Reflection analysis for Stoneley waves encountering interfacial delamination

• Published in: Composite structures 2020-12, Vol.253, p.112771, Article 112771
• Main Authors: Li, Ming-hang, Li, Bing, Zhang, Zhi-yuan, Gao, Guang-yuan
• Format: Article
• Language: English
• Subjects: Experimental validation; Interfacial delamination; Reflection coefficient; Stoneley wave; Ultrasonic guided wave
• ISSN: 0263-8223; 1879-1085
• DOI: 10.1016/j.compstruct.2020.112771

•The effect of delamination on reflection coefficient of Stoneley wave is discussed.•The variation of reflection coefficient is half-sine.•The variation of reflection coefficient can be interpreted by interference principle.•The variation of reflection coefficient is verified by experimental validation. Stoneley wave is a kind of ultrasonic guided wave propagating along a solid-solid bonded interface with two different materials. In this paper, the influence of interfacial delamination size on the reflection coefficient of Stoneley waves in a double-layered medium is investigated. According to the energy distribution of Stoneley waves, an appropriate integral region is selected, and the reflection coefficient of Stoneley waves encountering delamination is derived via reciprocity theorem. An example of delamination composed of two arcs is introduced. The effects of delamination radius, delamination width and Stoneley wave wavelength on the reflection coefficient are discussed. It is observed that the reflection coefficient decreases and gradually stabilizes as the delamination radius increases. Meanwhile, the variation of reflection coefficient with the ratio of the delamination width to the Stoneley wave wavelength is half-sine and this can be interpreted by the interference principle. Finally, some experimental validations are carried out on an aluminum-steel plate. The delamination location is tested by pulse-echo approach and the half-sine variation of the reflection coefficient with the ratio of the delamination width to the Stoneley wave wavelength is measured. The variation of reflection coefficient provides a reference for the measurement of the interfacial delamination size in nondestructive testing.