Structural health monitoring of rotary aerospace structures based on electromechanical impedance of integrated piezoelectric transducers

Abstract

Structural health monitoring of rotary aerospace structures is investigated in this research. A monitoring system is proposed based on the electromechanical impedance spectrum of piezoelectric transducers and a portable transceiver. To investigate the applicability and preliminary results of this method, a turbomachine prototype (laboratory device) is developed, and integrated composite piezoelectric films are deposited on the blades. Next, a self-diagnostic characterization is initially implemented to the piezo-films. Transceiver functionality and accuracy is verified using an Ivium impedance analyzer. The verified measuring path was used in structural health monitoring of pristine and damaged blades at rotational speed of 0 and 1000 r/min. The effects of damage formation and rotational speed on the impedance signature are discussed based on the variations in mechanical impedance using a two-dimensional model. Once damage occurs in a blade at each speed, it results in a frequency shift of the impedance signature at antiresonance peaks compared to the corresponding baseline. The results show a clear frequency shift of existing peaks and the appearance of new peaks as damage grows to a secure minimal detectable size. This achievement confirms the applicability of this method for incipient damage detection on rotary structures prior to any failure.

PZT/PZT and PZT/BiT Composite Piezo-Sensors in Aerospace SHM Applications: Photochemical Metal Organic + Infiltration Deposition and Characterization

“…Piezoelectric thin films have been used vastly as sensors, accelerometers, micro-motors, and many other low-force electromechanical (E/M) applications [1]. However, high-frequency transducers for structural health monitoring and vibration control systems usually require higher thicknesses to convey E/M stimulation loads appropriately [2,3,4,5,6,7,8,9]. Therefore, thin films cannot be applied this way.…”

Piezoelectric Transducer-Based Structural Health Monitoring for Aircraft Applications

“…The design and manufacture aspects of piezoelectric film deposition on different substrates are an interesting hotspot. For example, Hoshyarmanesh and Abbasi [123] deposited the integrated composite piezoelectric films on the blades of turbo-machine prototype. They developed a wireless data measurement system and investigated the influence of different temperatures and rotational speed on the EMI signatures.…”

PZT/PZT and PZT/BiT Composite Piezo-Sensors in Aerospace SHM Applications: Photochemical Metal Organic+Infiltration Deposition and Characterization

“…However, high-frequency transducers for structural health monitoring and vibration control systems usually require higher thickness to convey appropriately E/M stimulation loads. In such cases, there is a need for thick piezoelectric films with more than 10 microns thicknesses [2][3][4][5][6][7][8]. Therefore, thin films cannot be applicable this way.…”

“…During the second step, preparation of a homogenous suspended mixture is so important to reduce the possibility of the agglomeration [19,23]. Attention should be given to the inappropriate mixing of the powder within the piezoelectric solution and long staying of the mixture before deposition, which could possibly yield to 1) forming the surface layers, 2) strengthening the surface tension forces, 3) sedimentation of the suspended powder, and therefore, 4) agglomeration after the coating process. To avoid the agglomeration before and during the preparation process of thick films, researchers usually apply high molecular-weight solvents, such as acetic acid (60.05 g/mol), hexane (86.17 g/mol), methoxyethanol (76.09 g/mol), and α-terpined (154.25 g/mol) [1], binders including polyvinylpyrrolidone, plasticizers such as polyethylene glycol and organic diffusers such as buthoxyethoxy-ethyl acetate.…”