Numerical Investigation of Piezoelectric Element Coupling Degradation in Active Beam Systems

The objective of the present study is to develop modelling of the piezoelectric element edge delamination process and analysis of effects of the progressive adhesive interlayer damage on active beam dynamic behaviour. In the considered system piezoelectric patches are mounted to both opposite sides of the beam and operate as a collocated sensor/actuator pair with velocity feedback. Herein, the actuator coupling damage is described as a large reduction of the adhesive interlayer shear stiffness. It is assumed that the damaged zone of the decreased stiffness extends uniformly across the actuator from its edges to the centre. In the analysis, the beam is divided into sections due to its geometry and the supposed delaminated regions. The calculations are performed using the FE analysis. In the first step, the cantilever beam with piezoelectric elements bonded to the beam surface by a thin glue layer of uniform properties is analysed. The beam is excited by a time varying force. In order to validate the arranged FE model, the analytical and FE calculations of open and closed loop dynamic responses are performed. The compared results show quite good agreement and prove that the applied FE model of the considered system is correct and can be accepted for further numerical analysis. In the next step, FE simulations of the beam forced vibration suppressed by piezoelectric control system with velocity feedback are accomplished. The influence of the length of damaged zone on the dynamic characteristics and the control effectiveness is investigated. As expected, the size, type and location of the coupling damage influence on the dynamic characteristics of the examined beam and cause reduction of the system control efficiency.