The Ultrasonic Phased Array Fast Imaging Method for Delamination Defects in CFRP Laminates

Abstract Carbon fiber reinforced polymers (CFRP) are increasingly used in aerospace components, pressure vessels, and other structural applications due to their superior mechanical properties. However, during the complex curing process of composite manufacturing, defects such as delamination, fiber buckling, and fiber breakage can occur. If these defects are not detected in a timely manner, the composite structures may fail, posing serious risks to human safety. Ultrasonic testing is a highly reliable method for assessing the structural integrity of composites, with the total focusing method (TFM) widely regarded as the “gold standard” in nondestructive imaging due to its high resolution. However, traditional TFM methods often exhibit reduced defect detection efficiency in composites, owing to the material’s inhomogeneity and pronounced anisotropy giving rise to significant variations in velocity and attenuation of ultrasonic propagating wave. This study investigates the acoustic inhomogeneity in multidirectional composite laminates of varying thicknesses and develops a method to rapidly compute ultrasonic propagation time, accounting for the anisotropic nature of the composites. Experimental results demonstrate that the proposed approach significantly accelerates the detection of buried delamination defects in composites without compromising detection accuracy. The sensitivity to the buried delamination defect has been found to be 6 mm of its diameter.