Image processing for measuring damage and delamination in glass reinforced epoxy

This work proposed an image processing method for the measurement of damage and delamination in layered materials. Measurement of the damage and delamination area in composite materials has a significant importance as it provides an estimate of factors for implementation of fracture mechanics formulation. It is not always easy to measure delamination as it usually exists inter laminar. In this method, an image of the damaged composite material was processed by commercially available software and the delamination area was estimated within each layer. A strong back light was used for capturing images with prominent damaged areas and clear demarcation of such areas. This method proved itself simple, efficient, and cost effective. It has many advantages over simpler techniques like post experiment visual inspection. At the same time, it is cost effective for composites where standard non-destructive techniques may cost many folds more than the cost of the specimen. The results obtained for damage and delamination in cylindrical glass reinforced epoxy specimen were presented. Buckingham pi theorem was employed to develop a scale model consisting of four scales. Damage and delamination growth rate collapsed onto the same trend when scaled with the factors of n3 and n4, respectively. Accuracy and confidence in the measurement of delamination area reduced as the number of layers increased; however, overall damage area can be estimated precisely. This technique was used for in situ measurements while specimens were subjected to load, which provided damage and delamination growth rate, too.