Journal of physics d-applied physics vol:41 issue:21 pages:1-10
Lab experiments have shown that the imaging of nonlinear scatterers using time reversal acoustics can be a very promising tool for early stage damage detection. The potential applications are however limited by the need for an extremely accurate acquisition system. In order to let nonlinear features emerge from the background noise it is necessary to enhance the signal-to-noise ratio as much as possible. A comprehensive analysis to determine the nonlinear components in a recorded time signal, an alternative to those usually adopted (e. g. fast Fourier), is proposed here. The method is based on the nonlinear physical properties of the solution of the wave equation and takes advantage of the deficient system response scalability with the excitation amplitude. In this contribution, we outline the adopted procedure and apply it to a nonlinear time reversal imaging simulation to highlight the advantages with respect to traditional imaging based on a fast Fourier analysis of the recorded signals.