Finite Element Analysis of Beam with Smart Materials

Abstract

Impedance-based structural health-monitoring techniques are developed by utilizing a number of smart material technologies and represent a new non-destructive evaluation (NDE) method. The basic concept of this approach is monitoring the variations in mechanical impedance of the structure resulted by the presence of damage. Since it is very difficult to measure the structural mechanical-impedance, the new impedance methods utilize the electromechanical coupling properties of piezoelectric materials. The impedance-based structural health monitoring is done by using piezoelectric patches which are bonded to the host structure that act as both sensors and actuators on the system. When a PZT comes under a change in environment, it produces an electric charge. Conversely when an electric field is applied the PZT undergoes a mechanical strain. A sinusoidal voltage is used for the excitation of the PZT patch. As the patch is surface bonded to the host structure, the structure deforms along with it and gives a local dynamic response to the vibration. That response is then transmitted back from the PZT patch as an electrical response. The electrical response is then analysed where damage is shown as a phase shift or magnitude change in the impedance. In this project finite element simulation of the interaction between a PZT patch and a structure utilizing the electromechanical impedance (EMI) technique is studied. Simulation of the host structure with a piezoelectric patch at a high frequency range (up to 1000 kHz) using ANSYS version 13, was successfully performed. Advantages over the traditional FEA based impedance model and the impedance based analytical models include higher accuracy, direct acquisition of electrical admittance/impedance. This study proves that the FEM could emerge as an excellent alternative to structural health monitoring by visual inspection method.