Experimental investigation into probability of detection for fatigue cracks in sonic IR imaging

Probability of detection (POD) for defects under given test conditions is an important statistical technique for the detection reliability assessment. In this study, we investigate a set of 45 steel specimens with fatigue cracks in different lengths. Experimental results show that the increase of the crack length will enhance the crack heating response, and the logarithmic relationship between the response signal and the crack length has a better linearity compared to others. Based on experimental data and the statistic characteristics, the linear regression analysis is introduced to estimate the POD function. The study provides a quantitative evaluation for the crack detection reliability in sonic infrared imaging.