# Vibration Energy Harvesting from Plates by Means of Piezoelectric Dynamic Vibration Absorbers
## 6 Conclusions  
In many conditions relevant to industrial and civil applications, the response of a vibrating plate is dominated by the first mode of vibration as it has the lowest natural frequency and the simplest modal shape. Direct energy harvesting from plate vibrations by means of a piezoelectric patch bonded to the plate is not very efficient since the plate is stiff an the strain is small. The CPDVA transfers the vibration energy of the plate to the small cantilever of the harvester, which has a less stiff section (made of piezoelectric and plastic materials); hence, the generation of voltage is strongly enhanced. This result is confirmed both by simulations and by experimental tests carried out with impulsive excitation and air excitation. The RMSs of the OC voltage generated by the piezoelectric patch and by the CPDVA were calculated. The RMS of the OC voltage generated by the CPDVA is about five times larger than the one generated by the patch. In the presence of broadband excitation that includes both of the peaks generated by the CPDVA, experimental and calculated results show that the optimal configuration includes a CPDVA that is exactly tuned to the first natural frequency of the plate and is mounted at the center of the plate (which is a vibration anti-node for the first mode). Simulations showed that the harvester's performance is affected by location and tuning; nevertheless, the system is rather robust, and small variations in tuning and location do not have a large effect on the peaks of the FRF and, hence, on the generated voltage. Conversely, large variations in harvester position or tuning strongly modify the peaks of the FRF, and this effect can be exploited to optimize the harvester in the presence of specific loads: wind and rain loads, loads generated by traffic and narrow-band excitation due to machine unbalance. Possible future developments include the application of CPDVA to solar panels in order to develop a hybrid solar-v  
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