title: Harmonic generation of an obliquely incident ultrasonic wave in solid-solid contact interfaces.
abstract: The conventional acoustic nonlinear technique to evaluate the contact acoustic nonlinearity (CAN) at solid-solid contact interfaces (e.g., closed cracks), which uses the through-transmission of normally incident bulk waves, is limited in that access to both the inner and outer surfaces of structures for attaching pulsing and receiving transducers is difficult. The angle beam incidence and reflection technique, where both the pulsing and receiving transducers are located on the same side of the target, may allow the above problem to be overcome. However, in the angle incidence technique, mode-conversion at the contact interfaces as well as the normal and tangential interface stiffness should be taken into account. Based on the linear and nonlinear contact stiffness, we propose a theoretical model for the reflection of an ultrasonic wave angularly incident on contact interfaces. In addition, the magnitude of the CAN-induced second harmonic wave in the reflected ultrasonic wave is predicted. Experimental results obtained for the contact interfaces of A16061-T6 alloy specimens at various loading pressures showed good agreement with theoretical predictions. Such agreement proves the validity of the suggested oblique incidence model.
authors.affiliation: Department of Automotive Engineering, Hanyang Univ., Seoul, Republic of Korea.
authors.forename: Taehyung
authors.initials: T
authors.lastname: Nam
authors.forename: Taehun
authors.initials: T
authors.lastname: Lee
authors.forename: Chungseok
authors.initials: C
authors.lastname: Kim
authors.forename: Kyung-Young
authors.initials: KY
authors.lastname: Jhang
authors.forename: Nohyu
authors.initials: N
authors.lastname: Kim