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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.

The purpose of this paper is to compare the performance of the popular piezoelectric transducers, which may be used to harvest energy from the asphalt pavement. Part of the energies in the pavement caused by vehicle can be harvested by piezoelectric transducers. In order to get more energy from the pavement, the PZT 5H is selected to build the transducers because of its high (d·g) value. The electromechanical coupling factor k and the energy transmission coefficient max are used to evaluate the efficiency of the transducers, as well as its stiffness and durability. The multilayer, MFC (Macro-Fiber Composite), Moonie, Cymbal, Bridge, and THUNDER (Thin Layer Unimorph Ferroelectric Driver and Sensor) are discussed based on finite element analysis. Results show that the multilayer has the highest efficiency with k = 0.75 and max = 0.28. However, its high stiffness limits the ability to get more energy. THUNDER has similar efficiency (k = 0.74, max = 0.24) with multilayer and more storage electric energy. However, its stiffness is far less than pavement. Moonie is not suggested as a pavement generator for its low efficiency. MFC has the very flexible shape and acceptable efficiency (k = 0.24, max = 0.029). It is hard to use it directly in the pavement. The Bridge and Cymbal are suggested for harvesting energy from asphalt pavement for their reasonable efficiency and moderate stiffness close to asphalt pavement. The lifetimes of multilayer, Cymbal and Bridge are reasonable compared to the fatigue of pavement.

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