Numerical and experimental analysis of the critically refracted longitudinal beam

The critically refracted longitudinal (L-CR) wave can be used in numerous non-destructive testing (NDT) applications, such as characterization of surface geometric aspects, subsurface defect detection and mostly for residual stress measurement. However, very few works characterize the associated ultrasonic beam. This paper deals with characterization of the L-CR beam profile both numerically and experimentally in order to optimize the incident angle choice in order to have sufficient energy in the experimental signal. The simulations are performed in time and frequency domains concerning solid elastic, homogenous and isotropic materials taking into account the liquid-solid interaction of the excitation by a water-coupled transducer. In the obtained results all components of the refracted acoustical field are demonstrated, as well as energy distributions of L-CR wave obtained with different incident angles. (C) 2012 Elsevier B.V. All rights reserved.