Improved Global-Local method for ultrasonic guided wave scattering predictions in composite waveguides and defects

As structures increase in complexity, both in the use of advanced materials and high-performing designs such as composite assemblies, their health assessment becomes increasingly challenging. Ultrasonic guided waves (UGWs) have shown to be very promising in the inspection of large (i.e. aerospace components) attenuating (i.e. composite materials) structures and have been successfully employed for damage detection in a variety of fields. The intrinsic complex nature of UGWs, due to their dispersive behavior, combined with the structural complexity of the applications, though, requires improved inspection solutions of higher resolution and accuracy to ensure efficient and safe operations. The numerical simulation of UGW propagation becomes crucial to this end and has been addressed by many researchers with fully numerical, semi-analytical and hybrid approaches. The capability of predicting scattering of the UGWs’ interaction with a variety of damages and structural configurations can inform experimental testing in optimizing the sensitivity of UGW inspections to specific waveguides and defects and in interpreting the acquired data for the identification and quantification of structural health. In this work, an improved computational tool for UGW scattering predictions is presented. The approach relies on the Global-Local method and exploits the efficiency of the semi-analytical finite element (SAFE) method for the “regular” waveguide region and the resolution of full FE discretization for the area of local structural complexity. 2D and 3D applications of the Global-Local approach for UGW scattering predictions in composite structures over a wide range of frequencies will be presented, together with the validation of the method on different waveguides and demonstrations of the improved computational performance. The computational efficiency of the approach promises feasible and reliable UGWs predictions in multi-layered complex assemblies and different damage scenarios, and paves the way to virtual UGWs inspections and future integration in NDE testing.