Observation of CFRP microscopic damages by penetrant testing

Internal delamination is often the point of origin for CFRP structural damage, and as a result, the mechanism of this internal CFRP damage was studied in detail. However, obtaining surface damage information is also essential to better understand CFRP structural damage. In this report, fluorescent penetrant testing was used as the method for observing the formation process of fatigue damage on the surface. This particular method allowed for the rapid and clear observation of microscopic damages, such as transverse cracks, splitting, and delamination. Observations showed the progression of splitting demonstrating saw-like patterns of damage on the woven CFRP surface. Penetrant testing allowed for easy observation of the entire structure, readily identifying cracks in cross sections as well as the surface.