Total focusing method imaging of multidirectional CFRP laminate with model-based time delay correction

Precise knowledge of ultrasonic travel time in carbon fiber reinforced plastics (CFRP) is difficult to obtain due to the layered anisotropic nature. This paper proposes a model-based method to calculate the travel time of qP wave in CFRP laminates. The aim is to correct the time delays of total focusing method (TFM) applied to post-process the full matrix capture data for enhanced ultrasonic imaging. Experiments show that a 4.84 mm delamination is accurately sized by corrected TFM. The associated detection sensitivity is 46.0 dB and 3.6 dB above those of paintbrush acquisition and basic TFM, respectively.