[PhD Colloquium] Effect of Interface Roughness in Adhesively Bonded CFRP Joints – Experimental and Numerical Studies

This thesis focuses on surface preparation and its effect on the shear strength of adhesively bonded Single Lap Joints (SLJs) in Carbon Fiber Reinforced Polymer (CFRP), their fracture properties, and the associated Non-Destructive Evaluation (NDE) parameters. The surface preparation was carried out using different grades of emery paper so that the interfaces of different roughness were available for bonding. The morphology of the interfaces before bonding was captured with the light interferometry using Micro-System Analyzer. Roughness parameters were characterized by contact-based measurements. The correlations of the contact angle between the droplet of liquid and the bonding interface with varied surface roughness and the increase in area with respect to the smoothest surface were established. CFRP, one of the most preferred composite materials in the aerospace industry, has been chosen in this study. A band of NDE techniques was utilized to evaluate the effects of surface roughness in Adhesively Bonded Joints(ABJs) of CFRP adherends. This included Ultrasonic Testing (UT), Infra-Red Thermography (IRT), Acoustic Wave Propagation (AWP), Acoustic Emission Testing (AET), X-ray Radiography Testing (XRT), and Digital Image Correlation (DIC). The primary objective of evaluating the effect of interface surface roughness on the strength of adhesively bonded composites has been addressed adequately, which has yielded very significant, interesting and effective outcome. Further research along the same line can help in developing an effective and important NDE tool for health monitoring of adhesively bonded joints.

Speaker: MANE LAXMIKANT SARJERAO