Fabrication of hybrid composite T-joints by co-curing with 3D printed dual cure epoxy

Abstract

A 3D printed dual cure epoxy is evaluated as a bonding material for composite T-joint structures and compared with other traditional bonding materials by mechanical testing. The epoxy is processed in two steps. First, it is 3D printed using Digital Light Synthesis (DLS), a vat photopolymerization process, resulting in semi-rigid, but only partially cured part. This part is then integrated with pre-impregnated fiber reinforced epoxy resin sheets and co-cured in a second, thermally activated, stage.The bonding strength of the 3D printed epoxy is first investigated by single lap-shear joints and is then implemented in the manufacturing of composite T-joints. The T-joints utilizing 3D printed epoxy as a bonding material show sufficient joint strength in tensile pull-out tests when compared to other common bonding methods. In addition, the 3D printed joints provide a highly reproducible, defect-free bond with improved geometric accuracy. This technology enables the ability to manufacture hybrid composite structures with decreased manufacturing costs due to fewer fixtures, shorter manufacturing times, and a reduction in defects. Furthermore, these adhesive parts can utilize the design freedom of 3D printing by including intricate internal geometries, such as lattice structures, textures, or channels.