Papers by Keyword: Piezoelectric Composite

Abstract: It is vital to use acoustic emission technology to study on health monitoring of concrete. The aim of this study is to investigate the ability of the AE in order to test the effect of the stepwise displacement load on the damage mechanism of the concrete beams that embedded sensors under three-point bending. The result showed that as the damage increased, amplitude and energy increased. At the same time, embedded sensors can locate the position of the crack.

Abstract: Use relaxor ferroelectric single crystals PMNT as piezoelectric phase, epoxy resin as a non-piezoelectric phase material, take the cutting - filling method fabricated piezoelectric composite. Its structure character is achieved 1-3 type piezoelectric composites and piezoelectric crystal substrate composite again inseries by the integration, the composite horizontal and vertical bracket to be supported by piezoelectric crystal frame, it has a good impact resistance and affected by changes in ambient temperature characteristics. This composite material both has the advantages of 1-3 type composites, and has stable mechanical and thermal properties. Based on R.E.Newnhams series-parallel theory, combined with the structural characteristics of this composite, given the formula of piezoelectric composites density, piezoelectric constant, and dielectric constant. Fabricated the PMNT / epoxy composites and piezoelectric PZT / epoxy piezoelectric composite materials samples, which have the same scale, the same structural parameters. The experimental results show that, the piezoelectric composite test parameter values match theoretical calculations. The PMNT/epoxy composite has batter function than PZT/epoxy composite.

Abstract: This paper mainly states that under the PID program control, syntactic foam cantilever beam and piezoelectric composite cantilever beam which are studied with the momentary force and the alternating force signal, in the effective of active damping. The vibration stopping time changes under the momentary force and the amplitude changes under the alternating force signal. Comparing under the same initial amplitude, the amplitude changes of syntactic foam cantilever beam and piezoelectric composite cantilever beam under the active damping.

Abstract: This paper introduces several models for different piezoelectric composites with the modeling process and mechanism. In order to characterize the uniformity and stability, the volume density of particles and fibers changed with volume is studied. The models generated by ANSYS finite analysis are showed, which the codes are produced by the models.

Abstract: Strontium ferrite modified 0-3 cement-based piezoelectric composites were produced with piezoelectric ceramic [0.08Pb(Li1/4Nb3/4)O•0.47PbTiO3•0.45PbZrO3], sulphoaluminate cement and strontium ferrite by compressing technique, and the effects of poling conditions on the piezoelectric and dielectric properties were investigated. In order to contrast, a unmodified 0-3 cement-based piezoelectric composite was fabricated. The results show that the higher the poling electric field, the longer the poling time and the higher the poling temperature, the composites have the higher piezoelectric strain factor d33, piezoelectric voltage factor g33, dielectric constant εr and dielectric loss tanδ， and the strontium ferrite modified composites are polarized more easily, and have better properties than the unmodified composites. In the meantime, the optimum poling conditions were obtained, and the optimum poling field E, poling time t and poling temperature T were 5 kV/mm, 20 min and 80 °C.

Abstract: The interfacial reinforcement with interlaminar chopped fibers of piezoelectric composite under impact electro-mechanical load was studied using nonlinear finite element method. A meso- mechanical model based on the main toughness reinforcement mechanism of single fiber bridging and pull out was adopted, and then a tri-linear bridging law was obtained, while the interface chopped fibers by defining nonlinear bidirectional spring elements between coincident nodes on the two crack surfaces within bridging zone and the energy release rate was calculated using the virtual crack closure technique. The numerical investigation indicates that the interlaminar chopped fiber can effectively reduce the crack tip energy release rate whether the applied voltage is positive or negative, which was an effective technique improve the interfacial toughness of the piezoelectric composite adhesive structure.

Abstract: 1-3 type cement/epoxy resin based piezoelectric composite was designed and fabricated aiming at providing a new method for cement hydration monitoring. Combining with piezoelectric impedance technology, the cement hydration reaction process was monitored by using the composite. The research results show that in the initial cement hydration period, the resistance-frequency curves of the sensor drift toward low frequency direction, while the anti-resonance resistance value decreases gradually. With increasing cement hydration time, the resistance-frequency curves of the sensor drift toward high frequency direction and the anti-resonance resistance value shows fluctuation changes. The cement hydration reaction process can be divided into different periods according to changes of anti-resonance frequency and anti-resonance resistance value of the sensor.

Abstract: Sulphoaluminate cement and Lead Niobium-Magnesium Zirconate Titanate ceramic (PMN) were used as matrix and functional component to fabricate 1-3-2 piezoelectric ceramic-cement composites by dicing and filling method. The influences of base thickness on piezoelectric, dielectric and electromechanical coupling properties of the composites were analyzed and discussed. The results show that with increasing the base thickness, the piezoelectric stain factor d₃₃ increases gradually, while the piezoelectric voltage factor g₃₃ decreases. The relative dielectric factor ε_r decreases initially and then increases, while the dielectric loss tan δ increases initially and then decreases. When base thickness is 0.50 mm, ε_r has the minimum value of 1406. When base thickness is 3.00 mm, tan δ reaches the minimum value of 0.251. With increasing the base thickness, the planar electromechanical coupling coefficient K_p exhibits the decreasing trend, and the thickness electromechanical coupling coefficient K_t and acoustic impedance Z show the increasing trend.

Abstract: Two-step casting method was developed for preparing quasi constrained layer damping structural polymeric composite. Quasi constrained layer structural piezoelectric ceramic P82/carbon black(CB)/epoxy resin(EP) composites were successfully prepared when the ceramic content was less than 30% in volume. Dynamic mechanical analysis(DMA) showed that the composites with quasi constrained layer structure exhibited perfect damping properties. When the piezoelectric ceramic P82 volume fraction was 10%, the composite showed the highest loss factor peak value of 1.182, the widest damping temperature range of 44.2°C, and the largest loss area of 32.17. The storage moduli of composites with quasi constrained layer structures were higher than that with non quasi constrained layer structure.

Abstract: The PMN/EP composites were prepared by resin casting method from PMN powder pretreated with silane coupling agent KH-550. The microstructure of the PMN/EP composite was observed by SEM, the damping property and dielectric property of the composite were investigated by dynamic mechanical analyzer and impedance analyzer respectively. In the composite prepared with PMN powder pretreated by 1.5% silane coupling agent, much epoxy resin fragment is attached in the surface of PMN particles. When the silane coupling agent concentration is 1.5%, the composite shows the best damping property. Dielectric analyses suggest that the dielectric constant of the PMN/EP composite decreases with the increase of silane coupling agent content, however the dielectric loss increases with the increase of silane coupling agent content.