Mechanical Performance of Hybrid Metal-Composite Joints Reinforced with Additive-Manufactured Stainless Steel Pins: A Comparative Study of Pin Geometry and Fabric Architecture

Joining metals and polymer composites presents significant challenges to guaranteeing a solid junction. Penetrative reinforcement techniques involve creating arrays of metallic pin structures that extend from the metal substrate into the composite, providing supplementary geometrical interlocking between fibers and pins compared to simple bonding. While this method has been primarily studied with metals and unidirectional laminates, its effectiveness with other composites, such as fabrics, is less explored. In this study, pinned AISI 316L substrates were additively manufactured to produce single-lap shear specimens. Two distinct prepregs — one epoxy unidirectional (UD) and one epoxy twill (TW) — were selected for embedding the pins in a single-step co-curing operation. The mechanical performances of the samples were measured, analyzed, and compared.