Effects of Mechanical Surface Treatment on Bonding between Aluminum and Carbon/Epoxy Composites

Carbon fiber reinforced polymer composites, especially carbon/epoxy, have been attracting interest from offshore oil and gas industry as alternatives to metals for deepwater risers due to their very high performance besides being light weight. Composite risers, however, require an inner liner of metal to prevent leakage and damage to the outer composite layers. The bonding between the composites and the metal liner is critical for the overall integrity of the riser. In this study, two mechanical surface treatment methods, grit blasting and grooving, are used to modify aluminum liner surface. Representative composite pipe specimens consisting of these aluminum liners and carbon/epoxy composites were fabricated using filament winding process. Effects of the surface treatments on the liner-composites bonding are investigated by loading the specimens under axial compression. The liner-composite bonding, de-bonding process and the progressive failure mechanism were studied with the use of finite element simulation tools. The grooving method was found to provide a better bonding than the grit blasting process. Details of the fabrication and the testing, as well as the analysis of the results are presented in the paper.