Investigation of multifrequency piezoelectric energy harvester

This paper presents results of numerical and experimental investigations related to the piezoelectric energy harvester that operates at multifrequency mode. Employment of such operation principle provides an opportunity for obtaining frequency response characteristics of the harvester with several resonant frequencies and in this way increasing efficiency of the harvester at a wide spectrum of excitation frequencies. The proposed design of the energy harvester consists of five cantilevers which forms square type system. Cross sections of the cantilevers are modified by periodical cylindrical gaps in order to increase strain value and to obtain more uniform strain distribution along the cantilevers. Cantilevers are rigidly connected to each other and compose an indissoluble system. Square type harvester has seismic masses at every corner. These masses are placed under specific angle in order to reduce natural frequencies of the system and to create additional rotation moments in the body of harvester. Results of the numerical investigation revealed that harvester has five resonance frequencies in the range from 15Hz to 300Hz. Numerical analysis of the harvester revealed that the highest open circuit voltage density is 19.85mV/mm3. Moreover, density of the total electrical energy reached 27.5 mJ/mm^3. Experimental investigation confirmed that frequency response characteristics are obtained during numerical investigation and showed that energy density of the whole system reached 30.8 mJ/mm^3

Modeling and design optimization of butterfly type piezoelectric actuator

A study of a novel design miniature butterfly type piezoelectric actuator is proposed and analyzed in the paper. Actuator consists of butterfly type oscillator and two piezoceramic elements. Operating principle of the actuator is based on exciting electrodes of the piezoceramic elements using input voltage of the same frequency but different phases. Elliptic trajectory of the contact point movement is achieving when phases of the voltage differ by ?/2 on different electrodes. Numerical modelling and simulation of the piezoelectric actuator was performed using finite element method. Natural frequencies, modal shapes and actuator response to the different input voltage sets were analyzed. Optimization of actuator boundary conditions was carried out. Experimental prototype of the piezoelectric actuator was built and measurements of driven tip movements were performed. The results of numerical and experimental studies are discusse

Rod-shaped piezoelectric actuator with radial polarization

This paper analyzes contact point trajectories of the rod-type piezoelectric actuator, which has circular cross-section and is characterized by the non-uniform polarization. Radial polarization is used to achieve flexural oscillations in perpendicular planes and to increase number of degrees of freedom of the contact point movement. Particular electrode pattern of the actuator was determined and contact point trajectories were studied under different excitation regimes. A prototype of piezoelectric actuator was developed and experimental measurements of contact point trajectories were performed. The results of numerical modeling and experimental study are compared and discussed

Multifrequency piezoelectric energy harvester based on polygon-shaped cantilever array

This paper focuses on numerical and experimental investigations of a novel design piezoelectric energy harvester. Investigated harvester is based on polygon-shaped cantilever array and employs multifrequency operating principle. It consists of eight cantilevers with irregular design of cross-sectional area. Cantilevers are connected to each other by specific angle to form polygon-shaped structure. Moreover, seven seismic masses with additional lever arms are added in order to create additional rotation moment. Numerical investigation showed that piezoelectric polygon-shaped energy harvester has five natural frequencies in the frequency range from 10 Hz to 240 Hz, where the first and the second bending modes of the cantilevers are dominating. Maximum output voltage density and energy density equal to 50.03 mV/mm3 and 604 μJ/mm3, respectively, were obtained during numerical simulation. Prototype of piezoelectric harvester was made and experimental investigation was performed. Experimental measurements of the electrical characteristics showed that maximum output voltage density, energy density, and output power are 37.5 mV/mm3, 815.16 μJ/mm3, and 65.24 μW, respectively

Dependence between stiffness of fixed foundation and blower supports

This paper analyzes mechanical system consisting of two blowers, each having a separate frame. The system is fixed on one foundation. High-level vibrations are excited during its operation. Results of experimental research of this mechanical system are presented here. The developed finite element model provides the possibility to analyze natural frequencies of the system. The reasons of observed high-level vibrations were identified by comparing experimental and numerical results. The conception of vibration reduction was proposed based on the results of this investigatio

Radionuclide and heat transport from hypothetical SNF canister in crystalline basement, case of south-eastern Lithuania

The Strategy on Radioactive Waste Management of Lithuania (Radioaktyviųjų… 2008) envisages evaluating the possibilities of disposal of spent nuclear fuel and long-lived radioactive waste from operation and decommissioning of Ignalina NPP in a deep geological repository. The crystalline basement and sedimentary cover of south-eastern Lithuania was selected for the current model case studies due to availability of geological and hydrogeological data from previous explorations. Groundwater flow, radionuclide (iodine-129 as mobile and long-lived one) transport and heat transfer, modelling using computer code FEFLOW was performed. The model domain of south-eastern Lithuania comprises Protero-zoic-Archaean aquifer with overlaying aquifers system of sedimentary cover. The upward groundwater flow through defected canister located in tectonically damaged zone was conservatively generated. The main results of calculations are following: in case of upward groundwater flow, the maximum activity concentration of 129I in groundwater of the tectonic fracture zone above defected canister will not exceed 10−4 Bq/l; the maximum temperature in the tectonic fracture will obtain about 30-35°C and will not impact on the radionuclide transport. Location of model domain in south-eastern Lithuania does not mean any reference to the site for deep geological repository. The results show that doses obtained by human via drinking water should be below the dose constraint (0.2 mSv /year). Article in English. Radionuklidų ir šilumos sklaida iš hipotetinio PBK konteinerio kristalinio pamato uolienose (pietryčių Lietuvos pavyzdys) Santrauka. Radioaktyviųjų atliekų tvarkymo strategija numato galimybę panaudotą branduolinį kurą ir kitas ilgaamžes radioak- tyviąsias atliekas, susidariusias eksploatuojant Ignalinos AE ir susidarysiančias ją demontuojant, galutinai patalpinti giliai geologinėse formacijose. Dėl didelio geologinės bei hidrogeologinės informacijos kiekio šiame darbe nagrinėti tik Pietryčių Lietuvos kristalinis pamatas bei jį dengiantys nuosėdinių uolienų sluoksniai. Radionuklidų bei šilumos sklaidai kristalinio pamato uolienose vertinti naudota kompiuterinė programa FEFLOW 5.0. Pasirinkta konteinerio defekto scenarijus, taikant skaičiavimus, atliktus LEI ekspertų. Modelis apima archėjaus ir proterozojaus vandeningąjį sluoksnį bei nuosėdinėje dangoje slūgsančius vandeninguosius kompleksus. Modeliuotas požeminio vandens srautas, kylantis per tektoniškai pažeistą zoną, kurioje palaidotas PBK konteineris. Iš pagrindinių modeliavimo rezultatų nustatyta, kad ilgaamžio ir mažai sorbuojamo radionuklido 129I sklaidos intensyvumas mažai priklauso nuo geologinės aplinkos savybių, o šilumos sklaida neturi įtakos radionuklidų sklaidai. Žmogaus gaunama dozė, skaičiavimų duomenimis, nesieks ribinės vertės (0,2 mSv/metai). Reikšminiai žodžiai: panaudotas branduolinis kuras, geologinis atliekynas, kristalinis pamatas, požeminis vanduo, baigtiniai elementa

Piezoelectric cantilevers for energy harvesting with irregular design of the cross sections

Results of the numerical and experimental investi-gations of the piezoelectric rectangular cantilevers with ir-regular design of the cross section area are presented in this paper. The aim of the investigation was to analyse how mod-ification of the cross section area by periodical gaps acts on power density of the piezoelectric energy harvesting sys-tems based on a rectangular cantilever. It was found out, that modifications of the cross section area ensure higher strain values and allows to improve strain distribution in piezo ce-ramic layer and by this way to improve power density of the energy harvesting systems. Numerical investigations of the piezoelectric cantilevers with irregular design of the cross section area were performed in order to analyse strain dis-tribution and predict electrical characteristics of the im-proved energy harvesting systems. Experimental investiga-tions of the prototypes were performed and results of the numerical modelling were validated. Results of the numeri-cal and experimental investigation are discussed as well

Air flow pressure drop research of vehicle air filter with different inner liner design

Air filters was designed for air cleaning. They extends automotive and industrial devices life, because it cleans absorbing air from environment. For example it cleans air for internal combustion engines, air compressors, air conditioners and so on [1]. For better air cleaning it is necessary to create air filter housing model and make air flow calculations. Calculation results helps to adapt additional elements for longer air filter element life and better air filtration. During calculations was found one of the best technical solutions for better air filtration. Designed part was produced using 3D printer. Later with assembled filter some measurements and experiments were made. This article presents air flow pressure drop in air filter with different inner liners