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Propagation des ondes de Lamb dans des structures composites en présence de délaminage générés par LASER : simulation et expérimentations

Abstract : This dissertation addresses structural health monitoring (SHM) problematic, related to the use a Lamb wave-based ultrasonic technique for thin-walled structures, particularly focusing on delamination-type damage in composite structure components. The mechanical behavior of the delamination, as well as the interaction between Lamb waves and delamination are addressed.An experimental investigation is conducted employing an SHM system, which is composed of a signal generator, an amplifier, a multiplexer, specimens, a data acquisition system and a computer. The specimens are carbon fiber reinforced polymer laminate plates equipped with piezoelectric transducers (PZT). Sample set including intact and damaged with delaminations of different extent are employed for the experiments. The delaminations are generated using a Laser Shock technique, which can provide specific location and size of the delamination. PZT elements bonded to the structure surface are used as actuator and sensor of the Lamb waves in pitch-and-catch interrogations. Several damage indicators (DI) are implemented and employed to evaluate the severity of the delamination, based on time and frequency domain features. The proposed DIs are employed to evaluate the delamination severity and the nonlinear effects. Results show that the system’s sensitivity to various damage sizes induces different responses depending on DI considered.Finite element modeling of damaged structures includes a layered construction of the composite plates, split in the delamination area. The use of piezoelectric plate elements for the sensors-actuators enables a direct simulation of an SHM interrogation in terms of electric input and output signals.At the stage of delamination interface model parameters analysis, preliminary investigations are conducted on 2D models. Thus, relevant parameter ranges were examined, in terms of physical behaviour, but also in terms of DI. Finally, once those observations transposed to a 3D model, full structure model is built, leading to a comparison to the experimental observation, directly in signals and in terms of various DIs.
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Submitted on : Friday, June 3, 2022 - 4:30:31 PM
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  • HAL Id : tel-03688066, version 1

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Xixi Li. Propagation des ondes de Lamb dans des structures composites en présence de délaminage générés par LASER : simulation et expérimentations. Mécanique des matériaux [physics.class-ph]. HESAM Université, 2021. Français. ⟨NNT : 2021HESAE077⟩. ⟨tel-03688066⟩

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