Rayleigh wave interaction with a spherical ball in contact with a plane surface

Rayleigh waves are widely used in NDT for characterizing surface aspects of materials such as crack localization on flat surfaces. Previous investigations have been mainly focused on canonical geometries (plane, sphere, cylinder). Within the view to investigate more complex structures such as ball bearings, this paper proposes an experimental and a numerical study of the interaction between an ultrasonic surface wave propagating on the surface of an aluminum block with a spherical solid object, meanly a steel ball, like the ones found in ball bearings. The work is focused on characterizing the nature of the waves propagating on the sphere and the ones generated by these last after their interaction with the direct wave. The experimental part is carried out using a shear transducer to generate the surface waves and a laser vibrometer as a measurement tool. The complementary numerical study is performed using a finite element method.