An experimental study using ultrasonic nondestructive test was conducted to evaluate damaged areas of composite laminates due to the low-velocity impact. Gating technique was used to determine damaged areas three dimensionally and provide quantitative informations about ply by ply damage size.
The delamination-simulated specimens with artificial delaminations were manufactured and gating technique was verified. Then low-velocity impact tests were performed with a weight drop type impact test machine and the damaged areas due to impact were detected by C-scan. The ply by ply delamination areas evaluated by gating technique were compared with the delaminations from deply technique and analysis. For various impact energy levels the ply by ply damage areas and two dimensional projection from both sides of specimens were investigated and compared. As impact energy increases, ply by ply delamination areas as well as projection areas increase.
It is concluded that the damaged area inspected with two dimensional projection may not be more representative of the impact damage than the sum of ply by ply damaged areas and more precise evaluation is possible when the sum of ply by ply delamination is considered. From the accurate informations on impact damage simplified damage models were constructed.
