Application of the Reverse Time Migration Method to Ultrasonic Nondestructive Imaging for Anisotropic Materials

Abstract

In this study, we applied the reverse time migration (RTM) method to ultrasonic defect imaging in anisotropic materials. RTM offered that the defect shape could be uniquely determined by calculating a cross correlation of the incident and the reverse propagated waves from the array transducer. 2D simulations demonstrated that defect imaging by the RTM method requires an accurate numerical setup. We validated our technique using measured scattered waves from a slit in unidirectional solidified 316L stainless steel. By using the elastic constants determined from the ultrasonic wavefield data, the slit shape was correctly reconstructed. This provides a proof of principle that the RTM method is effective in nondestructive imaging of composite structures containing anisotropic materials.