Search results for "Piezoelectric"

Quasi-Static Displacement Self-Sensing Measurement for a 2-DOF Piezoelectric Cantilevered Actuator

2017

This paper proposes a self-sensing measurement technique to perform the precise estimation of the displacements along two axes in a two-degrees-of-freedom (2-DOF) piezoelectric actuator. For that, a new electrical circuit scheme that permits charge amplification is first proposed to match the different electrodes combination of the 2-DOF actuator. Then, a new bivariable observer that precisely estimates the displacements is calculated and implemented experimentally in a cascade with the electrical circuit to complete the self-sensing. The experimental tests and results verification with external sensors revealed that the measured displacements given by the developed self-sensing measurement…

Innovative method to estimate state of charge of the hydride hydrogen tank: application of fuel cell electric vehicles

2021

International audience; Significant attention has been paid to metal hydrides (MH) as an environmentally friendly and safe way to store hydrogen. This technology has considerable potential for the application of embedded hydrogen storage in fuel cell electric vehicles, but its widespread application faces a major problem in terms of estimating the remaining hydrogen amount in the tank. In this work, a new method is proposed for estimating the state of charge (SoC) of the hydrogen hydride tank (HHT) by application of piezoelectric material. The idea is to cover the entire inner wall of the metal-hydride tank with a layer of piezoelectric material. During the process of hydrogen absorption, t…

Energy harvesting using piezoelectric transducers for suspension systems

2020

Abstract Energy harvesting by using functional materials in suspension systems bear potential to win-back certain (even if low) amounts of vibrational energy, otherwise dissipated via the conventional (passive) dampers. Piezoelectric (PE) ceramics are functional materials that can be used for transforming mechanical energy into electrical and vice versa. In this paper, we study the capabilities and efficiency of energy harvesting (EH) with PE transducers under two different kinds of external excitation: i) Periodic and ii) stochastic. An appropriate nonlinear lumped parameter electromechanical model (LPEM) is brought into the two-port network notation. Laboratory experiments were conducted …

Quantification of propagating and standing surface acoustic waves by stroboscopic X-ray photoemission electron microscopy.

2018

The quantification of surface acoustic waves (SAWs) in LiNbO3 piezoelectric crystals by stroboscopic X-ray photoemission electron microscopy (XPEEM), with a temporal smearing below 80 ps and a spatial resolution below 100 nm, is reported. The contrast mechanism is the varying piezoelectric surface potential associated with the SAW phase. Thus, kinetic energy spectra of photoemitted secondary electrons measure directly the SAW electrical amplitude and allow for the quantification of the associated strain. The stroboscopic imaging combined with a deliberate detuning allows resolving and quantifying the respective standing and propagating components of SAWs from a superposition of waves. Furth…

Active repair technology applied to delaminated composite structures

2009

The main target of the present paper is represented by the fracture mechanics charac-terization of delaminated composite structures actively repaired through piezoelectric patches. A boundary element code, formulated for anisotropic piezoelectric solids, including, as limiting case, the applicability to linear elastic anisotropic materials has been then imple-mented. The modeling of the delaminated composite structures as well as of the assembled structures, made of the damaged components and the patches, has been achieved through the multidomain technique. Moreover, to take into account for the adhesive layer between the host structures and the piezoelectric patches, a "spring-model" has b…

BE contact analysis of delamination cracks actively repaired trhough piezoelectric active patches

2009

Analysis of piezoelectric active patches performances by boundary element techniques

2008

This paper presents the analysis of active piezoelectric patches for cracked structures by Boundary Element Method. A two dimensional boundary integral formulation based on the multidomain technique is used to model cracks and to assemble the multi-layered piezoelectric patches to the host damaged structures. The fracture mechanics behavior of the repaired structures is analyzed for both perfect and imperfect interface between patches and host beams. The imperfect interface, representing the adhesive between two different layers, is modeled by using a “Spring Model” that involves linear relationships between the interface tractions, in normal and tangential directions, and the respective di…

BE analysis of delaminated Composite Structures repaired with Piezoelectric Active patches

2009

The main target of the present paper is the analysis of the fracture mechanics behavior of delaminated composite structures actively repaired through piezoelectric patches. The aim at issue has been achieved by using a boundary element code implemented to study piezoelectric solids, including, as limiting case, the applicability to linear elastic anisotropic materials. The assembled structures, made up of the damaged composite components and the piezoelectric patches, have been modelled through the multidomain technique. To take into account for the adhesive layer among the host structure and the active patch, an interface spring-model has been also implemented. The multidomain technique co…

On the use of the electromechanical impedance technique for the assessment of dental implant stability: Modeling and experimentation

2014

We propose the electromechanical impedance technique to monitor the stability of dental implants. The technique consists of bonding one wafer-type piezoelectric transducers to the implant system. When subjected to an electric field, the transducer induces structural excitations which, in turn, affect the transducer’s electrical admittance. The hypothesis is that the health of the bone surrounding the implant affects the sensor’s admittance. A three-dimensional finite element model of a transducer bonded to the abutment of a dental implant placed in a host bone site was created to simulate the progress of the tissue healing that occurs after surgery. The healing was modeled by changing the …

A new method to calculate external mechanical work using force-platform data in ecological situations in humans: Application to Parkinson's disease

2016

Abstract Background and aim To accurately quantify the cost of physical activity and to evaluate the different components of energy expenditure in humans, it is necessary to evaluate external mechanical work ( W EXT ). Large platform systems surpass other currently used techniques. Here, we describe a calculation method for force-platforms to calculate long-term W EXT . Methods Each force-platform (2.46 × 1.60 m and 3.80 × 2.48 m) rests on 4 piezoelectric sensors. During long periods of recording, a drift in the speed of displacement of the center of mass (necessary to calculate W EXT ) is generated. To suppress this drift, wavelet decomposition is used to low-pass filter the source signal.…