Diffraction, attenuation, and source corrections for nonlinear Rayleigh wave ultrasonic measurements

Abstract

This research considers the effects of diffraction, attenuation, and the nonlinearity of generating sources on measurements of nonlinear ultrasonic Rayleigh wave propagation. A new theoretical framework for correcting measurements made with air-coupled and contact piezoelectric receivers for the aforementioned effects is provided based on analytical models and experimental considerations. A method for extracting the nonlinearity parameter β11 is proposed based on a nonlinear least squares curve-fitting algorithm that is tailored for Rayleigh wave measurements. Quantitative experiments are conducted to confirm the predictions for the nonlinearity of the piezoelectric source and to demonstrate the effectiveness of the curve-fitting procedure. These experiments are conducted on aluminum 2024 and 7075 specimens and a β11(7075)/β11(2024) measure of 1.363 agrees well with previous literature and earlier work. The proposed work is also applied to a set of 2205 duplex stainless steel specimens that underwent various degrees of heat-treatment over 24h, and the results improve upon conclusions drawn from previous analysis.

Modeling linear Rayleigh wave sound fields generated by angle beam wedge transducers

“…28 Therefore, the full footprint may be excluded underneath the wedge, as Fig. 9(b) shows, and the generated Rayleigh wave fields in this condition is what one cares most about.…”

Extraction of depth profiles of third-order elastic constants in cracked media

“…If effects of attenuation and diffraction are taken into account [13,14,15,16,17], both complex amplitudes A 1 and A 2 would depend on X and even on a stretched lateral coordinate. We shall not consider such effects here, but focus on the interaction coefficient β R , the acoustic nonlinearity parameter (ANP) for Rayleigh waves.…”

Nonlinear Rayleigh wave sound fields generated by a wedge transducer

“…1, a contact bulk transducer radiates P-wave into a wedge, and Rayleigh waves are generated on the surface of a specimen which is considered as an isotropic elastic half-space solid when the P-wave propagates to the specimen through the interface. The origin of the coordinate ( 1 1 1 x y z ) is in the center of transducer and that of ( 2 2 2 x y z ) locates in the intersection of transducer center axis and specimen surface, and the axis 1 z and 2 z are taken normal to the transducer and the plane stress-free surface of the specimen, respectively. The generation process of Rayleigh waves is shown in the x-z coordination which can be seen in the Fig.…”

“…In recent years, nonlinear Rayleigh waves have been widely used in nondestructive ultrasonic evaluation as they are particularly sensitive to the boundary conditions on the surface and the material properties in the near-surface region [1,2]. One of the advantages of using nonlinear Rayleigh waves is that nonlinear effects can be observed easily because the energy of the Rayleigh waves is concentrated in a thin layer, and even relatively low acoustic powers can produce a sufficiently high energy density [3][4][5].…”