جستجوی مقالات مرتبط با کلیدواژه "resonant frequency" در نشریات گروه "مکانیک"

Piezoelectric cantilevers are mostly used for vibration energy harvesting. Changing the shape of the cantilevers could affect the generated output power and voltage. In this work, vibration energy harvesting via piezoelectric resonant unimorph cantilevers is considered. Moreover, a new design to obtain more wideband piezoelectric energy harvester is suggested. This study also provides a comprehensive analysis of the output voltage relationships and deducing an essential precise rule of thumb to calculate resonance frequency in cantilever-type unimorph piezoelectric energy harvesters using the Rayleigh-Ritz method. The analytical formula is then analyzed and verified by experiment on a fabricated prototype. The analytical data was found in an agreement with the experimental results. An important finding is that among all the unimorph tapered cantilever beams with uniform thickness, the triangular cantilever, can lead to highest resonance frequency and by increasing the ratio of the trapezoidal bases, the resonance frequency decreases. It is concluded that the shape can have a significant effect on the output voltage and therefore maximum output power density. Some triangular cantilever energy harvesters can arrange in pizza form using cantilever arrays. This arrangement decreases the occupied space and can lead to increasing the power density and also operating bandwidth.

The most promising method for micro scale energy scavenging is via vibration energy harvesting which converts mechanical energy to electrical energy. Using piezoelectric cantilevers is the most common method for vibration energy harvesting. Changing the shape of the cantilevers can lead to changing the generated output voltage and power. In this work vibration energy harvesting via piezoelectric resonant unimorph cantilevers is studied and new design for obtaining more efficient piezoelectric energy harvester is suggested. This study provides comprehensive analysis of the output voltage relationships and deducing a considerable precise rule of thumb for calculating resonance frequency in cantilever-type unimorph piezoelectric energy harvesters using Rayleigh method. The analytical formula, is then analyzed and verified by FEM simulation in ABAQUS. The analytical data was found to be very close to simulation data. A key finding is that among all the unimorph trapezoidal V-shaped cantilever beams with uniform thickness, the triangular tapered cantilever, can lead to highest resonance frequency and by increasing the ratio of the trapezoidal bases, the resonance frequency decreases. These new findings provide guidelines on system parameters that can be manipulated for more efficient performance in different ambient source conditions.

The concept of “energy harvesting” is to design smart systems to capture the ambient energy and to convert it to usable electrical power for supplying small electronics devices and sensors. The goal is to develop autonomous and self-powered devices that do not need any replacement of traditional electrochemical batteries. Now piezoelectric cantilever structures are being used to harvest vibration energy for self-powered devices. However, the geometry of a piezoelectric cantilever beam will greatly affect its vibration energy harvesting ability. This paper deduces a remarkably precise analytical formula for calculating the fundamental resonant frequency of bimorph V-shaped cantilevers using Rayleigh method. This analytical formula, which is convenient for mechanical energy harvester design based on Piezoelectric effect, is then validated by ABAQUS simulation. This formula raises a new perspective that, among all the bimorph V-shaped cantilevers and in comparison with rectangular one, the simplest tapered cantilever beam can lead to maximum resonant frequency and highest sensitivity. The derived formula can be commonly used as a relatively precise rule of thumb in such systems.

Power supply is a bottle-neck problem of wireless micro-sensors, especially where the replacement of batteries is impossible or inconvenient. Now piezoelectric material is being used to harvest vibration energy for self-powered sensors. However, the geometry of a piezoelectric cantilever beam will greatly affect its vibration energy harvesting ability. This paper deduces a remarkably precise analytical formula for calculating the fundamental resonant frequency of V-shaped cantilevers using Rayleigh-Ritz method. This analytical formula, which is very convenient for mechanical energy harvester design based on Piezoelectric effect, is then validated by ABAQUS simulation. This formula raises a new perspective that, among all the V-shaped cantilevers and in comparison with rectangular one, the simplest tapered cantilever can lead to maximum resonant frequency and highest sensitivity.

The main aim of the vibration energy harvesters is to locally power autonomous devices such as wireless sensors. Generally, power levels are low and the environmental benefit of the technology is to replace batteries rather than saving energy per se. Piezoelectric vibrational energy harvesters are usually inertial mass based devices, where a cantilever beam with a piezoelectric outer layer is excited into resonance by a mechanical vibration source at the root of the cantilever beam. However, the geometry of a piezoelectric cantilever beam will greatly affect its vibration energy harvesting ability. This paper deduces a remarkably precise analytical formula for calculating the fundamental resonant frequency of unimorph V-shaped cantilevers using Rayleigh-Ritz method. This analytical formula, which is convenient for mechanical energy harvester design based on piezoelectric effect, is then validated by ABAQUS simulation. This formula raises a new perspective that, among all the unimorph V-shaped cantilever beams and in comparison with rectangular one (the simplest tapered cantilever), can lead to the highest resonant frequency and maximum sensitivity.