Study of Lamb wave scattering from a cylindrical hole by using finite element modeling and experimental measurements

Lamb waves are certain type of ultrasonic waves that can propagate in thin plates. Lamb waves are particularly useful in testing large plate-shaped structures. Moreover¡ due to extensive flexibility in modeling sophisticated structures¡ finite element modeling (FEM) has been used in numerous Lamb wave studies. Due to the complexity of the scattering problem¡ interpretation of results is not easy. FEM helps us to better understand the complex issues that are associated with the scattering phenomenon. In this paper¡ we first consider a number of different finite-element modeling approaches that can be used for modeling Lamb waves and among them¡ we choose the best model that can provide both good accuracy and high computational speed. We then use this approach for modelling the scattering of Lamb waves from a through-thickness cylindrical hole in a large plate. This study has applications in structural health monitoring and defect sizing in plates. It is found that a 2D planar finite element model has the lowest computational cost and an accuracy of better that 95%. To verify the FEM results¡ experimental measurements are also conducted on an aluminum plate in which a through-thickness cylindrical hole is machined. The FEM results agree very well with those obtained from the experiments. It is concluded that by using this model¡ the position and properties of defects could be easily determined in plate structures.