  This study formally adapts the time-domain linear sampling method (TLSM) for
ultrasonic imaging of stationary and evolving fractures in safety-critical
components. The TLSM indicator is then applied to the laboratory test data of
[22, 18] and the obtained reconstructions are compared to their
frequency-domain counterparts. The results highlight the unique capability of
the time-domain imaging functional for high-fidelity tracking of evolving
damage, and its relative robustness to sparse and reduced aperture data at
moderate noise levels. A comparative analysis of the TLSM images against the
multifrequency LSM maps of [22] further reveals that thanks to the
full-waveform inversion in time and space, the TLSM generates images of
remarkably higher quality with the same dataset.
