Flash thermography to detect and evaluate impacts in polycarbonate parts produced by additive manufacturing

In this work, active thermography has been evaluated for detecting impacts on polycarbonate parts produced by additive manufacturing with different fillers and under various impact energies. Polycarbonate is a material with very good impact resistance, very useful in sectors where security is critical (e.g., aeronautics, vehicle engineering, ballistics, defense, etc.). The impacts were specifically generated on the back face (non-visible) of the part, using a standardized test under controlled energy conditions. Specifically, flash thermography was used, and different processing techniques was applied. The most favorable results were obtained by principal component analysis (PCA). From a qualitative perspective, the proposed method allows to detect and evaluate the impact from the back side of the part (non-impacted side) taking into account the different material fillings. From a quantitative point of view, by using parametric and non-parametric tests, it can be shown that there are statistically significant differences between the image levels in the defect zone and the non-defect zone, and it is even possible to establish a correlation between the medians of the detected levels and the impact energy.