Energy Harvesting from Laminated Composite Beam with a Piezoelectric Layer under Forced Vibrations

Nowadays, piezoelectric transducers are widely applied because of their capability to convert environmental energies (e.g. mechanical vibrations) into the electrical energy. In an energy harvester structure, not only piezoelectric characteristics but also properties of the non-piezoelectric part of the energy harvesting structure are highly important. Therefore, in the present research, electrical energy generation from forced vibrations of a composite beam with the piezoelectric layer is considered. For this purpose, firstly, the governing equations of the system are obtained using Euler-Bernoulli beam theory. Then, Kantorovich method was used to calculate the output voltage for a composite beam with the piezoelectric layer. To verify the analytical method, the results were compared to the finite-element modeling results. Furthermore, the effects of fiber orientation angle and layup arrangement in the composite beam with piezoelectric layer on the amount of harvested energy were investigated. According to the obtained results, by increasing the elastic modulus of the composite beam and its effect on the damping ratio of the structure, considerably higher energy is harvested. Then, the effects of composite beam dimensions, the ratio of composite beam thickness to the piezoelectric layer thickness, the concentrated mass, and the damping ratio on the amount of harvested energy were studied. The results show that using the composite materials and by proper design of layup and fiber orientation angle in each layer, it is possible to get different equivalent elastic modulus in the composite beam, and consequently alter natural frequency of the system and output voltage amplitude of the circuit