Structural Damage Detection through EMI and Wave Propagation Techniques Using Embedded PZT Smart Sensing Units

Abstract

Lead Zirconate Titanate (PZT) sensors have become popular in structural health monitoring (SHM) using the electromechanical impedance (EMI) technique for damage identification. The vibrations generated during the casting process in concrete structures substantially impact the conductance signature’s (real part of admittance) magnitude and sensitivity. The concept of smart sensing units (SSU) is presented, composed of a PZT patch, an adhesive layer, and a steel plate. It is embedded in the concrete structure to study the impact of damage since it has high sensitivity to detect any structural changes, resulting in a high electrical conductance signature. The conductance signatures are obtained from the EMI technique at the damage state in the 10–500 kHz high-frequency range. The wave propagation technique proposes implementing the novel embedded SSUs to detect damage in the host structure. The numerical simulation is carried out with COMSOL multiphysics, and the received voltage signal is compared between the damaged and undamaged concrete beam with the applied actuation signal. A five-cycle sine burst modulated by a Hanning window is employed as the transient excitation signal. For numerical investigation, six cases are explored to better understand how the wave travels when a structural discontinuity is accounted for. The changes in the received signal during actuator–receiver mode in the damage state of the host structure are quantified using time of flight (TOF). Furthermore, the numerical studies are carried out by combining the EMI-WP technique, which implies synchronous activation of EMI-based measurements and wave stimulation. The fundamental idea is to implement EMI-WP to improve the effectiveness of SSU patches in detecting both near-field and far-field damage in structures. One SSU is used as an EMI admittance sensor for local damage identification. Meanwhile, the same EMI admittance sensor is used to acquire elastic waves generated by another SSU to monitor damages outside the EMI admittance sensor’s sensing area. Finally, the experimental validation is carried out to verify the proposed methodology. The results show that combining both techniques is an effective SHM method for detecting damage in concrete structures.

Piezoelectric Materials and Sensors for Structural Health Monitoring: Fundamental Aspects, Current Status, and Future Perspectives

“…This designed system is deployed in a supporting structure of a sailplane. Gayakwad et al developed smart sensing units (SSU) to improve the effectiveness of the monitoring system, which contain PZT patches to detect both near-field and far-field damage in concrete structures through EMI and wave propagation techniques [ 107 ]. The PZT patch in the SSU-1 is used as an EMI admittance sensor for local damage identification and, meanwhile, the same EMI sensor is used to acquire elastic waves generated by another PZT patch in SSU-2 to monitor damages outside the EMI admittance sensor’s sensing area, as shown in Figure 11 .…”

“… ( a ) Schematic representation of the combined EMI-WP technique for damage detection in concrete structure utilizing two SSUs; ( b ) the schematic diagram of concrete cube with embedded SSU and ( c ) an experimental specimen with embedded PZT patches and crack [ 107 ]. …”

Embedded Sensors for Structural Health Monitoring: Methodologies and Applications Review

“…The interest in the concept of self-monitoring structural components has grown in recent years due to its potential to enable the continuous monitoring of the next generation of smart structures [ 88 , 89 , 90 , 91 , 92 , 93 , 94 , 95 , 96 , 97 , 98 , 99 , 100 , 101 ]. Considering the studies developed, the applications of piezoelectric-embedded sensors for composite components are mainly based on structures or components of reinforced concrete [ 88 , 93 , 95 , 96 , 97 , 98 , 99 ].…”

Embedded Sensors for Structural Health Monitoring: Methodologies and Applications Review

“…Interest in the concept of self-monitoring structural components has grown in recent years due to its potential to enable continuous monitoring of the next generation of smart structures [91][92][93][94][95][96][97][98][99][100][101][102][103][104]. Considering the studies developed, the applications of piezoelectric embedded sensors for composite components are mainly based on structures or components of reinforced concrete [91,96,[98][99][100][101][102].…”