Effect of varying axial load under fixed boundary condition on admittance signatures of electromechanical impedance technique

In recent years, researchers in the field of structural health monitoring have been rigorously striving to replace the conventional nondestructive evaluation techniques with the smart material-based structural health monitoring techniques. These techniques possess distinct advantages over the conventional techniques, such as capable of providing autonomous, real-time, reliable, and cost-efficient monitoring. For instance, the electromechanical impedance technique employing smart piezo-impedance transducer (lead zirconate titanate) is known for its sensitivity in detecting damage. The admittance signatures of the electromechanical impedance technique for structural health monitoring are susceptible to variation in the static load applied on the host structure, which should not be ignored. This article presents a series of experimental, analytical, and numerical studies conducted to investigate the effect of varying axial load in the presence of fixed boundary condition on the admittance signatures. Theoretically, the extensional vibration is not affected by any static axial load acting in the same direction. However, it is useful in identifying the effect of stiffening caused by the boundary condition upon increase in the axial force, which contributes to the discrepancy between the experiments and the analytical models. This study suggests that the effect of boundary condition is substantial, which should be carefully considered in real-life application of the electromechanical impedance technique for structural health monitoring.