Damage imaging in composites using nonlinear vibro-acoustic wave modulations

Abstract

The paper deals with the application of nonlinear vibro‐acoustic modulation technique for detection and localization of impact damage in a laminated composite plate. An imaging procedure—based on the nonlinear vibro‐acoustic modulation sidebands—is proposed. The procedure relies on simultaneous low‐frequency modal and high‐frequency ultrasonic excitations. Laser scanning vibrometry is used to analyze the amplitude of modulation sidebands in vibro‐acoustic responses. This analysis is performed for different positions on monitored structure to reveal the location and shape of damage. The method is illustrated using a simple example of impact damage detection in a composite plate. The experimental damage detection results are compared with the results obtained from the previously used approach on the basis of higher harmonic generation. The proposed method demonstrates better ability to locate damage in these comparative tests without the need to increase the measurement bandwidth to the higher harmonics regime. The work shows that the local defect resonance analysis can improve damage detection results of both compared approaches.

Damage imaging in nonlinear vibro-acoustic modulation tests

“…In this case it can be seen that the location of damage can be easily identified in the center of the plate. Depending on the selected frequencies the shape of the delamination could be also evaluated using this technique 16 . What is important to note, however, is that the performed experimental tests verified that the imaging procedure could be used for each combination of LF and HF excitations where modulation sidebands are detected.…”

“…We have demonstrated that the original vibro-acoustic modulation technique can be modified to allow also for damage localization 16 . The proposed damage imaging procedure is based on the same principle that typical VAM techniquesimultaneous excitation of two mono harmonic waves (low frequency pump at frequency equal to LF and high frequency probe at frequency equal to HF) by fixed piezoceramic transducers.…”

“…This paper shows an example of the vibro-acoustic modulation technique used for damage imaging in laminated composite plate. Modification of the original VAM technique, described in detail in 16 , allows to detect and localize embedded delamination in a composite plate. Surface-bonded piezoceramic transducer are used for excitation.…”

Novel health monitoring technology for in‐service diagnostics of intake separation in aircraft engines

“…The NDT inspections are normally performed off‐line at a pre‐defined time intervals and cannot capture the problem that can be developed after exposure of aircraft engine structures to significant excitation, for example, as a consequence of intake separation occurrence. The structural health monitoring (SHM) framework can help in addressing this problem by providing continuous information about structures being monitored from embedded sensors …”

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