Finite element analysis of Cymbal piezoelectric transducers for harvesting energy from asphalt pavement

The purpose of this paper is to design a Cymbal for harvesting energy from asphalt pavement. Asphalt pavement is used popular on road. Part of the energies in the pavement caused by vehicle and gravity can be harvested by piezoelectric transducers. Cymbal is selected to harvest energy from asphalt pavement because of its low cost, high reliability and reasonable efficiency. The efficiency and coupling effects with pavement of Cymbals with various sizes are discussed through finite element analysis (FEA). The displacement difference at pavement surface between with and without Cymbal is developed to considering the coupling effects. The results show that the potential electric energy harvested from pavement increases with the diameter of Cymbal. However, the efficiency decreases with the increasing of Cymbal size. The diameter at 32 mm is suggested as the size of Cymbal. The potential electric energy increases near linearly with the diameter of end cap cavity base. Enough bonding area should be left to bond the end steel cap and PZT. There is a maximum electric energy existing when the top diameter of the end steel cap changes. The maximum electric energy is generated when the thickness of cap steel is about 0.3 mm. There is also a maximum electric energy existing when the height of end cap cavity changes. The Cymbals with thicker PZT can generate higher electric potential and storage electric energy. Considering the storage electric energy, cost, bonding between end steel cap and PZT and the pavement surface displacement, the Cymbal with 32 mm of total diameter, 22 mm of cavity base diameter, 10 mm of end cap top diameter, 0.3 mm of cap steel thickness, 2 mm of cavity height and 2 mm of PZT thickness is suggested as the optimum one for harvesting energy from asphalt pavement. The electric potential is about 97.33 V of the design Cymbal. 0.06 J electric energy can be storage in that Cymbal. Its potential maximum output power is about 1.2 mW at 20 Hz vehicle load frequency.