A theoretical model, along with experimental verification, is developed to describe the generation, propagation and reception of a Rayleigh wave using angle beam wedge transducers. The Rayleigh wave generation process using an angle beam wedge transducer is analyzed, and the actual Rayleigh wave sound source distributions are evaluated numerically. Based on the reciprocity theorem and considering the actual sound source, the Rayleigh wave beams are modeled using an area integral method. The leaky Rayleigh wave theory is introduced to investigate the reception of the Rayleigh wave using the angle beam wedge transducers, and the effects of the wave spreading in the wedge and transducer size are considered in the reception process. The effects of attenuations of the Rayleigh wave and leaky Rayleigh wave are discussed, and the received wave results with different sizes of receivers are compared. The experiments are conducted using two angle beam wedge transducers to measure the Rayleigh wave, and the measurement results are compared with the predictions using different theoretical models. It is shown that the proposed model which considers the wave spreading in both the sample and wedges can be used to interpret the measurements reasonably.

https://www.mdpi.com/1424-8220/17/6/1449/pdf

Measurement of Rayleigh Wave Beams Using Angle Beam Wedge Transducers as the Transmitter and Receiver with Consideration of Beam Spreading.

Modeling nonlinear Rayleigh wave fields generated by angle beam wedge transducers—A theoretical study

In this study, the reciprocity theorem for elastodynamics is transformed into integral representations, and the fundamental solutions of wave motion equations are obtained using Green’s function method that yields the integral expressions of sound beams of both bulk and Rayleigh waves. In addition to this, a novel surface integral expression for propagating Rayleigh waves generated by angle beam wedge transducers along the surface is developed. Simulation results show that the magnitudes of Rayleigh wave displacements predicted by this model are not dependent on the frequencies and sizes of transducers. Moreover, they are more numerically stable than those obtained by the 3-D Rayleigh wave model. This model is also applicable to calculation of Rayleigh wave beams under the wedge when sound sources are assumed to radiate waves in the forward direction. Because the proposed model takes into account the actual calculated sound sources under the wedge, it can be applied to Rayleigh wave transducers with diffe...

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

The time-of-flight diffraction (TOFD) technique is one of the most common sizing methods in practical use by industry today. This method was developed over 40 years ago and is based on the technology and state of knowledge present at that time. A combination of phased arrays and equivalent flaw sizing methods are proposed as the foundation for a new generation of sizing methods that go beyond TOFD sizing.

Ultrasonic flaw sizing - an overview

Characterization of planar flaws by an integrated approach using phased array and synthetic aperture focusing technique

Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1001&context=cnde_conf

Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

A new transducer beam model is developed for the generation of Rayleigh surface wave and Lamb plate waves by an angle beam transducer, which is one of the configurations commonly used for the generation of these wave types. The beam model is a fully 3‐D model that takes into account the fields generated by the transducer acting on the surface of a wedge. The model also accounts for the leaky wave nature of the surface or plate waves under the wedge surface through an explicitly defined leaky wave attenuation coefficient.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1050&context=cnde_conf

Ultrasonic beam models for the generation of surface waves and plate waves with angle beam transducers

In modeling ultrasonic phased array inspection systems one needs to characterize the electrical and electromechanical components of the system and the radiation properties of the individual array elements since both of these properties are important in being able to model the overall response of the array to any flaws present. Models for determining each of these elements will be obtained and issues unique to phased array systems will be discussed.

Ultrasonic phased array system modeling-issues and solutions

A complete ultrasonic measurement model for surface and plate wave inspections is obtained, where all the electrical, electromechanical, and acoustic/elastic elements are explicitly described. Reciprocity principles are used to describe the acoustic/elastic elements specifically in terms of an integral of the incident and scattered wave fields over the surface of the flaw. As with the case of bulk waves, if one assumes the incident surface waves or plate waves are locally planar at the flaw surface, the overall measurement model reduces to a very modular form where the far‐field scattering amplitude of the flaw appears explicitly.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1068&context=cnde_conf

Ultrasonic measurement models for surface wave and plate wave inspections

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=5195&context=rtd

Alexander Sedov

Papers

Equivalent flaw time-of-flight diffraction sizing with ultrasonic phased arrays

Ultrasonic beam models for the generation of surface waves and plate waves with angle beam transducers

Ultrasonic phased array system modeling-issues and solutions

Ultrasonic measurement models for surface wave and plate wave inspections

Waves of small but finite amplitude: asymptotic theory