PSI - Issue 71

Ajay Patel et al. / Procedia Structural Integrity 71 (2025) 196–202 201 where, 1 represents the baseline signature for the undamaged mild steel coupon and 2 are the corresponding signature for different corroded stages of the mild steel coupon as the time passes. As the corrosion of a mild steel coupon intensifies, the RMSD value tends to increase. This observation is clearly illustrated in the RMSD plot in Fig. 5, which depicts a rising trend in RMSD as corrosion progresses. This increase in RMSD reflects a growing disparity in corrosion measurements, highlighting the extent of the impact of corrosion on the steel surface.

Fig. 5. RMSD plot of mild steel coupons over time

3.3 Horizontal and Vertical shift of conductance spectra

Fig. 6(a) shows a horizontal shift in the conductance spectra, indicating a frequency shift in kHz. This shift correlates with increased corrosion or damage to the mild steel coupon as time progresses while immersed in a 3.5% NaCl solution to induce corrosion. Additionally, a vertical shift (Fig. 6(b)) in the conductance spectra is observed, representing a conductance shift measured in ohm -1 or S. Unlike the frequency shift, this vertical shift does not increase uniformly. This may be indicative of the corrosion rate.

(a) (b) Fig. 6. (a)Horizontal shift; (b)Vertical shift of conductance spectra at piezo resonance frequency.

Conclusion The simulation results indicate that the electrical signals produced by the PZT patch have the potential to identify alterations in the material properties caused by corrosion. By combining experimental data with coupled field analysis, a thorough understanding of the correlation between corrosion process with gravimetric mass loss and same process with numerical FE model with attached PZT patch response. The signatures were very indicative of structural changes due to corrosion lead mass loss. The damage index i.e., RMSD variation were plot and found satisfactory to detect the mass loss changes as the corrosion severity progresses. Furthermore, also highlights the horizontal and vertical shift of conductance peaks values measured at piezo resonance frequency range. Through result, it can be seen that the change in frequency due to mass loss is very prominent through conductance signature. Detecting corrosion at an early