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Vibration analysis and control of fluid containers using piezoelectrically-excited side wall
摘要： The vibration analysis and control of containers with heavy loaded fluid is undertaken in this paper. The problem of fluid–structure vibration is viewed and analyzed from several viewpoints including both analytical methods and numerical techniques. In order to effectively control the fluid–structure vibration, one of the side walls is made flexible where two piezoelectric patches are utilized to sense the distributed displacements resulting from fluid-structure movements, while the other one is used to actively control the vibration. For this, a boundary control technique is used to actively control the multi-modal vibration of fluid–structure. The simulation results for the analytical models are further validated using a comprehensive finite element method. Before applying the proposed controller, the results show that the fluid vibration is different in different heights and distances. However, the simulation results indicate that the piezoelectrically-excited beam is able to suppress the vibrations of all the positions very effectively and quickly. These results prove the feasibility of utilizing piezoelectrically-excited beams in vibration control of fluid–structure.
关键词： boundary control,piezoelectric-based vibration control,finite element method,Fluid–structure interaction
更新于2025-09-19 17:15:36
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Wearable piezoelectric nanogenerators based on reduced graphene oxide and in situ polarization-enhanced PVDF-TrFE films
摘要： PVDF-TrFE-based wearable nanogenerators were designed and fabricated with enhanced performances via reduced graphene oxides (rGO) and in situ electric polarization. Our laboratory-made polarization system may complete the in situ poling of PVDF-TrFE films in 5 min without heating, which has the advantages of high production efficiency, excellent piezoelectric performances, and favorable uniformity, compared to traditional poling approaches. The addition of rGO into PVDF-TrFE significantly improved the crystallinity of the b-phase PVDF-TrFE and enhanced the formation of hydrogen bonds via interaction of dipoles between rGO and PVDF-TrFE. This further improved the energy-harvesting performances of these piezoelectric nanogenerators with 1.6 times of the open-circuit voltage and 2 times of the power density than that of pure PVDF-TrFE-based devices. The high production efficiency and excellent piezoelectric performances of in situ polarized rGO/PVDF-TrFE make them of great potential for self-powered, wearable/portable devices.
关键词： Electronic materials,Reduced graphene oxide,PVDF-TrFE,Wearable piezoelectric nanogenerators,In situ polarization
更新于2025-09-19 17:15:36
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Large Piezoelectric Stability and Low Polarization Fatigue in 6Pb(Sc1/2Nb1/2)O3-70Pb(Mg1/3Nb2/3)O3-24PbTiO3 Crystals
摘要： The electrical properties and polarization fatigue of [001]-oriented 6Pb(Sc1/2Nb1/2)O3-70Pb(Mg1/3Nb2/3)O3-24PbTiO3 (6PSN-70PMN-24PT) crystals were investigated. Compared with binary Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) crystals, the ternary 6PSN-70PMN-24PT crystal showed a higher rhombohedral–tetragonal transition temperature (TR-T = 120°C) and a larger coercive field (Ec = 4 kV/cm). It was found that the piezoelectric constant (d33 ≈ 1200 pC/N) and electromechanical coupling coefficient (kt ≈ 61%) were weakly dependent on the thermal annealing temperature (Ta), maintaining over 90% of the original value at Ta < 120°C, indicating excellent piezoelectric thermal stability. Electric fatigue measurements showed that the ternary 6PSN-70PMN-24PT crystal exhibited slight fatigue characteristics below 105 bipolar cycles, while the binary PMN-PT crystal exhibited sudden polarization degradation when the cycle numbers were above 102 cycles. The improved fatigue stability for 6PSN-70PMN-24PT crystals was attributed to the large coercive field. The physical mechanisms of the enhanced coercive field and high transition temperature were discussed based on repulsive energy and polar domains.
关键词： piezoelectric stability,6PSN-70PMN-24PT,Ferroelectric crystal,fatigue
更新于2025-09-19 17:15:36
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Frequency characteristics of a GPL-reinforced composite microdisk coupled with a piezoelectric layer
摘要： This is the ?rst research on the frequency analysis of a graphene nanoplatelet composite (GPLRC) microdisk in the framework of a numerical-based generalized differential quadrature method. The stresses and strains are obtained using the higher-order shear deformable theory. Rule of mixture is employed to obtain varying mass density, thermal expansion, and Poisson’s ratio, while module of elasticity is computed by modi?ed Halpin–Tsai model. Governing equations and boundary conditions of the GPLRC microdisk covered with piezoelectric layer are obtained by implementing Hamilton’s principle. Regarding perfect bonding between the piezoelectric layer and core, the compatibility conditions are derived. In addition, due to the existence of piezoelectric layer, Maxwell’s equation is derived. The results show that outer-to-inner ratio of radius (Ro/Ri), ratios of length scale and nonlocal to thickness (l/h and μ/h), ratio of piezoelectric to core thickness (hp/h), applied voltage, and GPL weight fraction (gGPL) have signi?cant in?uence on the frequency characteristics of the GPLRC microdisk. Another important consequence is that in addition to the nonlinear indirect effects of applied voltage on the natural frequency of the GPLRC microdisk covered with piezoelectric for each speci?c value of Ro/Ri, the impact of the Ro/Ri on the natural frequency is indirect. A useful suggestion of this research is that, for designing the GPLRC circular microplate at the low value of the Ro/Ri should be more attention to the gGPL and Ro/Ri, simultaneously.
关键词： Higher-order shear deformable theory,Halpin–Tsai model,Microdisk,Piezoelectric layer,Hamilton’s principle,Maxwell’s equation,Generalized differential quadrature method,Frequency analysis,Graphene nanoplatelet composite (GPLRC)
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Singapore, Singapore (2019.4.27-2019.4.30)] 2019 IEEE 2nd International Conference on Power and Energy Applications (ICPEA) - Characteristics of Disturbance in Frequency 9 -150 kHz of Photovoltaic System under Fluctuated Solar Irradiance
摘要： Gallium nitride (GaN) is a wide bandgap semiconductor material and is the most popular material after silicon in the semiconductor industry. The prime movers behind this trend are LEDs, microwave, and more recently, power electronics. New areas of research also include spintronics and nanoribbon transistors, which leverage some of the unique properties of GaN. GaN has electron mobility comparable with silicon, but with a bandgap that is three times larger, making it an excellent candidate for high-power applications and high-temperature operation. The ability to form thin-AlGaN/GaN heterostructures, which exhibit the 2-D electron gas phenomenon leads to high-electron mobility transistors, which exhibit high Johnson’s figure of merit. Another interesting direction for GaN research, which is largely unexplored, is GaN-based micromechanical devices or GaN microelectromechanical systems (MEMS). To fully unlock the potential of GaN and realize new advanced all-GaN integrated circuits, it is essential to cointegrate passive devices (such as resonators and filters), sensors (such as temperature and gas sensors), and other more than Moore functional devices with GaN active electronics. Therefore, there is a growing interest in the use of GaN as a mechanical material. This paper reviews the electromechanical, thermal, acoustic, and piezoelectric properties of GaN, and describes the working principle of some of the reported high-performance GaN-based microelectromechanical components. It also provides an outlook for possible research directions in GaN MEMS.
关键词： HEMT,piezoelectric materials,micromachining,microelectromechanical systems,III-V,wide bandgap,resonators
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE International Conference on Sensors and Nanotechnology (SENSORS & NANO) - Penang, Malaysia (2019.7.24-2019.7.25)] 2019 IEEE International Conference on Sensors and Nanotechnology - Effect of Laser Power on the Formation of Porous Graphitic Carbon on Polyimide Film
摘要： This paper proposes a new linear ultrasonic motor using hybrid mode of the first symmetric and anti-symmetric longitudinal modes. The stator is constructed by two Langevin transducers in combination with two isosceles triangular beams. The triangular beams can transform the displacement in axial direction into the displacement in perpendicular direction and generate the oval trajectory of the driving foot, which is the merit of the simple structure. For better mode degeneration result, the influence of the triangular beam dimensions on the vibration frequency difference of the stator was analyzed by Finite Element Method (FEM) analysis. The overall dimensions of the prototype stator are 70 mm (length) × 15 mm (width) × 10 mm (thickness). Driven by ac signals with the driving frequency of 55 kHz and voltage 400 Vp?p, the motor can provide the no-load speed 63.87 mm/s and maximum thrust force 3.14 N, respectively. The frequency matching process of ultrasonic motor is simplified by adjusting the structure dimensions of the triangular beams.
关键词： Ultrasonic motor,piezoelectric transducer,hybrid mode.
更新于2025-09-19 17:13:59
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Laser dot projection videogrammetry for vibration measurement and control of a piezoelectric flexible cantilever plate
摘要： A novel full-field non-contact vibration measurement method is investigated for a piezoelectric flexible cantilever plate, using laser dot-projection videogrammetry. Several laser dots are projected as marks for visual system. The three-dimensional coordinates of each mark are monitored by a binocular stereo vision system, composed of two cameras. After image processing, the vibration signal of the first bending mode is obtained. For the first torsional mode, two laser displacement sensors are utilized to detect the vibration. To suppress the residual vibration quickly, an adaptive nonlinear controller and a fuzzy tuning nonlinear controller are designed and adopted. To verify the investigated measurement and control methods, experiments are conducted by using a piezoelectric flexible cantilever plate experimental platform. The experimental results demonstrate that the investigated laser dot projection measurement method is effective for first bending vibration detection. Furthermore, compared with PD control, the adopted nonlinear algorithms have better damping performance, especially for small amplitude residual vibration.
关键词： Vibration measurement,Nonlinear control algorithm,Piezoelectric flexible plate,Laser dot projection,Videogrammetry
更新于2025-09-19 17:13:59
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Origin of enhanced piezoelectric properties revealed through electric field driven studies in 0.94(Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3</sub> )a??0.06(Ba <sub/>0.85</sub> Ca <sub/>0.15</sub> Ti <sub/>0.9</sub> Zr <sub/>0.1</sub> O <sub/>3</sub> ) ceramics
摘要： A single phase 0.94(Na0.5Bi0.5TiO3)–0.06(Ba0.85Ca0.15Ti0.9Zr0.1O3) solid solution (i.e., BCZT-0.06) is prepared using a conventional solid-state sintering route with enhanced piezo and ferroelectric properties as compared to Na0.5Bi0.5TiO3 (NBT). In the context of understanding the origin of enhanced piezoelectric properties in a BCZT-0.06 specimen, electric field driven studies on different length scales, viz., global, local, and electronic structure, are carried out using x-ray/neutron diffraction, Raman scattering, and UV–Vis spectroscopic techniques. An analysis on different length scales of the electric field-driven BCZT-0.06 specimen displays minimum rhombohedral lattice distortion (δ r), reduced homogeneous lattice strain (δ), octahedral strain (ζ), and pronounced Ti-cation displacement along the polar [111] direction as compared to parent NBT. The enhanced ferro and piezoelectric responses observed in the BCZT-0.06 specimen have been attributed to the ease of non-180° domain re-orientation, domain switching, and domain wall motion due to reduced strain coupled with a polarization extension mechanism.
关键词： ferroelectric properties,electric field driven studies,solid solution,domain re-orientation,piezoelectric properties
更新于2025-09-19 17:13:59
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Multi-wavelength DFB laser array in InAs/GaAs quantum dot material epitaxially grown on Silicon
摘要： A ?rst proof-of-concept mm-sized implantable device using ultrasonic power transfer and a hybrid bi-directional data communication link is presented. Ultrasonic power transfer enables miniaturization of the implant and operation deep inside the body, while still achieving safe and high power levels (100 W to a few mWs) required for most implant applications. The current implant prototype measures 4 mm 7.8 mm and is comprised of a piezoelectric receiver, an IC designed in 65 nm CMOS process and an off-chip antenna. The IC can support a maximum DC load of 100 W for an incident acoustic intensity that is 5% of the FDA diagnostic limit. This demonstrates the feasibility of providing further higher available DC power, potentially opening up new implant applications. The proposed hybrid bi-directional data link consists of ultrasonic downlink and RF uplink. Falling edge of the ultrasound input is detected as downlink data. The implant transmits an ultra-wideband (UWB) pulse sequence as uplink data, demonstrating capability of implementing an energy-ef?cient M-ary PPM transmitter in the future.
关键词： implantable biomedical devices,active recti?er,mm-sized implants,ultrasonic power transfer,piezoelectric receivers,bi-directional data communication,CMOS,antennas,IMD,AC-DC converter,radio transmitters
更新于2025-09-19 17:13:59
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Band Tunability of Coupled Elastic Waves along Thickness in Laminated Anisotropic Piezoelectric Phononic Crystals
摘要： Although the passively adjusting and actively tuning of pure longitudinal (primary (P-)) and pure transverse (secondary or shear (S-)) waves band structures in periodically laminated piezoelectric composites have been studied, the actively tuning of coupled elastic waves (such as P-SV, P-SH, SV-SH, and P-SV-SH waves), particularly as the coupling of wave modes is attributed to the material anisotropy, in these phononic crystals remains an untouched topic. This paper presents the analytical matrix method for solving the dispersion characteristics of coupled elastic waves along the thickness direction in periodically multilayered piezoelectric composites consisting of arbitrarily anisotropic materials and applied by four kinds of electrical boundaries. By switching among these four electrical boundaries—the electric-open, the external capacitance, the electric-short, and the external feedback control—and by altering the capacitance/gain coe?cient in cases of the external capacitance/feedback-voltage boundaries, the tunability of the band properties of the coupled elastic waves along layering thickness in the concerned phononic multilayered crystals are investigated. First, the state space formalism is introduced to describe the three-dimensional elastodynamics of arbitrarily anisotropic elastic and piezoelectric layers. Second, based on the traveling wave solutions to the state vectors of all constituent layers in the unit cell, the transfer matrix method is used to derive the dispersion equation of characteristic coupled elastic waves in the whole periodically laminated anisotropic piezoelectric composites. Finally, the numerical examples are provided to demonstrate the dispersion properties of the coupled elastic waves, with their dependence on the anisotropy of piezoelectric constituent layers being emphasized. The in?uences of the electrical boundaries and the electrode thickness on the band structures of various kinds of coupled elastic waves are also studied through numerical examples. One main ?nding is that the frequencies corresponding to qH = nπ (with qH the dimensionless characteristic wavenumber) are not always the demarcation between pass-bands and stop-bands for coupled elastic waves, although they are de?nitely the demarcation for pure P- and S-waves. The other main ?nding is that the coupled elastic waves are more sensitive to, if they are a?ected by, the electrical boundaries than the pure P- and S-wave modes, so that higher tunability e?ciency should be achieved if coupled elastic waves instead of pure waves are exploited.
关键词： electrical boundaries,coupled elastic waves,dispersion curves,laminated piezoelectric phononic crystals,arbitrarily anisotropic materials,band tunability
更新于2025-09-19 17:13:59