An investigation into the effect of roughness conditions and materials on bond strength of CFRP/steel double strap joints

Different combinations of carbon fibre-reinforced polymer (CFRP) and adhesives were employed to connect two steel plates in double strap joints with various roughness levels. Three different bond lengths were also examined to decide which one was preferred for further testing. All specimens were subjected to static tensile test until failure. It was found that variations of surface roughness level between 0.73 and 7.75 μm had no significant effect on the ultimate loading capacity of the specimens. However, the CFRP type played a very important role in the bond strength and the failure modes. The best performing CFRP type was the CFRP plate. It was also found that the effective bond length was approximately 100 mm when using CFRP plates.