Papers by Keyword: Piezoelectricity

Abstract: This paper analyses the active vibration control technology on the piezoelectric ceramics car-body pieces in fuzzy control Strategy. Adaptive controllers, based on fuzzy logics, are synthesized for the control of vibration of body structure. Piezoelectric element, control system and body structure have been combined to be a intelligent response system to external drive and it’s own vibration. This system can effect reducing body structure’s reaction from environmental load with external energy. The availability of the control strategy has been confirmed by experiments.

Abstract: In this paper, based on the constitutive equations of piezoelectric effect and piezomagnetic effect, a 1-3 model of laminate magnetoelectricity composite materials is established. By combining material mechanical kinematic equations and circuit state equations, magnetical-mechanical-electrical equivalent circuit of laminate magnetoelectric composite materials is raised and magneto-electricity switch effect is analyzed. Upon these, a new kind of laminate magnetoelectricity composite material, Terfenol-D/PMNT/Terfenol-D, is put forward. Taking 1-3 model as an example, with the help of MATLAB, we simulate and calculate the magnetoelectric response of this new material. Through calculation, a conclusion is drawn that this new materials magnetoelectricity switch coefficient is higher than that of Terfenol-D/PZT/Terfenol-D. This theoretical basis will put this new material in a good position in magnetoelectric materials preparation.

Abstract: To improve the performances under low speed wind, a wind energy harvester similar to harmonicas was proposed. The harvester mainly includes a cuboid chamber and a cantilevered beam. The front wall of the chamber is opened as the air entrance and a rectangular hole is opened on the sidewall as the exit. The cantilever composed of a piezoelectric sheet and a flexible beam was fixed onto the sidewall of the chamber near the exit. Experimental results show that the width and height of the chamber significantly affect critical wind speed and output power, respectively. The initial attack angle of the cantilever has important influence on the critical wind speed. Blunt body at the air entrance could remarkably decrease the critical wind speed. For a prototype with a 60 mm×20 mm×13 mm chamber, the length of the cantilever of 30 mm and the length of the piezoelectric sheet of 8 mm, the measured maximum output power is 1.1 mW under 17 m/s wind.

Abstract: This paper analyses the active vibration control technology on the piezoelectric ceramics car-body pieces in fuzzy control Strategy. Adaptive controllers, based on fuzzy logics, are synthesized for the control of vibration of body structure. Piezoelectric element, control system and body structure have been combined to be a intelligent response system to external drive and it’s own vibration. This system can effect reducing body structure’s reaction from environmental load with external energy. The availability of the control strategy has been confirmed by experiments.

Abstract: This paper focuses on the design and development of a low-cost multifunctional composite component integrated into a shoe hill that generates power in the order of milliwats (mW) through piezoceramic (PZT) stacks and stores this harvested energy in a capacitor integrated into the composite. The use of a thin-film lithium battery integrated into the composite is also explored as a means of permanent power storage. PZT bimorph elements are stacked in a cantilever manner. The space in-between and around the elements is being filled with foam, which provides structural support as well as walking comfort. An insole composite with a PZT layer is also developed that is capable of producing 2.2mW of power to give a total power output of 12.2mW for the in-heel insole combination. The experimental results revealed that the use of PZT bimorph elements (d33=110) instead of polyvinylidene difluoride PVDF sheets (d33=20) increased the power generation potential over five folds, which is further compounded by stacking the PZT elements.

Abstract: BaBi2Nb2O9/PVDF (polyvinylidene fluoride) composite ultrafiltration (UF)membranes were prepared by alloying BaBi2Nb2O9 (BBN) particles uniformly in the PVDF solution (15% polymer weight) and used a phase-inversion method. This paper studied the effect of the concentration of BBN from 0% to 5% in 0.2Mpa on pure water flux and rejection rate to Bovine serum albumin (BSA). The cross-sectional structures of composite membranes were observed by scanning electron microscopy (SEM). Moreover, XRD results revealed the crystal structure of PVDF. The experimental results showed that the BBN/PVDF composite ultrafiltration membranes were superior in separation performances than the pure PVDF membranes due to the addition of BBN.

Abstract: Piezoelectricity in amorphous polymers is mainly due to the orientation polarization of the molecular dipoles. Aromatic polyimides are high-performance polymeric materials possessing large molecular dipoles. We already reported good magnetoelectric performance of laminate composites with Vitrovac 4040^® as magnetostrictive component and the 2,6(b-CN)APB/ODPA (poli 2,6) polyimide as the piezoelectric. Although the piezoelectric response of this polyimide is good, its mechanical properties can be improved. To combine the best mechanical and piezoelectric response in the same polymer, copolyimides have been synthesized by reaction of the 4,4-oxydiphtalic anhydride (ODPA) with a mixture of 1,3-Bis-2-cyano-3-(3-aminophenoxy) phenoxybenzene (diamine 2CN) and 1,3-Bis (3-aminophenoxy) benzene (diamine 0CN). We present the piezoelectric, mechanical and ME performance of laminate composites of these copolyimides.

Abstract: In this paper we shall rst describe low energy nuclear transmutation theory [LENT]and then apply it to describe how a \smart" material such as a piezoelectric rock when crushedcan induce nuclear reactions with production of neutrons which have been observed. An experimentalprogram being set up at Perugia for realizing LENT is also briey noted.

Abstract: (0.996-x) K0.5Na0.5NbO3- 0.004 BiFeO3- x LiSbO3 (x =0.00, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07) lead-free piezoelectric ceramics were prepared by the conventional mixed oxide method. The compositional dependence of the phase structure and the electrical properties of the ceramics were studied. A morphotropic phase boundary between the orthorhombic and tetragonal phases was identified in the composition range of 0.03 < x < 0.06. With the content of LS increases, the size of the pores significantly decreases. However, adding larger amount of LS makes the pore size increase slightly. The (0.996-x)KNN-0.004 BF-xLS(x=0.05) ceramics possess good electrical properties: d33 = 280 pC/N, kp = 53.3%, Tc = 345 °C, εr = 1613, Tan δ =2.07%. These results show that the ceramic is a promising lead-free piezoelectric material.

Abstract: Vibration feeder is the device of subsequent orientation feeding using vibration for the granular or power materials. This device could be used in food, medicine, chemistry and so on. We announce the phenomenon of materials handling based on testing and analyzing the granular materials in the multi-source piezoelectric vibratory feeder. The results show that the vibratory spreads is the traveling wave in this device, when the device is operated. The elastic particle is the elliptic movement at the end of the stuff box. The dynamic of material movement mainly come from the traveling wave caused by particle elliptical movement, the destruction to the grain’s natural balance status caused by the vibration and the geometric position-limit guiding structure of the device and so on.