An innovative method based on nonlinear Lamb waves behavior and Local Defect Resonance (LDR) is proposed for locating ad evaluating disbonds in Single-Lap Joints (SLJ) typically used in aerospace industry. The presence of damages/defects such as disbonds leads to the presence of sub-and super-harmonics components in the frequency response. Particular wave excitation frequencies promote nonlinear response of the structure causing LDR. The LDR frequency was experimentally evaluated through the appearance of a single subharmonic component in the frequency spectrum of signals received by piezoelectric transducers (PZTs) bonded on the structure. The nonlinear properties of Lamb waves were exploited to make defects generate subharmonic wave packets at LDR frequency. An algorithm was developed for damage/defect localization that was accurately performed by knowing (i) PZTs positions, (ii) Time of Flight (ToF) and (iii) propagation properties of subharmonics packet. Several disbonds with different dimensions were artificially reproduced on an aluminum SLJ: experimental results showed good accordance both in usual (single damage) and critical (multi-damage) scenario. The paper proposes a baseline-free method for the disbonds detection and localization in SLJs that uses the PZT signals without affecting adhesive interface, thus allowing an active health monitoring.
An innovative method based on nonlinear Lamb waves for locating disbonds in Single-Lap joints
Carrino S.
;Nicassio F.;Scarselli G.
2019-01-01
Abstract
An innovative method based on nonlinear Lamb waves behavior and Local Defect Resonance (LDR) is proposed for locating ad evaluating disbonds in Single-Lap Joints (SLJ) typically used in aerospace industry. The presence of damages/defects such as disbonds leads to the presence of sub-and super-harmonics components in the frequency response. Particular wave excitation frequencies promote nonlinear response of the structure causing LDR. The LDR frequency was experimentally evaluated through the appearance of a single subharmonic component in the frequency spectrum of signals received by piezoelectric transducers (PZTs) bonded on the structure. The nonlinear properties of Lamb waves were exploited to make defects generate subharmonic wave packets at LDR frequency. An algorithm was developed for damage/defect localization that was accurately performed by knowing (i) PZTs positions, (ii) Time of Flight (ToF) and (iii) propagation properties of subharmonics packet. Several disbonds with different dimensions were artificially reproduced on an aluminum SLJ: experimental results showed good accordance both in usual (single damage) and critical (multi-damage) scenario. The paper proposes a baseline-free method for the disbonds detection and localization in SLJs that uses the PZT signals without affecting adhesive interface, thus allowing an active health monitoring.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
