According to the concept of time reversibility of the Lamb wave, in the absence of damage, a Lamb wave signal can be reconstructed at the transmitter location if a time reversed signal is sent back from the receiver location. This property is used for baseline-free damage detection, where the presence of damage breaks down the time reversibility and the mismatch between the reconstructed and the input signal is inferred as the presence of damage. This paper presents an experimental and a simulation study of baseline-free damage detection in a stiffened aluminum plate by time reversed Lamb wave (TRLW). In this study, single Lamb wave mode (A0) is generated and sensed using piezoelectric (PZT) transducers through specific transducer placement and amplitude tuning. Different stiffening configurations such as plane and T-stiffeners are considered. Damage cases of disbonding of stiffeners from the base plate, and vertical and embedded cracks in the stiffened plate, are studied. The results show that TRLW based schemes can efficiently identify the presence of damage in a stiffened plate.
Time reversibility is the process in which a response signal recorded at a receiver location is reversed in time and transmitted back through the receiver to the original transmitter location. In the absence of any defect or damage in the path between the transmitter and the receiver locations, theoretically, the signal received back at the original transmitter location (reconstructed signal) is identical to the original input signal. Therefore, differences in the transmitted and reconstructed signals are an indication of the possibility of a defect being present. An experimental study of a baselinefree damage detection technique using time reversibility of Lamb wave for a woven-fabric composite laminate is presented in this article. The initial part of the study is aimed towards obtaining the best possible reconstruction of the input signal by tuning various parameters of interest, including an experimental study of the frequency-dependent attenuation of Lamb wave modes (amplitude tuning). A finite element simulation has also been carried out to study the effect of amplitude tuning. Finally, the time-reversal concept is used to detect damage in woven composite laminates without using any information from the undamaged structure. In this study, a small block mass bonded to the surface, surface erosion and local impact are considered as representative of different types of damage. The results obtained show that the Lamb wave technique using time-reversal concept identifies correctly the presence of damage in wovenfabric composite laminates, thus providing a basis for baseline-free damage detection in composite structures.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.