Interaction of Feature Guided Waves with Defects in Composite Structural Bends

Complex-shaped composite structures such as bends, stiffeners, and ribs are increasingly incorporated in aerospace applications because of their attractive mechanical properties and good moldability. However, damages like matrix cracking and delamination can be caused in these structures by stress concentration and out-of-plane impacts during the in-service use, consequently degrading the system integrity and reliability. Ultrasonic feature guided waves (FGW) can serve as promising candidates for their inspection as they can propagate along the feature long distances and potentially detect the possible defects. In this study, potential FGW modes have been identified in 90° carbon fiber/epoxy (CF/EP) quasi-isotropic bent plates by applying the Semi-Analytical Finite Element (SAFE) method. These modes show strong energy confinement in the bend region and have limited radiation to the adjacent plates, which are promising for the long-range inspection. The interaction of identified bend-guided waves with different types of defects is studied by the 3D Finite Element (FE) simulation. Their reflection coefficient spectra are calculated and the sensitivity to different defects is discussed. Preliminary experiments are also performed to validate the modeling results

Interaction of Feature Guided Waves with Defects in Composite Structural Bends

Complex-shaped composite structures such as bends, stiffeners, and ribs are increasingly incorporated in aerospace applications because of their attractive mechanical properties and good moldability. However, damages like matrix cracking and delamination can be caused in these structures by stress concentration and out-of-plane impacts during the in-service use, consequently degrading the system integrity and reliability. Ultrasonic feature guided waves (FGW) can serve as promising candidates for their inspection as they can propagate along the feature long distances and potentially detect the possible defects. In this study, potential FGW modes have been identified in 90° carbon fiber/epoxy (CF/EP) quasi-isotropic bent plates by applying the Semi-Analytical Finite Element (SAFE) method. These modes show strong energy confinement in the bend region and have limited radiation to the adjacent plates, which are promising for the long-range inspection. The interaction of identified bend-guided waves with different types of defects is studied by the 3D Finite Element (FE) simulation. Their reflection coefficient spectra are calculated and the sensitivity to different defects is discussed. Preliminary experiments are also performed to validate the modeling results.</p

Separation of Lamb modes at a plate edge by using orthogonality relation

International audienc

Application of orthogonality-relation for the separation of Lamb modes at a plate edge: Numerical and experimental predictions

International audienc

Comparison Between Ultrasonic and Mechanical Young’s Modulus of a Bio-composite Reinforced with Olive Wood Floor

International audienc

Scattering of the fundamental anti-symmetric Lamb wave at through-thickness notches in isotropic plates

Lamb wave based structural health monitoring technique is one of the promising techniques for detecting damage in structures. Among different types of guided waves, the fundamental anti-symmetric mode of Lamb wave (A0) has attracted considerable attention for damage detection in plates due to its outstanding properties, such as sensitivity to small and different types of defects, which make it a powerful tool for damage detection. Cracks are one of the major culprits in metallic structures which affect their durability and serviceability. Once the crack appears on the structures, it can affect its serviceability. It is important to detect cracks at early stage to avoid any catastrophic failure of the structures. This paper presents a study on the capability of using the A0 Lamb wave in detecting crack-like defects in aluminium plates, in which the scattering behaviour of the A0 Lamb wave at through-thickness notches in aluminium plates is studied in detail. 3D explicit finite element simulations are used to provide a comprehensive study on the scattering characteristics of the A0 Lamb wave at notches with different sizes and orientations. This study also considers different incident and scattered wave directions on the scattering characteristics. The results show that scattering characteristics of the A0 Lamb wave are sensitive to the size and orientation of notches. The findings of this study can improve the understanding of the capability of the A0 Lamb wave in detecting the crack-like defects and further advance damage detection techniques.Reza Soleimanpour, Ching-Tai N