PSI - Issue 70

Anubhav Kumar Singh et al. / Procedia Structural Integrity 70 (2025) 572–579

577

3. Results and Discussions Tests were conducted on a beam attached to a PZT patch over a wide frequency range, and electrical admittance responses were obtained for healthy and damaged beam conditions. An impedance analyser was used to measure admittance, and the frequency range (200 to 400 kHz) was selected. The tested beams were simply supported for all the measurements taken. Conductance and susceptance data were processed through a MATLAB program using above admittance equation. X (Conductance) and Y (Susceptance) data were obtained, and these parameters were used to determine the mass, stiffness, and damping parameters. The electrical admittance plots are shown below, which is one of the combinations (damping and stiffness in parallel and mass in series) from Hixson ’s table.

Fig. 3. Frequency vs. Conductance and Susceptance plots Artificial damage was introduced at three locations: A (d1 to d6), B (d7 to d12), and C (d13 to d18) with depth increment of 0.5 cm at each location, and responses were recorded in terms of admittance (conductance and susceptance). The conductance signature of all the cases has been combined and is shown below where d1 to d18 denotes damage. The shifting of the peak towards left (lower frequency range) shows a decrease in stiffness of the structure as damage severity increases.

Frequency vs. Conductance graph

3.20E-03

2.70E-03

2.20E-03

1.70E-03

1.20E-03 Conductance (S)

7.00E-04

20.00 22.00 24.00 26.00 28.00 30.00 32.00 34.00 36.00 38.00 40.00

x 10000

Frequency (Hz)

Healthy

d1 d8

d2 d9

d3

d4

d5

d6

d7

d10 d17

d11 d18

d12

d13

d14

d15

d16

Fig. 4. Frequency vs. Conductance graph for all cases

These responses were later utilized to obtain the equivalent stiffness and equivalent mass data through a program designed for correlating electrical impedance to mechanical impedance (mass, stiffness, damping), and then the percentage change of equivalent stiffness and equivalent mass was calculated with respect to the healthy beam. Based on the change in these parameters, the classification of moderate and severe damage was done.