Nondestructive evaluation of impact area on glass fiber reinforced polymer composite by digital image correlation method: experimental study

Abstract

The use of non-destructive tests on composite materials to inspect, identify, and observe defects to locate discontinuities or defects has received considerable attention in recent years. Among the existing methods, the use of a non-contact digital image overlay system for troubleshooting composites has been considered because of its advantages. In this research, using the digital image overlay method, the shape, position, and area of the failure area in six-layer glass/epoxy samples with impact damage with different energies under different loads have been investigated. Five composite specimens with impact energies of 5, 10, 20, 30, and 40 joules were tested. At an energy of 5 joules, the damage to the piece was very small, and at an energy of 40 joules, the amount of damage to the piece was such that the bullet got stuck inside the piece and the impact site remained as a hole in the piece. The areas obtained for the impact area in the strain contours at loads of 40% have values close to the actual area of damage. By comparing the area obtained from the strain contour at 40% load and the actual damage area, for the 10 joules, 20 joules, and 30-joule conditions, the difference in area is about 2.3%, about 2.5%, and 3.1%, respectively.