Detection of damages on biaxial GFRP composite material using non-destructive technique

Abstract

This exploratory research work presents a non-destructive evaluation (NDE) method based on optical metrology and ultrasonic C-scan technique. The Optical metrology technique has a 7 MW He–Ne laser, as the source, which is used to perform NDE of biaxial glass–epoxy composite material. This methodology acquires the images of the healthy and the tested samples (tensile, compression, three point and impact). Further, it is post-processed to yield their respective contours and thereby the damaged regions are identified by their pixel intensity values represented in yellow colour code. The second technique, ultrasonic C-scan used for the present study is of immersion pulse-echo method. Using this, the damaged regions are characterized by means of variations in their amplitude signals. C-scan gives more information about the cracks in the fibre and delamination in the composite by means of whitish blue colour code. Further failure analysis is also studied, using Abaqus software, and the results obtained from the analysis are compared with optical metrology and ultrasonic C-scan results. It is found that the results obtained from all three methodologies are indistinguishable from each other. Due to the high-resolution capability aspects, the optical metrology technique may be considered as an efficient tool for the detection of damaged area. Using these techniques, various damages such as interlaminar voids, porosity, resin rich areas and resin starvation, delamination, fibre fracture and matrix cracking are identified and analysed. Therefore, NDE techniques (C-scan, optical metrology) serve as an effective and reliable tool for the assessment and evaluation of extent of damages in the composite material.