Modelling vibrations of axial piezoelectric generator with active base

Modelling of an axial-type piezoelectric generator (PEG) is considered. PEG is an integral part of the system for converting mechanical vibration energy from the environment into electrical energy. The energy generator has an axial type of the configuration of elements, aimed on using bending and compressive loads simultaneously on piezoelectric elements. The base of the generator is made as an active pinching. A feature of PEG is that the generator has two types of piezoelectric elements: (1) elements located on the substrate in the form of a bimorph and (2) piezoelectric elements of a cylindrical shape, fixing the generator base, located on the same axis. PEG has a symmetrical structure about the center of proof mass. The results of modal and harmonic analysis of vibrations are given for vibration excitation of the PEG base in a certain frequency range. The analysis of the output characteristics is given.

OPTIMIZATION OF A PIEZOELECTRIC GENERATOR OF FLEXURAL VIBRATIONS WITH AN ACTIVE PIEZOMAGNETIC LAYER BASED ON A COMBINATION OF THE FINITE ELEMENT METHOD AND A GENETIC ALGORITHM

The construction of the piezoelectric generator (PEG) for the energy storage device has a significant effect on the electromechanical conversion characteristics, and the optimal choice of its geometric parameters is an important prerequisite for ensuring efficiency of the electromechanical conversion. This article discusses a PEG model based on circular three-layer plate in the ANSYS package. Two piezoactive layers, piezoelectric and piezomagnetic, are glued to a steel substrate. The program built in the MATLAB package allows to control ANSYS scripts to find the dependence of the electromechanical coupling coefficient on the geometric parameters of the object. The genetic algorithm is used to determine the maximum value of the electromechanical coupling coefficient when changing the radius and thickness of the layers within certain limits. Thus, a set of geometric dimensions is determined to achieve the best PEG energy conversion efficiency. After applying the optimization algorithm, the electromechanical coupling coefficient increases by 34% in comparison with the results of previous studies.

Properties of Car-Embedded Vibrating Type Piezoelectric Harvesting System

We investigated the harvesting performance of a double piezoelectric generator, which was embedded into the engine block of a small passenger car. The resonance frequency is approximately between 37 and 52 Hz, where the cantilever showed maximum displacement. In reality, the cantilever has a vibrating characteristic, which dramatically reduces displacement, even when the operating frequency deviates slightly from the resonance frequency. To acquire a large mechanical energy-to-electrical energy conversion, a multiple-piezoelectric generator was employed to absorb the energy even when the vibration switched from a resonance to a non-resonance frequency. In this study, a variable mass box was designed and installed in the engine block of a car. The variable mass box consisted of the serial connection of two masses with different weights. The operating frequency deviated from a resonance to a non-resonance frequency within a few hertz (3~4 Hz); the reduction in vibration was lower, leading to a significant acquisition of the resulting power. This is due to the variable matching of the generator, realized by the action of dual mass. This type of generator was installed in the engine block and produced up to 0.038 and 0.357 mW when the engine was operating at 2200 and 3200 rpm, respectively.

A Micro-Power Generator Based on Two Piezoelectric MFC Films

In order to realize the collection of micro or small vibration energy, a micro-power generator based on two piezoelectric Macro Fiber Composite (MFC) films is proposed. The piezoelectric generator consists of a double piezoelectric MFCs type vibrator and a displacement amplifying mechanism, which can achieve the output of high energy density. The design process of this kind of piezoelectric generator is presented. Based on LabVIEW platform and NI Data Acquisition (DAQ) card, the output voltage acquisition system of the generator is built, and the output voltage and power are collected and calculated. Experimental results show that the maximum output power is 6.2 mW under transient excitation. Under continuous excitation with a load resistance of 10 kΩ and an excitation frequency of 26 Hz, the maximum output of the generator is up to 11.9 mW. The research results lay a foundation for the application of the proposed micro-power piezoelectric generator.

Molecular engineering of piezoelectricity in collagen-mimicking peptide assemblies

Realization of a self-assembled, nontoxic and eco-friendly piezoelectric device with high-performance, sensitivity and reliability is highly desirable to complement conventional inorganic and polymer based materials. Hierarchically organized natural materials such as collagen have long been posited to exhibit electromechanical properties that could potentially be amplified via molecular engineering to produce technologically relevant piezoelectricity. Here, by using a simple, minimalistic, building block of collagen, we fabricate a peptide-based piezoelectric generator utilising a radically different helical arrangement of Phe-Phe-derived peptide, Pro-Phe-Phe and Hyp-Phe-Phe, based only on proteinogenic amino acids. The simple addition of a hydroxyl group increases the expected piezoelectric response by an order of magnitude (d35 = 27 pm V−1). The value is highest predicted to date in short natural peptides. We demonstrate tripeptide-based power generator that produces stable max current >50 nA and potential >1.2 V. Our results provide a promising device demonstration of computationally-guided molecular engineering of piezoelectricity in peptide nanotechnology.

Piezoelectric generator with nonlinear structure

Motion in nature is usually a low-frequency vibration such as walking, running, swinging arms, and so on, but traditional piezoelectric cantilever structures are inefficient at harvesting energy from low-frequency vibrations. T in the environment. To overcome this, a novel piezoelectric generator was designed. A cantilevered bimorph with a tip mass and a pair of preloading springs were fixed on its base to form a nonlinear piezoelectric generator. The energy transmission in the structure was analyzed. The harvester was modeled as a Euler–Bernoulli beam, and the piezoelectric material was assumed to be linear. The bending vibration was calculated using the Rayleigh–Ritz procedure, and the frequency characteristics of the output voltage were analyzed under different preloading distances. It was found that changing the preloading of the spring helped reduce the natural frequency of the cantilever, which facilitated conversion of ambient low-frequency vibrations into electrical energy. Then, the characteristics of low frequency energy harvesting were investigated experimentally. The theoretical results were consistent with the experimental data; moreover, the resonance frequency, which changes with the preloading distance, reduced from 43 to 35 Hz when the preloading distance was increased from 0 to 1 mm. In this paper, an effective structure to control the resonant frequency is proposed and its motion equation stated. The structure has potential for applications in predicting the effect of preloading distance on resonance frequency.