An Experimental Study of the Effect of Stitching on Low-Velocity-Impact (LVI) Damage and Compression-After-Impact (CAI) Strength

摘要

In this project, different laminates made with multi-axial glass fabrics as well as sewed and bound carbon-fiber laminates were examined for CAI strength. They were tested by measuring the compressive strength before and after LVI. The specimens have a lay-up sequence of [+45~(°),0~(°),-45~(°),90~(°)]4. Impact energies corresponding to 9, 12, 16, 20, 25, 30 and 40 Joules were imparted to flat panels at low-velocity. High-speed video imaging of the impact event was utilized to understand damage development, in real time. In order to differentiate the damage caused by the impactor, ultrasonic measurements were also conducted. It was found that the initial fiber misalignment caused by stitching was as significant in CAI knockdown as that caused by impact. Experimental results corresponding to these findings are presented.