- 标题
- 摘要
- 关键词
- 实验方案
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The sintering behavior and physical properties of Li <sub/>2</sub> CO <sub/>3</sub> -doped Bi <sub/>0.5</sub> (Na <sub/>0.8</sub> K <sub/>0.2</sub> ) <sub/>0.5</sub> TiO <sub/>3</sub> lead-free ceramics
摘要： In this study, Li2CO3-doped Bi0.5(Na0.8K0.2)0.5TiO3 (BNKT) ceramics were fabricated via the conventional solid-state reaction using ultrasound waves for preliminary milling. The milling time was shortened from 20 h to 1 h with ball milling. The phase structure of BNKT investigated by X-ray diffraction showed a single perovskite phase. With increasing Li2CO3 content, the phase structure of the ceramics changed from rhombohedral to tetragonal. At a sintering temperature of 1 100 8C and Li2CO3 content of 0.4 wt.%, the best physical properties of the ceramics, such as density (q), 5.9 g cm–3; electromechanical coupling factors (kp), 0.32; (kt), 0.29; remanent polarization (Pr), 12.0 lC cm–2; dielectric constant (er), 1 191; and highest dielectric constant (emax), 5 800, were obtained.
关键词： Lead-free ceramics,Electromechanical coupling factor,BNKT,Sintering temperature,Dielectric constant
更新于2025-09-23 15:23:52
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Frequency Comb Generation at 800 nm in Waveguide Array Quantum Well Diode Lasers
摘要： A capacitive-piezoelectric transducer combines capacitive and piezoelectric mechanisms to achieve a combination of electromechanical coupling and Q higher than otherwise attainable by either mechanism separately, has allowed demonstration of a 1.2-GHz contour-mode aluminum nitride (AlN) ring resonator with Q > 3000 on par with the highest measured d31-transduced AlN-only piezoelectric resonators past 1 GHz, and a 50-MHz disk array with an even higher Q > 12 000. Here, the key innovation is to separate the piezoelectric resonator from its metal electrodes by tiny gaps to eliminate metal material and metal-to-piezoelectric interface losses thought to limit thin-film piezoelectric resonator Q, while also maintaining high electric field strength to preserve a strong piezoelectric effect. While Q increases, electromechanical coupling decreases, but the k2 · Q product can still increase overall. More importantly, use of the capacitive-piezo transducer allows a designer to trade electromechanical coupling for Q, providing a very useful method to tailor Q and coupling for narrowband radio frequency (RF) channel-selecting filters for which Q trumps coupling. This capacitive-piezo transducer concept does not require dc-bias voltages and allows for much thicker electrodes that reduce series resistance without mass loading the resonant structure. The latter is especially important as resonators and their supports continue to scale toward even higher frequencies.
关键词： electromechanical coupling,oscillator,Micromechanical resonator,self-alignment,small gap,aluminum nitride,equivalent circuit,quality factor,filter
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Dark Pulses in a Long Ring Laser
摘要： A capacitive-piezoelectric transducer combines capacitive and piezoelectric mechanisms to achieve a combination of electromechanical coupling and Q higher than otherwise attainable by either mechanism separately, has allowed demonstration of a 1.2-GHz contour-mode aluminum nitride (AlN) ring resonator with Q > 3000 on par with the highest measured d31-transduced AlN-only piezoelectric resonators past 1 GHz, and a 50-MHz disk array with an even higher Q > 12 000. Here, the key innovation is to separate the piezoelectric resonator from its metal electrodes by tiny gaps to eliminate metal material and metal-to-piezoelectric interface losses thought to limit thin-film piezoelectric resonator Q, while also maintaining high electric field strength to preserve a strong piezoelectric effect. While Q increases, electromechanical coupling decreases, but the k2 · Q product can still increase overall. More importantly, use of the capacitive-piezo transducer allows a designer to trade electromechanical coupling for Q, providing a very useful method to tailor Q and coupling for narrowband radio frequency (RF) channel-selecting filters for which Q trumps coupling. This capacitive-piezo transducer concept does not require dc-bias voltages and allows for much thicker electrodes that reduce series resistance without mass loading the resonant structure. The latter is especially important as resonators and their supports continue to scale toward even higher frequencies.
关键词： electromechanical coupling,oscillator,Micromechanical resonator,self-alignment,small gap,aluminum nitride,equivalent circuit,quality factor,filter
更新于2025-09-19 17:13:59
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The effect of piezoelectric ceramic volume fraction on the thickness vibration characteristics of 1-3 piezocomposites
摘要： The thickness vibration mode of the piezoelectric composite is the most common operation mode in transducer applications. The study on the thickness vibration characteristics plays a key role in application.In this paper, the influence of volume fraction of piezo-ceramic on the thickness vibration characteristics of 1-3 piezoelectric composites was investigated. Through finite element analysis and simulation, the relationship between vibration performance parameters and the ceramic volume fraction of composites was obtained. The samples with volume fraction of 0.2 (cid:1) 0.6 were prepared by cutting and filling and tested by Impedance Analyzer.Experimental and simulation results were matched by comparison.
关键词： electromechanical coupling factor,finite element simulation,conductance,1-3 piezocomposite
更新于2025-09-11 14:12:44
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Comprehensive Analysis of Smart Beams
摘要： This paper introduces a comprehensive analysis tool and framework for studying the structural dynamic and aeroelastic behavior of smart beams. It includes the theory behind the components of this comprehensive analysis tool and a verification of the proposed framework. This tool is used to study the aeroelastic behavior of a smart beam. This analysis is followed by a failure analysis in order to ensure the integrity of the structure under operation. This comprehensive analysis tool couples the variational asymptotic beam sections, geometrically exact fully intrinsic beam equations, and the circuit equation for smart materials. It takes into account the electromechanical coupling behavior of smart materials both in the cross-sectional analysis and in the one-dimensional generalized beam theory.
关键词： smart beams,variational asymptotic beam sections,aeroelastic behavior,electromechanical coupling,geometrically exact fully intrinsic beam equations
更新于2025-09-10 09:29:36
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Improvement of electromechanical coupling coefficient in shear-mode of piezoelectric ceramics
摘要： Shear vibration mode of piezoelectric ceramic has been widely used in energy harvesting for its high electromechanical coupling coefficient (k15) and high piezoelectric constant (d15). In this study, the effects of dimensions on the piezoelectric shear performance of PZT-5A type ceramic were initially studied with ATILA/GiD finite element simulation to improve k15, and verified by experiments. We found out k15 dominantly correlates with the ratio of width to thickness, and dimension optimization was conducted for the first and high order shear vibrations. As a result, a maximum electromechanical coupling coefficient for k15 shear-mode reaching 0.612 was obtained in the first order harmonics. It is worth to note that the dimension ratio for optimized electromechanical coupling factor were in a similar scale regardless of the order of harmonics. In addition to the dimension optimization, the effect of mode coupling between shear vibration mode and unwanted mode was also investigated. The coupling between two vibrations did not only affect electromechanical coupling coefficient but also distorted resonance peak spectrum. Thus, the dimension ratios to avoid mode coupling was provided as the length should far away from the thickness. Finally, the effects of dimensions on mechanical quality factor were examined and the results were discussed. The mechanical quality factor will decrease when the mode coupling happens.
关键词： Electromechanical coupling coefficient,k15 shear-mode,Finite element analysis,Piezoelectric ceramics
更新于2025-09-10 09:29:36
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[ASME ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition - Oslo, Norway (Monday 11 June 2018)] Volume 7C: Structures and Dynamics - Optimal Placement and Sizing of Piezoelectric Material for Multiple-Mode Vibration Reduction
摘要： Modern turbomachinery blades have extremely low inherent damping, which can lead to high transient vibrations and failure through high-cycle fatigue. Recent research seeks methods to reduce vibration with minimal effect on the weight and aerodynamic efficiency of the blade. Smart materials present an interesting means to augment the mechanical characteristics of the blade while meeting the strict requirements of the turbomachinery environment. In particular, piezoelectric-based vibration reduction offers the potential to semi-actively reduce vibration while simultaneously harvesting enough energy to power the implementation. The placement and size of the piezoelectric material is critical to the vibration reduction capabilities of the system. Furthermore, the implementation should target multiple vibration modes. This work develops a procedure to optimize electromechanical coupling across multiple vibration modes for a representative turbine blade with a surface-mounted piezoelectric patch.
关键词： electromechanical coupling,piezoelectric material,turbomachinery blades,optimization,vibration reduction
更新于2025-09-09 09:28:46
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Applications of Piezoelectrics: Old and New
摘要： Piezoelectric materials convert electrical energy to mechanical energy and vice versa, resulting in observed properties that are electromechanically coupled. When a piezoelectric is deformed, that mechanical energy is transformed to electrical energy, which is known as the direct piezoelectric effect. When the reverse occurs, and an electric field is applied, the material physically deforms, resulting in the converse piezoelectric effect. Therefore, piezoelectric materials can be used in both sensor and actuator applications. The magnitude of the piezoelectric response is often expressed as the longitudinal piezoelectric coefficient, d33. When measuring the direct piezoelectric effect, d33 is the polarization generated per unit of mechanical stress, where the field and stress are along the same direction. In the converse effect, d33 is the induced mechanical strain per unit of electric field applied, with the field and stress also in the same direction. Another measure of effectiveness of a piezoelectric is called the electromechanical coupling factor, k. This value expresses the efficiency of conversion from mechanical to electrical energy or vice versa.
关键词： actuator applications,electromechanical coupling factor,sensor applications,direct piezoelectric effect,Piezoelectric materials,converse piezoelectric effect
更新于2025-09-09 09:28:46
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[ASME ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems - San Antonio, Texas, USA (Monday 10 September 2018)] Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation - Forced Vibration Analysis of FG-Graphene Platelet Reinforced Polymer Composite Shells Bonded With Piezoelectric Layers Considering Electroelastic Nonlinearities
摘要： In the present article, we focus on the forced vibration and control analysis of functionally graded (FG) graphene-polymer composites bonded with piezoelectric layers considering strong electric fields. Different non-uniform gradient distributions of graphene platelets (GPLs) are assumed through the thickness direction. The Modified Halpin-Tsai micromechanics model is used to obtain the effective material properties of GPL/polymer composites. Electromechanical coupling of piezoelectric layers is described by two rotationally invariant non-linear constitutive relations. A four-node shell element considering transverse shear effect based on the Reissner-Mindlins hypothesis has been developed for forced vibration and control analysis of smart FG-GPL/composites using the principle of virtual work considering nonlinear material law for the piezoelectric layers. The developed element is verified and compared with the numerical results those available in the literature. Different configurations of FG-GPL composite shells have been analysed and discussed to compare in terms of settling time, first resonance frequency and absolute amplitude corresponding to first resonant frequency by carrying out time and frequency response analysis, and the effects of weight fraction of GPLs on vibration response of such shell structures are also discussed. The influence of electromechanical nonlinear constitutive relations is also presented and discussed by performing active control analysis on different FG-GPL composite shell structures. Moreover, the results show that the GPL distribution and weight-fraction of GPLs have a significant effect on the vibration and damping characteristics of the FG-GPL composite shell structures.
关键词： graphene platelets,nonlinear electromechanical coupling,piezoelectric layers,functionally graded materials,forced vibration
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Hiroshima (2018.5.27-2018.6.1)] 2018 IEEE ISAF-FMA-AMF-AMEC-PFM Joint Conference (IFAAP) - Piezoelectric Resonating Force Sensor in the Second Vibration Mode
摘要： A resonating force sensor is studied, which is composed of a metal bridge coated with a piezoelectric ?lm for force detection. It is thought to operate the sensor at the second ?exural vibration mode having one node at the center of the bridge. Resonance frequency and piezoelectric coupling are investigated in the frame of an analytical model, and compared with ?nite element analysis (FEA) in a desired force range. The resonance frequency-force relation derived from the analytical model is close the the FEA result in the force range. The coupling factor-force relation from the analytical model agrees with the one from FEA in the small force region, but it shows lower coupling than the FEA result in the large force region.
关键词： Resonance sensor,Electromechanical coupling,Piezoelectric sensor,Force sensor,Resonance frequency,Second mode
更新于2025-09-04 15:30:14