Monitoring buckling of metal structures using PZT transducers

Piezoceramic (PZT) transducers are extensively used for damage detection in electromechanical impedance (EMI) based structural health monitoring (SHM) of aerospace, civil and mechanical (ACM) systems. In the EMI models, the PZT transducers are generally surface bonded to the host structure and subjected to actuation, so as to interrogate the structure for the desired frequency range. The interrogation results in the prediction of electromechanical admittance (inverse of EMI) signatures. These signatures work as indicator to estimate the health/integrity of the structure as changes in these signatures during the life of the structure may be caused by cracks or damages in the structure. Recent research shows that these signatures can be used to monitor not only the structural damages but also the load imposed on the structures. For the metallic structures, an important issue is their buckling subjected to compressive loading. This paper presents a study on monitoring of buckling of metal columns using PZT transducers. For this purpose, an experimental study is carried out to find the effect of loading patterns on metal structures. Various lab sized specimens with different boundary conditions for various load increments are tested and variations in PZT admittance signatures are recorded. Furthermore, a numerical study is carried out to support the findings obtained from the experiments. Additionally, root mean square deviation (RMSD) index is used to statistically evaluate the progressive loading on one of the specimens.