Translated Abstract
Phononic crystal (PC) is an artificial periodic composite structure which can control the elastic wave propagation in the specific frequency band. By the achievement on theory research, phononic crystals are gradually moving towards to the application. In this thesis, bandgap and point defect of the PCs are used to design a new style of vibration energy harvesting system which can collect the vibration spread in board-band and on a large area. Compared with traditional harvesters, this new system can isolate the mechanical vibration much more efficiently.Two types of PCs’ dynamic characteristics were simulated. The results indicated that Bragg’s PC had much more better performance than local resonator PC in isolating vibration. Point defect in Bragg’s PC could localize the wave propagation. By placing the point defect in the 2rd period, the best localization could be reached. GA combined with PWE was used to do the optimization for a low and broad bandgap. The results showed that raising the density ratio of the scatters and base will result in broad bandgap. When the elastic constant ratio was between 102 and 104, the bandgap was low and broad. The shape of the scatter was also optimized.The manufacturing process for the optimized PC was studied. The performance of isolation and localization of the PC was experimentally studied. By comparing the products of silicon rubber mould and ceramic mould, we found samples produced by silicon rubber mould were easier in demoulding and had a higher surface accuracy. According to the shirinkage of these samples, compensation factors of silicon rubber mould were calculated as 5% in detail and 1.3% in overall. The experiment results indicated that PC can isolate the vibration between 137 and 460Hz. By getting rid of the damping effect, the vibration acceleration amplitude was decayed to 0.1%~0.01% of the input value. Point defect could bring a extremely narrow bandpass which have a peak frequency of 288Hz in bandgap. The bandpass frequency had no response to the position changing of the point defect.By removing the damping effect, point defect could amplify the vibration 1.5 times in comparation with the input value.The energy harvesting system was designed and manufactured, then its performance in isolating vibration and transforming energy were studied. Piezoelectric transducer was studied. The results showed the 1st eigfrequency of the beam was 285Hz and the most appropriate outside load resistance was 200Kohm. The embedded position of the piezoelectric transducer was found by the experiments. In the last, the experiment results indicated that when the piezoelectric transducer was placed in the 2nd period, it can output maximum power, 1.68μW, which was 4.41~68.9 times higher than that in 1st or 3rd period. It was equal to 2.1~8.3 times in voltage.
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