PSI - Issue 70

Arpit Singh et al. / Procedia Structural Integrity 70 (2025) 580–587

583

to the dimensions of the parent structure, leading to negligible inertial and stiffness contributions. Both sides of the patch have the same dynamic stiffness from the structure, regardless of its position on the host structure. The EMI technique allows for ongoing observation of impedance fluctuations, which can enable early structural weakness detection to guide timely maintenance measures. One of its main advantages is that the method offers real-time diagnostics to improve proactive infrastructure management. This allows continued evaluation with minimal interference of the structure under observation. The baseline data taken from the undamaged structure are compared to subsequent readings, allowing the piezoelectric sensor data to be treated with advanced algorithms to be able to identify specific damage or degradation types. Mechanical impedance changes caused by damage are measured using electromechanical admittance (EMI) tests, taking advantage of the converse piezoelectric effect of lead zirconate titanate (PZT) sensors. In certain frequency ranges, the electromechanical admittance response is given mathematically as follows (Eq. 2): Y= V̅ I̅ =G+JB=4ωj l 2 h [ε 3T̅ 3 - 2d 32 1 Y̅ E (1-v) + 2d 32 1 Y̅ E (1-v) ( Z a,eff Z a,eff +Z s,eff )( ta k n l kl )] (2) Structural stiffness property changes that alter structural parameters and impedance cause variations in admittance. Such variations can be used as measures of the structure's health. To determine the magnitude of the difference between two signatures and quantify the severity of damage, the EMI technique employs the RMSD value as a scalar indicator of damage, for which widespread use has become common. It can be calculated using the equation that follows (Eq. 3): RMSD=√ ∑ (G i -G i 0 ) 2 N i ∑ (G i 0 ) N i 2 (3) The RMSD value usually rises as damage becomes more severe, and it's also affected by changes in the amplitude of the EM admittance. Therefore, this electromechanical impedance technique seems to be a useful tool for proactive structural health monitoring. The strategy relies on the interaction of electrical signals and mechanical properties to ensure higher safety factors, lower maintenance costs, and longer lifetimes for key infrastructures. As soon as technology advances, it will undoubtedly be included in the management system for smart infrastructure. 3. Experimental Set-Up In the SHM, piezoelectric sensors have been employed to identify early indicators of deterioration or damage in various structures. In this case, the beam is a simple model made to study real-world models of applications that include, but are not restricted to, structures like monitoring buildings and bridges, like a dam. This is an outline of the typical experimental configuration for employing a PZT sensor on the specimen and an SHM beam.

Table 1: The table given below has the mix proportion data used for casting of the beam.

Characteristic compressive strength

M30

Type of cement

OPC 43 20 mm 100 mm

Maximum size of aggregate

Slump

SG of Sand SG of CA Zone of sand

2.63 2.80

Zone II

Fig. 1: Beam with sensor placement