A Study on the Analysis of Bonding Characteristics according to Surface Roughness of Steel/CFRP Multi-Material

The bond strength according to the surface roughness of a steel/carbon-fiber-reinforced polymer (CFRP) multimaterial was evaluated and analyzed. First, we prepared a single-lap shear specimen to calculate the bonding strength and analyzed the bonding strength according to the change in the bonding thickness of the adhesive to derive the bonding thickness of 0.3 mm. Next, a bonding test was performed according to the surface roughness of steel and CFRP; the surface roughness (Ra) of the steel specimen was 1.0 similar to 2.0 and that of the CFRP specimen was 1.2 similar to 2.0. The surface roughness suitable for steel and CFRP was selected by manufacturing a bond specimen with an adhesive thickness of 0.3 mm and measuring the bond strength. Finally, we analyzed the bond strength according to the surface roughness of steel/steel, CFRP/CFRP and steel/CFRP bond specimens and derived the surface roughness suitable for steel/CFRP multimaterial.