In this work, the piezoelectric response of modified asphalt design that can significantly solve damage that arises from overloading and high traffic load effects during the service-life were studied. The piezoelectric response of standard and modified binder with 0%, 5%, 10% and 15% of kaolin and hydrated lime content have been studied using voltmeter and Marshall compressive test machine. The olin and hydrated lime induces the piezoelectric response compared to the standard asphalt mixture. Various types of loadings have been considered throughout this study. It was determined that the type of modifier and applied load have an effect on the result of piezoelectric response on the surface and within an asphalt pavement structure. Also the result showed that modification of bitumen by kaolin and hydrated lime enhances its performance characteristics as properties. The rheological studies on kaolin and hydrated lime modified bitumen were made through penetration test. It was observed that kaolin and hydrated lime showed an effect on penetration. Better results were obtained when hydrated lime concentration The mechanical properties of the standard asphalt mixture and modified asphalt mixture with kaolin and hydrated lime were evaluated using Marshall immersion test. This study showed that %,10% and 15% of modifier satisfy the minimum Ethiopia road authority acceptance criteria of air voids(except at 5%,10% hydrated lime and kaolin content respectively), void mineral aggregate, void filled with asphalt and Marshall
grain sizes and microstructures with d ∗ 33 ranging between 30 and 350 pC/N , but values as high as 500 pC/N have been reported . The extrinsic contribution from the motion of the domain walls may be a consistent part of the total piezoelectric response, so that the nature of the domains and mobility of the domain walls certainly contributes to the variability of the results from sample to sample; in addition, since the domain wall contributions are frequency dependent and nonlinear, techniques probing different strain amplitudes and frequencies obtain different results on a same sample. Yet, there are other factors determining the measured d ∗ ij , and a major difficulty is obtaining complete poling of the ferroelectric domains, with the spontaneous polarization P s as parallel as possible to
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In recent decades, a number of experiments with coherent acoustic phonons have been performed in PE semiconduc- tors and related nanolayers [4 – 11]. All of these works use femtosecond optical excitation to modulate the polarization in a PE sample by the generation of photocarriers, resulting in instantaneous stress. This stress generates terahertz coherent phonons (high-frequency acoustic waves), which, due to the PE field, modulate the optical properties in the same or a neighboring nanolayer for detecting the coherent phonons with the probe optical pulse. Importantly, the PE field enables the generation and detection of elastic shear perturbations which accompany transverse acoustic (TA) phonons [6 – 11]. The other electron-phonon interaction mechanism, the deformation potential (DP), does not couple electrons in an isotropic conduction band with shear perturbations. The theory of the generation and detection processes resulting from the PE effect has been reported in several publications [7,12]. In previous experiments with coherent phonons, the PE field in the sample has been measured indirectly by monitoring the optical properties. In this case, the PE effect is often masked or hidden by the DP mechanism , which produces an efficient optical response due to the modulation of the band-gap value .
Lead titanate PT ceramics modified by rare earth elements and alkaline earth elements have emerged as highly promising materials for several piezoelectric applications. This is due to existence of large electromechanical anisotropy in the coupling factors along and transfers direction of polarization -.
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in the temperature range from 183 ºC to 188 ºC [ 51 ]. The control sample showed a minor α-β transformation and the formation of a pre-crystalline shoulder at a lower temperature, which is believed to be the δ-phase produced by drawing or stretching. The reason is related to the CB filler particles interfering with the – CF 2 – CH 2 – (head to tail) polarization of the PVDF, and is associated with the generation of head-head and tail-to-tail defects in the polymer chain [11,12,13]. According to Zhao [ 52 ], the defects in the crystal structure of PVDF produced by drawing destroy the perfection of any crytallinity that may be present in the amorphous regions. This change is observed as a reduction of the melting point and a reduction in the enthalpy of the DSC curves. In the case of the composite fibers, the energy of drawing was responsible for crosslinking smaller defective crystals and transforming a small quantity of α-form to γ form (i.e. a mixture of α and β ) and a large quantity into the δ form that has almost the same thermal behavior as the α form. However, the δ form is prone to switching to the β form after being poled by high power electric fields. The poling process dramatically increased the β content, resulting in the enhancement of piezoelectric effects in the drawn samples. The new phase in the polymer composite is considered to be the δ form due to evidence from the x-ray diffraction tests.
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arrangement ideal for launching and detecting surface waves. Translated to the ear, the three rows of outer hair cells (OHCs) are conjectured to be the interdigital transducers. In the simplest (degenerate) SAW resonator, only a single set of three electrodes is required to create resonance between the fingers, a situation presumed to apply in the cochlea, where OHC2 is assumed to respond in antiphase to OHC1 and 3. The antiphasic response is not to displacement, but to intracochlear fluid pressure. An examination of the literature interprets OHCs as responding directly to pressure via their cell bodies, and two populations, with opposite response polarities, are observed. Whether an OHC behaves in one way or the other depends on its membrane potential and turgor pressure, so it is conjectured that OHC1/3 operate at a membrane potential of about –70 mV, whereas in OHC2 it is about –50 mV. At low sound pressure levels, two mechanisms for creating an electrical response in OHCs are identified: one involves the piezoelectric response of the OHC wall to pressure, the other a transient sodium current which acts as a biological ‘transistor’ to amplify the transducer voltage.
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The necessity of large voltage-induced deformations is a reason for the use of piezoelectric ceramics as piezo- electric layers. These ceramics are based on a ferroelec- tric perovskite materials, such as lead zirconate titanate (PZT). Large piezoelectric response of PZT ceramics is achieved due to extrinsic contributions to piezoelectric co- e ffi cients due to movements of domain walls in an applied electric field. Since the movements of domain walls are irreversible in high electric fields, the characteristic fea- ture of the actuation is a pronounced hysteresis . This © Owned by the authors, published by EDP Sciences, 2013
The direct piezoelectric effect of the piezoelectric layer subjected to outer pressure is investigated in detail. It is always assumed in the analytical analysis of the piezoelectric structures that the electric potential in the piezoelectric layers varies linearly and the displacements change in the form of prescribed functions across its thickness (Kapuria 1997). However, it has been shown that the distributions of the mechanical displacements and electric potential of piezoelectric response are very complicated and cannot be treated as pure elastic structures or piezoelectric structures. Therefore, three-dimensional analysis of piezoelastic behavior of structures is recommended even for thin laminated structures. Since a comprehensive and exact study of active piezoelectric structures is still unavailable, the present work provides an enhanced insight to the mechanical and electric behaviors of this type of smart structure. Results presented in this paper are also useful for assessing approximate analysis.
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Smart multi‐layered hybrid beams with some sensory and actuator piezoelectric layers constitute an im‐ portant element of adaptive structures. These structural systems are generally made of composite and sandwich laminates because of their high stiffness to weight ratio. Considerable attention has been received in literature on behaviour of hybrid smart structures and reviewed by many researchers Benjeddou, 2000; Sunar and Rao, 1999; Saravanos and Heyliger, 1999; Tang et al., 1996 . Saravanos and Heyliger 1995 developed a Unified mechanics with the capability to model both sensory and active composite laminates with embedded piezoelectric layers. Layerwise formulations enable analysis of both global and local electromechanical response. They presented an approximate finite element solutions for the static and free vibration analysis of beams. But the computational effort increases with the number of layers. Many researchers used Equivalent single layer theory approximations Correia et al., 2000; Mitchell and Reddy, 1995 for the structural analysis. Since the same global variation of dis‐ placement is assumed across the thickness independent of material properties and lay‐up, such analysis fails to report the zigzag nature of in‐plane displacements variations.
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major or minor axis of the MEMS chip were created. Both investigated cases have identical holder configurations next to this, with the first holder having two 750µm high inlets on the sides of the spring connections of the microphone design (long axis), while the second configuration has been rotated in the plane of the membrane by 90° and has inlets at the sides of the membrane highest movement (short axis). For both cases FEM simulations and electrical measurements were performed with the same setup as in the previously shown configurations. The resulting directionality projections along the elevation are shown in Fig. 8. For both cases a good agreement between the simulations and measurements can be seen for each orientation of the maximum sound response. However, specifically at the highest resonance frequency, the shape of directionality pattern changes from the desired first order directionality to a pattern more resembling a subcardioid or shotgun directivity. Having the inlets at the end of the long axis of the membrane shows an almost identical behavior to the configuration with four air inlets and identical inlet height. The directionality at the first resonance frequency shows an angular offset of 23°, while the other three frequency bands have a first order directional response with a maximum at an incident normal to the membrane. Having the inlets at the sides of the membrane spring connections results in a larger offset angle of 54° for the first frequency band, which is confirmed both experimentally and in simulation. The three subsequent frequency bands show experimentally and in simulation a reduced directionality for the case with the backside inlets positioned at the membrane side, with an additional experimentally determined tilt of the maximum response by 11° for second band and 21° for third resonance band. Specifically, for the highest frequency band the measured directionality resembles more closely a response equivalent to the one obtained from a holder and microphone system with a closed backside cavity than the similar open cavity cases.
The directionality response of the presented microphone design family shows a maximum acoustic response for the 1 st frequency which is normal or in-plane relative to the micro- phone membrane, depending on the acoustic access to the microphone back cavity. This is similar to work shown in , with the mathematical description showing this difference to originate due to the acoustic access to the backside of the microphone membrane. For microphone designs having more than two resonance frequency bands some of the assumptions of this model fail, but the response presented here still shows that the acoustically open backside holders create a similar directionality response in all four frequency operation bands, while the closed backside holder configuration limits this directionality response. A packaging design for multiband Ormia-inspired MEMS microphones including this constraint is therefore a necessity for these type of MEMS directional microphones. For the presented asymmetric designs an addi- tional constraint on the directional response has been shown related to the size of the back cavity air inlets using FEM simulations. An experimental comparison especially in the low micrometer height range was limited due to fabrication tolerances of the 3D-printer used for the housings investigated in this work. Nevertheless, the simulations related to the available experimental configurations showed a good overlap with the measured microphone and housing systems. The physical origins of this directionality behavior lie in both the membrane geometry as well as the change in acoustic impedance through the narrowing of the acoustic access ducts to the back of the membrane, which is an effect used in
Fundamental of the piezoelectric transducer is related with orientation electric dipole. The polarization process of piezoelectric material is shown in Figure 2.1. Due to the absence of electric field, the unpoled electric dipoles are oriented randomly. When an electric field is applied longitudinally, electric dipoles are aligned themselves in a single direction that closes to the electric field. In addition, the piezoelectric material expands and contracts due to its crystalline structure. Since all the electric dipoles are pointing to the same direction, a net with same polarization occurs. After the electric field is removed, the orientation of electric dipole will remain the same position and it called as remnant polarization.
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polynomials, especially the Lagrange and Hermite polynomials. One of the main trade-offs while pursuing the conventional finite element method is that, the more complex the geometry is, the more complex becomes the meshing and the computational time increases. Analytical representation of curves, lines, surfaces and conics have different methods of representing each of them. This form of representation is easier for a designer to understand and get a physical context about the formulas and coordinates. However, it becomes counterintuitive as the geometry becomes complex. The intersection of surfaces with different forms of representation is often difficult to comprehend. Furthermore analytical methods are not suited to represent freeform curves and surfaces. Parametric curves like cubic splines, Bezier curves, B-splines and NURBS possess a common mathematical form for all type of geometrical entities. The data associated with parametric representation can be easily stored in matrix form and conversion between various formats is easier, i.e. the parametric curves can be manipulated and local changes made by simple steps. The first phase includes developing algorithms and programs for NURBS curves, surfaces and volumes, testing the numerical stability of programs, derivatives and numerical integration. The present work aims at proposing a computational method to study the dynamics of piezoelectric sensors, actuators, power harvesters using a numerical technique based on NURBS.
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Apart from PZT, other materials have since then, been identified regarding piezoelectric effect. For instance, in 1969, polivinylidene fluoride (PVDF) a strong uniaxial drawn strong piezoelectricity. Additionally, it also came to known that piezoelectric effect could be derived from other plastics such as nylon and polyvinyl chloride (PVC) (Garcia, et al., 2007): though of lower intensity. Currently, studies on grain-oriented glass-ceramic, a glassy and a more crystalline phase composite, is still being studied for its latent promise for a bright future in the piezoelectricity. Piezoelectric Effect Electromechanical coupling dictates that stress (T), electric field (E), strain (S), polarization (P), and flux density mechanical properties are all interrelated in piezoelectric crystals (Zhang, et al., 2006).
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As to interconnection mode, by series mode, parallel mode or series-parallel mixed mode, several piezoelectric vibrators can be interconnected to form mul- tilayer piezoelectric vibrator so as to enable small piezoelectric material to have relatively high power generation capacity under weak motivation and in wide frequency band. n pieces of paralleled piezoelectric vibrators can increase the output current by n times, and n pieces of serialized piezoelectric vibrators can increase the output voltage by n times. Paralleled piezoelectric vibratos have great output current and great equivalent capacitors, and are applicable to small load impedance situation; serialized piezoelectric vibratos have high output vol- tage and small equivalent capacitors, and are applicable to great load impedance situation. Therefore, through the optimization of the series-parallel mixed mode of piezoelectric vibrators, the voltage and current output characteristics of pie- zoelectric power generation equipment can be optimized, which is beneficial for electric power grid connection. From analytical calculations, reference  de- monstrates that the multilayer piezoelectric vibrator consisting of 145 piece se- ries-parallel piezoelectric vibrators (height 1.8 cm, section area 1 cm 2 ) has 1 - 10
four equivalent domains and of 54.7 . In this study, we expected that if the number of the equivalent domains constructing the engineered domain conﬁguration is same, the smaller angle can cause the larger piezoelectric properties. The result in Fig. 6 supported the above hypothesis. Therefore, when the E-ﬁeld was applied along the  c direction of BaTiO 3 single crystals, the ortho-
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Received: 30 August 2014 – Revised: 17 November 2014 – Accepted: 2 December 2014 – Published: 7 April 2015 Abstract. Acoustic piezoelectric resonators are widely used as precise analytical chemistry tools for the real- time monitoring of a negligibly small amount of surface-attached mass of biological components, in particular, in environmental biosensor measurements. The surface acoustic wave (SAW)-based sensors and the quartz crystal microbalance (QCM) compared in our work belong to the leading group due to their considerable advantages. These piezoelectric resonators are considered now as high-resolution analytical tools allowing researchers to discriminate between components due to the selective polymer coating on the resonator surface. The gravimet- rical measurements performed with the SAW-based or QCM sensors provide the experimental data with high precision for the detection of surface mass for the thin adsorbed layer rigidly attached to the oscillator surface. The new challenge is the analysis of soft and biological materials, where the viscous losses of energy can essen- tially influence measured characteristics. Modelling is the important part of the analysis allowing researchers to quantify the results of the experiments. The present work provides a general theory of SH-SAW devices probing soft and biological materials. The results are compared with QCM-D operated in liquid media.
Khrissy Arcelly Reis Medeiros, et al. presents the “Optimization of flow rate measurement using piezoelectric accelerometers: Application in water industry”. This paper shows that method of measurement of water flow rate using piezoelectric accelerometer. The piezoelectric accelerometer is useful for measurement of vibration. Hence, system is based on FIV technique i.e. Flow Induced Vibration. This system is specifically used in water industry. System is unable to measure flow variation during measurement so obtained flow rate is not accurate. 
In this article, displacement, and circumferential, axial and effective stresses of a thick-walled smart composite cylinder with end-caps, made from piezoelectric materials (PVDF reinforced by DWBNNT's) and subjected to mechanical, electrical and thermal fields are studied. Apart from the piezoelectric nature of the materials used and the associated model for evaluating the overall mechanical characteristics, the contribution of the paper include consideration of 3-dimensional structural analysis and orthotropic composite
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This thesis presents a coupled mechanical device that generates power by a direct conversion of the airflow into mechanical vibrations. The mechanism experiences a fluid force that changes with its orientation causing vibrations. The device consists of two tightly coupled parts: a mechanical resonator that produces high-frequency mechanical oscillations from quasi-steady airflow resulting in large amplitude vibrations and a piezoelectric power generator harvesting the energy from the resonator’s motion. Instantaneous velocity interactions were studied using numerical modeling and experimental tests. The proposed energy harvester allows for locking up the device’s lowest natural frequency to the vortex-shedding resonant frequency induced by the ambient energy source. Furthermore, an array consisting of 8 harvesters was constructed and a net feasible power output was measured. A single energy harvester vibrating at its first Eigen frequency mode demonstrated a peak-to-peak output voltage of over 80V at 10Hz, from an input wind velocity of ~7 m/s.
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