Enhancing the interfacial bonding strength between 3D-printed aluminium substrates and carbon fibre–reinforced polymers

Abstract

Carbon fibre–reinforced polymers (CFRP) are increasingly utilised as materials within hybrid components in combination with plastics and metals. Although hybrid components provide a combination of advantages from the constituent materials, there are some challenges for the manufacture of high-quality hybrid components, including weak interface bonding between the constituent materials. This research focuses on utilising additive manufacturing (AM) technology to control an aluminium substrate's surface features to enhance interfacial bonding with a CFRP laminate. For this purpose, different surface structures were designed and manufactured using laser powder bed fusion (LPBF) technology to understand the influence of surface geometry and roughness on the interface. A lattice structure with a unit cell size of 3 × 3 × 1.5 mm was manufactured to create a substrate surface with porosity. A second substrate surface was designed with the same lattice structure; however, the voids were filled to present an equivalent surface topology (EST), excluding porosity. This comparison provides an understanding of the influence of the porosity of the substrate surface on interfacial bonding strength. Interfacial bonding between the aluminium substrates and a CFRP laminate was assessed using short beam strength (SBS) and flatwise tensile tests. The results from the SBS testing indicated a 3D-printed substrate with random surface roughness increased the interlaminar shear strength of the hybrid component by almost 200% compared to a hybrid laminate with non-printed substrate. The results from flatwise tensile tests illustrated that the out-of-plane bonding strength can also be improved significantly (almost 100%).