Three component time reversal imaging using nonlinear elasticity.

Abstract

The time reversed elastic nonlinearity diagnostic (TREND) has been shown to have the ability to image near surface nonlinear scatterers (e.g., cracks and disbonds) using the normal (out of plane) component of motion. This technique has been advanced with the addition of three‐component vector wave field detection using laser vibrometry. This advancement provides the ability of TREND to detect and image features of various orientations, increasing its capability and decreasing the likelihood of overlooking features due to the inability to excite them. Furthermore, the ability to selectively focus each component of motion provides the means to investigate the mechanism of the nonlinear wave generation at the nonlinear scattering sites. Experimental data are presented from samples containing known defects (location and orientation) confirming the sensitivity of three‐component time reversal imaging in both linear and nonlinear ultrasonics to feature orientation.