Effect of external vibrations on Electro-Mechanical impedance signatures in damage detection

Abstract

Piezoelectric Lead Zirconate Titanate (PZT) transducers have gained their application in Structural Health Monitoring (SHM). The surface bonded PZT patches are actuated by an external voltage under a specified frequency range and the Electro Mechanical Impedance (EMI) Signatures are captured which can be utilized to assess and monitor structural health. Generally, with the assumption of the structure is excited only by the PZT actuator the health of the structure is assessed and monitored. However, the changes in the EMI signatures due to external vibrations are not taken into account and interpretation will lead to wrong assessments. The current paper focuses on the study of external vibration with different excitation frequencies and amplitudes on EMI signatures of healthy and damaged beams. Finite element analysis is conducted on a cantilever aluminium flat and the conductance signatures are extracted and the influence of external vibrations on EMI signatures is analyzed and presented.