Mode-Selective Excitation and Detection of Ultrasonic Guided Waves for Delamination Detection in Laminated Aluminum Plates

Department of Civil Engineering and Engineering Mechanics, University of Arizona, Tucson, AZ, USA.
IEEE transactions on ultrasonics, ferroelectrics, and frequency control (Impact Factor: 1.51). 03/2011; 58(3):567-77. DOI: 10.1109/TUFFC.2011.1839
Source: PubMed


Selective modes of guided Lamb waves are generated in a laminated aluminum plate for damage detection using a broadband piezoelectric transducer structured with a rigid electrode. Appropriate excitation frequencies and modes for inspection are selected from theoretical and experimental dispersion curves. Dispersion curves are obtained experimentally by short time Fourier transform of the transient signals. Sensitivity of antisymmetric and symmetric modes for delamination detection are investigated. The antisymmetric mode is found to be more reliable for delamination detection. Unlike other studies, in which the attenuation of the propagating waves is related to the extent of the internal damage, in this investigation, the changes in the time-of-flight (TOF) of guided Lamb waves are related to the damage progression. The mode conversion phenomenon of Lamb waves during progressive delamination is investigated. Close matching between the theoretical and experimentally derived dispersion curves and TOF assures the reliability of the results presented here.

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Available from: Tribikram Kundu, Jan 21, 2016
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    • "In this method, time of flight (TOF) of guided waves, such as Lamb waves and surface acoustic waves, are extracted from multiple surface-mounted sensors. In recent studies, real-time structural health monitoring frameworks based on guided waves' TOF have evolved by using various types of active and passive sensors [7] [8] [9]. However, the Lamb-wave-based triangulation method imposes critical limitations in anisotropic structures due to the directional dependence of their dispersion relationship and the resultant variations of wave speed as a function of wave propagation directions. "
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    • "And then, Lamb wave monitoring signals can be acquired on-line when the structure is in service. The state of the structure can be determined by using some SHM algorithms [2] [3] [4] [5] [6] [7] to measure the difference between the Lamb wave baseline signal and the Lamb wave monitoring signals. Such a process can be implemented well in laboratory for the steady structural boundary condition. "
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    • "In many cases the investigation by the means of the guided waves are performed using only fundamental A 0 and S 0 wave modes. In recent years some works have been done in the investigation of these waves broadband excitation using piezoelectric wafer active sensors (PWAS) [4]–[9], evaluating such factors as the size of the element, selective excitation and mode control schemes which are basically used in SHM applications. The objective of this research was to investigate the use of piezoceramic ultrasonic transducers for the broadband generation of Lamb waves in different thickness isotropic plates and to determine how efficiency of the generated guided waves asymmetric and symmetric modes changes due the change of the object thickness. "
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