Geometry complex structure inspection using stretchable eddy current array sensors

Eddy-current testing (ECT) is widely used for the inspection and evaluation of structures made from conductive materials. In recent years, significant efforts have been made to improve the reliability and sensitivity of ECT sensors, including the development of state-of-the-art flexible eddy current sensor arrays based on polyimide substrates. These probes can adapt to uneven surfaces due to their flexibility. However, there are still situations where these probes fail. In this work, we propose a stretchable EC sensor array probe with a soft substrate material, designed to deform and conform to complex surfaces. A 3D simulation model was developed to study the effect of the probe's stretchability on defect detection. A prototype of the probe was fabricated and tested on various samples. Experimental results demonstrate that the proposed probe successfully inspected pit defect with 2 mm radius and 0.5 mm depth on a bent pipe with bending radius of 6 inches, where the flexible probe had previously failed.