Experimental and Numerical Study on Damage Detection in I-Type Steel Beam Based on PZT Admittance Signals

In recent decade, the electromechanical impedance (EMI) technique for structural nondestructive detection has been developed rapidly, and many researchers have carried out some experimental studies on simple structures. However, the numerical and experimental studies on relative complex structures are implemented less. In this study, firstly, a numerical EM admittance analysis of a I-type steel beam is operated by the use of the finite element method. Subsequently, the numerical results are validated by an experimental study. In this experiment, a PZT active sensor is bonded to the surface of the I-type steel beam, and the damage is detected by monitoring the variations of EM admittance measurements. Besides, a damage index, the root-mean-square deviation of real admittance (RMSDR) is defined, by which the extent of damage of the I-type beam is also evaluated. From this study it is found that the high order modes of the I-type steel beam are very dense, and the detection effect of damage extent is not ideal only depending on the EM admittance spectroscopy. By the use of the RMSDR index not only the occurrence of damage is detected clearly, but also can the damage extent of the I-type beam correctly reflect qualitatively in different frequency ranges.