Evaluation of Damage in Composite Laminated Sheets with Circular Defects under Tensile Loading Using Digital Image Correlation Method

Nowadays, the use of a non-contact digital imaging system for non-destructive testing on composite materials has received much attention because of its advantages. In this research, the shape, position and area of ​​the breakdown region in glass/epoxy samples with blind holes and different depths under tensile loading have been investigated using a non-contact digital imaging system. Specimens with a 10 mm diameter blind, depths of 0.5, 1 and 1.5 mm, and an average thickness of 4 mm have been subjected to the tensile loading. Lateral strain contours for all three samples have been obtained at different loads. By increasing the lateral strain loading, it focuses on an area on the surface of each specimen that corresponds to the position of the blind hole. Then the lateral strain is measured separately in length and width for each specimen. Increasing the amount of loading and the depth of the breakdown have resulted in greater strain concentration in the breakdown area as well as increasing the accuracy of the digital images correlation system. The position, shape, area, and diameter of the blind hole measured by digital image correlation method have been compared with real values, which considering the acceptable consistency of the results of the digital image correlation method with the features of each sample, It can be used as an efficient method for detecting and evaluating failures in composite structures.