an accepted alternative to electrical-equivalent lumped-parameter models and finite-element analysis (FEA) for simulating Electromechanical Devices. Their key advantages are moderate computational effort, reasonable accuracy, and flexibility in model size. MECs are easily extended into three dimensions. But despite the successful use of MEC as a modeling tool, a generalized 3-D formulation useable for a comprehensive computer-aided design tool has not yet emerged (unlike FEA, where general modeling tools are readily available). This paper discusses the framework of a 3-D MEC modeling approach, and presents the implementation of a variable-sized reluctance network distribution based on 3-D elements. Force calculation and modeling of moving objects are considered. Two experimental case studies, a soft-ferrite inductor and an induction machine, show promising results when compared to measurements and simulations of lumped parameter and FEA models.
B. Tyler White - One of the best experts on this subject based on the ideXlab platform.
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Advances in Polymeric Materials for Electromechanical Devices
Macromolecular rapid communications, 2018Co-Authors: B. Tyler White, Timothy E. LongAbstract:Electroactive polymers (EAP) provide lightweight and cost-effective materials that enable the next generation of Electromechanical Devices. Commercial polymers have historically dominated research in EAP Devices due to their availability. However, several drawbacks of these materials have limited their commercial applications, necessitating new materials for the commercial success of future EAP Devices. This review highlights recent advances in novel EAPs for ionic polymer-metal composites (IPMC) and dielectric elastomer actuators (DEA). Ion-containing block copolymers and charged segmented condensation polymers demonstrate suitable Electromechanical properties competitive with Nafion-based IPMCs. In addition, swelling ionic polymer membranes with free ionic liquid enhances ionic conductivity and promotes Electromechanical actuation. Synthetic approaches to increasing permittivity in dielectric elastomers are also explored as a method of producing more efficient DEAs. Incorporating polar functional groups into siloxane and acrylic elastomers through grafting or blending provides high-dielectric elastomers for use in DEAs with low driving voltages.