Introducing an innovative FRF-based method for identification of an adhesive joint characteristics

An energy harvesting system can be attached to the host structure using adhesive joint with viscoelastic behavior. Adhesive joints having nonlinear properties, significantly alter the dynamics of a piezoelectric energy harvesting system and, as a result, have the potential to dramatically alter the output voltage. In this paper, an innovative FRF-based method is introduced to identify adhesive joint characteristics of a piezoelectric energy harvester in cantilever beam configuration which is jointed to a base structure in root. To this end, a novel viscoelastic model is considered for the adhesive joint, which consists of two longitudinal and torsional springs and two longitudinal and torsional dashpots. Additionally, the system is analytically modeled using Euler-Bernoulli beam theory, strain rate damping and the piezoelectric constitutive relations. The adhesive joint characteristics are identified through Genetic Algorithm method employing experimental tests data and model updating. The identified nonlinear pre-strain-dependent characteristics verify both the proposed analytical model and the joint identification method. Furthermore, the effects of the adhesive joint`s thickness and pre-strain loading on its characteristics are investigated.