Study on low frequency energy harvesting system in laminated aluminum beam structures with delamination

Abstract

Piezoelectric material based energy harvesting system (EHS) has been designed and developed to study the influence of delamination on EHS in low frequency vibrating beam structures. The stiffness reduction due to the presence of delamination of specified size and its location is evaluated using the harvested energy in different vibrating elastic modes. Four aluminium beam specimens were fabricated, each having two layers of 1 mm thickness and a specified dimension of delamination was introduced by using a thin Teflon film. The beam without delamination is considered to be healthy and served as the reference structure. The PZT-5H patches were surface bonded on the beams to work as energy harvesting transducers. A suitable electronic circuit is developed to receive the energy from the vibrating beam. The experimental results in terms of energy generated by the four laminated beams have been compared with analytical results at resonant conditions and correlated to assess the effect of delamination on energy produced by low frequency vibration modes. The location of delamination has made a significant change in the harvested energy of second and third bendings; in particular, the delaminations at edge and root have displayed a clear trend. Resonant and off-resonant excitations have revealed that the edge delaminated beam produces lower energy output. The current work has demonstrated that energy harvesting from different elastic modes and with a variable frequency at constant force excitation can be a useful health monitoring technique, employing low frequency vibration, besides utilising the harvested energy itself.