Effects of surface treatments on fatigue performance of adhesively bonded single lap joint carbon fiber based polymer composites

In the period following the advent of new technologies, alternative joining techniques began to supplant traditional mechanical fasteners in applications involving carbon fiber-reinforced polymers. The majority of challenges associated with mechanical fasteners, including stress concentration, weight and the absorption of radar signals as well as corrosion, were effectively addressed by the introduction of adhesive bonding in the field of CFRPs. Nevertheless, several factors exert a significant influence on the adhesion strength, including the presence of contaminants and an excess of matrix on the surface layer. The objective of this thesis is to examine the effects of applying surface treatment on the fatigue performance of adhesively bonded carbon fibre-reinforced polymer composite plates. Carbon fibre-reinforced polymer laminates with a stacking sequence of [45/-45/45/0/-45/90]s were manufactured using unidirectional prepregs by the autoclave technique. Two different surface treatments, namely laser treatment and electrospinning, were applied to the adhesion surface of the carbon fibre-reinforced polymer laminates. Load-controlled tension-tension fatigue tests were conducted to investigate the fatigue performance of composites subjected to different surface treatments. Specimens were subjected to cyclic loading at stress levels ranging from 30% to 50% of the average maximum single lap shear load, as determined from static single lap shear tests. The effects of surface treatments on the fatigue performance of the adhesion surface were interpreted using SEM images, stiffness degradation, and Wöhler curves.