Preparation And Research On Vibration Energy Harvesting Of Macro Fiber Composite

The traditional energy supply methods can no longer meet the demand of miniaturization and low-power devices.And piezoelectric vibration energy harvesting technology provides a new method for power supply of micro power devices.As a new type of intelligent material,Macro fiber composite(MFC)has the advantages of good flexibility and electromechanical coupling performance,low cost and so on.It has a broad application prospect in the field of vibration energy collection.In this paper,MFC piezoelectric fiber composites were prepared by using the dicing-filling-pressing method with piezoelectric ceramic(PZT-5H),epoxy resin and interdigital electrode.The microstructure of the MFC cross-section was observed with a metallurgical microscope,and results exhibited that well coupling among the fibers,epoxy and interdigitated electrodes.The maximum tensile strength along the fiber direction and perpendicular to the fiber direction can reach 72 MPa and 40 MPa,respectively.In addition,MFC has obvious plane resonance peaks and thickness resonance peaks in the low frequency and high frequency regions,respectively,and with the increase of PZT volume fraction,the MFC vibration resonance peaks become more obvious.MFC Energy Harvester(MEH)were fabricated using d₃₃ and d₃₁ MFC as piezoelectric devices and beryllium bronze as substrate,respectively.The effects of vibration source,MFC structure parameters and cantilever structure on the electrical output performance were studied.The results exhibited the output voltage of the two types of MEH is decidedly dependent on the excitation frequency and acceleration have great influence.The higher the excitation acceleration is,the higher the output voltage of MEH is,and the output voltage of MEH reaches the maximum at the first resonance frequency.Increasing the thickness and volume fraction of piezoelectric fiber can effectively increase the output voltage of MEH,but it also leads to the poor flexibility of MFC.Therefore,it is necessary to select the appropriate thickness of piezoelectric fiber(0.3 mm)and volume fraction(71.5%).With the increase of electrode spacing,the output voltage of d₃₃ MEH increases gradually,but has little effect on d₃₁ type MEH.The inverted trapezoidal piezoelectric vibrator can produce larger output voltage and smaller resonance frequency,but its reliability becomes worse.A bimorph piezoelectric vibrator was fabricated,and the influence of connection mode on its electrical output performance was considered under 2 g fixed acceleration and first resonance frequency.The results exhibited that series method can increase the output voltage of MEH,but has little effect on the output current.And parallel method can increase the output current of MEH,but has little effect on the output voltage.For the d₃₃ and d₃₁ MEH types of the same size,under the same conditions,the d₃₃ type MEH can generate a larger voltage,and the d₃₁ type MEH can generate a larger current.The d₃₃ type MEH composed of MFC with 0.3 mm thickness,71.5%volume fraction,0.8 mm electrode spacing and rectangular cantilever beam can light up 88 green LED lamp beads effortlessly,and can support the normal operation of small calculator.