Characterization of interfacial stiffness in film–substrate structure using Scholte waves

Abstract

This study uses Scholte waves to characterize the interfacial stiffness of a film–substrate structure. A theoretical model was formulated to investigate the dispersion relationships of Scholte waves in immersed film–substrate structures, and simulations of different interfacial states ranging from perfect to weak bonds were performed. The numerical results showed that Scholte waves are sensitive to the variation in the interfacial stiffness, providing the possibility of using the Scholte waves to characterize the bond condition in the film–substrate structure. Experimental tests were conducted on bonded samples under different bond conditions to confirm the theoretical predictions, and the results showed the differences in the dispersion characteristics for different bonding states. The quantification of the interfacial stiffness coefficient between the film and substrate was realized using the inversion method, demonstrating the potential of Scholte waves to evaluate the interfacial properties of a bonded structure.